Neuromuscular development in Novocrania anomala: evidence for the presence of serotonin and a spiralian-like apical organ in lecithotrophic brachiopod larvae

DEFF Research Database (Denmark)

Altenburger, Andreas; Wanninger, Andreas Wilhelm Georg

2010-01-01

SUMMARY The phylogenetic position of Brachiopoda remains unsettled, and only few recent data on brachiopod organogenesis are currently available. In order to contribute data to questions concerning brachiopod ontogeny and evolution we investigated nervous and muscle system development in the cran......SUMMARY The phylogenetic position of Brachiopoda remains unsettled, and only few recent data on brachiopod organogenesis are currently available. In order to contribute data to questions concerning brachiopod ontogeny and evolution we investigated nervous and muscle system development...... stages. In the juveniles, the nervous system stained by a-tubulin is characterized by two ventral neurite bundles with three commissures. Our data are the first direct proof for the presence of an immunoreactive neurotransmitter in lecithotrophic brachiopod larvae and demonstrate the existence of flask...

Biogeography of late Silurian and devonian rugose corals

Science.gov (United States)

Oliver, W.A.

1977-01-01

Three marine benthic faunal realms can be recognized in the Early and Middle Devonian. The Eastern Americas Realm consisted of most of the eastern half of North America and South America north of the Amazon. This realm extended in a southwest direction from the Devonian equator to approximately 35??S and was an isolated epicontinental sea during much of its history. The Eastern Americas Realm was bounded on the west by the Transcontinental Arch, on the north by the Canadian Shield and on the east and southeast by a peninsular extension of the Old Red Continent. These barriers were emergent during much, but not all, of Devonian time. Seaways beyond these barriers belonged to the Old World Realm. The Malvinokaffric Realm that was farther south was apparently temperate to arctic in climate and latitudinal position and contained few corals. Rugose corals in the Eastern Americas Realm show increasing generic-level endemism from the Late Silurian through the Early Devonian; during the late Early Devonian, 92% of the rugosan genera are not known anywhere else in the world. Endemism decreased through the Middle Devonian to zero in the early Late Devonian. The Early Devonian increase in endemism paralleled, and was probably related to, the development of the Old Red Continent as a barrier between America and Africa-Europe. The waning of endemism in the Middle Devonian reflects the breaching of the land barriers. This permitted some migration in and out of the realm in early Middle Devonian time but greatest movements were in late Middle Devonian time. Principal migration directions were from western or Arctic North America into the Michigan-Hudson Bay area and from the southern Appalachian area into Africa. ?? 1977.

The Cannery Formation--Devonian to Early Permian arc-marginal deposits within the Alexander Terrane, Southeastern Alaska

Science.gov (United States)

Karl, Susan M.; Layer, Paul W.; Harris, Anita G.; Haeussler, Peter J.; Murchey, Benita L.

2011-01-01

The Cannery Formation consists of green, red, and gray ribbon chert, siliceous siltstone, graywacke-chert turbidites, and volcaniclastic sandstone. Because it contains early Permian fossils at and near its type area in Cannery Cove, on Admiralty Island in southeastern Alaska, the formation was originally defined as a Permian stratigraphic unit. Similar rocks exposed in Windfall Harbor on Admiralty Island contain early Permian bryozoans and brachiopods, as well as Mississippian through Permian radiolarians. Black and green bedded chert with subordinate lenses of limestone, basalt, and graywacke near Kake on Kupreanof Island was initially correlated with the Cannery Formation on the basis of similar lithology but was later determined to contain Late Devonian conodonts. Permian conglomerate in Keku Strait contains chert cobbles inferred to be derived from the Cannery Formation that yielded Devonian and Mississippian radiolarians. On the basis of fossils recovered from a limestone lens near Kake and chert cobbles in the Keku Strait area, the age of the Cannery Formation was revised to Devonian and Mississippian, but this revision excludes rocks in the type locality, in addition to excluding bedded chert on Kupreanof Island east of Kake that contains radiolarians of Late Pennsylvanian and early Permian age. The black chert near Kake that yielded Late Devonian conodonts is nearly contemporaneous with black chert interbedded with limestone that also contains Late Devonian conodonts in the Saginaw Bay Formation on Kuiu Island. The chert cobbles in the conglomerate in Keku Strait may be derived from either the Cannery Formation or the Saginaw Bay Formation and need not restrict the age of the Cannery Formation, regardless of their source. The minimum age of the Cannery Formation on both Admiralty Island and Kupreanof Island is constrained by the stratigraphically overlying fossiliferous Pybus Formation, of late early and early late Permian age. Because bedded radiolarian

Brachiopod associations from the Middle Ordovician of the Oslo Region, Norway

DEFF Research Database (Denmark)

Candela, Yves; Hansen, Thomas

2010-01-01

The marine upper Darriwilian (Middle Ordovician) Elnes Formation of southern Norway contains very rich and diverse invertebrate faunas. Stratigraphically detailed recent collections of these well-preserved faunas have permitted a more thorough description of the various faunal groups and their pr......The marine upper Darriwilian (Middle Ordovician) Elnes Formation of southern Norway contains very rich and diverse invertebrate faunas. Stratigraphically detailed recent collections of these well-preserved faunas have permitted a more thorough description of the various faunal groups...... by linguliformeans although some sections of the formation are dominated by the plectambonitoids Alwynella ildjernensis Spjeldnaes or Cathrynia aequistriata (Hadding) or by orthid brachiopods. Statistical analysis of the brachiopod fauna reveals that the general depositional trend of the Elnes Formation...... in muddy to marly deposits formed around maximal storm wave base and an orthid-dominated association representing an environment characterised by a fairly coarse or hard bottom substrate formed well above storm wave base but below fair weather wave base....

Stratigraphic architecture of Devonian lacustrine basins of northern Scotland

DEFF Research Database (Denmark)

Kristiansen, Thorben; Moreau, Julien; Andrews, Steven D.

of this important surface has received relatively little attention. We have utilized vintage onshore seismic to gain a better understanding of the pre-Devonian basement physiography. Onshore exposures of the top Moine, base Devonian unconformity surface is exposed have been visited to ground truth our subsurface...... interpretations. The studied deposits have been deeply buried then exhumed so that they are exposed widely onshore. Post Caledonian tectonism has faulted and folded the Devonian succession making it challenging to reconstruct the stratigraphy and the basin architecture from geological data only. The Devonian...

Brachiopod faunas after the end Ordovician mass extinction from South China: Testing ecological change through a major taxonomic crisis

Science.gov (United States)

Huang, Bing; Harper, David A. T.; Rong, Jiayu; Zhan, Renbin

2017-05-01

Classification of extinction events and their severity is generally based on taxonomic counts. The ecological impacts of such events have been categorized and prioritized but rarely tested with empirical data. The ecology of the end Ordovician extinction and subsequent biotic recovery is tracked through abundant and diverse brachiopod faunas in South China. The spatial and temporal ranges of some 6500 identified specimens, from 10 collections derived from six localities were investigated by network and cluster analyses, nonmetric multidimensional scaling and a species abundance model. Depth zonations and structure of brachiopod assemblages along an onshore-offshore gradient in the late Katian were similar to those in the latest Ordovician-earliest Silurian (post-extinction fauna). Within this ecological framework, deeper-water faunas are partly replaced by new taxa; siliciclastic substrates continued to be dominated by the more 'Ordovician' orthides and strophomenides, shallow-water carbonate environments hosted atrypides, athyridides and pentamerides, with the more typical Ordovician brachiopod fauna continuing to dominate until the late Rhuddanian. The end Ordovician extinctions tested the resilience of the brachiopod fauna without damage to its overall ecological structure; that commenced later at the end of the Rhuddanian.

Devonian climate and reef evolution: Insights from oxygen isotopes in apatite

Science.gov (United States)

Joachimski, M. M.; Breisig, S.; Buggisch, W.; Talent, J. A.; Mawson, R.; Gereke, M.; Morrow, J. R.; Day, J.; Weddige, K.

2009-07-01

Conodonts, microfossils composed of carbonate-fluor apatite, are abundant in Palaeozoic-Triassic sediments and have a high potential to preserve primary oxygen isotope signals. In order to reconstruct the palaeotemperature history of the Devonian, the oxygen isotope composition of apatite phosphate was measured on 639 conodont samples from sequences in Europe, North America and Australia. The Early Devonian (Lochkovian; 416-411 Myr) was characterized by warm tropical temperatures of around 30 °C. A cooling trend started in the Pragian (410 Myr) with intermediate temperatures around 23 to 25 °C reconstructed for the Middle Devonian (397-385 Myr). During the Frasnian (383-375 Myr), temperatures increased again with temperatures to 30 °C calculated for the Frasnian-Famennian transition (375 Myr). During the Famennian (375-359 Myr), surface water temperatures slightly decreased. Reconstructed Devonian palaeotemperatures do not support earlier views suggesting the Middle Devonian was a supergreenhouse interval, an interpretation based partly on the development of extensive tropical coral-stromatoporoid communities during the Middle Devonian. Instead, the Devonian palaeotemperature record suggests that Middle Devonian coral-stromatoporoid reefs flourished during cooler time intervals whereas microbial reefs dominated during the warm to very warm Early and Late Devonian.

Taxonomic diversity dynamics of early cretaceous brachiopods and gastropods in the Azerbaijanian domains of the Lesser Caucasus (Neo-Tethys Ocean

Directory of Open Access Journals (Sweden)

Ruban Dmitry A.

2014-01-01

Full Text Available Palaeontological data available from the Azerbaijanian domains (Somkhit-Agdam, Sevan-Karabakh, and Miskhan-Kafan tectonic zones of the Lesser Caucasus permit reconstruction of the regional taxonomic diversity dynamics of two groups of Early Cretaceous marine benthic invertebrates. Stratigraphical ranges of 31 species and 14 genera of brachiopods and 40 species and 31 genera of gastropods are considered. The total number of species and genera of brachiopods was low in the Berriasian-Valanginian and then rose to peak in the Barremian. Then, the diversity declined in the Aptian, and brachiopods are not known regionally from the Albian. Gastropods appeared in the Hauterivian and experienced a strong radiation in the Barremian. The diversity of species and genera declined in the Aptian (with a minor radiation in the Middle Aptian, and no gastropods are reported from the Albian. Globally, the number of brachiopod genera remained stable through the Early Cretaceous, and the number of gastropod genera increased stepwise with the maximum in the Albian. The regional and global patterns of the diversity dynamics differed for the both groups of marine benthic invertebrates. The Barremian maximum of the taxonomic diversity coincided with the regional flourishing of reefal ecosystems. The taxonomic diversity dynamics of brachiopods in the Azerbaijanian domains of the Lesser Caucasus is very similar to those of the Northern Caucasus, which is an evidence of proximity of these regions during the Early Cretaceous.

Prelude of benthic community collapse during the end-Permian mass extinction in siliciclastic offshore sub-basin: Brachiopod evidence from South China

Science.gov (United States)

Wu, Huiting; He, Weihong; Weldon, Elizabeth A.

2018-04-01

Analysis of the Permian-Triassic palaeocommunities from basinal facies in South China provides an insight into the environmental deterioration occurring in the prelude to the mass extinction event. Quantitative and multivariate analyses on three brachiopod palaeocommunities from the Changhsingian to the earliest Triassic in basinal facies in South China have been undertaken in this study. Although the end-Permian extinction has been proved to be a one-stepped event, ecological warning signals appeared in the palaeocommunities long before the main pulse of the event. A brachiopod palaeocommunity turnover occurred in the upper part of the Clarkina changxingensis Zone, associated with a significant decrease of palaeocommunity diversity and brachiopod body size. During this turnover the dominant genera changed from Fusichonetes and Crurithyris (or/and Paracrurithyris) to the more competitive genus Crurithyris (or/and Paracrurithyris). The brachiopod palaeocommunity turnover was supposed to be triggered by the decreased marine primary productivity and increased volcanic activity. Moreover, such early warning signals are found not only in the deep-water siliceous facies, but also in the shallow-water clastic facies and carbonate rock facies in South China.

Growth increments of the recent brachiopod Magellania venosa mechanically marked in Paso Comau and Comau Fjord, Chile, 2011/2012, supplement to: Baumgarten, Sebastian; Laudien, Jürgen; Jantzen, Carin; Häussermann, Verena; Försterra, Günter (2013): Population structure, growth and production of a recent brachiopod from the Chilean fjord region. Marine Ecology, 35(4), 401-413

KAUST Repository

Baumgarten, Sebastian

2015-01-01

Magellania venosa, the largest recent brachiopod, occurs in clusters and banks in population densities of up to 416 ind/m**2 in Comau Fjord, Northern Chilean fjord region. Below 15 m, it co-occurs with the mytilid Aulacomya atra and it dominates the benthic community below 20 m. To determine the question of why M. venosa is a successful competitor, the in situ growth rate of the brachiopod was studied and its overall growth performance compared with that of other brachiopods and mussels. The growth in length was measured between February 2011 and March 2012 after mechanical tagging and calcein staining. Settlement and juvenile growth were determined from recruitment tiles installed in 2009 and from subsequent photocensus. Growth of M. venosa is best described by the general von Bertalanffy growth function, with a maximum shell length (Linf) of 71.53 mm and a Brody growth constant (K) of 0.336/year. The overall growth performance (OGP index = 5.1) is the highest recorded for a rynchonelliform brachiopod and in the range of that for Mytilus chilensis (4.8-5.27), but lower than that of A. atra (5.74). The maximal individual production (PInd) is 0.29 g AFDM/ind/year at 42 mm shell length and annual production ranges from 1.28 to 89.25 g AFDM/year/m**2 (1-57% of that of A. atra in the respective fjords). The high shell growth rate of M. venosa, together with its high overall growth performance may explain the locally high population density of this brachiopod in Comau Fjord. However, the production per biomass of the population (P/B-ratio) is low (0.535) and M. venosa may play only a minor role in the food chain. Settling dynamics indicates that M. venosa is a pioneer species with low juvenile mortality. The coexistence of the brachiopod and bivalve suggests that brachiopod survival is affected by neither the presence of potential brachiopod predators nor that of space competitors (i.e. mytilids).

Brachiopods and rugose corals in an upper Serpukhovian (Mississippian) biostrome: preliminary results from the Djebel Arhlal (Bechar Basin, Algeria)

Energy Technology Data Exchange (ETDEWEB)

Atif, K. F. T.; Aretz, M.; Legrand-Biain, M.; Bouzidi, A.; Aimouche, M.

2016-10-01

The Djebel Arhlal is the southernmost outcrop of upper Serpukhovian strata in the Bechar Basin. Here the Djenien member of the Djenien Formation is three-folded and it contains a 10 m-thick coral biostrome in its middle unit formed by Siphonodendron, Diphyphyllum and Lithostrotion. Distances between in situ colonies are in the order of several decimetres and the space between them is filled with bioclastic limestone containing coral rubble. Few brachiopods and solitary corals are found as dwellers within the biostrome, but these groups are much more common in the strata below and above the coral biostrome. This is especially true for the brachiopods, which reach diversities of more than a dozen species in specific horizons. They mainly belong to the orders Productida, Spiriferida and Athyridida. Agitated open-marine platform interior or platform margin settings are the general facies encountered in the Djenien member at the Djebel Arhlal. The field data, including brachiopod coquinas and many fragmented brachiopods and corals, are confirmed by microfacies analysis. However, the coral biostrome records a quieter setting at the interface of middle and outer ramp settings, as seen in the co-existence of in situ coral growth, input of reworked material, deposition of carbonate mud, and sparitic textures. This autoparabiostrome at Djebel Arhlal is compared to other rather thick and of exceptional horizontal extension upper Serpukhovian biostromes (few kilometres). (Author)

Microstructural growth increments in the brachiopods Liothyrella uva and L. neozelanica: preliminary study of growth analysis and proxy calibration

Science.gov (United States)

Romanin, Marco; Aleksandra Bitner, Maria; Brand, Uwe

2017-04-01

Brachiopods secrete low-Mg calcite shells in near equilibrium with the surrounding sea water, with respect to their secondary and tertiary layers. For this reason, in recent years they have been intensively studied as archives for oceanographic and environmental proxies. The primary layer has been shown not to be deposited in equilibrium with the ambient sea water, leading to a novel cleaning protocol proposed by Zaki et al (2015). In the spite of improving on existing proxies, the shell microstructure and growth has to be taken in to account in their applications. The secretion of the primary layer is known to be external of the shell, but in SEM investigations of Liothyrella uva and L. neozelanica we discovered that the primary layer has its origin within the fibres of the secondary layer. Furthermore, the primary layer calcite is not a continuum but instead it consists of a 'new' band for each major growth increment. There is overlap between the preceding and subsequent 'band' (or shingles) of the primary layer, which may extend into the secondary/tertiary layer. This finding may lead to more comprehensive knowledge of shell microstructure processes in L. uva and L. neozelanica that may be applied and extended to other modern and fossil brachiopods, including age dating of brachiopods. This discovery may make brachiopod archives more reliable and consistent proxies when applied to and interpreting their geological record.

GRI's Devonian Shales Research Program

International Nuclear Information System (INIS)

Guidry, F.K.

1991-01-01

This paper presents a summary of the key observations and conclusions from the Gas Research Institute's (GRI's) Comprehensive Study Well (CSW) research program conducted in the Devonian Shales of the Appalachian Basin. Initiated in 1987, the CSW program was a series of highly instrumented study wells drilled in cooperation with industry partners. Seven wells were drilled as part of the program. Extensive data sets were collected and special experiments were run on the CSW's in addition to the operator's normal operations, with the objectives of identifying geologic production controls, refining formation evaluation tools, and improving reservoir description and stimulation practices in the Devonian Shales. This paper highlights the key results from the research conducted in the CSW program in the areas of geologic production controls, formation evaluation, stimulation and reservoir engineering, and field operations. The development of geologic, log analysis, and reservoir models for the Shales from the data gathered and analysis, and reservoir models for the Shales from the data gathered and analyzed during the research is discussed. In addition, on the basis of what was learned in the CSW program, GRI's plans for new research in the Devonian Shales are described

The eoorthid brachiopod Apheoorthina in the Lower Ordovician of NW Argentina and the dispersal pathways along western Gondwana

Directory of Open Access Journals (Sweden)

Diego F. Muñoz

2016-08-01

Full Text Available The eoorthid brachiopod Apheoorthina is reported for the first time from the Lower Ordovician of NW Argentina. It is represented by a species similar to A. ferrigena from the Tremadocian of the Prague Basin, increasing the faunal affinities between the Central Andean Basin and the South European microcontinents, in particular the Bohemian region (Perunica. Nine out of the fourteen brachiopod genera reported from the Tremadocian of the Central Andean Basin (~64% are shared with the Mediterranean region, four of which (~28% have been recorded in the Prague Basin, and two (Kvania and Apheoorthina are restricted to the Central Andes and Perunica. Dispersal pathways around Gondwana are analyzed in the light of major factors affecting large-scale distribution of brachiopods (environment, larval capacity for dispersal, oceanic currents. The presence in Apheoorthina aff. ferrigena of a well-preserved larval protegulum measuring 420 μm in width and 210 μm in length strongly suggests that this species had planktotrophic larvae capable of long-distance dispersal. According to recent ocean-atmosphere general circulation models for the Ordovician Period, the Central Andean margin was dominated by the cold-water Antarctica Current. Despite the complex non-zonal pattern produced by current deflections around the peri-Gondwanan microcontinents, the general westward circulation sense favoured larval dispersal from the Andean region to North Africa, Avalonia, the Armorican Terrane Assemblage, and Perunica. On the other hand, the eastwards flowing Gondwana Current connected the North Gondwana waters with the South American epicontinental seas, which could explain the reversed migration of some brachiopods.

87Sr/86Sr ratios in permo-carboniferous sea water from the analyses of well-preserved brachiopod shells

International Nuclear Information System (INIS)

Popp, B.N.; Anderson, T.F.

1986-01-01

Sr isotopic analyses of well-preserved portions of Permo-Carboniferous brachiopods distributed globally confirm the general shape of the Sr isotope age curve established by previous workers for this time interval. There is little variation between the SR isotopic composition of unaltered portions of brachiopods and that of portions of the same shell interpreted to be diagenetically altered (based on cathodoluminescence, elemental, and stable isotopic data). However, the Sr isotopic composition in diagenetically altered micritic matrix adjacent to the shell is more radiogenic. The Sr isotopic composition in the unaltered portions of calcitic megafossils has potential as a stratigraphic tool. (author)

Population structure, growth and production of a recent brachiopod from the Chilean fjord region

KAUST Repository

Baumgarten, Sebastian; Laudien, Jü rgen; Jantzen, Carin; Hä ussermann, Verena; Fö rsterra, Gü nter

2013-01-01

-57% of that of A. atra in the respective fjords). The high shell growth rate of M. venosa, together with its high overall growth performance may explain the locally high population density of this brachiopod in Comau Fjord. However, the production per biomass

Placoderms (Armored Fish): Dominant Vertebrates of the Devonian Period

Science.gov (United States)

Young, Gavin C.

2010-05-01

Placoderms, the most diverse group of Devonian fishes, were globally distributed in all habitable freshwater and marine environments, like teleost fishes in the modern fauna. Their known evolutionary history (Early Silurian-Late Devonian) spanned at least 70 million years. Known diversity (335 genera) will increase when diverse assemblages from new areas are described. Placoderms first occur in the Early Silurian of China, but their diversity remained low until their main evolutionary radiation in the Early Devonian, after which they became the dominant vertebrates of Devonian seas. Most current placoderm data are derived from the second half of the group's evolutionary history, and recent claims that they form a paraphyletic group are based on highly derived Late Devonian forms; 16 shared derived characters are proposed here to support placoderm monophyly. Interrelationships of seven placoderm orders are unresolved because Silurian forms from China are still poorly known. The relationship of placoderms to the two major extant groups of jawed fishes—osteichthyans (bony fishes) and chondrichthyans (cartilaginous sharks, rays, and chimaeras)—remains uncertain, but the detailed preservation of placoderm internal braincase structures provides insights into the ancestral gnathostome (jawed vertebrate) condition. Placoderms provide the most complex morphological and biogeographic data set for the Middle Paleozoic; marked discrepancies in stratigraphic occurrence between different continental regions indicate strongly endemic faunas that were probably constrained by marine barriers until changes in paleogeography permitted range enlargement into new areas. Placoderm distributions in time and space indicate major faunal interchange between Gondwana and Laurussia near the Frasnian-Famennian boundary; closure of the Devonian equatorial ocean is a possible explanation.

East Greenland tetrapods are Devonian in age

Science.gov (United States)

Marshall, J. E. A.; Astin, T. R.; Clack, J. A.

1999-07-01

Palynological dates unambiguously resolve the stratigraphic age of the East Greenland sedimentary rocks containing the earliest well-preserved tetrapod remains. This is the first time that spore samples have been discovered in the sedimentary succession that has yielded Acanthostega and Ichthyostega, two tetrapods that are regarded as critically important taxa for our understanding of the origin and early evolution of the tetrapods. These palynological assemblages conclusively show that the rocks are Devonian in age. The evidence resolves a 60-year-old dispute regarding the age of these rocks and contradicts a recent controversial study suggesting a much younger (Carboniferous, Viséan) age for these tetrapods. Spore samples bracketing the in situ occurrences of both tetrapod genera place them securely within the Famennian Age of the Devonian Period and at least as old as Famennian 2b. The ages of all known Devonian tetrapods are reviewed and related to a common palynological standard. This review places Ichthyostega and Acanthostega as the earliest of the Famennian tetrapods.

Decadal climate variation recorded in modern global carbonate archives (brachiopods, molluscs)

Science.gov (United States)

Romanin, Marco; Zaki, Amir H.; Davis, Alyssa; Shaver, Kristen; Wang, Lisha; Aleksandra Bitner, Maria; Capraro, Luca; Preto, Nereo; Brand, Uwe

2017-04-01

The progress of the Earth's warming trend has rapidly accelerated in the last few decades due to the increase in emission of anthropogenic greenhouse gases. The exchange of heat between the atmosphere and seawater has consequently elevated the rate of temperature buildup in the low and high latitude ocean. Records of the variation in seawater temperature in response to local and global changes in climate are preserved within the carbonate structures of marine biogenic archives. Investigating the isotopic composition of the archives' growth increments documents the magnitude of sea surface temperature (SST) change. A long-term (1956-2012) record of temperature change in sub-tropical seawater was acquired from the giant clam Tridacna maxima collected from the Red Sea in conjunction with published results of the oyster Hyotissa hyotis (Titschack et al., 2010). Variation in polar-subpolar SST was obtained from the brachiopod Magellania venosa recovered from the coastal area of southern Chile, and from the proxy record of Hemithiris psittacea of Hudson Bay (Brand et al., 2014). The former reveals a long-term (1961-2012) time-series of Antarctic-induced oceanographic change in the southern hemisphere, while the latter represents a trend of Hudson Bay seawater SST in the northern hemisphere. Evaluation of the isotopic compositions confirms the equilibrium incorporation of oxygen isotopes with respect to ambient seawater in brachiopods and some bivalves. A general trend of decreasing δ18O values in the Red Sea molluscs is observed, indicating an increase in tropical seawater temperature of about 0.79°C since 1988. The δ18O values of the polar-subpolar brachiopods display similar depletion slopes but of larger magnitudes than that of the Red Sea archives. This signifies a rise in seawater temperature of about 1.47°C in Hudson Bay since 1991, and about 2.08°C in southern Chile since 1988. The 2013 IPCC report suggests an increase in SST of +0.094°C per decade (average

Phylogenetic paleobiogeography of Late Ordovician Laurentian brachiopods

Directory of Open Access Journals (Sweden)

Jennifer E. Bauer

2014-12-01

Full Text Available Phylogenetic biogeographic analysis of four brachiopod genera was used to uncover large-scale geologic drivers of Late Ordovician biogeographic differentiation in Laurentia. Previously generated phylogenetic hypotheses were converted into area cladograms, ancestral geographic ranges were optimized and speciation events characterized as via dispersal or vicariance, when possible. Area relationships were reconstructed using Lieberman-modified Brooks Parsimony Analysis. The resulting area cladograms indicate tectonic and oceanographic changes were the primary geologic drivers of biogeographic patterns within the focal taxa. The Taconic tectophase contributed to the separation of the Appalachian and Central basins as well as the two midcontinent basins, whereas sea level rise following the Boda Event promoted interbasinal dispersal. Three migration pathways into the Cincinnati Basin were recognized, which supports the multiple pathway hypothesis for the Richmondian Invasion.

Biodiversity, biogeography and phylogeography of Ordovician rhynchonelliform brachiopods

DEFF Research Database (Denmark)

Harper, David A. T.; Mac Ørum Rasmussen, Christian; Liljeroth, Maria

2013-01-01

-levels were high. Pivotal to the entire diversification is the role of gamma (inter-provincial) diversity and by implication the spread of the continents and frequency of island arcs and microcontinents. The phylogeographical analysis demonstrates that this new palaeogeographical configuration...... with local biodiversity epicentres, notably on the South China Palaeoplate; low-latitude porambonitoid-dominated faunas with early plectambonitoid and clitambonitoid representatives, as well as high-latitude assemblages mostly dominated by orthoids, can be recognized, but many taxa are rooted in Late......The phylogeographical evolution and the consequent changing distribution and diversity of rhynchonelliform brachiopods through the Ordovician are linked to the dynamic palaeogeography of the period. The Early Ordovician (Tremadocian and Floian) is characterized by globally low-diversity faunas...

Late Ordovician palaeogeography and the positions of the Kazakh terranes through analysis of their brachiopod faunas

Science.gov (United States)

Popov, Leonid E.; Cocks, Robin M.

2017-09-01

Detailed biogeographical and biofacies analyses of the Late Ordovician brachiopod faunas with 160 genera, grouped into 94 faunas from individual lithotectonic units within the Kazakh Orogen strongly support an archipelago model for that time in that area. The Kazakh island arcs and microcontinents within several separate clusters were located in the tropics on both sides of the Equator. Key units, from which the Late Ordovician faunas are now well known, include the Boshchekul, Chingiz-Tarbagatai, and Chu-Ili terranes. The development of brachiopod biogeography within the nearly ten million year time span of the Late Ordovician from about 458 to 443 Ma (Sandbian, Katian, and Hirnantian), is supported by much new data, including our revised identifications from the Kazakh Orogen and elsewhere. The Kazakh archipelago was west of the Australasian segment of the Gondwana Supercontinent, and relatively near the Tarim, South China and North China continents, apart from the Atashu-Zhamshi Microcontinent, which probably occupied a relatively isolated position on the south-western margin of the archipelago. Distinct faunal signatures indicate that the Kazakh terranes were far away from Baltica and Siberia throughout the Ordovician. Although some earlier terranes had joined each other before the Middle Ordovician, the amalgamation of Kazakh terranes into the single continent of Kazakhstania by the end of the Ordovician is very unlikely. The Late Ordovician brachiopods from the other continents are also compared with the Kazakh faunas and global provincialisation statistically determined.

Element/Ca, C and O isotope ratios in modern brachiopods

DEFF Research Database (Denmark)

Ullmann, C. V.; Frei, Robert; Korte, Christoph

2017-01-01

Fossil brachiopods are of major importance for the reconstruction of palaeoenvironmental conditions, particularly of the Paleozoic. In order to better understand signals of ancient shell materials, modern analogue studies have to be conducted. Here we present C and O isotope data in conjunction...... with ambient seawater. Some species – especially in the suborder Terebratellidina – show partly distinct disequilibrium signals, suggesting some degree of phylogenetic control on the expression of vital effects. Mn/Ca and Fe/Ca ratios measured in the modern species form a baseline to assess fossil preservation...

18 CFR 270.303 - Natural gas produced from Devonian shale.

Science.gov (United States)

2010-04-01

... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Natural gas produced... DETERMINATION PROCEDURES Requirements for Filings With Jurisdictional Agencies § 270.303 Natural gas produced from Devonian shale. A person seeking a determination that natural gas is produced from Devonian shale...

The Devonian Marcellus Shale and Millboro Shale

Science.gov (United States)

Soeder, Daniel J.; Enomoto, Catherine B.; Chermak, John A.

2014-01-01

The recent development of unconventional oil and natural gas resources in the United States builds upon many decades of research, which included resource assessment and the development of well completion and extraction technology. The Eastern Gas Shales Project, funded by the U.S. Department of Energy in the 1980s, investigated the gas potential of organic-rich, Devonian black shales in the Appalachian, Michigan, and Illinois basins. One of these eastern shales is the Middle Devonian Marcellus Shale, which has been extensively developed for natural gas and natural gas liquids since 2007. The Marcellus is one of the basal units in a thick Devonian shale sedimentary sequence in the Appalachian basin. The Marcellus rests on the Onondaga Limestone throughout most of the basin, or on the time-equivalent Needmore Shale in the southeastern parts of the basin. Another basal unit, the Huntersville Chert, underlies the Marcellus in the southern part of the basin. The Devonian section is compressed to the south, and the Marcellus Shale, along with several overlying units, grades into the age-equivalent Millboro Shale in Virginia. The Marcellus-Millboro interval is far from a uniform slab of black rock. This field trip will examine a number of natural and engineered exposures in the vicinity of the West Virginia–Virginia state line, where participants will have the opportunity to view a variety of sedimentary facies within the shale itself, sedimentary structures, tectonic structures, fossils, overlying and underlying formations, volcaniclastic ash beds, and to view a basaltic intrusion.

Invasive species and biodiversity crises: testing the link in the late devonian.

Directory of Open Access Journals (Sweden)

Alycia L Stigall

Full Text Available During the Late Devonian Biodiversity Crisis, the primary driver of biodiversity decline was the dramatic reduction in speciation rates, not elevated extinction rates; however, the causes of speciation decline have been previously unstudied. Speciation, the formation of new species from ancestral populations, occurs by two primary allopatric mechanisms: vicariance, where the ancestral population is passively divided into two large subpopulations that later diverge and form two daughter species, and dispersal, in which a small subset of the ancestral population actively migrates then diverges to form a new species. Studies of modern and fossil clades typically document speciation by vicariance in much higher frequencies than speciation by dispersal. To assess the mechanism behind Late Devonian speciation reduction, speciation rates were calculated within stratigraphically constrained species-level phylogenetic hypotheses for three representative clades and mode of speciation at cladogenetic events was assessed across four clades in three phyla: Arthropoda, Brachiopoda, and Mollusca. In all cases, Devonian taxa exhibited a congruent reduction in speciation rate between the Middle Devonian pre-crisis interval and the Late Devonian crisis interval. Furthermore, speciation via vicariance is almost entirely absent during the crisis interval; most episodes of speciation during this time were due to dispersal. The shutdown of speciation by vicariance during this interval was related to widespread interbasinal species invasions. The lack of Late Devonian vicariance is diametrically opposed to the pattern observed in other geologic intervals, which suggests the loss of vicariant speciation attributable to species invasions during the Late Devonian was a causal factor in the biodiversity crisis. Similarly, modern ecosystems, in which invasive species are rampant, may be expected to exhibit similar shutdown of speciation by vicariance as an outcome of the

Invasive species and biodiversity crises: testing the link in the late devonian.

Science.gov (United States)

Stigall, Alycia L

2010-12-29

During the Late Devonian Biodiversity Crisis, the primary driver of biodiversity decline was the dramatic reduction in speciation rates, not elevated extinction rates; however, the causes of speciation decline have been previously unstudied. Speciation, the formation of new species from ancestral populations, occurs by two primary allopatric mechanisms: vicariance, where the ancestral population is passively divided into two large subpopulations that later diverge and form two daughter species, and dispersal, in which a small subset of the ancestral population actively migrates then diverges to form a new species. Studies of modern and fossil clades typically document speciation by vicariance in much higher frequencies than speciation by dispersal. To assess the mechanism behind Late Devonian speciation reduction, speciation rates were calculated within stratigraphically constrained species-level phylogenetic hypotheses for three representative clades and mode of speciation at cladogenetic events was assessed across four clades in three phyla: Arthropoda, Brachiopoda, and Mollusca. In all cases, Devonian taxa exhibited a congruent reduction in speciation rate between the Middle Devonian pre-crisis interval and the Late Devonian crisis interval. Furthermore, speciation via vicariance is almost entirely absent during the crisis interval; most episodes of speciation during this time were due to dispersal. The shutdown of speciation by vicariance during this interval was related to widespread interbasinal species invasions. The lack of Late Devonian vicariance is diametrically opposed to the pattern observed in other geologic intervals, which suggests the loss of vicariant speciation attributable to species invasions during the Late Devonian was a causal factor in the biodiversity crisis. Similarly, modern ecosystems, in which invasive species are rampant, may be expected to exhibit similar shutdown of speciation by vicariance as an outcome of the modern biodiversity

Revisions to the original extent of the Devonian Shale-Middle and Upper Paleozoic Total Petroleum System

Science.gov (United States)

Enomoto, Catherine B.; Rouse, William A.; Trippi, Michael H.; Higley, Debra K.

2016-04-11

Technically recoverable undiscovered hydrocarbon resources in continuous accumulations are present in Upper Devonian and Lower Mississippian strata in the Appalachian Basin Petroleum Province. The province includes parts of New York, Pennsylvania, Ohio, Maryland, West Virginia, Virginia, Kentucky, Tennessee, Georgia, and Alabama. The Upper Devonian and Lower Mississippian strata are part of the previously defined Devonian Shale-Middle and Upper Paleozoic Total Petroleum System (TPS) that extends from New York to Tennessee. This publication presents a revision to the extent of the Devonian Shale-Middle and Upper Paleozoic TPS. The most significant modification to the maximum extent of the Devonian Shale-Middle and Upper Paleozoic TPS is to the south and southwest, adding areas in Tennessee, Georgia, Alabama, and Mississippi where Devonian strata, including potential petroleum source rocks, are present in the subsurface up to the outcrop. The Middle to Upper Devonian Chattanooga Shale extends from southeastern Kentucky to Alabama and eastern Mississippi. Production from Devonian shale has been established in the Appalachian fold and thrust belt of northeastern Alabama. Exploratory drilling has encountered Middle to Upper Devonian strata containing organic-rich shale in west-central Alabama. The areas added to the TPS are located in the Valley and Ridge, Interior Low Plateaus, and Appalachian Plateaus physiographic provinces, including the portion of the Appalachian fold and thrust belt buried beneath Cretaceous and younger sediments that were deposited on the U.S. Gulf Coastal Plain.

Biostratigraphic analysis of core samples from wells drilled in the Devonian shale interval of the Appalachian and Illinois Basins

Energy Technology Data Exchange (ETDEWEB)

Martin, S.J.; Zielinski, R.E.

1978-07-14

A palynological investigation was performed on 55 samples of core material from four wells drilled in the Devonian Shale interval of the Appalachian and Illinois Basins. Using a combination of spores and acritarchs, it was possible to divide the Middle Devonian from the Upper Devonian and to make subdivisions within the Middle and Upper Devonian. The age of the palynomorphs encountered in this study is Upper Devonian.

Mollusc and brachiopod skeletal hardparts: Problematic archives of past seawater properties (Invited)

Science.gov (United States)

Immenhauser, A.; Schone, B. R.; Hoffmann, R.; Niedermayr, A.

2013-12-01

Biomineralized exo- or endoskeletons of fossil marine invertebrates are widespread and diverse components of the Phanerozoic rock record of Earth's past and present oceans. Exoskeletons serve as protection against environmental pressure or predators, whilst endoskeletons may act as support or serves as an attachment for muscles and ligaments and hence as a mechanism for transmitting muscular forces. Biogenic hardparts represent sophisticated products resulting from the hierarchical interaction of inorganic minerals (95%) and macromolecular organic matrix, forming commonly less than 5%. The significance of biogenic carbonate archives lies in the time-resolved growth-increments and their respective multi-proxy geochemical signatures that have been widely used to assess past oceanic seawater properties. We here compile and review published work dealing with crystallization pathways of skeletal hardparts secreted by molluscs (i.e., bivalves and cephalopods) as well as brachiopods as widely used archives of ancient neritic epeiric settings. Bivalves and cephalopods (e.g., extinct ammonoids and belemnites and extant Sepia, Nautilus and Spirula) all form accretionary calcitic, aragonitic or vateritic skeletal hardparts. Despite the fact that molluscs and brachiopods form part of very different branches of the animal phylogenetic tree, their biomineralization strategies are surprisingly similar. Our main focus lies in a critical assessment of the complex pathways of ions and aquo-complexes from their source (seawater) to the final product (biomineral). We do this as an attempt to critically test the commonly held hypothesis that many fossil shell hardparts precipitated, under favourable conditions and pending subsequent diagenetic alteration, in equilibrium with seawater. Two main observations stand out: (1) the present knowledge on pathways and mechanisms (e.g., ion channel trans-membrane or endocytosis and vesicle transport, precursor mineralogies etc.) is surprisingly

Hydrogeologic characterization of devonian aquifers in Uruguay

International Nuclear Information System (INIS)

Massa, E.

1988-01-01

This article carried out the assistance research project implementation in devonian sedimentary units as a potentials aquifers and their best use to school supplying and rural population in central area of Uruguay.

Inferring seawater temperature over the past 2,500 years in the Southern California Bight on the basis of brachiopods

Science.gov (United States)

Tomašových, Adam; Müller, Tamás; Kidwell, Susan M.

2017-04-01

Use of calcite δ18O in brachiopod shells in assessing past variations in seawater temperature remains poorly constrained in the absence of other methods due to vital effects and unknown variations in seawater density, salinity. Here, in order to evaluate past changes in seawater temperature of mainland shelf habitats off the Southern California Bight over the past 2,500 years, we analyze δ18O and Mg/Ca ratio of dead shells of the terebratulid brachiopod Laqueus erythraeus collected at 60-80 m water depths and age-dated by radiocarbon-calibrated amino acid racemization. These dead Holocene shells show excellent preservation (Mn concentrations < 10 ppm and Sr concentrations above 800 ppm). Although historical changes in sea-surface temperature in the southern California Bight were inferred on the basis of alkenones and δ18O in of planktonic foraminifers, temperature history of deeper shelf below storm wave base in this region remains unclear. First, we investigate thermal sensitivity of Mg/Ca ratio (using Laser Ablation Inductively Coupled Plasma Mass Spectrometry and wavelength-dispersive spectrometry) in the terebratulid brachiopod Laqueus erythraeus (collected in 1994 at Santa Catalina Island at 116 m water depth). At this depth, annual temperature range is relatively small (between 9-11°C), although at times of El Nino events in 1982-1983, 1986-1987, and 1992-1993, monthly temperature attained 13 °C. We find that δ18O measured along a growth profile of a shell precipitated in oxygen isotopic equilibrium with ambient seawater, and maxima in Mg/Ca ratio coincide with minima in δ18O, suggesting that fluctuations in Mg/Ca ratio trace temperature fluctuations, as observed also in other brachiopod species. Second, preliminary observations of Holocene shells show that Mg/Ca ratios show centennial-scale fluctuations but on average remain remarkably constant, with minima and maxima staying within intra-shell seasonal variations captured by extant specimens

Subsurface geology of the upper Devonian-lower Mississippian black-shale sequence in eastern Kentucky

International Nuclear Information System (INIS)

Dillman, S.B.

1980-01-01

The Upper Devonian-Lower Mississippi black-shale sequence is an important source of natural gas in eastern Kentucky and with technological advances may be an important source of synthetic oil and uranium on the flanks of the Cincinnati arch. To enhance the understanding and development of these resources in the black-shale sequence, eight isopach maps, eight structure-contour maps and nine isopach maps of highly radioactive black shale were constructed. Structural features including the Rome trough, Rockcastle River uplift, Pine Mountain thrust fault, Kentucky River and Paint Creek fault zones and unnamed basinal areas in Greenup, Pike, and Knott counties were identified on the maps. Faults bounding the Rome trough and other structures were active intermittently throughout Late Devonian time. Other structures show only post-Devonian activity, whereas some show both Devonian and post-Devonian activity. Comparison of structure-contour and isopach maps allow the differentiation of syn- and post-sedimentray structural activity relative to the black-shale sequence. A north-south trending hinge line separates a broad platform area from an area of rapid eastward thickening into the Appalachian basin. Units 7 through 1 progressively onlap the Cincinnati arch; units 4 through 1 cover the arch

Resolving early Mid-Ordovician (Kundan) bioevents in the East Baltic based on brachiopods

DEFF Research Database (Denmark)

Rasmussen, Christian Mac Ørum; Harper, David Alexander Taylor

2008-01-01

Bed-by-bed sampling of brachiopods from selected Kundan Stage localities in the East Baltic has permitted the construction of a-diversity curves, unprecedented in detail from this particular stage and region. These a-diversity curves can be correlated between the investigated sections, along...... an east to west transect of some 200 km and indicate bioevents associated with intervals of increased palaeo-water depth. The highest peaks in a-diversity occur when biofacies analysis and sedimentological evidence indicate drowning events. The events involve mainly taxa endemic to the Baltic province...

A bradoriid and brachiopod dominated shelly fauna from the furongian (Cambrian) of Västergötland, Sweden

DEFF Research Database (Denmark)

Topper, Timothy Paul; Skovsted, Christian B.; Harper, David Alexander Taylor

2013-01-01

A small assemblage of shelly fossils, dominated by the brachiopod Treptotreta jucunda and the bradoriid arthropod Mongolitubulus aspermachaera new species is described from a Furongian limestone of Västergötland, south-central Sweden. Mongolitubulus aspermachaera is represented in the assemblage ...... include typical Baltic Furongian representatives, such as the trilobite Parabolina, the agnostoid Agnostus and the phosphatocopids Hesslandona and Vestrogothia....

The axial skeleton of the Devonian tetrapod Ichthyostega.

Science.gov (United States)

Ahlberg, Per Erik; Clack, Jennifer A; Blom, Henning

2005-09-01

Ichthyostega was the first Devonian tetrapod to be subject to a whole-body reconstruction. It remains, together with Acanthostega, one of only two Devonian tetrapods for which near-complete postcranial material is available. It is thus crucially important for our understanding of the earliest stages of tetrapod evolution and terrestrialization. Here we show a new reconstruction of Ichthyostega based on extensive re-examination of original material and augmented by recently collected specimens. Our reconstruction differs substantially from those previously published and reveals hitherto unrecognized regionalization in the vertebral column. Ichthyostega is the earliest vertebrate to show obvious adaptations for non-swimming locomotion. Uniquely among early tetrapods, the presacral vertebral column shows pronounced regionalization of neural arch morphology, suggesting that it was adapted for dorsoventral rather than lateral flexion.

Sedimentology and facies analysis of Devonian Rocks, southern district of Mackenzie, North West Territories, Canada

NARCIS (Netherlands)

Meijer Drees, N.C.

1989-01-01

The Devonian rock succession in the southern part of the District of Mackenzie consists of interbedded evaporites and carbonates, fossiliferous carbonates and shales. Inthe study areathe Devonian succession unconformably overlies LowerPaleozoic orPrecambrian strata and thins in a northeastward

Devonian alkaline magmatic belt along the northern margin of the North China Block: Petrogenesis and tectonic implications

Science.gov (United States)

Zhang, Qi-Qi; Zhang, Shuan-Hong; Zhao, Yue; Liu, Jian-Min

2018-03-01

Some Devonian magmatic rocks have been identified from the northern margin of the North China Block (NCB) in recent years. However, their petrogenesis and tectonic setting are still highly controversial. Here we present new geochronological, Sr-Nd-Hf isotopic and whole-rock chemical data on several newly identified and previously reported Devonian alkaline complexes, including mafic-ultramafic rocks (pyroxenites and gabbros), alkaline rocks (syenites, monzonites) and alkaline granites in the northern NCB. We firstly identified some mafic-ultramafic rocks coeval with monzonite and quartz monzonite in the Sandaogou and Wulanhada alkaline intrusions. New zircon U-Pb dating of 16 samples from the Baicaigou, Gaojiacun, Sandaogou, Wulanhada and Chifeng alkaline intrusions combined with previous geochronological results indicate that the Devonian alkaline rocks emplaced during the early-middle Devonian at around 400-380 Ma and constitute an E-W-trending alkaline magmatic belt that extend ca. 900 km long along the northern margin of the NCB. Whole-rock geochemical and Sr-Nd-Hf isotopic data reveal that the Devonian alkaline rocks were mainly originated from partial melting of a variably enriched lithospheric mantle with different involvement of ancient lower crustal component and fractional crystallization. The Devonian alkaline magmatic belt rocks in the northern NCB are characterized by very weak or no deformations and were most likely related to post-collision extension after arc-continent collision between the Bainaimiao island arc and the northern margin of North China Craton during the latest Silurian. Partial melting of subcontinental lithospheric mantle to produce the Devonian alkaline magmatic rocks suggests that the northern North China Craton has an inhomogeneous, variably enriched subcontinental lithospheric mantle and was characterized by significant vertical crustal growth during the Devonian period.

A lower Devonian point in the geological timescale

International Nuclear Information System (INIS)

Richards, J.R.; Barkas, J.P.; Vallance, T.G.

1977-01-01

The Gocup Granite, in southeastern New South Ales, intrudes low-grade metasediments tentatively assigned to the Ludlovian on fragmentary conodont evidence, and is overlain by a unit rich in volcanic material but containing a good brachiopod fauna of lower to middle Siegenian age. The K-Ar age of four muscovite samples is 409 +- 3 m.y.; a Rb-Sr whole-rock isochron on five samples yields a Model age 402 +- 3 m.y., initial 87 Sr/ 86 Sr 0.7090 +- 0.003. Preliminary data by X-ray fluorescence and unspiked strontium mass spectrometry illustrate the effects of some sources of experimental error. (auth.)

Seawater strontium isotope curve at the Silurian/Devonian boundary: a study of the global Silurian/Devonian boundary stratotype

Czech Academy of Sciences Publication Activity Database

Frýda, J.; Hladil, Jindřich; Vokurka, K.

2002-01-01

Roč. 35, č. 1 (2002), s. 21-28 ISSN 0016-6995 R&D Projects: GA ČR GA205/98/0454; GA ČR GA205/01/0143 Institutional research plan: CEZ:AV0Z3013912 Keywords : strontium chemostratigraphy * Silurian/Devonian * Barrandian area Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.410, year: 2002

Intergrated study of the Devonian-age black shales in eastern Ohio. Final report

Energy Technology Data Exchange (ETDEWEB)

Gray, J.D.; Struble, R.A.; Carlton, R.W.; Hodges, D.A.; Honeycutt, F.M.; Kingsbury, R.H.; Knapp, N.F.; Majchszak, F.L.; Stith, D.A.

1982-09-01

This integrated study of the Devonian-age shales in eastern Ohio by the Ohio Department of Natural Resources, Division of Geological Survey is part of the Eastern Gas Shales Project sponsored by the US Department of Energy. The six areas of research included in the study are: (1) detailed stratigraphic mapping, (2) detailed structure mapping, (3) mineralogic and petrographic characterization, (4) geochemical characterization, (5) fracture trace and lineament analysis, and (6) a gas-show monitoring program. The data generated by the study provide a basis for assessing the most promising stratigraphic horizons for occurrences of natural gas within the Devonian shale sequence and the most favorable geographic areas of the state for natural gas exploration and should be useful in the planning and design of production-stimulation techniques. Four major radioactive units in the Devonian shale sequence are believed to be important source rocks and reservoir beds for natural gas. In order of potential for development as an unconventional gas resource, they are (1) lower and upper radioactive facies of the Huron Shale Member of the Ohio Shale, (2) upper Olentangy Shale (Rhinestreet facies equivalent), (3) Cleveland Shale Member of the Ohio Shale, and (4) lower Olentangy Shale (Marcellus facies equivalent). These primary exploration targets are recommended on the basis of areal distribution, net thickness of radioactive shale, shows of natural gas, and drilling depth to the radioactive unit. Fracture trends indicate prospective areas for Devonian shale reservoirs. Good geological prospects in the Devonian shales should be located where the fracture trends coincide with thick sequences of organic-rich highly radioactive shale.

Climate effects caused by land plant invasion in the Devonian

Science.gov (United States)

Hir guillaume, Le; yannick, Donnadieu; yves, Goddéris; brigitte, Meyer-Berthaud; gilles, Ramstein

2017-04-01

Land plants invaded continents during the Mid-Paleozoic. Their spreading and diversification have been compared to the Cambrian explosion in terms of intensity and impact on the diversification of life on Earth. Whereas prior studies were focused on the evolution of the root system and its weathering contribution, here we investigated the biophysical impacts of plant colonization on the surface climate through changes in continental albedo, roughness, thermal properties, and potential evaporation using a 3D-climate model coupled to a global biogeochemical cycles associated to a simple model for vegetation dynamics adapted to Devonian conditions. From the Early to the Late Devonian, we show that continental surface changes induced by land plants and tectonic drift have produced a large CO2 drawdown without being associated to a global cooling, because the cooling trend is counteracted by a warming trend resulting from the surface albedo reduction. If CO2 is consensually assumed as the main driver of the Phanerozoic climate, during land-plant invasion, the modifications of soil properties could have played in the opposite direction of the carbon dioxide fall, hence maintaining warm temperatures during part of the Devonian.

Radiometric evidence of Middle Devonian inversion of the Hill End Trough, northeast Lachlan Fold Belt

International Nuclear Information System (INIS)

Pakham, G.H.

1999-01-01

The publication of a new geological time-scale by the Australian Geological Survey Organisation and radiometric dates from the Hill End goldfield have prompted the re-examination of the timing of deformation of the Hill End Trough to determine whether it occurred in Middle Devonian or Early Carboniferous time. Palaeontological evidence from the western trough margin and the Capertee High dates the end of deposition in the trough as late Emsian or early Eifelian (385-382 Ma). After a mid-Devonian hiatus of at least 15 million years, paralic sedimentation commenced on the Molong and Capertee Highs in late Frasnian or early Famennian time (367-363 Ma). No Upper Devonian sedimentary formations occur in the Hill End Trough. Structural relationships indicate that the oldest mineral veins at Hill End preceded cleavage formation in the deformed trough sedimentary rocks. Early vein muscovites have Middle Devonian 40 Ar/ 39 Ar dates of 380-370 Ma. Regional metamorphic biotites from Hill End have well constrained 40 Ar/ 39 Ar closing ages of 360-358 Ma (mid-Famennian). The metamorphic (thermal) maximum which outlasted penetrative deformation. is estimated here by modelling to have been about 370 Ma (latest Givetian). This clearly places the earlier main deformation in the Middle Devonian. Deformation probably began by terminating trough deposition in latest Emsian to early Eifelian time and ended in early Givetian time at about 375 Ma ago. Published pressure and temperature data from the Hill End goldfield suggest that deformation thickened the 6 km sediment column to around 11 km. The thermal model suggests there was post-deformation erosion of about 4km and little if any further erosion occurred during Late Devonian to Early Carboniferous time. The shortening accompanying the inversion of the northern Hill End Trough may have been taken up in the region to the south, both east and west of the Copperhannia Thrust, and east of the southern termination of the Capertee High

Petroleum data for the pre-mid-Devonian basal clastics play, southern Mackenzie Valley

Energy Technology Data Exchange (ETDEWEB)

Lemieux, Y. [Natural Resources Canada, Yellowknife, NT (Canada). Geological Survey of Canada; Gal, L.P. [Northwest Territories Geoscience Office, Yellowknife, NT (Canada)

2008-07-01

This document presented petroleum data from the Mackenzie Corridor exploration area in the Northwest Territories. Both quantitative and qualitative geoscience data was compiled as part of a project under the Secure Canadian Energy Supply program of the Geological Survey of Canada. Three separate reservoir facies have been identified within the study area for their attributes relevant to petroleum exploration. This document defined and described the pre-mid-Devonian basal clastics play in the southern Great Slave Plains region where potential Lower Paleozoic source rocks include organic-rich beds of the Mirage Point and Chinchaga Formations, and regionally widespread, Middle to lower Upper Devonian shale. The play is analogous to the oil producing Middle Devonian clastic plays onlapping the Peace River Arch in northwestern Alberta. The seals, migration and trap styles for the reservoirs were discussed. Exploration risks include a thin and discontinuous reservoir with poor porosity; isolation from potential source beds; inadequate reservoir seals; and timing of hydrocarbon migration with respect to trap development. The petroleum play information was based on very few well penetrations. As such, the pre-mid-Devonian basal clastics play is considered to be a conceptual play that has not yet been adequately explored. 40 refs., 3 tabs., 12 figs.

Sedimentology, conodonts and ostracods of the Devonian - Carboniferous strata of the Anseremme railway bridge section, Dinant Basin, Belgium

Science.gov (United States)

Casier, J.-G.; Mamet, B.; Preat, A.; Sandberg, C.A.

2004-01-01

Seven major carbonate microfacies are defined in the Devonian - Carboniferous (D/C) strata (50 m) of the Anseremme railway bridge section, south of Dinant. They permit recognition of several levels encompassing the Etroeungt and Hastie??re formations. "Bathymetric" sequences range from open marine, below the storm wave base, to semi-restricted lagoon. This sequence records a shallowing-upward trend of the relative sea level, from environments below the storm wave base to strongly eroded supraticial pre-evaporitic environments. Faunal components (echinoderms, brachiopods...) indicate open-marine domain for the first six microfacies located within the dysphoticeuphotic zone in relatively shallow waters. The textures of the rocks (mudstones to rudstones) associated with lamination characteristics indicate the position of the storm (SWB) and the fair-weather (FWWB) wave bases. Microfacies seven suggests a semi-restricted platform with salinity fluctuations from hypersaline brines to brackish waters. Thus, the boundary of the Etroeungt/Hastie??re formations is marked by an abrupt drop in sea level. Carbonate micro-conglomerates recording an important erosive phase and a sedimentary hiatus. The environment is again open marine in the upper part of the Hastie??re Formation. Our conclusion is that the Anseremme section is not a reliable continuous succession for the study of the D/C boundary. This confirms the VAN STEENWINKEL (1988, 1993 hypothesis based on other arguments. Conodont faunas demonstrate that the Devonian sequence spans the five youngest conodont zones, but that two of these zones are not represented. The Epinette Formation is dated as the youngest part of the Middle expansa Zone. Thus, the boundary with the Late praesulcata Zone probably coincides with the sharp sedimentological change at the base of the Etroeungt Formation, which is interpreted to belong entirely to this zone. The disconformably overlying basal bed 159 of the Hastie??re Formation is dated

Synchrotron radiation X-ray tomographic microscopy (SRXTM of brachiopod shell interiors for taxonomy: Preliminary report

Directory of Open Access Journals (Sweden)

Motchurova-Dekova Neda

2010-01-01

Full Text Available Synchrotron radiation X-ray tomographic microscopy (SRXTM is a non-destructive technique for the investigation and visualization of the internal features of solid opaque objects, which allows reconstruction of a complete three-dimensional image of internal structures by recording of the differences in the effects on the passage of waves of energy reacting with those structures. Contrary to X-rays, produced in a conventional X-ray tube, the intense synchrotron light beams are sharply focused like a laser beam. We report encouraging results from the use of SRXTM for purely taxonomic purposes in brachiopods: an attempt to find a non-destructive and more efficient alternative to serial sectioning and several other methods of dissection together with the non-destructive method of X-ray computerised micro-tomography. Two brachiopod samples were investigated using SRXTM. In “Rhynchonella” flustracea it was possible to visualise the 3D shape of the crura and dental plates. In Terebratulina imbricata it was possible to reveal the form of the brachidium. It is encouraging that we have obtained such promising results using SRXTM with our very first two fortuitous samples, which had respectively fine-grained limestone and marl as infilling sediment, in contrast to the discouraging results communicated to us by some colleagues who have tested specimens with such infillings using X-ray micro-tomography. In future the holotypes, rare museum specimens or delicate Recent material may be preferentially subjected to this mode of analysis.

Devonian magmatism in the Timan Range, Arctic Russia - subduction, post-orogenic extension, or rifting?

Science.gov (United States)

Pease, V.; Scarrow, J. H.; Silva, I. G. Nobre; Cambeses, A.

2016-11-01

Devonian mafic magmatism of the northern East European Craton (EEC) has been variously linked to Uralian subduction, post-orogenic extension associated with Caledonian collision, and rifting. New elemental and isotopic analyses of Devonian basalts from the Timan Range and Kanin Peninsula, Russia, in the northern EEC constrain magma genesis, mantle source(s) and the tectonic process(es) associated with this Devonian volcanism to a rift-related context. Two compositional groups of low-K2O tholeiitic basalts are recognized. On the basis of Th concentrations, LREE concentrations, and (LREE/HREE)N, the data suggest two distinct magma batches. Incompatible trace elements ratios (e.g., Th/Yb, Nb/Th, Nb/La) together with Nd and Pb isotopes indicate involvement of an NMORB to EMORB 'transitional' mantle component mixed with variable amounts of a continental component. The magmas were derived from a source that developed high (U,Th)/Pb, U/Th and Sm/Nd over time. The geochemistry of Timan-Kanin basalts supports the hypothesis that the genesis of Devonian basaltic magmatism in the region resulted from local melting of transitional mantle and lower crust during rifting of a mainly non-volcanic continental rifted margin.

EARLY ORDOVICIAN AND DEVONIAN CONODONTS FROM THE WESTERN KARAKORAM AND HINDU KUSH, NORTHERNMOST PAKISTAN

Directory of Open Access Journals (Sweden)

JOHN A. TALENT

1999-07-01

Full Text Available Extensive tracts of Devonian and older sedimentary and igneous units occur within the axial region of the western Karakoram Block of northernmost Pakistan over a distance in excess of 200 km between the the headwaters of the Karambar valley in northwestern Gilgit Agency to southwestern Chitral. Conodont data indicate that the oldest sedimentary unit so far discriminated within this belt, the Yarkhun Formation, includes horizons of Ordovician (Arenig age, consistent with an earlier-presented acritarch-based Arenig age for part of the same unit. Conodont data from the "Lun Shales", a stratigraphic potpourri with little-known Silurian and Devonian tracts, demonstrate the presence of Early Devonian (early Emsian horizons. The Shogrâm Formation, widely distributed through the region, spans an appreciable interval of the Middle and Late Devonian mid-Givetian through until at least early Famennian. A major lacuna in sedimentation may be present, represented by all or most of the earlier half of Frasnian time. A biostratigraphically and possibly biogeographically important new species, Icriodus homeomorphus, is described; it is encountered in horizons of early Famennian age (Late triangularis Zone to ?Early crepida Zone. 

Hydrogeology and simulation of ground-water flow in the Silurian-Devonian aquifer system, Johnson County, Iowa

Science.gov (United States)

Tucci, Patrick; McKay, Robert M.

2006-01-01

Bedrock of Silurian and Devonian age (termed the “Silurian-Devonian aquifer system”) is the primary source of ground water for Johnson County in east-central Iowa. Population growth within municipal and suburban areas of the county has resulted in increased amounts of water withdrawn from this aquifer and water-level declines in some areas. A 3-year study of the hydrogeology of the Silurian-Devonian aquifer system in Johnson County was undertaken to provide a quantitative assessment of ground water resources and to construct a ground-water flow model that can be used by local governmental agencies as a management tool.

Cyclostratigraphic calibration of the Famennian stage (Late Devonian, Illinois Basin, USA)

Science.gov (United States)

Pas, Damien; Hinnov, Linda; Day, James E. (Jed); Kodama, Kenneth; Sinnesael, Matthias; Liu, Wei

2018-04-01

The Late Devonian biosphere was affected by two of the most severe biodiversity crises in Earth's history, the Kellwasser and Hangenberg events near the Frasnian-Famennian (F-F) and the Devonian-Carboniferous (D-C) boundaries, respectively. Current hypotheses for the causes of the Late Devonian extinctions are focused on climate changes and associated ocean anoxia. Testing these hypotheses has been impeded by a lack of sufficient temporal resolution in paleobiological, tectonic and climate proxy records. While there have been recent advances in astronomical calibration that have improved the accuracy of the Frasnian time scale and part of the Famennian, the time duration of the entire Famennian Stage remains poorly constrained. During the Late Devonian, a complete Late Frasnian-Early Carboniferous succession of deep-shelf deposits accumulated in the epieric sea in Illinois Basin of the central North-American mid-continent. A record of this sequence is captured in three overlapping cores (H-30, Sullivan and H-32). The H-30 core section spans the F-F boundary; the Sullivan section spans almost all of the Famennian and the H-32 section sampled spans the interval of the Upper Famennian and the D-C boundary. To have the best chance of capturing Milankovitch cycles, 2000 rock samples were collected at minimum 5-cm-interval across the entire sequence. Magnetic susceptibility (MS) was measured on each sample and the preservation of climatic information into the MS signal was verified through geochemical analyses and low-temperature magnetic susceptibility acquisition. To estimate the duration of the Famennian Stage, we applied multiple spectral techniques and tuned the MS signal using the highly stable 405 kyr cycle for Sullivan and the obliquity cycle for the H-30 and H-32 cores. Based on the correlation between the cores we constructed a Famennian floating astronomical time scale, which indicates a duration of 13.5 ± 0.5 myr. An uncertainty of 0.5 myr was estimated for

The first direct evidence of a Late Devonian coelacanth fish feeding on conodont animals

OpenAIRE

Zaton, M.; Broda, K.; Qvarnström, M.; Niedzwiedzki, G.; Ahlberg, P.E.

2017-01-01

We describe the first known occurrence of a Devonian coelacanth specimen from the lower Famennian of the Holy Cross Mountains, Poland, with a conodont element preserved in its digestive tract. A small spiral and phosphatic coprolite (fossil excrement) containing numerous conodont elements and other unrecognized remains was also found in the same deposits. The coprolite is tentatively attributed to the coelacanth. Although it is unclear whether the Late Devonian coelacanth from Poland was an a...

Determination of organic-matter content of Appalachian Devonian shales from gamma-ray logs

International Nuclear Information System (INIS)

Schmoker, J.W.

1981-01-01

The organic-matter content of the Devonian shale of the Appalachian basin is important for assessing the natural-gas resources of these rocks, and patterns of organic-matter distribution convey information on sedimentary processes and depositional environment. In most of the western part of the Appalachian basin the organic-matter content of the Devonian shale can be estimated from gamma-ray wire-line logs using the equation: phi 0 = (γ/sub B/ - γ)/1.378A, where phi 0 is the organic-matter content of the shale (fractional volume), γ the gamma-ray intensity (API units), γ/sub B/ the gamma-ray intensity if no organic matter is present (API units), and A the slope of the crossplot of gamma-ray intensity and formation density (API units/(g/cm 3 )). Organic-matter contents estimated using this equation are compared with organic-matter contents determined from direct laboratory analyses of organic carbon for 74 intervals of varying thickness from 12 widely separated wells. The organic-matter content of these intervals ranges from near zero to about 20% by volume. The gamma-ray intensity of the Cleveland Member of the Ohio Shale and the lower part of the Olentangy Shale is anomalously low compared to other Devonian shales of similar richness, so that organic-matter content computed for each of these units from gamma-ray logs is likely to be too low. Wire-line methods for estimating organic-matter content have the advantages of economy, readily available sources of data, and continuous sampling of the vertically heterogenous shale section. The gamma-ray log, in particular, is commonly run in the Devonian shale, its response characteristics are well known, and the cumulative pool of gamma-ray logs forms a large and geographically broad data base. The quantitative computation of organic-matter content from gamma-ray logs should be of practical value in studies of the Appalachian Devonian shale. 16 figures

Soil development on loess overlying Cretaceous sediments and Devonian limestones

Czech Academy of Sciences Publication Activity Database

Žigová, Anna; Šťastný, Martin

2015-01-01

Roč. 12, č. 3 (2015), s. 267-278 ISSN 1214-9705 Institutional support: RVO:67985831 Keywords : loess * Cretaceous and Devonian rocks * mineral composition * soil development * Luvic Chernozem * Albic Luvisol Subject RIV: DF - Soil Science Impact factor: 0.561, year: 2015

Devonian and Lower Carboniferous conodont biostratigraphy, Spanish Central Pyrenees

NARCIS (Netherlands)

Boersma, Kerst Th.

1973-01-01

Conodont faunas were collected from the Devonian and Lower Carboniferous in an area ranging from the Rio Fsera (prov. of Huesca) in the west to the Rio Llobregat (prov. of Barcelona) in the east. Most conodont zones and -Faunas recognized in Germany and Spain could be distinguished. The ages of the

Terrestrial P and Reactive N and Marine Productivity in the Late Devonian Appalachian Basin

Science.gov (United States)

Tuite, M. L.; Macko, S. A.

2009-12-01

A causal link between the Late Devonian emergence of forest ecosystems and episodic black shale deposition has been proposed by several authors. Most attribute increases in epicontinental basin productivity to elevated rates of terrestrial phosphorus weathering facilitated by the co-evolution of root systems and soils. Two reasons to suspect that an increase in the P weathering flux was not the primary cause of organic-rich shale deposition are as follows. First, most Late Devonian black shales were deposited during sea level transgressions, periods when riverine fluxes of sediment and mineral nutrients such as P to marine basins were diminished. Second, Late Devonian forests were restricted to warm, moist lowlands where P was sequestered in soils as inorganic, occluded forms. However, the export flux of reactive N from these forests to adjacent epeiric seas by riverine and atmospheric deposition was enhanced by the warm, wet climate and expanding areal extent of forests. Abundant terrestrial reactive N primed the marine eutrophication pump by extending the residence time of P in the photic zone, permitting extensive growth of primary biomass. The consequent flux of organic matter to the sea floor created anoxic bottom waters that, in turn, allowed for the remobilization of P into the water column. Based on abundance and isotopic analyses of organic and inorganic C, N, P, and S from terrestrial and marine environments within and adjacent to the Late Devonian Appalachian Basin, this latter scenario is supported.

End-Devonian extinction and a bottleneck in the early evolution of modern jawed vertebrates.

Science.gov (United States)

Sallan, Lauren Cole; Coates, Michael I

2010-06-01

The Devonian marks a critical stage in the early evolution of vertebrates: It opens with an unprecedented diversity of fishes and closes with the earliest evidence of limbed tetrapods. However, the latter part of the Devonian has also been characterized as a period of global biotic crisis marked by two large extinction pulses: a "Big Five" mass extinction event at the Frasnian-Famennian stage boundary (374 Ma) and the less well-documented Hangenberg event some 15 million years later at the Devonian-Carboniferous boundary (359 Ma). Here, we report the results of a wide-ranging analysis of the impact of these events on early vertebrate evolution, which was obtained from a database of vertebrate occurrences sampling over 1,250 taxa from 66 localities spanning Givetian to Serpukhovian stages (391 to 318 Ma). We show that major vertebrate clades suffered acute and systematic effects centered on the Hangenberg extinction involving long-term losses of over 50% of diversity and the restructuring of vertebrate ecosystems worldwide. Marine and nonmarine faunas were equally affected, precluding the existence of environmental refugia. The subsequent recovery of previously diverse groups (including placoderms, sarcopterygian fish, and acanthodians) was minimal. Tetrapods, actinopterygians, and chondrichthyans, all scarce within the Devonian, undergo large diversification events in the aftermath of the extinction, dominating all subsequent faunas. The Hangenberg event represents a previously unrecognized bottleneck in the evolutionary history of vertebrates as a whole and a historical contingency that shaped the roots of modern biodiversity.

Geology of the Devonian black shales of the Appalachian Basin

Science.gov (United States)

Roen, J.B.

1984-01-01

Black shales of Devonian age in the Appalachian Basin are a unique rock sequence. The high content of organic matter, which imparts the characteristic lithology, has for years attracted considerable interest in the shales as a possible source of energy. The recent energy shortage prompted the U.S. Department of Energy through the Eastern Gas Shales Project of the Morgantown Energy Technology Center to underwrite a research program to determine the geologic, geochemical, and structural characteristics of the Devonian black shales in order to enhance the recovery of gas from the shales. Geologic studies by Federal and State agencies and academic institutions produced a regional stratigraphic network that correlates the 15 ft black shale sequence in Tennessee with 3000 ft of interbedded black and gray shales in central New York. These studies correlate the classic Devonian black shale sequence in New York with the Ohio Shale of Ohio and Kentucky and the Chattanooga Shale of Tennessee and southwestern Virginia. Biostratigraphic and lithostratigraphic markers in conjunction with gamma-ray logs facilitated long-range correlations within the Appalachian Basin. Basinwide correlations, including the subsurface rocks, provided a basis for determining the areal distribution and thickness of the important black shale units. The organic carbon content of the dark shales generally increases from east to west across the basin and is sufficient to qualify as a hydrocarbon source rock. Significant structural features that involve the black shale and their hydrocarbon potential are the Rome trough, Kentucky River and Irvine-Paint Creek fault zone, and regional decollements and ramp zones. ?? 1984.

The global stratotype section and point of the Silurian-Devonian boundary

Czech Academy of Sciences Publication Activity Database

Chlupáč, I.; Hladil, Jindřich

2000-01-01

Roč. 225, - (2000), s. 1-6+1 Pl. ISSN 0341-4116 Institutional research plan: CEZ:AV0Z3013912 Keywords : Silurian-Devonian * global stratotype section and point (GSSP) * stratigraphy Subject RIV: DB - Geology ; Mineralogy

Refining the Early Devonian time scale using Milankovitch cyclicity in Lochkovian–Pragian sediments (Prague Synform, Czech Republic)

Czech Academy of Sciences Publication Activity Database

da Silva, A.C.; Hladil, Jindřich; Chadimová, Leona; Slavík, Ladislav; Hilgen, F. J.; Bábek, O.; Dekkers, M. J.

2016-01-01

Roč. 455, 1 December (2016), s. 125-139 ISSN 0012-821X R&D Projects: GA ČR GA14-18183S Institutional support: RVO:67985831 Keywords : orbital time scale * spectral analysis * Devonian * magnetic susceptibility * gamma ray spectrometry * limestone * Early Devonian * Lochkovian * Pragian * Emsian * Barrandian * peri-Gondwanan basins Subject RIV: DB - Geology ; Mineralogy Impact factor: 4.409, year: 2016

Devonian (Emsian-Eifelian) fish from the Lower Bokkeveld Group (Ceres Subgroup), South Africa

Science.gov (United States)

Anderson, M. E.; Almond, J. E.; Evans, F. J.; Long, J. A.

1999-07-01

Four major groups of fish are represented by fragmentary remains from South Africa's Lower Bokkeveld Group of Early to Middle Devonian age: the Acanthodii, Chondrichthyes, Placodermi and Osteichthyes. These represent the oldest known occurrences of these groups in southern Africa, as well as an important addition to the very meagre record of earlier Devonian fish from the Malvinokaffric Province of southwestern Gondwana. Bokkeveld fish material comes from the Gydo (Late Emsian) and Tra Tra (Middle Eifelian) Formations of the Western Cape and Eastern Cape Provinces. The cosmopolitan marine acanthodian Machæracanthus is represented only by isolated fin spines which may belong to two different species on the basis of their external ornamentation, cross-sectional outline and internal histology. The elasmobranchs are represented by four elements: (1) a flattened chondrocranium which bears affinity to the Late Devonian-Carboniferous symmoriid (protacrodont) 'cladodont' sharks. It is probably the earliest known (Emsian) shark chondrocranium; (2) an isolated, primitive scapulocoracoid with a very short coracoidal ridge; (3) ankylosed and isolated radials, interpreted as parts of pterygial plates of a paired fin of an unknown chondrichthyan bearing affinity to the Middle Devonian Zamponiopteron from Bolivia; and (4) isolated barlike structures, perhaps gill arch or a jaw elements, thought to be from the same taxon as (3). The placoderms are represented by an incomplete trunk armour and fragmentary, finely ornamented plates of a primitive antiarch. The Osteichthyes are represented by a single large scale of an unidentified dipnoan from the Eifelian of the Cedarberg range, as well as a probable sarcopterygian dermal plate from the Emsian of the Prince Albert area. These are among the earliest sarcopterygian remains recorded from the Malvinokaffric Province.

Thermal maturity of northern Appalachian Basin Devonian shales: Insights from sterane and terpane biomarkers

Science.gov (United States)

Hackley, Paul C.; Ryder, Robert T.; Trippi, Michael H.; Alimi, Hossein

2013-01-01

To better estimate thermal maturity of Devonian shales in the northern Appalachian Basin, eleven samples of Marcellus and Huron Shale were characterized via multiple analytical techniques. Vitrinite reflectance, Rock–Eval pyrolysis, gas chromatography (GC) of whole rock extracts, and GC–mass spectrometry (GCMS) of extract saturate fractions were evaluated on three transects that lie across previously documented regional thermal maturity isolines. Results from vitrinite reflectance suggest that most samples are immature with respect to hydrocarbon generation. However, bulk geochemical data and sterane and terpane biomarker ratios from GCMS suggest that almost all samples are in the oil window. This observation is consistent with the presence of thermogenic gas in the study area and higher vitrinite reflectance values recorded from overlying Pennsylvanian coals. These results suggest that vitrinite reflectance is a poor predictor of thermal maturity in early mature areas of Devonian shale, perhaps because reported measurements often include determinations of solid bitumen reflectance. Vitrinite reflectance interpretations in areas of early mature Devonian shale should be supplanted by evaluation of thermal maturity information from biomarker ratios and bulk geochemical data.

Facies-succession and architecture of the third-order sequences and their stratigraphic framework of the Devonian in Yunnan-Guizhou-Guangxi area, South China

Directory of Open Access Journals (Sweden)

Mei Mingxiang

2013-01-01

Full Text Available The Caledonian orogeny at the end of the Silurian resulted in great changes in the palaeogeography in the Yunnan-Guizhou-Guangxi area of South China; the continental area of the Early Paleozoic evolved into the extensive Dian-Qian-Gui Sea in the Late Paleozoic. Early in the Devonian, as a result of a major transgression, seawater encroached gradually from the south to the north and clastic facies were deposited. Carbonate deposition was then established in the Yunnan-Guizhou-Guangxi area, with a palaeogeography marked by attached platforms, isolated platforms and narrow basins. As a result of the Ziyun movement towards the end of the Devonian, the Upper Devonian strata are regressive and thin out from the open-sea to the land areas. A study of the nature and distribution of sedimentary facies in space and time recognises 13 third-order sequences in the Devonian strata in Yunnan-Guizhou-Guangxi area, and these form two second-order sequences. The strata of the Lower Devonian comprise 5 third-order sequences (SQ1 to SQ5, which are dominated by transgressive clastics. 4 third-order sequences (SQ6 to SQ9 in the Middle Devonian are characterized by alternations of transgressive clastics and highstand carbonates. In the Upper Devonian, carbonates constitute 4 third-order sequences (SQ10 to SQ13, which are generally marked by the transgressive limestones and highstand dolomites. On the basis of earlier biostratigraphic studies, sea-level changes represented by the third-order sequences with their different facies successions are explored, and the sequence stratigraphic framework is established. Therefore, the Devonian strata in the study area provide an example for further understanding of depositional trends within the sequence-stratigraphic framework.

Vascular plants from the Devonian to Lower Cretaceous in southern Africa

Directory of Open Access Journals (Sweden)

J. M. Anderson

1983-11-01

Full Text Available The succession of pre-angiospermous megafloras in southern Africa from the Devonian to Lower Cretaceous is outlined. Interrelationships between continental drift, global climatic trends, and floral and faunal evolution are emphasized. Data are given on numbers of assemblages sampled; on species diversity; and on relative abundance of each genus per productive ‘formation’. A total of 79 genera and about 250 species are recognized in the 150 assemblages from the 11 horizons considered. Floras are unknown from the Carboniferous and are as yet undescribed from the Jurassic. Aside from these gaps, a good idea of the floral development is obtained. Diversity lows of around 5 to 10 species per ‘formation’ are witnessed in the Devonian, whereas a peak of 112 species is encountered in the Upper Triassic Molteno Formation. Diversity remains around 20 to 30 species for all other ‘formations’.

Platystrophia (Orthida and new related Ordovician and Early Silurian brachiopod genera

Directory of Open Access Journals (Sweden)

Harper, David A. T.

2007-03-01

Full Text Available More than 150 Ordovician and Early Silurian brachiopod species have been assigned to the genus Platystrophia King, 1850 mainly on the basis of their Spirifer-like shell exteriors. King’s concept of the genus was based on Platystrophia biforata King, which is not conspecific with Terebratulites biforatus Schlotheim, traditionally regarded as the type species of Platystrophia. Porambonites costatus Pander, 1830 is formally proposed as the type species of the genus to replace P. biforata; the latter is considered to be a nomen dubium. In our revised diagnosis, Platystrophia is restricted to a group of Arenig to upper Caradoc species from Baltica and Avalonia, whereas the Ashgill and lower Silurian taxa of these regions, hitherto assigned to Platystrophia, are placed in the new genus Neoplatystrophia. Platystrophia ponderosa Foerste, 1909 from the Upper Ordovician of North America is proposed as the type species of a new genus Vinlandostrophia. Two new species, Platystrophia baltica and Platystrophia pogrebovi from the Llanvirn–Caradoc of the East Baltic are also described.

A new Late Devonian genus with seed plant affinities.

Science.gov (United States)

Wang, Deming; Liu, Le

2015-02-26

Many ovules of Late Devonian (Famennian) seed plants have been well studied. However, because few taxa occur with anatomically preserved stems and/or petioles, the vascular system of these earliest spermatophytes is little understood and available data come mostly from Euramerica. There remains great controversy over the anatomical differentiation of Late Devonian and Carboniferous seed plant groups of Buteoxylonales, Calamopityales and Lyginopteridales. Protostele evolution of these early spermatophytes needs more research. A new taxon Yiduxylon trilobum gen. et sp. nov. with seed plant affinities has been discovered in the Upper Devonian (Famennian) Tizikou Formation of Hubei Province, China. It is represented by stems, helically arranged and bifurcate fronds with two orders of pinnae and planate pinnules. Both secondary pinnae and pinnules are borne alternately. Stems contain a small protostele with three primary xylem ribs possessing a single peripheral protoxylem strand. Thick secondary xylem displays multiseriate bordered pitting on the tangential and radial walls of the tracheids, and has biseriate to multiseriate and high rays. A narrow cortex consists of inner cortex without sclerotic nests and sparganum-type outer cortex with peripheral bands of vertically aligned sclerenchyma cells. Two leaf traces successively arise tangentially from each primary xylem rib and they divide once to produce four circular-oval traces in the stem cortex. Four vascular bundles occur in two C-shaped groups at each petiole base with ground tissue and peripheral bands of sclerenchyma cells. Yiduxylon justifies the assignment to a new genus mainly because of the protostele with protoxylem strands only near the periphery of primary xylem ribs, leaf trace origination and petiolar vascular supply structure. It shares many definitive characters with Calamopityales and Lyginopteridales, further underscoring the anatomical similarities among early seed plants. The primary vascular

Assessment of Appalachian basin oil and gas resources: Devonian gas shales of the Devonian Shale-Middle and Upper Paleozoic Total Petroleum System: Chapter G.9 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

Science.gov (United States)

Milici, Robert C.; Swezey, Christopher S.; Ruppert, Leslie F.; Ryder, Robert T.

2014-01-01

This report presents the results of a U.S. Geological Survey (USGS) assessment of the technically recoverable undiscovered natural gas resources in Devonian shale in the Appalachian Basin Petroleum Province of the eastern United States. These results are part of the USGS assessment in 2002 of the technically recoverable undiscovered oil and gas resources of the province. This report does not use the results of a 2011 USGS assessment of the Devonian Marcellus Shale because the area considered in the 2011 assessment is much greater than the area of the Marcellus Shale described in this report. The USGS assessment in 2002 was based on the identification of six total petroleum systems, which include strata that range in age from Cambrian to Pennsylvanian. The Devonian gas shales described in this report are within the Devonian Shale-Middle and Upper Paleozoic Total Petroleum System, which extends generally from New York to Tennessee. This total petroleum system is divided into ten assessment units (plays), four of which are classified as conventional and six as continuous. The Devonian shales described in this report make up four of these continuous assessment units. The assessment results are reported as fully risked fractiles (F95, F50, F5, and the mean); the fractiles indicate the probability of recovery of the assessment amount. The products reported are oil, gas, and natural gas liquids. The mean estimates for technically recoverable undiscovered hydrocarbons in the four gas shale assessment units are 12,195.53 billion cubic feet (12.20 trillion cubic feet) of gas and 158.91 million barrels of natural gas liquids

Ichnology applied to sequence stratigraphic analysis of Siluro-Devonian mud-dominated shelf deposits, Paraná Basin, Brazil

Science.gov (United States)

Sedorko, Daniel; Netto, Renata G.; Savrda, Charles E.

2018-04-01

Previous studies of the Paraná Supersequence (Furnas and Ponta Grossa formations) of the Paraná Basin in southern Brazil have yielded disparate sequence stratigraphic interpretations. An integrated sedimentological, paleontological, and ichnological model was created to establish a refined sequence stratigraphic framework for this succession, focusing on the Ponta Grossa Formation. Twenty-nine ichnotaxa are recognized in the Ponta Grossa Formation, recurring assemblages of which define five trace fossil suites that represent various expressions of the Skolithos, Glossifungites and Cruziana ichnofacies. Physical sedimentologic characteristics and associated softground ichnofacies provide the basis for recognizing seven facies that reflect a passive relationship to bathymetric gradients from shallow marine (shoreface) to offshore deposition. The vertical distribution of facies provides the basis for dividing the Ponta Grossa Formation into three major (3rd-order) depositional sequences- Siluro-Devonian and Devonian I and II-each containing a record of three to seven higher-order relative sea-level cycles. Major sequence boundaries, commonly coinciding with hiatuses recognized from previously published biostratigraphic data, are locally marked by firmground Glossifungites Ichnofacies associated with submarine erosion. Maximum transgressive horizons are prominently marked by unbioturbated or weakly bioturbated black shales. By integrating observations of the Ponta Grossa Formation with those recently made on the underlying marginal- to shallow-marine Furnas Formation, the entire Paraná Supersequence can be divided into four disconformity-bound sequences: a Lower Silurian (Llandovery-Wenlock) sequence, corresponding to lower and middle units of the Furnas; a Siluro-Devonian sequence (?Pridoli-Early Emsian), and Devonian sequences I (Late Emsian-Late Eifelian) and II (Late Eifelian-Early Givetian). Stratigraphic positions of sequence boundaries generally coincide with

Distribution and Thermal Maturity of Devonian Carbonate Reservoir Solid Bitumen in Desheng Area of Guizhong Depression, South China

Directory of Open Access Journals (Sweden)

Yuguang Hou

2017-01-01

Full Text Available The distribution of solid bitumen in the Devonian carbonate reservoir from well Desheng 1, Guizhong Depression, was investigated by optical microscope and hydrocarbon inclusions analysis. Vb and chemical structure indexes measured by bitumen reflectance, laser Raman microprobe (LRM, and Fourier transform infrared spectroscopy (FTIR were carried out to determine the thermal maturity of solid bitumen. Based on the solid bitumen thermal maturity, the burial and thermal maturity history of Devonian carbonate reservoir were reconstructed by basin modeling. The results indicate that the fractures and fracture-related dissolution pores are the main storage space for the solid bitumen. The equivalent vitrinite reflectance of solid bitumen ranges from 3.42% to 4.43% converted by Vb (% and LRM. The infrared spectroscopy analysis suggests that there are no aliphatic chains detected in the solid bitumen which is rich in aromatics C=C chains (1431–1440 cm−1. The results of Vb (%, LRM, and FTIR analysis demonstrate that the solid bitumen has experienced high temperature and evolved to the residual carbonaceous stage. The thermal evolution of Devonian reservoirs had experienced four stages. The Devonian reservoirs reached the highest reservoir temperature 210–260°C during the second rapid burial-warming stage, which is the main period for the solid bitumen formation.

Unusual central Nevada geologic terranes produced by Late Devonian Antler orogeny and Alamo impact

Science.gov (United States)

Poole, Forrest G.; Sandberg, Charles

2015-01-01

This Special Paper is the product of nearly 25 years of geologic investigations. It is an exposition of two small areas, both less than 25 km east of the Mississippian Roberts Mountains allochthon, but each displaying a different, unique geologic terrane, previously undocumented in Nevada and perhaps in North America. One area, the Bisoni-McKay, at the south end of the Fish Creek Range, displays an olistostrome, shed eastward during the late Late Devonian (early Famennian) from a migrating Antler orogenic forebulge. The other, the Warm Springs–Milk Spring, at the south end of the Hot Creek Range, displays a deeper marine terrane affected by the early Late Devonian (middle Frasnian) Alamo impact.

The rise of fire: Fossil charcoal in late Devonian marine shales as an indicator of expanding terrestrial ecosystems, fire, and atmospheric change

Science.gov (United States)

Rimmer, Susan M.; Hawkins, Sarah J.; Scott, Andrew C.; Cressler, Walter L.

2015-01-01

Fossil charcoal provides direct evidence for fire events that, in turn, have implications for the evolution of both terrestrial ecosystems and the atmosphere. Most of the ancient charcoal record is known from terrestrial or nearshore environments and indicates the earliest occurrences of fire in the Late Silurian. However, despite the rise in available fuel through the Devonian as vascular land plants became larger and trees and forests evolved, charcoal occurrences are very sparse until the Early Mississippian where extensive charcoal suggests well-established fire systems. We present data from the latest Devonian and Early Mississippian of North America from terrestrial and marine rocks indicating that fire became more widespread and significant at this time. This increase may be a function of rising O2 levels and the occurrence of fire itself may have contributed to this rise through positive feedback. Recent atmospheric modeling suggests an O2 low during the Middle Devonian (around 17.5%), with O2 rising steadily through the Late Devonian and Early Mississippian (to 21–22%) that allowed for widespread burning for the first time. In Devonian-Mississippian marine black shales, fossil charcoal (inertinite) steadily increases up-section suggesting the rise of widespread fire systems. There is a concomitant increase in the amount of vitrinite (preserved woody and other plant tissues) that also suggests increased sources of terrestrial organic matter. Even as end Devonian glaciation was experienced, fossil charcoal continued to be a source of organic matter being introduced into the Devonian oceans. Scanning electron and reflectance microscopy of charcoal from Late Devonian terrestrial sites indicate that the fires were moderately hot (typically 500–600 °C) and burnt mainly surface vegetation dominated by herbaceous zygopterid ferns and lycopsids, rather than being produced by forest crown fires. The occurrence and relative abundance of fossil charcoal in

Devonian sand injections and volcanism in the Murzuq Basin (south-west Libya)

DEFF Research Database (Denmark)

Moreau, Julien; Ghienne, Jean-Francois

system is original by its interaction with volcanism and its situation in an epicontinental intracratonic basin. The sand injections form a seal-bypass system between the Ordovician-Cambrian reservoirs and the Lower Devonian sandstones, breaching through the Silurian shale seal (and source rock...

Givetian (Middle Devonian) cladoxylopsid 'ferns' from Orkney, Northern Scotland

OpenAIRE

Berry, Christopher Mark; Hilton, Jason

2006-01-01

Two large fossil plants are described from the Givetian (Middle Devonian) Eday\\ud Flags, South Ronaldsay, Orkney Isles, northern Scotland. Fossils with branches joined to stems of\\ud this age are rare. Each specimen comprises a robust and tapering main trunk from which numerous\\ud closely spaced branches arise distally. Although poorly preserved such that generic identifications are\\ud not possible, both specimens display the characteristic architecture of the plant order Pseudosporochnales\\u...

Assessing the completeness of the fossil record using brachiopod Lazarus taxa

Science.gov (United States)

Gearty, W.; Payne, J.

2012-12-01

Lazarus taxa, organisms that disappear from the fossil record only to reappear later, provide a unique opportunity to assess the completeness of the fossil record. In this study, we apply logistic regression to quantify the associations of body size, geographic extent, and species diversity with the probability of being a Lazarus genus using the Phanerozoic fossil record of brachiopods. We find that both the geographic range and species diversity of a genus are inversely associated with the probability of being a Lazarus taxon in the preceding or succeeding stage. In contrast, body size exhibits little association with the probability of becoming a Lazarus taxon. A model including species diversity and geographic extent as predictors performs best among all combinations examined, whereas a model including only shell size as a predictor performs the worst - even worse than a model that assumes Lazarus taxa are randomly drawn from all available genera. These findings suggest that geographic range and species richness data can be used to improve estimates of extensions on the observed fossil ranges of genera and, thereby, better correct for sampling effects in estimates of taxonomic diversity change through the Phanerozoic.

Late Devonian (Frasnian) bivalves from the Nocedo Formation: the results of Wilhelm Kegel’s 1927 field trip to northern Spain

NARCIS (Netherlands)

Amler, M.R.W.

2010-01-01

During a field trip to the Peña-Corada Unit of the southernmost Esla region of the Cantabrian Mountains in 1927, the German stratigrapher Wilhelm Kegel sampled brachiopods and bivalves from a section in the Laoz valley near La Ercina. The stratigraphic position is believed to be part of the Nocedo

Regressive transgressive cycle of Devonian sea in Uruguay verified by Palynology

International Nuclear Information System (INIS)

Da Silva, J.

1990-01-01

This work is about the results and conclusions of the populations palinomorphs study, carried out in Devonian formations in the center of Uruguay. The existence of a regressive transgressive cycle is verified by analyzing the vertical distribution of palinomorphs as well as is mentioned the presence of chintziest for the section studied - hoesphaeridium Cyathochitina kinds

Wangshangkia, a new Devonian ostracod genus from Dushan of Guizhou, South China

Science.gov (United States)

Song, Junjun; Gong, Yiming

2018-02-01

Wangshangkia, a new genus of Ostracoda, from the Late Devonian in Dushan of Guizhou, South China, is described. This genus belongs to the family Bairdiocyprididae Shaver, 1961 and includes two new species, i.e. Wangshangkia dushaniensis and W. bailouiensis. The new genus is characterized by a wide ventral carina with radial striae. It is reported from the Famennian of South China and disappeared just below the Devonian-Carboniferous boundary. Wangshangkia is essentially a benthic crawler and is restricted to the shallow-marine depositional environment with a low hydrodynamic condition. Wangshangkia: urn:lsid:zoobank.org:act:34BF01D4-D202-492D-8E27-BC508EF7EFFB W. dushaniensis: urn:lsid:zoobank.org:act:D267C362-7510-4D19-996B-EA1848D7D025 W. bailouiensis: urn:lsid:zoobank.org:act:FE988AA0-7363-4D9E-A5AB-1526C8DBCDD9

Towards a High-resolution Time Scale for the Early Devonian

Science.gov (United States)

Dekkers, M. J.; da Silva, A. C.

2017-12-01

High-resolution time scales are crucial to understand Earth's history in detail. The construction of a robust geological time scale, however, inevitably becomes increasingly harder further back in time. Uncertainties associated with anchor radiometric ages increase in size, not speaking of the mere presence of suitable datable strata. However, durations of stages can be tightly constrained by making use of cyclic expressions in sediments, an approach that revolutionized the Cenozoic time scale. When precisely determined durations are stitched together, ultimately, a very precise time scale is the result. For the Mesozoic and Paleozoic an astronomical solution as a tuning target is not available but the dominant periods of eccentricity, obliquity and precession are reasonably well constrained for the entire Phanerozoic which enables their detection by means of spectral analysis. Eccentricity is time-invariant and is used as the prime building block. Here we focus on the Early Devonian, on its lowermost three stages: the Lochkovian, Pragian and Emsian. The uncertainties on the Devonian stage boundaries are currently in the order of several millions of years. The preservation of climatic cycles in diagenetically or even anchimetamorphically affected successions, however, is essential. The fit of spectral peak ratios with those calculated for orbital cycles, is classically used as a strong argument for a preserved climatic signal. Here we use primarily the low field magnetic susceptibility (MS) as proxy parameter, supported by gamma-ray spectrometry to test for consistency. Continuous Wavelet Transform, Evolutive Harmonic Analysis, Multitaper Method, and Average Spectral Misfit are used to reach an optimal astronomical interpretation. We report on classic Early Devonian sections from the Czech Republic: the Pozar-CS (Lochkovian and Pragian), Pod Barrandovem (Pragian and Lower Emsian), and Zlichov (Middle-Upper Emsian). Also a Middle-Upper Emsian section from the US

From success to persistence: Identifying an evolutionary regime shift in the diverse Paleozoic aquatic arthropod group Eurypterida, driven by the Devonian biotic crisis.

Science.gov (United States)

Lamsdell, James C; Selden, Paul A

2017-01-01

Mass extinctions have altered the trajectory of evolution a number of times over the Phanerozoic. During these periods of biotic upheaval a different selective regime appears to operate, although it is still unclear whether consistent survivorship rules apply across different extinction events. We compare variations in diversity and disparity across the evolutionary history of a major Paleozoic arthropod group, the Eurypterida. Using these data, we explore the group's transition from a successful, dynamic clade to a stagnant persistent lineage, pinpointing the Devonian as the period during which this evolutionary regime shift occurred. The late Devonian biotic crisis is potentially unique among the "Big Five" mass extinctions in exhibiting a drop in speciation rates rather than an increase in extinction. Our study reveals eurypterids show depressed speciation rates throughout the Devonian but no abnormal peaks in extinction. Loss of morphospace occupation is random across all Paleozoic extinction events; however, differential origination during the Devonian results in a migration and subsequent stagnation of occupied morphospace. This shift appears linked to an ecological transition from euryhaline taxa to freshwater species with low morphological diversity alongside a decrease in endemism. These results demonstrate the importance of the Devonian biotic crisis in reshaping Paleozoic ecosystems. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

The silurian and devonian vertebrates of Bolivia

Directory of Open Access Journals (Sweden)

1986-01-01

formas de amplia repartición (Rhenanidos, algunos Acanthodios, Actinopterygios de tipo Moythomasia, formas con afinidades transpacíficas (Acanthodios próximos de Sinacanthus y formas tal vez endémicas (Pucapampella, Zamponiopteron. Silurian and Devonian vertebrate remains are described from various localities in Bolivia. Most of the material occurs in concretions in the marine Devonian of the Altiplano and Subandean area, and some isolated specimens have been found in sandstones and lutites. The jawless vertebrates are known only from isolated thelodont scales which occur in the Uppermost Silurian or Lower Devonian of Seripona, Chuquisaca. All the other vertebrate remains belong to gnathosthomes, in particular to the acanthodians, placoderms, chondrichthyans and actinopterygians. The acanthodians are represented by some ischnacanthid dentigerous jaw bones and climatiid spines and shoulder girdles. They are fairly abundant and show no marked differences from acanthodian remains known elsewhere in the Siluro-Devonian of Europe and North America. However, some isolated spines are suggestive of the genus Sinacanthus, known from the Lower Devonian of China The placoderms are represented only by the rhenanid Bolivosteus chacomensis Goujet et al, known from two well preserved braincases. This genus closely resembles Gemuendina (Lower Devonian of Germany with respect to the overall shape of the braincase, but its shoulder girdle differs substantially. The chondrichthyans are the most abundant vertebrates in the Devonian of Bolivia They are represented by isolated spines and endoskeletal elements lined with prismatic calcified cartilage Among them, some peculiar occipital regions of braincases are referred here to Pucapampella rodrigae n.g , n sp. These brain-cases differ from all other known Devonian chondrichthyan braincases in showing a ventrally continuous occipital fissure which completely separates the occiput from the rest of the brain-case. The strongly vaulted

An exceptionally preserved Late Devonian actinopterygian provides a new model for primitive cranial anatomy in ray-finned fishes

Science.gov (United States)

Giles, Sam; Darras, Laurent; Clément, Gaël; Blieck, Alain; Friedman, Matt

2015-01-01

Actinopterygians (ray-finned fishes) are the most diverse living osteichthyan (bony vertebrate) group, with a rich fossil record. However, details of their earliest history during the middle Palaeozoic (Devonian) ‘Age of Fishes' remains sketchy. This stems from an uneven understanding of anatomy in early actinopterygians, with a few well-known species dominating perceptions of primitive conditions. Here we present an exceptionally preserved ray-finned fish from the Late Devonian (Middle Frasnian, ca 373 Ma) of Pas-de-Calais, northern France. This new genus is represented by a single, three-dimensionally preserved skull. CT scanning reveals the presence of an almost complete braincase along with near-fully articulated mandibular, hyoid and gill arches. The neurocranium differs from the coeval Mimipiscis in displaying a short aortic canal with a distinct posterior notch, long grooves for the lateral dorsal aortae, large vestibular fontanelles and a broad postorbital process. Identification of similar but previously unrecognized features in other Devonian actinopterygians suggests that aspects of braincase anatomy in Mimipiscis are apomorphic, questioning its ubiquity as stand-in for generalized actinopterygian conditions. However, the gill skeleton of the new form broadly corresponds to that of Mimipiscis, and adds to an emerging picture of primitive branchial architecture in crown gnathostomes. The new genus is recovered in a polytomy with Mimiidae and a subset of Devonian and stratigraphically younger actinopterygians, with no support found for a monophyletic grouping of Moythomasia with Mimiidae. PMID:26423841

New U-Pb zircon ages and the duration and division of Devonian time

Science.gov (United States)

Tucker, R.D.; Bradley, D.C.; Ver Straeten, C.A.; Harris, A.G.; Ebert, J.R.; McCutcheon, S.R.

1998-01-01

Newly determined U-Pb zircon ages of volcanic ashes closely tied to biostratigraphic zones are used to revise the Devonian time-scale. They are: 1) 417.6 ?? 1.0 Ma for an ash within the conodont zone of Icriodus woschmidti/I. w. hesperius Lochkovian); 2) 408.3 ?? 1.9 Ma for an ash of early Emsian age correlated with the conodont zones of Po. dehiscens--Lower Po. inversus; 3) 391.4 ?? 1.8 Ma for an ash within the Po. c. costatus Zone and probably within the upper half of the zone (Eifelian); and 4) 381.1 ?? 1.3 Ma for an ash within the range of the Frasnian conodont Palmatolepis punctata (Pa. punctata Zone to Upper Pa. hassi Zone). U-Pb zircon ages for two rhyolites bracketing a palyniferous bed of the pusillites-lepidophyta spore zone, are dated at 363.8 ?? 2.2 Ma and 363 ?? 2.2 Ma and 363.4 ?? 1.8 Ma, respectively, suggesting an age of ~363 Ma for a level within the late Famennian Pa. g. expansa Zone. These data, together with other published zircon ages, suggest that the base and top of the Devonian lie close to 418 Ma and 362 Ma, respectively, thus lengthening the period of ~20% over current estimates. We suggest that the duration of the Middle Devonian (Eifelian and Givitian) is rather brief, perhaps no longer than 11.5 Myr (394 Ma-382.5 Ma), and that the Emsian and Famennian are the longest stages in the period with estimated durations of ~15.5 Myr and 14.5 Myr, respectively.

Uranium laterite from Ipora/Amorinopolis region- Goias, Brazil

International Nuclear Information System (INIS)

Fernandes, S.M.

1983-01-01

The present study gives an account of the uranium bearing laterite in the district of Amorinopolis, GO. Emphasis is given in the study of its mineralogy and of the mineralization controls. The uranium mineralization is chiefly found within the arkosic sandstones at the base of the Devonian Ponta Grossa Formation. The ore is tabular and concordant with the bedding, the controls being simultaneously litho-stratigraphic and biochemical. Narrow permeable horizons of arkosic sandstone lie between impermeable shale an siltstone layers. Within the permeable horizon fossil remains (probably brachiopods) are replaced by uranium minerals. The oxidized iron minerals may have acted to insulate and preserve the secondary soluble uranium minerals. (author)

Lower and Middle Devonian Malvinokaffric ostracods from the Precordillera Basin of San Juan, Argentina

Science.gov (United States)

Salas, María J.; Rustán, Juan J.; Sterren, Andrea F.

2013-08-01

Ostracod from the upper Lower to Middle Devonian rocks of the Argentine Precordillera Basin (Talacasto and Punta Negra formations) are studied. One new genus Pircawayra nov. gen., and five species (including three new: Pircawayra gigantea nov. gen. and sp., Lapazites trinodis nov. sp. and Keslingiella? teresae nov. sp.) are defined. The recorded ostracod fauna closely resembles that coeval from Bolivia and South Africa, exhibiting a remarkable endemism, not only at the genus level, but also at the species level. In addition to its low-diversity, the Malvinokaffric ostracod association is also characterized by having large, thick, coarsely ornamented and swollen valves. The similar ostracod composition from the Andean and South African basins suggests faunal exchange between these two areas. Based on the ostracod faunas, the Malvinokaffric Realm is clearly recognizable at least up to the Middle Devonian.

Lower Devonian lithofacies and palaeoenvironments in the southwestern margin of the East European Platform (Ukraine, Moldova and Romania

Directory of Open Access Journals (Sweden)

Natalia Radkovets

2016-11-01

Full Text Available Lower Devonian palaeoshelf deposits extend along the western margin of the East European Platform from the Baltic Sea to the Black Sea. These deposits have been studied on the territory of Ukraine (Volyn-Podillyan Plate, Dobrogean Foredeep and correlated with coeval deposits in Moldova and Romania (Moldovian Platform. The investigation of the Lower Devonian deposits, their thickness, petrographic and lithological characteristics allowed reconstruction of two types of lithofacies and distinguishing two different depositional environments. The first lithofacies belonging to the Lochkovian stage, consists of clayey-carbonate rocks and represents a continuation of the Upper Silurian marine strata. The other lithofacies encompassing the Pragian–Emsian comprises terrigenous reddish-brown rocks, which are roughly equivalent to the Old Red Sandstone, completes the Lower Devonian section. Establishing the occurrence and thickness distribution of the terrigenous lithofacies across the study area is important, because it forms potential reservoir rocks for both conventional and unconventional (tight gas hydrocarbons. Gas accumulation in these reservoir rocks has been discovered at the Lokachi field.

Discovery of the fossiliferous Cu Brei Formation (Lower Devonian) in the Kon Tum Block (South Viet Nam)

Science.gov (United States)

Thanh, Tong-Dzuy; Duyen, Than Duc; Hung, Nguyen Huu; My, Bui Phu

2007-01-01

Lower Devonian corals and stromatoporoids have recently been discovered in limestones among low grade metamorphic rocks on the western margin of the Kon Tum Block (South Viet Nam). This unit has been identified as the Cu Brei Formation. Coral and stromatoporoid species have been described including Squameofavosites aff. spongiosus, Parallelostroma cf. multicolumnum, Amphipora cf. rasilis, A. cf. raritalis, Simplexodictyon cf. artyschtense, Stromatopora cf. boriarchinovi and Stromatopora sp. indet. The Cu Brei Formation is exposed in a small area 6 km in length and 3 km wide at the foot of Cu Brei Mountain (Sa Thay District, Kon Tum Province). As this formation is in marine shelf facies it is probable that further exposures of Lower Devonian sediments may be discovered in the Kon Tum Block. This discovery raises the question of the tectonic history of the metamorphic Kon Tum Block. It is possible that the block was not an area of positive uplift from the beginning of Paleozoic as has been supposed, but was submerged in a marine environment, at least on its outer margins, in the Devonian, and possibly even earlier, in Early Paleozoic.

Root evolution at the base of the lycophyte clade: insights from an Early Devonian lycophyte

Science.gov (United States)

Matsunaga, Kelly K. S.; Tomescu, Alexandru M. F.

2016-01-01

Background and Aims The evolution of complex rooting systems during the Devonian had significant impacts on global terrestrial ecosystems and the evolution of plant body plans. However, detailed understanding of the pathways of root evolution and the architecture of early rooting systems is currently lacking. We describe the architecture and resolve the structural homology of the rooting system of an Early Devonian basal lycophyte. Insights gained from these fossils are used to address lycophyte root evolution and homology. Methods Plant fossils are preserved as carbonaceous compressions at Cottonwood Canyon (Wyoming), in the Lochkovian–Pragian (∼411 Ma; Early Devonian) Beartooth Butte Formation. We analysed 177 rock specimens and documented morphology, cuticular anatomy and structural relationships, as well as stratigraphic position and taphonomic conditions. Key Results The rooting system of the Cottonwood Canyon lycophyte is composed of modified stems that bear fine, dichotomously branching lateral roots. These modified stems, referred to as root-bearing axes, are produced at branching points of the above-ground shoot system. Root-bearing axes preserved in growth position exhibit evidence of positive gravitropism, whereas the lateral roots extend horizontally. Consistent recurrence of these features in successive populations of the plant preserved in situ demonstrates that they represent constitutive structural traits and not opportunistic responses of a flexible developmental programme. Conclusions This is the oldest direct evidence for a rooting system preserved in growth position. These rooting systems, which can be traced to a parent plant, include some of the earliest roots known to date and demonstrate that substantial plant–substrate interactions were under way by Early Devonian time. The morphological relationships between stems, root-bearing axes and roots corroborate evidence that positive gravitropism and root identity were evolutionarily

ANALYSIS OF DEVONIAN BLACK SHALES IN KENTUCKY FOR POTENTIAL CARBON DIOXIDE SEQUESTRATION AND ENHANCED NATURAL GAS PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Brandon C. Nuttall

2003-02-10

Proposed carbon management technologies include geologic sequestration of CO{sub 2}. A possible, but untested, strategy is to inject CO{sub 2} into organic-rich shales of Devonian age. Devonian black shales underlie approximately two-thirds of Kentucky and are generally thicker and deeper in the Illinois and Appalachian Basin portions of Kentucky. The Devonian black shales serve as both the source and trap for large quantities of natural gas; total gas in place for the shales in Kentucky is estimated to be between 63 and 112 trillion cubic feet. Most of this natural gas is adsorbed on clay and kerogen surfaces, analogous to the way methane is stored in coal beds. In coals, it has been demonstrated that CO{sub 2} is preferentially adsorbed, displacing methane at a ratio of two to one. Black shales may similarly desorb methane in the presence of CO{sub 2}. If black shales similarly desorb methane in the presence of CO{sub 2}, the shales may be an excellent sink for CO{sub 2} with the added benefit of serving to enhance natural gas production. The concept that black, organic-rich Devonian shales could serve as a significant geologic sink for CO{sub 2} is the subject this research. To accomplish this investigation, drill cuttings and cores will be selected from the Kentucky Geological Survey Well Sample and Core Library. CO{sub 2} adsorption analyses will be performed in order to determine the gas-storage potential of the shale and to identify shale facies with the most sequestration potential. In addition, new drill cuttings and sidewall core samples will be acquired to investigate specific black-shale facies, their uptake of CO{sub 2}, and the resultant displacement of methane. Advanced logging techniques (elemental capture spectroscopy) will be used to investigate possible correlations between adsorption capacity and geophysical log measurements.

ANALYSIS OF DEVONIAN BLACK SHALES IN KENTUCKY FOR POTENTIAL CARBON DIOXIDE SEQUESTRATION AND ENHANCED NATURAL GAS PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Brandon C. Nuttall

2003-04-28

Proposed carbon management technologies include geologic sequestration of CO{sub 2}. A possible, but untested, strategy is to inject CO{sub 2} into organic-rich shales of Devonian age. Devonian black shales underlie approximately two-thirds of Kentucky and are generally thicker and deeper in the Illinois and Appalachian Basin portions of Kentucky. The Devonian black shales serve as both the source and trap for large quantities of natural gas; total gas in place for the shales in Kentucky is estimated to be between 63 and 112 trillion cubic feet. Most of this natural gas is adsorbed on clay and kerogen surfaces, analogous to the way methane is stored in coal beds. In coals, it has been demonstrated that CO{sub 2} is preferentially adsorbed, displacing methane at a ratio of two to one. Black shales may similarly desorb methane in the presence of CO{sub 2}. If black shales similarly desorb methane in the presence of CO{sub 2}, the shales may be an excellent sink for CO{sub 2} with the added benefit of serving to enhance natural gas production. The concept that black, organic-rich Devonian shales could serve as a significant geologic sink for CO{sub 2} is the subject this research. To accomplish this investigation, drill cuttings and cores will be selected from the Kentucky Geological Survey Well Sample and Core Library. CO{sub 2} adsorption analyses will be performed in order to determine the gas-storage potential of the shale and to identify shale facies with the most sequestration potential. In addition, new drill cuttings and sidewall core samples will be acquired to investigate specific black-shale facies, their uptake of CO{sub 2}, and the resultant displacement of methane. Advanced logging techniques (elemental capture spectroscopy) will be used to investigate possible correlations between adsorption capacity and geophysical log measurements.

ANALYSIS OF DEVONIAN BLACK SHALES IN KENTUCKY FOR POTENTIAL CARBON DIOXIDE SEQUESTRATION AND ENHANCED NATURAL GAS PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Brandon C. Nuttall

2003-02-11

Proposed carbon management technologies include geologic sequestration of CO{sub 2}. A possible, but untested, strategy is to inject CO{sub 2} into organic-rich shales of Devonian age. Devonian black shales underlie approximately two-thirds of Kentucky and are generally thicker and deeper in the Illinois and Appalachian Basin portions of Kentucky. The Devonian black shales serve as both the source and trap for large quantities of natural gas; total gas in place for the shales in Kentucky is estimated to be between 63 and 112 trillion cubic feet. Most of this natural gas is adsorbed on clay and kerogen surfaces, analogous to the way methane is stored in coal beds. In coals, it has been demonstrated that CO{sub 2} is preferentially adsorbed, displacing methane at a ratio of two to one. Black shales may similarly desorb methane in the presence of CO{sub 2}. If black shales similarly desorb methane in the presence of CO{sub 2}, the shales may be an excellent sink for CO{sub 2} with the added benefit of serving to enhance natural gas production. The concept that black, organic-rich Devonian shales could serve as a significant geologic sink for CO{sub 2} is the subject this research. To accomplish this investigation, drill cuttings and cores will be selected from the Kentucky Geological Survey Well Sample and Core Library. CO{sub 2} adsorption analyses will be performed in order to determine the gas-storage potential of the shale and to identify shale facies with the most sequestration potential. In addition, new drill cuttings and sidewall core samples will be acquired to investigate specific black-shale facies, their uptake of CO{sub 2}, and the resultant displacement of methane. Advanced logging techniques (elemental capture spectroscopy) will be used to investigate possible correlations between adsorption capacity and geophysical log measurements.

U-Pb dating of silicic lavas, sills and syneruptive resedimented volcaniclastic deposits of the Lower Devonian Crudine Group, Hill End Trough, New South Wales

International Nuclear Information System (INIS)

Jagodzinski, E.A.; Black, L.P.

1999-01-01

The Hill End Trough of central-western New South Wales was an elongate deep marine basin that existed in the Lachlan Fold Belt from the early Late Silurian to late Early Devonian. It is represented by a regionally extensive. unfossiliferous sequence of interbedded turbidites and hemipelagites of substantially silicic Volcanic derivation, which passes laterally into contemporaneous shallow-water sedimentary rocks. The Turondale and Merrions Formations of the Lower Devonian Crudine Group are two prominent volcanogenic formations in the predominantly sedimentary trough sequence. They contain a range of primary and resedimented volcanic facies suitable for U-Pb dating. These include widespread subaqueous silicic lavas and/or lava cryptodomes. and thick sequences of crystal-rich volcaniclastic sandstone emplaced by a succession of muss-flows that were generated by interaction between contemporaneous subaerial pyroclastic flows and the sea. Ion microprobe dating of the two volcanogenic formations by means of the commonly used SL 13 zircon standard yields ages ranging between 411.3 ± 5.1 and 404.8 ± 4.8 Ma. Normalising the data against a different zircon standard (QGNG) yields preferred slightly older mean ages that range between 413.4 ± 6.6 and 407.1 ± 6.9 Ma. These ages broadly approximate the Early Devonian age that has been historically associated with the Crudine Group. However, the biostratigraphically inferred late Lochkovian - early Emsian (mid-Early Devonian) age for the Merrions Formation is inconsistent with the current Australian Phunerozoic Timescale, which assigns an age of 410 Ma to the Silurian-Devonian boundary, and ages of 404.5 Ma and 395.5 Ma to the base and top of the Pragian, respectively. There is, however, good agreement if the new ages are compared with the most recently published revision of the Devonian time-scale. This suggests that the Early Devonian stage boundaries of the Australian Phanerozoic Timescale need to be revised downward. The

Evolution of the Southern Margin of the Donbas (Ukraine) from Devonian to early Carboniferous Times.

NARCIS (Netherlands)

McCann, T.; Saintot, A.N.

2003-01-01

A Devonian-Early Carboniferous succession comprising thick clastic and carbonate sediments with interbedded volcanics was examined along the southern margin of the Donbas fold belt. Ukraine. Following initial rifting and subsidence, a continental (fluvial, lacustrine) succession was established.

Late Devonian glacial deposits from the eastern United States signal an end of the mid-Paleozoic warm period

Science.gov (United States)

Brezinski, D.K.; Cecil, C.B.; Skema, V.W.; Stamm, R.

2008-01-01

A Late Devonian polymictic diamictite extends for more than 400??km from northeastern Pennsylvania across western Maryland and into east-central West Virginia. The matrix-supported, unbedded, locally sheared diamictite contains subangular to rounded clasts up to 2??m in diameter. The mostly rounded clasts are both locally derived and exotic; some exhibit striations, faceting, and polish. The diamictite commonly is overlain by laminated siltstone/mudstone facies associations (laminites). The laminites contain isolated clasts ranging in size from sand and pebbles to boulders, some of which are striated. The diamictite/laminite sequence is capped by massive, coarse-grained, pebbly sandstone that is trough cross-bedded. A stratigraphic change from red, calcic paleo-Vertisols in strata below the diamictite to non-calcic paleo-Spodosols and coal beds at and above the diamictite interval suggests that the climate became much wetter during deposition of the diamictite. The diamictite deposit is contemporaneous with regressive facies that reflect fluvial incision during the Late Devonian of the Appalachian basin. These deposits record a Late Devonian episode of climatic cooling so extreme that it produced glaciation in the Appalachian basin. Evidence for this episode of climatic cooling is preserved as the interpreted glacial deposits of diamictite, overlain by glaciolacustrine varves containing dropstones, and capped by sandstone interpreted as braided stream outwash. The Appalachian glacigenic deposits are contemporaneous with glacial deposits in South America, and suggest that Late Devonian climatic cooling was global. This period of dramatic global cooling may represent the end of the mid-Paleozoic warm interval that began in the Middle Silurian. ?? 2008 Elsevier B.V. All rights reserved.

The Upper Devonian deposits in the northern part of Leon (Cantabrian Mountains, Northwestern Spain)

NARCIS (Netherlands)

Loevezijn, van G.B.S.; Raven, J.G.M.

1983-01-01

During the Late Devonian, deposition in the Cantabrian Mountains was largely controlled by movements along faults. By way of intermitting subsidence of the area south of the Sabero-Gordón line and the connected progradation of the coast during the Frasnian and early Famennian, three regressive

Late Devonian spermatophyte diversity and paleoecology at Red Hill, north-central Pennsylvania, USA

Energy Technology Data Exchange (ETDEWEB)

Cressler, Walter L. III. [Francis Harvey Green Library, 29 West Rosedale Avenue, West Chester University, West Chester, PA, 19383 (United States); Prestianni, Cyrille [Universite de Liege, Boulevard du Rectorat B18, Liege 4000 (Belgium); LePage, Ben A. [The Academy of Natural Sciences, 1900 Benjamin Franklin Parkway, Philadelphia, PA, 19103 and PECO Energy Company, 2301 Market Avenue, S9-1, Philadelphia, PA 19103 (United States)

2010-08-01

Early spermatophytes have been discovered at Red Hill, a Late Devonian (Famennian) fossil locality in north-central Pennsylvania, USA. The Red Hill locality contains an Archaeopteris-dominated flora within an outcrop of the Duncannon Member of the Catskill Formation. Palynological analyses of the plant fossil-bearing horizons within the Red Hill outcrop indicate deposition within the VCo palynozone. This is the earliest time horizon known to contain evidence for spermatophytes, and is contemporaneous with well-known spermatophyte-bearing deposits in West Virginia and Belgium. Some of the spermatophyte material from Red Hill compares well with Aglosperma sp., previously known as isolated ovules from the latest Devonian of South Wales and England, thus extending its geographic and stratigraphic range. Red Hill specimens of Aglosperma sp. occur both as isolated ovules and attached to dichotomously forking axes. Additional spermatophyte cupules discovered at Red Hill are morphologically similar to those of the previously described Late Devonian spermatophytes Elkinsia Rothwell, Scheckler, et Gillespie, Moresnetia Stockmans, and Xenotheca Arber et Goode. Some of the Red Hill cupule complexes are distinct from the aforementioned taxa in consisting of slender dichotomously forking axes terminating in paired cupules with highly fused and symmetric cupule quadrant lobes. The distinctive nature of these Red Hill specimens warrants the creation of Duodimidia pfefferkornii Cressler, Prestianni, et LePage gen. et sp. nov. Plant fossil remains with sphenopteroid foliage are also present at Red Hill, possibly attributable to the spermatophytes. Previous systematic sampling of the rich plant-fossil bearing layer at Red Hill and analysis of its floristic diversity and abundance as well as the presence and absence of charcoal suggests a pattern of floral turnover from a local-scale Rhacophyton-dominated community to spermatophyte colonization following disturbance by wildfires

Sedimentary uranium deposit of the Ipora/Amorinopolis region, state of Goias, Brazil

International Nuclear Information System (INIS)

Fernandes, S.M.; Leonardos, O.H.

1984-01-01

The uranium mineralization is chiefly found within arkosic sandstones at the base of the Devonian Ponta Grossa Formation. The ore is tabular and concordant with the bedding, the controls being simultaneously litho-stratigraphical and biochemical. Narrow permeable horizons of arkosic sandstone lie between impermeable shale and siltstone layers. Within the permeable horizon, the fossil remains (probably brachiopods) are replaced by uranium minerals. The oxidized iron minerals may have acted as to insulate and preserve the secondary soluble uranium minerals. The mineral paragenesis is represented by renardite, meta - autunite I, fourmarierite, Koninckite, ranquilite, meta-uranocircite II, barite, apatite, calophane, wavelite, varscite, an unnamed uranium mineral, quartz, calcedony, goethite, lepidocrocite and hematite. (Author) [pt

Assessment of undiscovered continuous gas resources in Upper Devonian Shales of the Appalachian Basin Province, 2017

Science.gov (United States)

Enomoto, Catherine B.; Trippi, Michael H.; Higley, Debra K.; Rouse, William A.; Dulong, Frank T.; Klett, Timothy R.; Mercier, Tracey J.; Brownfield, Michael E.; Leathers-Miller, Heidi M.; Finn, Thomas M.; Marra, Kristen R.; Le, Phuong A.; Woodall, Cheryl A.; Schenk, Christopher J.

2018-04-19

Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean undiscovered, technically recoverable continuous resources of 10.7 trillion cubic feet of natural gas in Upper Devonian shales of the Appalachian Basin Province.

Devonian and Lower Carboniferous Conodonts of the Cantabrian Mountains (Spain) and their stratigraphic application

NARCIS (Netherlands)

Adrichem Boogaert, van H.A.

1967-01-01

A short review of the literature on the stratigraphy of the Devonian and the Lower Carboniferous of the Cantabrian Mountains precedes the report of the author's stratigraphic and palaeontologic observations in León: the Río Esla area (Gedinnian to Viséan), the central Cantabrian area (Famennian to

ANALYSIS OF DEVONIAN BLACK SHALES IN KENTUCKY FOR POTENTIAL CARBON DIOXIDE SEQUESTRATION AND ENHANCED NATURAL GAS PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Brandon C. Nuttall

2003-10-29

CO{sub 2} emissions from the combustion of fossil fuels have been linked to global climate change. Proposed carbon management technologies include geologic sequestration of CO{sub 2}. A possible, but untested, sequestration strategy is to inject CO{sub 2} into organic-rich shales. Devonian black shales underlie approximately two-thirds of Kentucky and are thicker and deeper in the Illinois and Appalachian Basin portions of Kentucky than in central Kentucky. The Devonian black shales serve as both the source and trap for large quantities of natural gas; total gas in place for the shales in Kentucky is estimated to be between 63 and 112 trillion cubic feet. Most of this natural gas is adsorbed on clay and kerogen surfaces, analogous to methane storage in coal beds. In coals, it has been demonstrated that CO{sub 2} is preferentially adsorbed, displacing methane. Black shales may similarly desorb methane in the presence of CO{sub 2}. The concept that black, organic-rich Devonian shales could serve as a significant geologic sink for CO{sub 2} is the subject of current research. To accomplish this investigation, drill cuttings and cores were selected from the Kentucky Geological Survey Well Sample and Core Library. Methane and carbon dioxide adsorption analyses are being performed to determine the gas-storage potential of the shale and to identify shale facies with the most sequestration potential. In addition, sidewall core samples are being acquired to investigate specific black-shale facies, their potential CO{sub 2} uptake, and the resulting displacement of methane. Advanced logging techniques (elemental capture spectroscopy) are being investigated for possible correlations between adsorption capacity and geophysical log measurements. For the Devonian shale, average total organic carbon is 3.71 (as received) and mean random vitrinite reflectance is 1.16. Measured adsorption isotherm data range from 37.5 to 2,077.6 standard cubic feet of CO{sub 2} per ton (scf/ton) of

ANALYSIS OF DEVONIAN BLACK SHALES IN KENTUCKY FOR POTENTIAL CARBON DIOXIDE SEQUESTRATION AND ENHANCED NATURAL GAS PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Brandon C. Nuttall

2004-04-01

CO{sub 2} emissions from the combustion of fossil fuels have been linked to global climate change. Proposed carbon management technologies include geologic sequestration of CO{sub 2}. A possible, but untested, sequestration strategy is to inject CO{sub 2} into organic-rich shales. Devonian black shales underlie approximately two-thirds of Kentucky and are thicker and deeper in the Illinois and Appalachian Basin portions of Kentucky than in central Kentucky. The Devonian black shales serve as both the source and trap for large quantities of natural gas; total gas in place for the shales in Kentucky is estimated to be between 63 and 112 trillion cubic feet. Most of this natural gas is adsorbed on clay and kerogen surfaces, analogous to methane storage in coal beds. In coals, it has been demonstrated that CO{sub 2} is preferentially adsorbed, displacing methane. Black shales may similarly desorb methane in the presence of CO{sub 2}. The concept that black, organic-rich Devonian shales could serve as a significant geologic sink for CO{sub 2} is the subject of current research. To accomplish this investigation, drill cuttings and cores were selected from the Kentucky Geological Survey Well Sample and Core Library. Methane and carbon dioxide adsorption analyses are being performed to determine the gas-storage potential of the shale and to identify shale facies with the most sequestration potential. In addition, sidewall core samples are being acquired to investigate specific black-shale facies, their potential CO{sub 2} uptake, and the resulting displacement of methane. Advanced logging techniques (elemental capture spectroscopy) are being investigated for possible correlations between adsorption capacity and geophysical log measurements. For the Devonian shale, average total organic carbon is 3.71 percent (as received) and mean random vitrinite reflectance is 1.16. Measured adsorption isotherm data range from 37.5 to 2,077.6 standard cubic feet of CO{sub 2} per ton (scf

ANALYSIS OF DEVONIAN BLACK SHALES IN KENTUCKY FOR POTENTIAL CARBON DIOXIDE SEQUESTRATION AND ENHANCED NATURAL GAS PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Brandon C. Nuttall

2004-01-01

CO{sub 2} emissions from the combustion of fossil fuels have been linked to global climate change. Proposed carbon management technologies include geologic sequestration of CO{sub 2}. A possible, but untested, sequestration strategy is to inject CO{sub 2} into organic-rich shales. Devonian black shales underlie approximately two-thirds of Kentucky and are thicker and deeper in the Illinois and Appalachian Basin portions of Kentucky than in central Kentucky. The Devonian black shales serve as both the source and trap for large quantities of natural gas; total gas in place for the shales in Kentucky is estimated to be between 63 and 112 trillion cubic feet. Most of this natural gas is adsorbed on clay and kerogen surfaces, analogous to methane storage in coal beds. In coals, it has been demonstrated that CO{sub 2} is preferentially adsorbed, displacing methane. Black shales may similarly desorb methane in the presence of CO{sub 2}. The concept that black, organic-rich Devonian shales could serve as a significant geologic sink for CO{sub 2} is the subject of current research. To accomplish this investigation, drill cuttings and cores were selected from the Kentucky Geological Survey Well Sample and Core Library. Methane and carbon dioxide adsorption analyses are being performed to determine the gas-storage potential of the shale and to identify shale facies with the most sequestration potential. In addition, sidewall core samples are being acquired to investigate specific black-shale facies, their potential CO{sub 2} uptake, and the resulting displacement of methane. Advanced logging techniques (elemental capture spectroscopy) are being investigated for possible correlations between adsorption capacity and geophysical log measurements. For the Devonian shale, average total organic carbon is 3.71 (as received) and mean random vitrinite reflectance is 1.16. Measured adsorption isotherm data range from 37.5 to 2,077.6 standard cubic feet of CO{sub 2} per ton (scf/ton) of

Dolomitization and sedimentary cyclicity of the Ordovician, Silurian, and Devonian rocks in South Estonia

Directory of Open Access Journals (Sweden)

Kallaste, Toivo

2006-03-01

Full Text Available The distribution and composition of dolomitized rocks and stoichiometry of dolomite in southern Estonia in the Ordovician, Silurian, and Devonian were studied on the background of the facies, sedimentary cyclicity (nine shallowing-up cycles, and evolution of the palaeobasins. The composition of rocks and lattice parameters of dolomite were investigated using the X-ray diffraction, X-ray fluorescence, titration and gravimetric analyses, and porosity measurements. The formation of dolostones is directly determined by the cyclic evolution of palaeobasins. Dolomitized rocks belong to the shallow-water inner shelf or tidal/lagoonal facies belt of regressive phases of sedimentary cycles. Sediments of the deep shelf/transitional environment and transgressive phases are not dolomitized. The most stoichiometric is secondary replacive dolomite of Silurian and upper Ordovician dolostones, formed during the early diagenesis of normal-marine (saline shallow-shelf calcitic sediments. The content of insoluble residue does not affect the stoichiometry. The changes in lattice parameters are induced by the Ca/Mg ratio in the dolomite lattice. The dolomite of the dolostones contacting limestone or containing calcite has an expanded lattice. The primary (syngenetic dolostone of the lagoonal or tidal flat belt has also an expanded lattice. No dolomitizing effect of the waters of the Devonian palaeobasin on the underlying rocks was revealed. The whole data set of the studied dolostones is consistent with the marine water environment in the palaeobasin at the corresponding time and shows no sign of the inflow of external fluids. It suggests that the microbial model of dolomite formation may characterize the Ordovician, Silurian, and Devonian in southern Estonia. The occurrence of dolostones between undolomitized rocks limits the time of dolomitization to the early diagenetic stage.

Ichnologic Note. Evidence of Predation on the Rugose Coral Calceola Sandalina (Devonian, Czech Republic)

Czech Academy of Sciences Publication Activity Database

Galle, Arnošt; Mikuláš, Radek

2003-01-01

Roč. 10, - (2003), s. 37-41 ISSN 1042-0940 R&D Projects: GA AV ČR IAA3013207 Institutional research plan: CEZ:AV0Z3013912 Keywords : corals * Calceola * Devonian Subject RIV: DB - Geology ; Mineralogy http://rzblx1.uni-regensburg.de/ezeit/detail.phtml?bibid=CASCR&colors=7&lang=en&jour_id=41560

Wolfcampian brachiopods from the Bird Spring Group, Wamp Spring area, Las Vegas Range, Clark County, Nevada ( USA).

Science.gov (United States)

Mills, P.C.; Langenheim, R.L.

1987-01-01

The Wamp Spring section of the Bird Spring Group is subdivided into a basal platy limestone member, lower cliff-forming member, and upper cliff-forming member. Triticites, Schwagerina, and Schubertella kingi in the platy limestone member indicate an early Wolfcampian age. Schwagerina, Schubertella kingi, and a distinctive assemblage of brachiopods, similar to the West Texas fauna, indicate that the upper cliff-forming member is late Wolfcampian. The lower cliff-forming member is tentatively assigned to the middle Wolfcampian. The Wamp Spring sequence correlates temporally with the BSe 'formation' of the Bird Spring Group. The fossil-rich upper cliff-forming limestone member includes the new species Pontisia boodi, Crurithyris wampensis, and Calliprotonia(?) n. sp. A, as well as Hustedia culcitula, Crenispirifer(?) sp., Cenorhynchia(?) sp., Kutorginella(?) sp., marginiferids, lyssacine hexactinellid sponges, pleurotomarid and bellerophontid gastropods, cidaroid echinoids, rugose corals, cylindrical cryptostome bryozoans, and nuculids. -from Authors

DEVONIAN RUGOSE CORALS FROM THE KARAKORUM MOUNTAINS (NORTHERN PAKISTAN

Directory of Open Access Journals (Sweden)

STEFAN SCHRÖDER

2004-11-01

Full Text Available The Karakorum Block is regarded as a microplate of "Gondwanan" origin and was part of the Cimmerian continent ("Mega Lhasa" which rifted away from the northern margin of Gondwana during the Late Palaeozoic/Early Mesozoic. From the Northern Karakorum Range (Yarkhun and Karambar River Valleys: structurally belonging to the Northern Sedimentary Belt an Upper Givetian to Lower Frasnian rugose coral fauna of the Shogram Formation is described. The fauna is dominated by cosmopolitan genera such as Hexagonaria, Disphyllum, Macgeea and the Temnophyllum/Spinophyllum group, generally showing a geographically wide distribution, although being absent from the Eastern Americas Realm in the Upper Givetian/Lower Frasnian. Therefore its components are of little use for biogeographical deductions at sub-realm level, and in explaining the relation between the Karakorum Range and other Cimmerian crustal blocks. A remarkable exception is the first record of the genus Pseudopexiphyllum outside of Turkey, indicating a connection to the western part of the Cimmerides. On species level, the coral fauna of the Shogram Formation is characterized by the development of a diverse and rather unique fauna including about 35 taxa, that differs from the faunas known from neighbouring crustal blocks. So far, faunistic links to the Central Iranian Microcontinent (Yazd-, and Tabas-Block, the northwest Iranian Plate (Elburz, Central Pamir, the Lhasa Block and Western Qiangtang are not clear, and although each of these fragments are believed to be closely connected they were apparently not in direct contact during the Devonian. However, the Karakorum fauna is remarkably close to one known from the Helmand Block in Afghanistan, showing a very similar generic composition that includes numerous morphologically closely related, although not identical species. Accordingly, the restricted faunal exchange led to the development of new taxa. Distribution of the new species of Spinophyllum

Conodont-bearing formations of Devonian and Lower Carboniferous age in northern León and Palencia (Spain)

NARCIS (Netherlands)

Adrichem Boogaert, van H.A.

1965-01-01

Conodonts have been extracted from calcareous units of the Devonian and Lower Carboniferous sequence from 3 areas in the S. part of the Cantabrian Mountains. There can be distinguished Emsian, Givetian, Frasnian, Famennian and Viséan faunas.

A Large Trace Fossil in Nodular Limestones (Lower Devonian, Czech Republic): Sedimentological Consequences, Ethology and Taphonomy

Czech Academy of Sciences Publication Activity Database

Mikuláš, Radek; Hladil, Jindřich

2015-01-01

Roč. 22, č. 2 (2015), s. 69-76 ISSN 1042-0940 R&D Projects: GA ČR GA14-18183S Institutional support: RVO:67985831 Keywords : bioturbation * Fodinichnia * carbonate * nodules * Devonian * Czech Republic Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.935, year: 2015

Early Devonian polygnathids of Northeast Asia and correlation of Pragian/Emsian strata of the marginal seas of Angarida

Czech Academy of Sciences Publication Activity Database

Baranov, V.; Slavík, Ladislav; Blodgett, R. B.

2014-01-01

Roč. 89, č. 3 (2014), s. 645-678 ISSN 1214-1119 Institutional support: RVO:67985831 Keywords : Early Devonian * Pragian/Emsian strata * Angarida Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.515, year: 2014

Correlation of Early Devonian (Lochkovian-early Pragian) conodont faunas of the South Urals (Russia)

Czech Academy of Sciences Publication Activity Database

Mavrinskaya, T.; Slavík, Ladislav

2013-01-01

Roč. 88, č. 3 (2013), s. 283-296 ISSN 1214-1119 Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100131201 Institutional support: RVO:67985831 Keywords : South Urals, West Zilair Zone, Lower Devonian, global conodont correlation, Lochkovian, Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.495, year: 2013

A rich ichnofossil assemblage from the Frasnian (Upper Devonian) deposits at Andoma Hill, Onega Lake, Russia

Czech Academy of Sciences Publication Activity Database

Mikuláš, Radek; Meškis, S.; Ivanov, A.; Lukševičs, E.; Zupinš, I.; Stinkulis, G.

2013-01-01

Roč. 88, č. 2 (2013), s. 389-400 ISSN 1214-1119 Institutional research plan: CEZ:AV0Z30130516 Institutional support: RVO:67985831 Keywords : ichnology * East European Platform * Main Devonian field * Old Red Sandstone facies Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.495, year: 2013

Devonian trilobites of the southern Cantabrian Mountains (northern Spain) with a systematic description of the Asteropyginae

NARCIS (Netherlands)

Smeenk, Z.

1983-01-01

This paper shows the results of a research into the Devonian trilobites of the southern Cantabrian Mountains. The systematics of the most common group, the subfamily of the Asteropyginae, forms the major part of this work. More than 50 species, belonging to sixteen (sub)genera are distinguished;

Concentration mechanisms of uranium in the mineralized fractures of the Lower Devonian of the Belgian Ardennes - The case of the Oizy area

International Nuclear Information System (INIS)

Charlet, J.M.; Doremus, P.; Quinif, Y.

1987-01-01

During a reconnaissance survey for uranium in the Belgian Paleozoic several anomalies or U occurrences have been discovered in the Lower Devonian by a car-borne radiometric survey. These anomalies appear in relation with mobilization and reconcentration processes at the boundary of redox fronts or following alteration fronts in the detrital series of the Lower Devonian. This paper describes the Oizy anomaly which occurs in a fracturated zone of the Gedinnian formations of the Ardenne Anticline and puts it back in the general context of the U concentrations of the Lower Devonian of the Belgian Ardennes. After a lithostratigraphic, structural and radiometric study of the quarry where the U concentrations occur, a laboratory study of the surrounding rocks has been performed by various techniques (γ- and α-spectrometry, X-ray diffraction, autoradiography and low-level counting technique, analytical chemistry). One can conclude that the mineralized fractures of Oizy are due to a downward remobilization of U by subsurface processes during post-Hercynian periods. 26 refs.; 11 figs.; 1 plate; 2 tabs

PALEOMAGNETISM OF SILURIAN AND DEVONIAN VOLCANICS FROM THE CHINGIZ ISLAND ARC, KAZAKHSTAN, AND ITS BEARING ON TECTONIC EVOLUTION OF THE URAL-MONGOL BELT

Directory of Open Access Journals (Sweden)

Natalia M. Levashova

2011-01-01

Full Text Available The tectonic and paleogeographic evolution of the Ural-Mongol belt between the cratons of Baltica, Siberia, and Tarim is the key to the formation of the Eurasian supercontinent during Paleozoic time, but the views on this complicated process remain very disparate and sometimes controversial. Three volcanic formations of the Middle Silurian, LowertoMiddle Devonian and Middle Devonian age from the southwestern boundary of the Chingiz Range (NE Kazakhstan yields what are interpreted as primary paleomagnetic directions that help clarify the evolution of the belt. A singlepolarity characteristic component in midSilurian andesites yields a positive intraformational conglomerate test, whereas dualpolarity prefolding components are isolated from the two Devonian collections. These new data were evaluated together with previously published paleomagnetic results from Paleozoic rocks in the Chingiz Range, and allow us to establish with confidence the hemisphere in which the area was located at a given time. We conclude that NE Kazakhstan was steadily moving northward crossing the equator in Silurian time. These new paleomagnetic data from the Chingiz range also agree with and reinforce the hypothesis that the strongly curved volcanic belts of Kazakhstan underwent oroclinal bending between Middle Devonian and Late Carboniferous time. A comparison of the Chingiz paleolatitudes with those of Siberia shows similarities between the northward motion and rotational history of the Chingiz unit and those of Siberia, which imposes important constraints on the evolving paleogeography of the Ural-Mongol belt.

ANALYSIS OF DEVONIAN BLACK SHALES IN KENTUCKY FOR POTENTIAL CARBON DIOXIDE SEQUESTRATION AND ENHANCED NATURAL GAS PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Brandon C. Nuttall

2003-07-28

CO{sub 2} emissions from the combustion of fossil fuels have been linked to global climate change. Proposed carbon management technologies include geologic sequestration of CO{sub 2}. A possible, but untested, sequestration strategy is to inject CO{sub 2} into organic-rich shales. Devonian black shales underlie approximately two-thirds of Kentucky and are thicker and deeper in the Illinois and Appalachian Basin portions of Kentucky than in central Kentucky. The Devonian black shales serve as both the source and trap for large quantities of natural gas; total gas in place for the shales in Kentucky is estimated to be between 63 and 112 trillion cubic feet. Most of this natural gas is adsorbed on clay and kerogen surfaces, analogous to methane storage in coal beds. In coals, it has been demonstrated that CO{sub 2} is preferentially adsorbed, displacing methane. Black shales may similarly desorb methane in the presence of CO{sub 2}. The concept that black, organic-rich Devonian shales could serve as a significant geologic sink for CO{sub 2} is the subject of current research. To accomplish this investigation, drill cuttings and cores were selected from the Kentucky Geological Survey Well Sample and Core Library. Methane and carbon dioxide adsorption analyses are being performed to determine the gas-storage potential of the shale and to identify shale facies with the most sequestration potential. In addition, sidewall core samples are being acquired to investigate specific black-shale facies, their potential CO{sub 2} uptake, and the resulting displacement of methane. Advanced logging techniques (elemental capture spectroscopy) are being investigated for possible correlations between adsorption capacity and geophysical log measurements. Initial estimates indicate a sequestration capacity of 5.3 billion tons CO{sub 2} in the Lower Huron Member of the Ohio shale in parts of eastern Kentucky and as much as 28 billion tons total in the deeper and thicker portions of the

Devonian post-orogenic extension-related volcano-sedimentary rocks in the northern margin of the Tibetan Plateau, NW China: Implications for the Paleozoic tectonic transition in the North Qaidam Orogen

Science.gov (United States)

Qin, Yu; Feng, Qiao; Chen, Gang; Chen, Yan; Zou, Kaizhen; Liu, Qian; Jiao, Qianqian; Zhou, Dingwu; Pan, Lihui; Gao, Jindong

2018-05-01

The Maoniushan Formation in the northern part of the North Qaidam Orogen (NQO), NW China, contains key information on a Paleozoic change in tectonic setting of the NQO from compression to extension. Here, new zircon U-Pb, petrological, and sedimentological data for the lower molasse sequence of the Maoniushan Formation are used to constrain the timing of this tectonic transition. Detrital zircons yield U-Pb ages of 3.3-0.4 Ga with major populations at 0.53-0.4, 1.0-0.56, 2.5-1.0, and 3.3-2.5 Ga. The maximum depositional age of the Maoniushan Formation is well constrained by a youngest detrital zircon age of ∼409 Ma. Comparing these dates with geochronological data for the region indicates that Proterozoic-Paleozoic zircons were derived mainly from the NQO as well as the Oulongbuluk and Qaidam blocks, whereas Archean zircons were probably derived from the Oulongbuluk Block and the Tarim Craton. The ∼924, ∼463, and ∼439 Ma tectonothermal events recorded in this region indicate that the NQO was involved in the early Neoproterozoic assembly of Rodinia and early Paleozoic microcontinental convergence. A regional angular unconformity between Devonian and pre-Devonian strata within the NQO suggests a period of strong mountain building between the Oulongbuluk and Qaidam blocks during the Silurian, whereas an Early Devonian post-orogenic molasse, evidence of extensional collapse, and Middle to Late Devonian bimodal volcanic rocks and Carboniferous marine carbonate rocks clearly reflect long-lived tectonic extension. Based on these results and the regional geology, we suggest that the Devonian volcano-sedimentary rocks within the NQO were formed in a post-orogenic extensional setting similar to that of the East Kunlun Orogen, indicating that a major tectonic transition from compression to extension in these two orogens probably commenced in the Early Devonian.

Petrological, geochemical, isotopic, and geochronological constraints for the Late Devonian-Early Carboniferous magmatism in SW Gondwana (27-32°LS): an example of geodynamic switching

Science.gov (United States)

Dahlquist, Juan A.; Alasino, Pablo H.; Basei, Miguel A. S.; Morales Cámera, Matías M.; Macchioli Grande, Marcos; da Costa Campos Neto, Mario

2018-04-01

We report a study integrating 13 new U-Pb LA-MC-ICP-MS zircon ages and Hf-isotope data from dated magmatic zircons together with complete petrological and whole-rock geochemistry data for the dated granitic rocks. Sample selection was strongly based on knowledge reported in previous investigations. Latest Devonian-Early Carboniferous granite samples were collected along a transect of 900 km, from the inner continental region (present-day Eastern Sierras Pampeanas) to the magmatic arc (now Western Sierras Pampeanas and Frontal Cordillera). Based on these data together with ca. 100 published whole-rock geochemical analyses we conclude that Late Devonian-Early Carboniferous magmatism at this latitude represents continuous activity (ranging from 322 to 379 Ma) on the pre-Andean margin of SW Gondwana, although important whole-rock and isotopic compositional variations occurred through time and space. Combined whole-rock chemistry and isotope data reveal that peraluminous A-type magmatism started in the intracontinental region during the Late Devonian, with subsequent development of synchronous Carboniferous peraluminous and metaluminous A-type magmatism in the retro-arc region and calc-alkaline magmatism in the western paleomargin. We envisage that magmatic evolution was mainly controlled by episodic fluctuations in the angle of subduction of the oceanic plate (between flat-slab and normal subduction), supporting a geodynamic switching model. Subduction fluctuations were relatively fast (ca. 7 Ma) during the Late Devonian and Early Carboniferous, and the complete magmatic switch-off and switch-on process lasted for 57 Ma. Hf T DM values of zircon (igneous and inherited) from some Carboniferous peraluminous A-type granites in the retro-arc suggest that Gondwana continental lithosphere formed during previous orogenies was partly the source of the Devonian-Carboniferous granitic magmas, thus precluding the generation of the parental magmas from exotic terranes.

X-ray tomographic microscopy tightens affinity of the early Cambrian Oymurania to the brachiopod stem group

Directory of Open Access Journals (Sweden)

Artem Kouchinsky

2017-03-01

Full Text Available The geologically rapid biotic evolution in the early Cambrian is marked by the first appearance of major groups of animals in the fossil record (e.g., Budd and Jensen 2000; Kouchinsky et al. 2012. Along with the earliest crown-group representatives of the phylum Brachiopoda, more basal branches of the phylogenetic tree belonging to the stem-group Brachiopoda, such as tannuolinids and mikwitziids, diversified and became widespread during the early Cambrian (e.g., Williams and Holmer 2002; Balthasar et al. 2009; Skovsted et al. 2014. Synchrotron-radiation X-ray tomographic microscopy (SRXTM of Oymurania gravestocki reveals the microstructure of its calcium-phosphatic shell differentiated into two layers and intersecting systems of canals. The outer layer shows the acrotretoid columnar microstructure and the inner layer consists of continuous prismatic columns. Phosphatized setae preserved within tangential canals, as well as perpendicular canals of Micrina–Setatella type demonstrate homology with the tannuolinid Micrina and the mickwitziid Setatella. A unique and novel combination of microstructural features in Oymurania confirms its evolutionary position within the brachiopod stem group.

Formation evaluation in Devonian shale through application of new core and log analysis methods

International Nuclear Information System (INIS)

Luffel, D.L.; Guidry, F.K.

1990-01-01

In the Devonian shale of the Appalachian Basin all porosity in excess of about 2.5 percent is generally occupied by free hydrocarbons, which is mostly gas, based on results of new core and log analysis methods. In this study, sponsored by the Gas Research Institute, reservoir porosities averaged about 5 percent and free gas content averaged about 2 percent by bulk volume, based on analyses on 519 feet of conventional core in four wells. In this source-rich Devonian shale, which also provides the reservoir storage, the rock everywhere appears to be at connate, or irreducible, water saturation corresponding to two or three percent of bulk volume. This became evident when applying the new core and log analysis methods, along with a new plotting method relating bulk volume of pore fluids to porosity. This plotting method has proved to be a valuable tool: it provides useful insight on the fluid distribution present in the reservoir, it provides a clear idea of porosity required to store free hydrocarbons, it leads to a method of linking formation factor to porosity, and it provides a good quality control method to monitor core and log analysis results. In the Devonian shale an important part of the formation evaluation is to determine the amount of kerogen, since this appears as hydrocarbon-filled porosity to conventional logs. In this study Total Organic Carbon and pyrolysis analyses were made on 93 core samples from four wells. Based on these data a new method was used to drive volumetric kerogen and free oil content, and kerogen was found to range up to 26 percent by volume. A good correlation was subsequently developed to derive kerogen from the uranium response of the spectral gamma ray log. Another important result of this study is the measurement of formation water salinity directly on core samples. Results on 50 measurements in the four study wells ranged from 19,000 to 220,000 ppm NaCl

U-Pb zircon geochronology of Late Devonian to Early Carboniferous extension-related silicic volcanism in the northern New England Fold Belt

International Nuclear Information System (INIS)

Bryan, S.E.; Holcombe, R.J.; Fielding, C.R.; Allen, C.M.

2004-01-01

Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis of zircons confirm a Late Devonian to Early Carboniferous age (ca 360-350 Ma) for silicic volcanic rocks of the Campwyn Volcanics and Yarrol terrane of the northern New England Fold Belt (Queensland). These rocks are coeval with silicic volcanism recorded elsewhere in the fold belt at this time (Connors Arch, Drummond Basin). The new U-Pb zircon ages, in combination with those from previous studies, show that silicic magmatism was both widespread across the northern New England Fold Belt (>250 000 km 2 and >500 km inboard of plate margin) and protracted, occurring over a period of -15 million years. Zircon inheritance is commonplace in the Late Devonian - Early Carboniferous volcanics, reflecting anatectic melting and considerable reworking of continental crust. Inherited zircon components range from ca 370 to ca 2050 Ma, with Middle Devonian (385-370 Ma) zircons being common to almost all dated units. Precambrian zircon components record either Precambrian crystalline crust or sedimentary accumulations that were present above or within the zone of magma formation This contrasts with a lack of significant zircon inheritance in younger Permo-Carboniferous igneous rocks intruded through,and emplaced on top of, the Devonian-Carboniferous successions. The inheritance data and location of these volcanic rocks at the eastern margins of the northern New England Fold Belt, coupled with Sr-Nd, Pb isotopic data and depleted mantle model ages for Late Palaeozoic and Mesozoic magmatism, imply that Precambrian mafic and felsic crustal materials (potentially as old as 2050 Ma), or at the very least Lower Palaeozoic rocks derived from the reworking of Precambrian rocks, comprise basement to the eastern parts of the fold belt. This crustal basement architecture may be a relict from the Late Proterozoic breakup of the Rodinian supercontinent. Copyright (2004) Geological Society of Australia

Partial preservation of the Tentaculites Crotalinus shell from Ponta Grossa Formation (Devonian)

International Nuclear Information System (INIS)

Ciguel, J.H.G.; Roesler, O.

1988-01-01

This paper deals with an analysis of a single specimen of Tentaculites crotalinus SALTER emend. CIGUEL et al. (1984) that present a possible partial preservation of the shell. It comes from an outcrop of the Grossa Formation (Devonian) near Jaguariaiva, State of Parana. The skeletal microstructure of the Tentaculitoidea shell rather poorly Known. Thus, the phylogenetic relationships of these invertebrates still uncertain. Tentaculitids are very common fossils in Devonian Ponta Grossa Formation (Parana Basin) but so far Known only from external and internal moulds. The objective of this study is to demonstrate wheter the layer found in between the internal and external mould is or not a case shell preservation. The chemical composition of this layer and of the external mould was analysed by X rays. X rays difratometry was applied only to the matrix (at the external mould). The structure of the supposed shell remain was studied by binocular stereomicroscope and scanning electron microscope. It revealed a foliate structure due to several paralel to subparalel oriented lamelae, with a chemical composition distinct from the matrix, and some elements possibly mantained from the original shell composition. Thus, a partial preservation of the original shell seems to be the better explanation for this case. This shell would be composed by calcium carbonate disposed in laminar layers, the outer ones being impregnated by Fe and Mn molecules during the diagenetic processes. The skeletal composition and microstructure would suggest a molluscan affinity for the tentaculitida Order. (auThor) [pt

Investigation of mineral composition of differently treated devonian, quaternary and triassic clays of Latvia

International Nuclear Information System (INIS)

Kosorukovs, A.; Viss, R.

1999-01-01

Clayey fractions (particle size less than 5 μm )of the Latvian Devonian (Kuprava and Liepa deposits), Quaternary (Laza and Ugale deposits) and Triassic (Akmene deposit, Republic of Lithuania) clays have been obtained. The clayey fractions were converted in the form in which all the cations were exchanged for magnesium ions. After the ion exchange the fractions were treated with dimethyl sulfoxide or glycerol in the course for two days, one sample being subjected to thermal treatment at 550±110 C for two hours. Diffractograms for the treated samples have been obtained using a DRON-2,0 diffractometer (Co-radiation). Analysis of the obtained diffractograms show that: 1) the main clayey minerals of the Devonian clays occur to be hydromicas (mainly hydromuscovite) containing admixtures of kaolinite and quartz; 2) the main clayey minerals of the Quarternary clays also occur to be hydromicas - mixtures of hydrobiotite and hydromuscovite containing admixtures of kaolinite and iron-containing chlorite; 3) smectite occurs to be the main mineral of the Triassic clay; it contains admixtures of hydromica and chlorite; 4) the Triassic and Quaternary clays contain fine- and coarse-grained carbonates, mainly calcite, in quantities of 10-16%; 5) iron and titanium are included in fine grained minerals. (author)

Middle Devonian palynomorphs from southern Moravia: an evidence of rapid change from terrestrial deltaic plain to carbonate platform conditions

Czech Academy of Sciences Publication Activity Database

Vavrdová, Milada; Dašková, Jiřina

2011-01-01

Roč. 62, č. 2 (2011), s. 109-119 ISSN 1335-0552 Institutional research plan: CEZ:AV0Z30130516 Keywords : Devonian marine transgression * basal elastics * miospores * acritarchs Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.787, year: 2011

The Carboniferous of the Western Karakoram (Pakistan)

Science.gov (United States)

Gaetani, M.; Zanchi, A.; Angiolini, L.; Olivini, G.; Sciunnach, D.; Brunton, H.; Nicora, A.; Mawson, R.

2004-05-01

The results of the study of the Carboniferous successions in the western part of the Northern Karakoram during three geological expeditions are summarized here. Rocks of that period are not uniformly preserved in the several thrust sheets forming the Northern Karakoram. In most of them only the basal part of the Carboniferous, up to the Visean, is preserved, whilst in the Karambar thrust sheet a more complete section—previously almost unknown—is preserved. Four new lithostratigraphic units, time-constrained by brachiopod and conodont biostratigraphy, are described, from bottom to top: (1) the Margach Formation: prevailing dark shales with subordinate fine subarkoses and quartzarenites, up to 300 m thick (mid-Famennian to middle Tournaisian); (2) the Ribat Formation: grey crinoidal limestones passing upwards to dark marly limestones and marls, at least 300 m thick (middle Tournaisian to Serpukhovian); (3) the Lupsuk Formation: subarkoses to feldspathic quartzarenites in thick beds, alternating with dark shales and siltstones, up to 400 m thick (Serpukhovian to uppermost Carboniferous); (4) within the Lupsuk Formation a local member, the Twin Valleys Member, up to 100 m thick, a bioclastic limestone intercalation of post-Moscovian age, is distinguished. The Carboniferous successions are invariably sealed by the arkoses to quartzarenites of the Gircha Formation, 133 m above the base of which, in the Karambar area, an Asselian brachiopod fauna was recovered. The Carboniferous succession is interpreted as recording the evolution of the passive margin of the Northern Karakoram Terrane, from early rifting stage in the Late Devonian to syn-rift events during the Late Carboniferous. The basal part of the Gircha Formation, of latest Carboniferous-earliest Permian age, is considered to have been deposited above a break-up unconformity, linked to the early drifting in the seaway bordering the Karakoram. In the palaeontological appendix the most significant brachiopod taxa

Sequence stratigraphy and a revised sea-level curve for the Middle Devonian of eastern North America

Science.gov (United States)

Brett, Carlton E.; Baird, G.C.; Bartholomew, A.J.; DeSantis, M.K.; Ver Straeten, C.A.

2011-01-01

The well-exposed Middle Devonian rocks of the Appalachian foreland basin (Onondaga Formation; Hamilton Group, Tully Formation, and the Genesee Group of New York State) preserve one of the most detailed records of high-order sea-level oscillation cycles for this time period in the world. Detailed examination of coeval units in distal areas of the Appalachian Basin, as well as portions of the Michigan and Illinois basins, has revealed that the pattern of high-order sea-level oscillations documented in the New York-Pennsylvania section can be positively identified in all areas of eastern North America where coeval units are preserved. The persistence of the pattern of high-order sea-level cycles across such a wide geographic area suggests that these cycles are allocyclic in nature with primary control on deposition being eustatic sea-level oscillation, as opposed to autocylic controls, such as sediment supply, which would be more local in their manifestation. There is strong evidence from studies of cyclicity and spectral analysis that these cycles are also related to Milankovitch orbital variations, with the short and long-term eccentricity cycles (100. kyr and 405. kyr) being the dominant oscillations in many settings. Relative sea-level oscillations of tens of meters are likely and raise considerable issues about the driving mechanism, given that the Middle Devonian appears to record a greenhouse phase of Phanerozoic history. These new correlations lend strong support to a revised high-resolution sea-level oscillation curve for the Middle Devonian for the eastern portion of North America. Recognized third-order sequences are: Eif-1 lower Onondaga Formation, Eif-2: upper Onondaga and Union Springs formations; Eif-Giv: Oatka Creek Formation; Giv-1: Skaneateles, Giv-2: Ludlowville, Giv-3: lower Moscow, Giv-4: upper Moscow-lower Tully, and Giv-5: middle Tully-Geneseo formations. Thus, in contrast with the widely cited eustatic curve of Johnson et al. (1985), which

Conodont biostratigraphy and depositional history of the Middle Devonian to Lower Carboniferous in the Cantabrian zone (Cantabrian Mountains, Spain)

NARCIS (Netherlands)

Raven, J.G.M.

1983-01-01

Within the Cantabrian zone during the Devonian and Early Carboniferous three large palaeogeographical units were of importance: the Asturian geanticline, the Palencian basin and the Asturo-Leonesian basin. These units have a different history of sedimentation, particularly the Palencian basin.

Boron isotopes in brachiopods during the end-Permian mass extinction: constraints on pH evolution and seawater chemistry

Science.gov (United States)

Jurikova, Hana; Gutjahr, Marcus; Liebetrau, Volker; Brand, Uwe; Posenato, Renato; Garbelli, Claudio; Angiolini, Lucia; Eisenhauer, Anton

2017-04-01

The global biogeochemical cycling of carbon is fundamental for life on Earth with the ocean playing a key role as the largest and dynamically evolving CO2 reservoir. The boron isotope composition (commonly expressed in δ11B) of marine calcium carbonate is considered to be one of the most reliable paleo-pH proxies, potentially enabling us to reconstruct past ocean pH changes and understand carbon cycle perturbations along Earth's geological record (e.g. Foster et al., 2008; Clarkson et al., 2015). Brachiopods present an advantageous and largely underutilised archive for Phanerozoic carbon cycle reconstructions considering their high abundance in the geological record and its origin dating back to the early Cambrian. Moreover, their shell made of low-magnesium calcite makes these marine calcifiers more resistant to post-depositional diagenetic alteration of primary chemical signals. We have investigated the δ11B using MC-ICP-MS (Neptune Plus) and B/Ca and other elemental ratios (Mg/Ca, Sr/Ca, Al/Ca, Li/Ca, Ba/Ca, Na/Ca and Fe/Ca) using ICP-MS-Quadrupole (Agilent 7500cx) from the same specimens in pristine brachiopod shells from two sections from northern Italy during the Late Permian. These sections cover the δ13C excursion in excess of ˜4 ‰ (Brand et al., 2012) and are associated with major climate and environmental perturbations that lead to the mass extinction event at the Permian-Triassic boundary. Particular emphasis will be placed on the implications of our new paleo-pH estimates on the seawater chemistry during the Late Permian. Brand, U., Posenato, R., Came, R., Affek, H., Angiolini, L., Azmy, K. and Farabegoli, E.: The end-Permian mass extinction: A rapid volcanic CO2 and CH4-climatic catastrophe, Chemical Geology 323, 121-144, doi:10.1016/j.chemgeo.2012.06.015, 2012. Clarkson, M.O., Kasemann, S.A., Wood, R.A., Lenton, T.M., Daines, S.J., Richoz, S., Ohnemueller, F., Meixner, A., Poulton, S.W. and Tipper, E.T.: Ocean acidification and the Permo

Lower Paleozoic carbonate rocks of Baird Mountains Quadrangle, Alaska

Energy Technology Data Exchange (ETDEWEB)

Dumoulin, J.A.; Harris, A.G.

1985-04-01

Lower Paleozoic carbonate rocks in the Baird Mountains quadrangle form a relatively thin (about 550 m), chiefly shallow-water succession that has been imbricately thrust and metamorphosed to lower greenschist facies. Middle and Upper Cambrian rocks - the first reported from the western Brooks Range - occur in the northeastern quarter of the quadrangle, south of Angayukaqsraq (formerly Hub) Mountain. They consist of marble grading upward into thin-bedded marble/dolostone couplets and contain pelagiellid mollusks, acetretid brachiopods, and agnostid trilobites. Sedimentologic features and the Pelagiellas indicate a shallow-water depositional environment. Overlying these rocks are Lower and Middle Ordovician marble and phyllite containing graptolites and conodonts of midshelf to basinal aspect. Upper Ordovician rocks in this area are bioturbated to laminated dolostone containing warm, shallow-water conodonts. In the Omar and Squirrel Rivers areas to the west, the Lower Ordovician carbonate rocks show striking differences in lithofacies, biofacies, and thickness. Here they are mainly dolostone with locally well-developed fenestral fabric and evaporite molds, and bioturbated to laminated orange- and gray-weathering dolomitic marble. Upper Silurian dolostone, found near Angayukaqsraq Mountain and on the central Squirrel River, contains locally abundant corals and stronmatoporoids. Devonian carbonate rocks are widely distributed in the Baird Mountains quadrangle; at least two distinct sequences have been identified. In the Omar area, Lower and Middle Devonian dolostone and marble are locally cherty and rich in megafossils. In the north-central (Nakolik River) area, Middle and Upper Devonian marble is interlayered with planar to cross-laminated quartz-carbonate metasandstone and phyllite.

Devonian/Carboniferous boundary glacioeustatic fluctuations in a platform-to-basin direction: A geochemical approach of sequence stratigraphy in pelagic settings

Czech Academy of Sciences Publication Activity Database

Bábek, O.; Kumpan, T.; Kalvoda, J.; Matys Grygar, Tomáš

2016-01-01

Roč. 337, MAY (2016), s. 81-99 ISSN 0037-0738 Institutional support: RVO:61388980 Keywords : Element geochemistry * Hangenberg event * Glacioeustasy * Devonian/Carboniferous boundary * Sedimentation rate Subject RIV: DD - Geochemistry Impact factor: 2.373, year: 2016

Outlook of searching for oil and gas formations in the lower Frasnian-middle Devonian oil and gas complex in northern regions of the Timano-Pechora Province

Energy Technology Data Exchange (ETDEWEB)

Aleksin, G.A.; Rapoport, B.I.; Rassomakhin, V.Y.; Rossikhin, Y.A.

1981-01-01

In the northern part of the Timano-Pechora Province, highly promising middle Devonian and lower Frasnian terrigenous deposits are broadly developed. Seismic exploration has established a reduction in thicknesses of the subdomanic deposits in the near-anticline zones of structures of the ancient formation which are associated with zones of oil and gas accumulation are confined to traps of nonanticlinal and mixed types. In order to realize the program for studying terrigenous deposits of the Devonian it is necessary to accelerate drilling of search and parametric wells 8 of Kumzha, 1 of Vydshor, and 1 of Nosovaya. It is necessary to begin drilling well 5 at the Laydozhskiy field in the anticline of the new elevation revealed from results of detailed seismic work. It is necessary to drill wells on the lower Paleozoic deposits at the Diyatynskiy, Myadloveyyakhskiy, Nyamyurkhitskiy, Sadayeginskiy, East Khoreyverskiy elevations of the North Khoreyverskiy Basin, on structures of the Sorokin swell, on the Malozemel'sko-Kolguyevskiy monocline. It is necessary to accelerate searches at the khyl'chuyuskiy, Yareyyuskiy, North Khar'yaginskiy, Inzyreyskiy and other areas of the Kolvinskiy megaswell. The most important primary task of investigating the lower Frasnian-middle Devonian complex is to trace the zones of development of terrigenous deposits of the middle Devonian and zones of their thinning, as well as to prepare all structures in these deposits for seismic exploration by MOGT.

Horizontal Devonian shale well, Columbia Natural Resources, Inc. 's, Pocohontas Development Corp. Well 21747, Martin County, Kentucky

Energy Technology Data Exchange (ETDEWEB)

Koziar, G.; Ahmad, M.M.; Friend, L.L.; Friend, M.L.; Rothman, E.M.; Stollar, R.L. (Columbia Gas System Service Corp., Columbus, OH (United States))

1991-05-01

Columbia Gas and the United States Department of Energy (DOE) have successfully completed field work on a horizontally drilled Devonian shale well located in Martin County, Kentucky. The objective of this cofunded project is to assess the effectiveness and economic feasibility of applying horizontal drilling and hydraulically fracturing stimulation techniques to enhance the extraction of natural gas from the Devonian shale. The well is comprised of three segments: a conventional vertical section, an angle build section and a horizontal section. The well reached a measured depth (MD) of 6263 feet, 3810 feet true vertical depth (TVD), with a horizontal displacement of 2812 feet achieved in the desired direction of N10{degrees}W. Both air and foam were used as drilling fluids. The vertical, lateral and tangent sections were drilled using conventional rotary drilling methods. Downhole motors were used to build angle. A total combined final open flow of 3.1 MMcfd was measured from all zones. Total well expenditures are approximately $1,460,000. Of this amount, $700,000 is directly related to the research and learning curve experience aspects. It is projected that the same horizontal well could be drilled with existing technology for $700,000. If advanced can be made in MWD systems for air drilling environments, wells of this type could be drilled routinely for $500,000. It appears that application of horizontal drilling will result in at least acceleration of gas production and possibly the addition of recoverable reserves from the Devonian shale. Production data, necessary to validate this statement, are also required to determine the economics. As we gain experience and technology advances, cost reductions will occur; this will result in economic improvement.

Peeking out of the basins: looking for the Late Devonian Kellwasser Event in the open ocean in the Central Asian Orogenic Belt, southwestern Mongolia

Science.gov (United States)

Thomas, R. M., Jr.; Carmichael, S. K.; Waters, J. A.; Batchelor, C. J.

2017-12-01

Two of the top five most devastating mass extinctions in Earth's history occurred during the Late Devonian (419.2 Ma - 358.9 Ma), and are commonly associated with the black shale deposits of the Kellwasser and Hangenberg ocean anoxia events. Our understanding of these extinction events is incomplete partly due to sample bias, as 95% of the field sites studying the Late Devonian are limited to continental shelves and continental marine basins, and 77% of these sites are derived from the Euramerican paleocontinent. The Samnuuruul Formation at the Hoshoot Shiveetiin Gol locality (HSG), located in southwestern Mongolia, offers a unique opportunity to better understand global oceanic conditions during the Late Devonian. The HSG locality shows a continuous sequence of terrestrial to marine sediments on the East Junggar arc; an isolated, open-ocean island arc within the Central Asian Orogenic Belt (CAOB). Samples from this near shore locality consist of volcanogenic silts, sands and immature conglomerates as well as calc-alkalic basalt lava flows. Offshore sections contain numerous limestones with Late Devonian fossil assemblages. Preliminary biostratigraphy of the associated marine and terrestrial sequences can only constrain the section to a general Late Devonian age, but TIMS analysis of detrital zircons from volcanogenic sediments from the Samnuuruul Formation in localities 8-50 km from the site suggests a late Frasnian age (375, 376 Ma). To provide a more precise radiometric age of the HSG locality, zircon geochronology using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) will be performed at UNC-Chapel Hill. If the HSG section crosses the Frasnian-Famennian boundary, geochemical, mineralogical, and ichnological signatures of the Kellwasser Event are expected to be preserved, if the Kellwasser Event was indeed global in scope (as suggested by Carmichael et al. (2014) for analogous sites on the West Junggar arc in the CAOB). Black shale

Bibliography of the paleontology and paleoecology of the Devonian-Mississippian black-shale sequence in North America

Energy Technology Data Exchange (ETDEWEB)

Barron, L.S.; Ettensohn, F.R.

1980-06-01

The Devonian-Mississippian black-shale sequence is one of the most prominent and well-known stratigraphic horizons in the Paleozoic of the United States, yet the paleontology and its paleoecologic and paleoenvironmental implications are poorly known. This is in larger part related to the scarcity of fossils preserved in the shale - in terms of both diversity and abundance. Nonetheless, that biota which is preserved is well-known and much described, but there is little synthesis of this data. The first step in such a synthesis is the compilation of an inclusive bibliography such as this one. This bibliography contains 1193 entries covering all the major works dealing with Devonian-Mississippian black-shale paleontology and paleoecology in North America. Articles dealing with areas of peripheral interest, such as paleogeography, paleoclimatology, ocean circulation and chemistry, and modern analogues, are also cited. In the index, the various genera, taxonomic groups, and other general topics are cross-referenced to the cited articles. It is hoped that this compilation will aid in the synthesis of paleontologic and paleoecologic data toward a better understanding of these unique rocks and their role as a source of energy.

Evolution of an intra-oceanic island arc during the late Silurian to late Devonian, New England fold belt

International Nuclear Information System (INIS)

Offler, R.; Gamble, J.

2002-01-01

Geochemical studies of volcanic rocks in the Gamilaroi terrane and Calliope Volcanic Assemblage, New England Fold Belt, eastern Australia, indicate that the setting in which these rocks formed changed in both space and time. The Upper Silurian to Middle Devonian basalts of the Gamilaroi terrane show flat to slightly light rare-earth element (LREE) depleted chondrite normalised patterns, depletion of high field strength elements (HFSE) relative to N-MORB, low Ti/V and high Ti/Zr ratios, high Ni, Cr and large-ion lithophile element (LILE) contents, features characteristic of intra-oceanic island arc basaltic magmas. They are associated with low-K, less mafic volcanics, showing moderate LREE enrichment, low Nb and Y contents and Rb/Zr ratios. The depletion of HFSE in the basalts indicates that the magmas were derived from a refractory source in a supra-subduction zone setting. The presence of such a zone implies that the arc was associated with a backarc basin, the location of which was to the west where a wide backarc region existed from the Middle Silurian. This polarity of arc and backarc basin suggests that the subduction zone dipped to the west. In contrast to their older counterparts, Middle to Upper Devonian basalts of the Gamilaroi terrane have MORB-like chondrite normalised patterns and higher Ti and lower LILE contents. Moreover, they have low Ti/Zr ratios and MORB-like Ti/V ratios and HFSE contents, features typical of backarc basins. Dolerites of the Gamilaroi terrane also have predominantly backarc basin signatures. These features suggest that both the basalts and dolerites have been emplaced in an extensional environment produced during the rifting of the intra-oceanic island arc lithosphere. A progressive increase in Ti/V ratios, and TiO 2 and Fe 2 O 3 contents at constant MgO, of stratigraphically equivalent basalts, towards the north-northwest part of the belt, is consistent with either greater extension to the north or melting of a more fertile magma

STRONTIUM DISTRIBUTION IN UPPER DEVONIAN CONODONT ELEMENTS: A PALAEOBIOLOGICAL PROXY

Directory of Open Access Journals (Sweden)

ANDREY V. ZHURAVLEV

2017-04-01

Full Text Available Conodonts are an extinct group of marine animals possessing debated affinities. The conodont elements are composed of calcium phosphate [apatite (CaF] and collagen-like proteins. Distribution of Sr in the bioapatite of albid, lamellar and paralamellar tissues of some Upper Devonian conodont element crowns from NW Russia was studied by microprobe. The calcium phosphate of the lamellar and paralamellar tissues demonstrates periodical oscillation of Sr contents across the lamellae (0.4-0.5 wt% in the outer part of lamella, and 0.2 wt% in the inner part. The albid tissue contains Sr of less than 0.4 wt%. It is suggested that oscillations of Sr concentrations reflect the periodic growth of the lamellae, and the average Ca/Sr ratio can be a proxy of the growth rate.

Horizontal Devonian shale well, Columbia Natural Resources, Inc.`s, Pocohontas Development Corp. Well 21747, Martin County, Kentucky. Final report

Energy Technology Data Exchange (ETDEWEB)

Koziar, G.; Ahmad, M.M.; Friend, L.L.; Friend, M.L.; Rothman, E.M.; Stollar, R.L. [Columbia Gas System Service Corp., Columbus, OH (United States)

1991-05-01

Columbia Gas and the United States Department of Energy (DOE) have successfully completed field work on a horizontally drilled Devonian shale well located in Martin County, Kentucky. The objective of this cofunded project is to assess the effectiveness and economic feasibility of applying horizontal drilling and hydraulically fracturing stimulation techniques to enhance the extraction of natural gas from the Devonian shale. The well is comprised of three segments: a conventional vertical section, an angle build section and a horizontal section. The well reached a measured depth (MD) of 6263 feet, 3810 feet true vertical depth (TVD), with a horizontal displacement of 2812 feet achieved in the desired direction of N10{degrees}W. Both air and foam were used as drilling fluids. The vertical, lateral and tangent sections were drilled using conventional rotary drilling methods. Downhole motors were used to build angle. A total combined final open flow of 3.1 MMcfd was measured from all zones. Total well expenditures are approximately $1,460,000. Of this amount, $700,000 is directly related to the research and learning curve experience aspects. It is projected that the same horizontal well could be drilled with existing technology for $700,000. If advanced can be made in MWD systems for air drilling environments, wells of this type could be drilled routinely for $500,000. It appears that application of horizontal drilling will result in at least acceleration of gas production and possibly the addition of recoverable reserves from the Devonian shale. Production data, necessary to validate this statement, are also required to determine the economics. As we gain experience and technology advances, cost reductions will occur; this will result in economic improvement.

Environmental conditions as the cause of the great mass extinction of marine organisms in the Late Devonian

Science.gov (United States)

Barash, M. S.

2017-08-01

During the Late Devonian extinction, 70-82% of all marine species disappeared. The main causes of this mass extinction include tectonic activity, climate and sea-level fluctuations, volcanism, and the collision of the Earth with cosmic bodies (impact events). The major causes are considered to be volcanism accompanying formation of the Viluy traps and, probably, basaltic magmatism in the Southern Urals, alkaline magmatism within the East European platform, and volcanism in northern Iran and northern and southern China. Several large impact craters of Late Devonian age have been documented in different parts of the world. The available data indicate that this time period on the Earth was marked by two major sequences of events: terrestrial events that resulted in extensive volcanism and cosmic (or impact) events. They produced similar effects such as emissions of harmful chemical compounds and aerosols to cause greenhouse warming and the darkening of the atmosphere, which prevented photosynthesis and cause ocean stagnation and anoxia. This disrupted the food chain and reduced ecosystem productivity. As a result, all vital processes were disturbed and a large part of the marine biota became extinct.

Toward an exact age of Middle Devonian Čelechovice corals - past problems in biostratigraphy and present solutions complemented by new magnetosusceptibility measurements

Czech Academy of Sciences Publication Activity Database

Hladil, Jindřich; Pruner, Petr; Venhodová, Daniela; Hladilová, T.; Man, Otakar

2002-01-01

Roč. 7, - (2002), s. 65-71 ISSN 0945-7275 R&D Projects: GA AV ČR IAA3013802 Institutional research plan: CEZ:AV0Z3013912 Keywords : magnetosusceptibility stratigraphy * Devonian * Moravia Subject RIV: DB - Geology ; Mineralogy

Geological investigation of shaft mine in Devonian limestone in Kansas City, Missouri and other potentially dry excavated subsurface space in part of the Forest City Basin

Energy Technology Data Exchange (ETDEWEB)

Goebel, E.D.

1977-10-01

A high quality limestone is currently being mined from a deep shaft mine (1072 feet) in Middle Devonian rocks (Callaway) within the city limits of Kansas City, Missouri. About 15 acres of essentially dry space (room and pillar) with up to 14-foot ceilings have been developed. There are few natural joints observable in the rock within the mine. Some of these are periodically damp. More than 80% of the mine is dry. Saltwater from aquifers (Pennsylvanian) cut by the shaft accumulates behind the shaft at the pump station at 850 feet and at the bottom of the shaft (Devonian-Ordovician rocks). As long as the pumps lift the water to the surface, the mine can be kept relatively dry. Grouting of the aquifer's rocks in the shaft may seal off that source of water. The Burlington limestone of the Mississippian System is potentially mineable on the property now developed. The Burlington limestone, the Middle Devonian limestone, and the Kimmswick (Middle Ordovician) limestone are all potentially mineable by shaft mining in the northern part of Greater Kansas City and northward into the Forest City Basin.

Questioning hagfish affinities of the enigmatic Devonian vertebrate Palaeospondylus

Science.gov (United States)

Johanson, Zerina; Smith, Moya; Sanchez, Sophie; Senden, Tim; Trinajstic, Kate; Pfaff, Cathrin

2017-07-01

Palaeospondylus gunni Traquair, 1890 is an enigmatic Devonian vertebrate whose taxonomic affinities have been debated since it was first described. Most recently, Palaeospondylus has been identified as a stem-group hagfish (Myxinoidea). However, one character questioning this assignment is the presence of three semicircular canals in the otic region of the cartilaginous skull, a feature of jawed vertebrates. Additionally, new tomographic data reveal that the following characters of crown-group gnathostomes (chondrichthyans + osteichthyans) are present in Palaeospondylus: a longer telencephalic region of the braincase, separation of otic and occipital regions by the otico-occipital fissure, and vertebral centra. As well, a precerebral fontanelle and postorbital articulation of the palatoquadrate are characteristic of certain chondrichthyans. Similarities in the structure of the postorbital process to taxa such as Pucapampella, and possible presence of the ventral cranial fissure, both support a resolution of Pa. gunni as a stem chondrichthyan. The internally mineralized cartilaginous skeleton in Palaeospondylus may represent a stage in the loss of bone characteristic of the Chondrichthyes.

Zircon dating of Devonian-Carboniferous rocks from the Bombala area, New South Wales

International Nuclear Information System (INIS)

Sircombe, K.N.; McQueen, K.G.

2000-01-01

Zircons from two igneous and two sedimentary units in the Bombala area of southeastern New South Wales have been examined by the sensitive high resolution ion microprobe (SHRIMP) to establish a time frame in which to interpret these rocks. Previous studies have correlated these rocks with Late Devonian units of the south coast, solely upon the basis of stratigraphy and lithology as palaeontological evidence was absent. The two igneous units are the Hospital Porphyry and Paradise Porphyry occurring beneath the sedimentary units. Both give a Frasnian age that can be correlated with the Boyd Volcanic Complex. The sedimentary samples are from the basal and upper sections of the Rosemeath Formation, a fluvial 'redbed' consisting of conglomerate, coarse sandstone, and associated red siltstone and mudstone. Detrital zircons from the basal conglomeratic section at Kilbrechin indicate a dominant provenance from local Silurian granites and volcanics and a maximum depositional age that can be correlated with the Frasnian-Famennian Merrimbula Group. However, detrital zircons from the upper coarse sandstone section of the Rosemeath Formation at Endeavour Lookout challenge the positive correlation trend with a lack of Silurian-age grains and a presence of grains ranging from Late Devonian to Early Carboniferous in age. These results imply either that the south coast correlation is not valid for the upper sequences, or that the Merrimbula Group sequences also extend upward into the Carboniferous. The general coarseness of the Rosemeath Formation also suggests a relatively local provenance. No Early Carboniferous source is known in the immediate vicinity suggesting that Early Carboniferous igneous activity in this region of the Lachlan Orogen may have been more extensive than is currently realised. Copyright (1999) Geological Society of Australia

The morphogroups of small agglutinated foraminifera from the Devonian carbonate complex of the Prague Synform, (Barrandian area, Czech Republic)

Czech Academy of Sciences Publication Activity Database

Holcová, K.; Slavík, Ladislav

2013-01-01

Roč. 386, č. 5 (2013), s. 210-214 ISSN 0031-0182 Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100131201 Institutional support: RVO:67985831 Keywords : Barrandian area * Early Devonian * foraminifera * morphogroups Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.752, year: 2013

The sedimentary record and petrophysical logs from the Spanish Central Pyrenees: Implications for paleoclimate change in the Early Devonian

Czech Academy of Sciences Publication Activity Database

Slavík, Ladislav; Valenzuela-Ríos, J. I.; Hladil, Jindřich; Chadimová, Leona; Liao, J-Ch.; Hušková, Aneta; Calvo, H.; Hrstka, Tomáš

2015-01-01

Roč. 21, - (2015), s. 350-350 ISSN 1608-8166. [International Congress on Stratigraphy /2./. STRATI 2015. 19.07.2015-23.07.2015, Graz] Institutional support: RVO:67985831 Keywords : stratigraphy * Early Devonian * sedimentary record * paleoclimate change * Spanish Central Pyrenees Subject RIV: DB - Geology ; Mineralogy http://www.zobodat.at/pdf/Ber-Inst-Erdwiss-Univ-Graz_21_0001-0437.pdf

A Porolepiform Rhipidistian from the Lower Devonian of the Canadian Arctic

Directory of Open Access Journals (Sweden)

H.-P. Schultze

2000-01-01

Full Text Available A holoptychiid fish is described from the Lower Devonian of Arctic Canada. The new form is distinct from other holoptychiids by the presence of a large supraorbital bone and a boomerang-shaped tabular. Nasogaluakus n. gen. is the oldest and most primitive holoptychiid based on a phylogenetic analysis of porolepiforms and their closest relatives. The sequence of the genera corresponds to their stratigraphic appearance. Ein Holoptychiide aus dem Unterdevon der kanadischen Arktis wird beschrieben. Er unterscheidet sich durch ein großes Supraorbitale und die Bumerang-Form des Tabulare von allen übrigen Holoptychiiden. Nasogaluakus n. gen. ist der älteste und primitivste Holoptychiide, was durch eine phylogenetische Analyse der Porolepiformes belegt wird. Die Abfolge der Gattungen in diesem Verwandtschaftsschema stimmt mit ihrem zeitlichen Auftreten überein. doi:10.1002/mmng.20000030106

Impact Ejecta Layer from the Mid-Devonian: Possible Connection to Global Mass Extinctions

Science.gov (United States)

Ellwood, Brooks B.; Benoist, Stephen L.; Hassani, Ahmed El; Wheeler, Christopher; Crick, Rex E.

2003-06-01

We have found evidence for a bolide impacting Earth in the mid-Devonian (~380 million years ago), including high concentrations of shocked quartz, Ni, Cr, As, V, and Co anomalies; a large negative carbon isotope shift (-9 per mil); and microspherules and microcrysts at Jebel Mech Irdane in the Anti Atlas desert near Rissani, Morocco. This impact is important because it is coincident with a major global extinction event (Kacák/otomari event), suggesting a possible cause-and-effect relation between the impact and the extinction. The result may represent the extinction of as many as 40% of all living marine animal genera.

Silurian and Devonian source rocks and crude oils from the western part of Libya: Organic geochemistry, palynology and carbon stratigraphy

NARCIS (Netherlands)

Elkelani, Mohamed M.A.

2015-01-01

The Early Silurian “hot” shales and Late Devonian black shales are major regional oil and gas source rocks in North Africa. Their deposition probably played a major role in global carbon cycling in general because of the large areas of the ocean affected. Comparing the Libyan δ13C record with

A microanatomical and histological study of the postcranial dermal skeleton of the Devonian actinopterygian Cheirolepis canadensis

Directory of Open Access Journals (Sweden)

Louise Zylberberg

2016-06-01

Full Text Available The Devonian stem-actinoterygian Cheirolepis canadensis is potentially important to understand the evolution of the dermal skeleton of osteichthyans, but the last detailed histological study on this taxon was published more than forty years ago. Here, we present new data about the morphology and the histological structure of scales, fulcra, and fin-rays in the Devonian actinopterygian Cheirolepis canadensis through SEM and photomicroscopy. The scales have a typical palaeoniscoid organisation, with ganoine layers overlaying dentine and a bony basal plate, but the ganoine surface lacks the characteristic microtubercles that have been described on the ganoine surface of the scales of polypterids and many other actinopterygians. Fin-rays are composed of segmented and ramified lepidotrichia that show a structure reminiscent of scales, with ganoine and dentine components lying on a thick bony base. We describe articular processes between lepidotrichia that are reminiscent of, and plausibly homologous with, the peg-and-socket articulations between the scales. The analysis of the postcranial dermal skeleton of Cheirolepis canadensis shows that structural similarities between scales and lepidotrichia of this basal actinopterygian are greater than in more recent actinopterygians. The new data on histological and microanatomical structure of the dermal skeleton lend additional support to the hypothesis that lepidotichia are derivatives of scales, though they are also compatible with the more general hypothesis that scales, lepidotrichia and fulcra belong to the same morphogenetic system.

How Reducing was the Late Devonian Ocean? The Role of Extensive Expansion of Anoxia in Marine Biogeochemical Cycles of Redox Sensitive Metals.

Science.gov (United States)

Sahoo, S. K.; Jin, H.

2017-12-01

The evolution of Earth's biogeochemical cycles is intimately linked to the oxygenation of the oceans and atmosphere. The Late Devonian is no exception as its characterized with mass extinction and severe euxinia. Here we use concentrations of Molybdenum (Mo), Vanadium (V), Uranium (U) and Chromium (Cr) in organic rich black shales from the Lower Bakken Formation of the Williston Basin, to explore the relationship between extensive anoxia vs. euxinia and it's relation with massive release of oxygen in the ocean atmosphere system. XRF data from 4 core across the basin shows that modern ocean style Mo, U and Cr enrichments are observed throughout the Lower Bakken Formation, yet V is not enriched until later part of the formation. Given the coupling between redox-sensitive-trace element cycles and ocean redox, various models for Late Devonian ocean chemistry imply different effects on the biogeochemical cycling of major and trace nutrients. Here, we examine the differing redox behavior of molybdenum and vanadium under an extreme anoxia and relatively low extent of euxinia. The model suggests that Late Devonian was perhaps extensively anoxic- 40-50% compared to modern seafloor area, and a very little euxinia. Mo enrichments extend up to 500 p.p.m. throughout the section, representative of a modern reducing ocean. However, coeval low V enrichments only support towards anoxia, where anoxia is a source of V, and a sink for Mo. Our model suggests that the oceanic V reservoir is extremely sensitive to perturbations in the extent of anoxic condition, particularly during post glacial times.

Stratigraphy and facies of the Nocedo, Fueyo and Ermita formations (Upper Devonian to lowermost Carboniferous) in León, N Spain

NARCIS (Netherlands)

Loevezijn, van G.B.S.

1986-01-01

The Asturo-Leonese Basin is one of the three large palaeogeographical units of the Cantabrian Zone. In the north the basin is bounded by the Asturian Geanticline and the Palencian Basin. In the south the Palaeozoic succession is covered by Mesozoic and Tertiairy deposits. The Upper Devonian to

A global cyclostratigraphic framework constrains the timing and pacing of environmental changes over the Late Devonian (Frasnian - Famennian) mass extinction

Science.gov (United States)

De Vleeschouwer, David; Da Silva, Anne-Christine; Day, James E.; Whalen, Michael; Claeys, Philippe

2016-04-01

Milankovitch cycles (obliquity, eccentricity and precession) result in changes in the distribution of solar energy over seasons, as well as over latitudes, on time scales of ten thousands of years to millions of years. These changing patterns in insolation have induced significant variations in Earth's past climate over the last 4.5 billion years. Cyclostratigraphy and astrochronology utilize the geologic imprint of such quasi-cyclic climatic variations to measure geologic time. In recent years, major improvements of the Geologic Time Scale have been proposed through the application of cyclostratigraphy, mostly for the Mesozoic and Cenozoic (Gradstein et al., 2012). However, the field of Paleozoic cyclostratigraphy and astrochronology is still in its infancy and the application of cyclostratigraphic techniques in the Paleozoic allows for a whole new range of research questions. For example, unraveling the timing and pacing of environmental changes over the Late Devonian mass extinction on a 105-year time-scale concerns such a novel research question. Here, we present a global cyclostratigraphic framework for late Frasnian to early Famennian climatic and environmental change, through the integration of globally distributed sections. The backbone of this relative time scale consists of previously published cyclostratigraphies for western Canada and Poland (De Vleeschouwer et al., 2012; De Vleeschouwer et al., 2013). We elaborate this Euramerican base by integrating new proxy data -interpreted in terms of astronomical climate forcing- from the Iowa basin (USA, magnetic susceptibility and carbon isotope data) and Belgium (XRF and carbon isotope data). Next, we expand this well-established cyclostratigraphic framework towards the Paleo-Tethys Ocean, using magnetic susceptibility and carbon isotope records from the Fuhe section in South China (Whalen et al., 2015). The resulting global cyclostratigraphic framework implies an important refinement of the late Frasnian to

Environmental changes close to the Lower-Middle Devonian boundary; the Basal Choteč Event in the Prague Basin (Czech Republic)

Czech Academy of Sciences Publication Activity Database

Vodrážková, S.; Frýda, J.; Suttner, T. J.; Koptíková, Leona; Tonarová, P.

2013-01-01

Roč. 59, č. 2 (2013), s. 425-449 ISSN 0172-9179 R&D Projects: GA ČR GAP210/10/2351 Institutional support: RVO:67985831 Keywords : Basal Choteč Event * carbon isotope geochemistry * environmental changes * Lower-Middle Devonian * microfacies analysis * Prague Basin Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.338, year: 2013

UPPER FRASNIAN (UPPER DEVONIAN POLYGNATHUS AND ICRIODUS CONODONTS FROM THE BAHRAM FORMATION, HUR SECTION, KERMAN PROVINCE, SOUTHEASTERN IRAN

Directory of Open Access Journals (Sweden)

TAYEBEH AHMADI

2012-07-01

Full Text Available Conodont fauna from the Upper Devonian (Frasnian Bahram Formation at the Hur section, north of Kerman, southeast Iran, is dominated by species of Icriodus and Polygnathus. This fauna allowed discrimination of two biointervals from the Lower rhenana Zone to an Upper rhenana-linguiformis interval. The age of the lower part of the studied section is tentatively considered to be older than the Lower rhenana Zone. 

Association between catastrophic paleovegetation changes during Devonian-Carboniferous boundary and the formation of giant massive sulfide deposits

Science.gov (United States)

Menor-Salván, Cesar; Tornos, Fernando; Fernández-Remolar, David; Amils, Ricardo

2010-11-01

The Iberian Pyrite Belt (SW Iberia) is one of the largest sulfur anomalies in the Earth's crust. In the southern Iberian Pyrite Belt, more than 820 Mt of exhalative massive sulfides were deposited in less than one million years at the Devonian-Carboniferous boundary. The shale of the ore-bearing horizon contains biomarkers indicating major biogenic activity in a methanogenic setting, including a five-fold increase in typical vascular plant biomarkers and a significant anomaly in those probably indicating the presence of thermophilic Archaea. This contrasts with signatures in the average sedimentary rocks of the basin that indicate the sediments settled in oxic to sub-oxic environments, and that they have only minor biomarkers derived from continental paleoflora. These data show that the formation of the mineralization was not only related to major hydrothermal activity synchronous with volcanism but may also have been controlled by the input of large amounts of organic matter, mostly derived from the degradation of woodland detritus sourced in the nearby continent. This massive influx of organic matter could have accelerated extremophilic microbial activity that used short-chain hydrocarbons as electron donors for seawater sulfate reduction, resulting in concomitant massive sulfide precipitation. We propose that the giant massive sulfide deposits resulted from overlapping of geological and biological processes that occurred at the Devonian to Carboniferous transition, including: (1) continent collision during the onset of the Variscan orogeny leading to major paleogeographic changes and volcanism; (2) dramatic stress of continental ecosystems due to the combination of climatic change, volcanism, variations in the sea level and erosion on a regional scale; (3) major biomass destruction and increase of organic supply to marine environments; and, (4) generation of anoxic conditions and the thriving of sulfate reducing microorganisms. Under these conditions, massive

Petrogenesis of the postcollisional Middle Devonian monzonitic to granitic magmatism of the Sierra de San Luis, Argentina

Science.gov (United States)

López de Luchi, Mónica G.; Siegesmund, Siegfried; Wemmer, Klaus; Nolte, Nicole

2017-09-01

Middle Devonian granitoids intruded the Eastern Sierras Pampeanas basement ca. 600 km east of the inferred proto-Pacific margin of Gondwana along which a ca. 390 Ma collisional event developed. In the Sierra de San Luis, voluminous Middle Devonian (393-382 Ma) batholiths are composed of I- to A-type hybrid Monzonite and Granite suites. Shoshonite and subordinated high-K series, stocks, synplutonic dikes and enclaves make up the Monzonite Suite; rocks are metaluminous alkali-calcic magnesian porphyritic or equigranular monzonite, quartz monzonite, monzodiorite and scarce monzogabbro. High-K and subordinated shoshonite series metaluminous to mildly peraluminous magnesian alkali-calcic to calc-alkalic porphyritic or equigranular quartz monzonite, granodiorite, monzogranite and equigranular leucomonzogranites make up the Granite Suite plutons and batholiths. Only a small group of highly evolved granites are ferroan. SiO2 (46-62%), Cr, Ni, V, Sc, LILE, LREE, Th, Zr and variable, Sr/Y, (La/Yb)N and (Tb/Yb)N, smooth Eu/Eu*, moderate Na2O (ca 3.5), and troughs at Nb and Ta for Monzonite Suite rocks suggest an subduction-related enriched lithospheric mantle source. Sm-Nd data (TDM 0.98-1.08 Ga, εNd(380 Ma) 0.66-1.47) and 87Sr/86Sri (0.703520-0.704203) are compatible with an enriched mantle source. The metaluminous porphyritic quartz monzonite-monzogranite and the mildly peraluminous equigranular biotite monzogranites of the Granite Suite are characterized by relatively moderate Al2O3, CaO, and 87Sr/86Sri, high LILE, Cr, variable Sr/Y, (La/Yb)N and Eu/Eu* and low Rb/Sr ( 1.5, ASI 1.05-1.18, and Ga/Al 2.6-3.9, εNd(380 Ma) - 3.74 to - 3.95 and (87Sr/86Sr)i 0.710743-0.712955 which would point to metasedimentary or felsic igneous crustal sources. Nevertheless their TDM 1.36-1.38 Ga is considerably younger than the mean 1.8-1.6 Ga Eastern Sierras Pampeanas crustal residence age and less radiogenic. Middle Devonian magmatism would record an episode of crustal growth by enriched

Sequence stratigraphy from ``spot'' outcrops—example from a carbonate-dominated setting: Devonian-Carboniferous transition, Dinant synclinorium (Belgium)

Science.gov (United States)

Van Steenwinkel, M.

1990-12-01

The application of sequence stratigraphy appears to be perfectly valid in isolated "spot" outcrops, which usually are badly exposed and located in areas of strong tectonic overprint. The case study presented here is in a carbonate-dominated setting at the northern edge of the Cornwall-Rhenish basin, during latest Devonian and earliest Carboniferous times. The approach taken involved the analysis of facies and vertical facies evolutions, in combination with detailed biostratigraphy. The subsequent deduction of deepening and shallowing events, and the understanding of the sedimentary response to these events in different palaeogeographical positions, are the basis for lateral correlation of facies sequences. A similar trend in the changes of deepenings and shallowings throughout the area, regardless of lateral facies differentiation, indicates a relationship between bathymetric changes and relative sea-level changes, that is independent of local differences in the sedimentation or subsidence rates. The studied stratigraphic interval, with its apparently "abrupt" changes in facies or lithology, is the sedimentary response to six, gradually changing trends in the rate of relative sea-level fall and rise. End-Devonian, offshore highstand deposits (1) are capped by an unconformity surface or by a surface of submarine erosion and nondeposition, representing a sequence boundary (2). The overlying lowstand unit consists of a basal (3) and an upper (4) part. The basal part contains an oolitic and crinoidal sand shoals, associated with a transgressive lag deposit in offshore position; the upper, main part is a prograding wedge of shallow-marine crinoidal sands, intercalated with increasingly deeper-water shaly facies (higher-order fluctuation). This lowstand unit was deposited during the initial, slow phase of relative sea-level rise. It levelled the topographic relief before the final drowning during the subsequent rapid (near the rise inflection point) relative sea

Stable isotope analysis of Dacryoconarid carbonate microfossils: a new tool for Devonian oxygen and carbon isotope stratigraphy.

Science.gov (United States)

Frappier, Amy Benoit; Lindemann, Richard H; Frappier, Brian R

2015-04-30

Dacryoconarids are extinct marine zooplankton known from abundant, globally distributed calcite microfossils in the Devonian, but their shell stable isotope composition has not been previously explored. Devonian stable isotope stratigraphy is currently limited to less common invertebrates or bulk rock analyses of uncertain provenance. As with Cenozoic planktonic foraminifera, isotopic analysis of dacryoconarid shells could facilitate higher-resolution, geographically widespread stable isotope records of paleoenvironmental change, including marine hypoxia events, climate changes, and biocrises. We explored the use of Dacryoconarid isotope stratigraphy as a viable method in interpreting paleoenvironments. We applied an established method for determining stable isotope ratios (δ(13) C, δ(18) O values) of small carbonate microfossils to very well-preserved dacryoconarid shells. We analyzed individual calcite shells representing five common genera using a Kiel carbonate device coupled to a MAT 253 isotope ratio mass spectrometer. Calcite shell δ(13) C and δ(18) O values were compared by taxonomic group, rock unit, and locality. Single dacryoconarid calcite shells are suitable for stable isotope analysis using a Kiel-IRMS setup. The dacryoconarid shell δ(13) C values (-4.7 to 2.3‰) and δ(18) O values (-10.3 to -4.8‰) were consistent across taxa, independent of shell size or part, but varied systematically through time. Lower fossil δ(18) O values were associated with warmer water temperature and more variable δ(13) C values were associated with major bioevents. Dacryoconarid δ(13) C and δ(18) O values differed from bulk rock carbonate values. Dacryoconarid individual microfossil δ(13) C and δ(18) O values are highly sensitive to paleoenvironmental changes, thus providing a promising avenue for stable isotope chemostratigraphy to better resolve regional to global paleoceanographic changes throughout the upper Silurian to the upper Devonian. Our results

LATE DEVONIAN-CARBONIFEROUS CONODONTS FROM EASTERN IRAN

Directory of Open Access Journals (Sweden)

MEHDI YAZDI

1999-07-01

Full Text Available Conodont data from acid-leaching 110 samples from two Late Devonian-Carboniferous areas in the Shotori Range (Tabas region of eastern Iran are presented. At Howz-e-Dorah, a section (88 samples commencing high in the Bahram Formation (Givetian-early Frasnian extended through the Shishtu Formation (Frasnian, Early hassi Zone or older, to latest Tournaisian, anchoralis-latus Zone and the Sardar Formation (earliest Visean, texanus Zone, to late Namurian, sinuatus-corrugatus-sulcatus Zone and into the Jamal Formation (Permian. Four less exhaustively sampled sections (22 samples show the Kale Sardar area to be tectonically more complicated than the Howz-e-Dorah area. Useful marker horizons in the Howz-e-Dorah section, well constrained by conodont data, are: the early Frasnian (no older than Early hassi Zone biostromal beds of the Shishtu Formation, an early Famennian (Late triangularis to Early crepida interval of oolitic limestone, a cyclothem sequence straddling the Early Carboniferous-Late Carboniferous boundary, and an Early Permian interval of siliceous sand ("the white quartzite" of previous authors. Additionally, several iron-rich horizons, readily traceable from locality to locality, are well constrained by conodont ages. Eighty-five conodont species/subspecies are documented representing 24 genera.. Two new species, Polygnathus capollocki and Polygnathus ratebi and one new subspecies, Icriodus alternatus mawsonae are described. 

Ontogenetic and intraspecific variation in the late Emsian - Eifelian (Devonian) conodonts Polygnathus serotinus and P. bultyncki in the Prague Basin (Czech Republic) and Nevada (western U.S.)

Science.gov (United States)

Klapper, Gilbert; Vodrážková, Stanislava

2013-06-01

Klapper, G. and Vodražkova, S. 2013. Ontogenetic and intraspecific variation in the late Emsian - Eifelian (Devonian) conodonts Polygnathus serotinus and P. bultyncki in the Prague Basin (Czech Republic) and Nevada (western U.S.). Acta Geologica Polonica, 63 (2), 153-174, Warszawa. Samples from populations of Polygnathus serotinus Telford 1975 and P. bultyncki Weddige 1977 from the Prague Basin and Nevada display normal variation for Devonian conodont species. A considerable number of previous authors, however, have proposed unnecessary synonyms of these two species, primarily because they have not recognized ontogenetic variation. In contrast, we interpret the variation as ontogenetic as well as intraspecific and present detailed synonymies as a result. A third species, P. praetrigonicus Bardashev 1992, which has been carried in open nomenclature for many years, is an important indicator of the basal costatus Zone in the Prague Basin, New York, and Nevada. We review the stratigraphic distribution of these three species and the conodont zonation across the Emsian-Eifelian (Lower-Middle Devonian) boundary. Polygnathus pseudocostatus sp. nov. (partitus-costatus zones, central Nevada) is described herein. We have observed a decrease in the pit size during ontogeny in P. bultyncki although we have not measured enough specimens to rule out intraspecific versus ontogenetic variation.

First shark from the Late Devonian (Frasnian) Gogo Formation, Western Australia sheds new light on the development of tessellated calcified cartilage.

Science.gov (United States)

Long, John A; Burrow, Carole J; Ginter, Michal; Maisey, John G; Trinajstic, Kate M; Coates, Michael I; Young, Gavin C; Senden, Tim J

2015-01-01

Living gnathostomes (jawed vertebrates) comprise two divisions, Chondrichthyes (cartilaginous fishes, including euchondrichthyans with prismatic calcified cartilage, and extinct stem chondrichthyans) and Osteichthyes (bony fishes including tetrapods). Most of the early chondrichthyan ('shark') record is based upon isolated teeth, spines, and scales, with the oldest articulated sharks that exhibit major diagnostic characters of the group--prismatic calcified cartilage and pelvic claspers in males--being from the latest Devonian, c. 360 Mya. This paucity of information about early chondrichthyan anatomy is mainly due to their lack of endoskeletal bone and consequent low preservation potential. Here we present new data from the first well-preserved chondrichthyan fossil from the early Late Devonian (ca. 380-384 Mya) Gogo Formation Lägerstatte of Western Australia. The specimen is the first Devonian shark body fossil to be acid-prepared, revealing the endoskeletal elements as three-dimensional undistorted units: Meckel's cartilages, nasal, ceratohyal, basibranchial and possible epibranchial cartilages, plus left and right scapulocoracoids, as well as teeth and scales. This unique specimen is assigned to Gogoselachus lynnbeazleyae n. gen. n. sp. The Meckel's cartilages show a jaw articulation surface dominated by an expansive cotylus, and a small mandibular knob, an unusual condition for chondrichthyans. The scapulocoracoid of the new specimen shows evidence of two pectoral fin basal articulation facets, differing from the standard condition for early gnathostomes which have either one or three articulations. The tooth structure is intermediate between the 'primitive' ctenacanthiform and symmoriiform condition, and more derived forms with a euselachian-type base. Of special interest is the highly distinctive type of calcified cartilage forming the endoskeleton, comprising multiple layers of nonprismatic subpolygonal tesserae separated by a cellular matrix, interpreted

First shark from the Late Devonian (Frasnian Gogo Formation, Western Australia sheds new light on the development of tessellated calcified cartilage.

Directory of Open Access Journals (Sweden)

John A Long

Full Text Available Living gnathostomes (jawed vertebrates comprise two divisions, Chondrichthyes (cartilaginous fishes, including euchondrichthyans with prismatic calcified cartilage, and extinct stem chondrichthyans and Osteichthyes (bony fishes including tetrapods. Most of the early chondrichthyan ('shark' record is based upon isolated teeth, spines, and scales, with the oldest articulated sharks that exhibit major diagnostic characters of the group--prismatic calcified cartilage and pelvic claspers in males--being from the latest Devonian, c. 360 Mya. This paucity of information about early chondrichthyan anatomy is mainly due to their lack of endoskeletal bone and consequent low preservation potential.Here we present new data from the first well-preserved chondrichthyan fossil from the early Late Devonian (ca. 380-384 Mya Gogo Formation Lägerstatte of Western Australia. The specimen is the first Devonian shark body fossil to be acid-prepared, revealing the endoskeletal elements as three-dimensional undistorted units: Meckel's cartilages, nasal, ceratohyal, basibranchial and possible epibranchial cartilages, plus left and right scapulocoracoids, as well as teeth and scales. This unique specimen is assigned to Gogoselachus lynnbeazleyae n. gen. n. sp.The Meckel's cartilages show a jaw articulation surface dominated by an expansive cotylus, and a small mandibular knob, an unusual condition for chondrichthyans. The scapulocoracoid of the new specimen shows evidence of two pectoral fin basal articulation facets, differing from the standard condition for early gnathostomes which have either one or three articulations. The tooth structure is intermediate between the 'primitive' ctenacanthiform and symmoriiform condition, and more derived forms with a euselachian-type base. Of special interest is the highly distinctive type of calcified cartilage forming the endoskeleton, comprising multiple layers of nonprismatic subpolygonal tesserae separated by a cellular matrix

Iron in the Middle Devonian aquifer system and its removal at Võru County water treatment plants, Estonia

OpenAIRE

Mariina Hiiob; Enn Karro

2012-01-01

Groundwater abstracted from the Middle Devonian aquifer system is the main source of drinking water in South Estonia. High iron and manganese concentrations in groundwater are the greatest problems in this region. The total iron concentrations up to 16 mg L–1 are mainly caused by a high Fe2+ content in water, pointing to the dominance of reducing conditions in the aquifer system. A pilot study was carried out to estimate the effectiveness of 20 groundwater purification plants with eight diffe...

Overview of the stratigraphy and initial quantitative biogeographical results from the Devonian of the Albergaria-a-Velha Unit (Ossa-Morena Zone, W. Portugal)

Czech Academy of Sciences Publication Activity Database

Machado, G.; Vavrdová, Milada; Fonseca, P. E.; Chaminé, H.; Tavares Rocha, F.

2008-01-01

Roč. 64, 2-4 (2008), s. 109-113 ISSN 0036-5343 Institutional research plan: CEZ:AV0Z30130516 Keywords : Gondwana * Laurussia * Devonian * Ossa Morena Subject RIV: DB - Geology ; Mineralogy http://www.nm.cz/publikace/archiv-en.php?id=4&rok=64&kcislu=2-4&f_=Show

Carbon isotopic record from Upper Devonian carbonates at Dongcun in Guilin, southern China, supporting the world-wide pattern of carbon isotope excursions during Frasnian-Famennian transition

Institute of Scientific and Technical Information of China (English)

无

2003-01-01

Two positive δ13C excursions are presented in records from the Frasnian-Famennian (F-F) marine carbonate sediments in Europe, America, Africa, and Australia, having been considered as a worldwide pattern, and attributed to enhanced organic carbon burial during the F-F biological mass extinction. However, this worldwide pattern has not been revealed from the well-deposited Late Devonian sequences in southern China. In this paper, a detailed investigation has been made on the Late Devonian section at Dongcun, Guilin, southern China to constrain perturbations in δ13C of carbonates in the F-F deposited sequence. The result from this section also indicates two positive δ13C excursions during the F-F transition. The first excursion with an amplitude of 1.5‰ occurred at the bottom of linguiformis Zone, later than the early excursion existing in the Late rhenana Zone of the Late Devonian profiles in other continents, especially, in central Europe. This difference has been expected to be a result as conodont Palmatolepis linguiformis occurred earlier in southern China than other sites. The second excursion with an amplitude of 2.1‰ is located at the F-F boundary, same as the records from other continents. This result strongly supports the view that two carbon isotope positive excursions during the F-F transition are common in carbonate sediments, resulting from worldwide increases of organic carbon burial intensity.

Upper Devonian (Frasnian) non-calcified, algae, Alberta: Geological relevance to Leduc platforms and petroleum source rocks

Energy Technology Data Exchange (ETDEWEB)

Dix, G.R. (Univ. of British Columbia, Vancouver, BC (Canada))

1990-12-01

Several types of non-calcified fossil algae comparable to extant brown and green benithic macrophytes occur abundantly on two bedding planes in drill core from argillaceous slope carbonates of the Ireton Formation in northern Alberta. Fossiliferous strata abruptly overlie part of a stepped-back margin of the Sturgeon Lake carbonate platform (Leduc Formation), southeast of the Peace River Arch. Fossils are flattened organic fragments, some representing nearly complete specimens. Tentative comparisons are made with some Paleozoic algae; some of the Sturgeon Lake flora may be new species or genera. Preliminary examination of selected cores from the Ireton Formation and organic-rich Duvernay Formation in central Alberta indicates a widespread distribution of algal-derived organic matter within Upper Devonian basinal strata. The geological relevance of non-calcified algae to Devonian carbonate platforms and basins is postulated in three cases. Their presence in slope sediments may indicate that algal lawns flourished in muddy, upper slope environments. Fossils accumulated either in situ, or were ripped up and quickly buried within downshope resedimented deposits. All or some algal fragments may have been swept from the adjacent carbonate platform during storms. Prolific shallow water algal growth may have occurred simultaneously with oceanic crises when shallow water carbonate production either decreased or was shut down. The present position of fossil algae, therefore, would mark a bedding surface that is stratigraphically equivalent to an intraplatform disconformity. Regardless of the original environment, a sufficient accumulation of non-calcified algae in slope strata represents a viable petroleum source proximal to carbonate platforms. 46 refs., 9 figs.

The ammonoids from the Three Forks Shale (Late Devonian of Montana

Directory of Open Access Journals (Sweden)

D. Korn

2006-08-01

Full Text Available The ammonoid fauna from the Late Devonian Three Forks Shale of Montana is revised. Six taxa were recognised, which belong to the genera Tornoceras, Pernoceras, Raymondiceras, Platyclymenia, Pleuroclymenia, and Carinoclymenia. The ammonoid assemblage suggests a stratigraphic position within the middle Famennian, most probably the Platyclymenia annulata Zone. The ammonoids display extreme septal crowding in intermediate as well as adult growth stages, which can be regarded as evidence for instable palaeoecological conditions during lifetime of the animals. Die Ammonoideenfauna aus dem oberdevonischen Three Forks Shale von Montana wird revidiert. Sechs Taxa werden unterschieden; sie gehören zu den Gattungen Tornoceras, Pernoceras, Raymondiceras, Platyclymenia, Pleuroclymenia und Carinoclymenia. Die Ammonoideen-Vergesellschaftung spricht für eine stratigraphische Position im mittleren Famennium, wahrscheinlich in der Platyclymenia annulata Zone. Die Ammonoideen zeigen auffällige Drängung der Septen in intermediären und adulten Wachstumsstadien, die als Hinweis auf instabile Lebensbedingungen für die Tiere gewertet werden kann. doi:10.1002/mmng.200600008

A new elasmobranch Karksiodus mirus gen. et sp. nov. from the Burtnieki Regional Stage, Middle Devonian of Estonia

OpenAIRE

Alexander Ivanov; Tiiu Märss; Anne Kleesment

2011-01-01

Teeth of a new elasmobranch Karksiodus mirus gen. et sp. nov. were discovered on two levels in the sandstones of the Karksi outcrop (South Estonia), corresponding to the Härma Beds, lower part of the Burtnieki Regional Stage (Givetian, Middle Devonian). These teeth differ from all known Palaeozoic elasmobranch teeth in the presence of a unique wide transversal tube-shaped basal canal, in very fine and dense striation of cusps and in an arched base without well-developed extensions. The order ...

Provenance and paleogeography of the Devonian Durazno Group, southern Parana Basin in Uruguay

Science.gov (United States)

Uriz, N. J.; Cingolani, C. A.; Basei, M. A. S.; Blanco, G.; Abre, P.; Portillo, N. S.; Siccardi, A.

2016-03-01

A succession of Devonian cover rocks occurs in outcrop and in the subsurface of central-northern Uruguay where they were deposited in an intracratonic basin. This Durazno Group comprises three distinct stratigraphic units, namely the Cerrezuelo, Cordobés and La Paloma formations. The Durazno Group does not exceed 300 m of average thickness and preserves a transgressive-regressive cycle within a shallow-marine siliciclastic shelf platform, and is characterized by an assemblage of invertebrate fossils of Malvinokaffric affinity especially within the Lower Devonian Cordobés shales. The sedimentary provenance of the Durazno Group was determined using petrography, geochemistry, and morphological studies of detrital zircons as well as their U-Pb ages. Sandstone petrography of Cerrezuelo and La Paloma sequences shows that they have a dominantly quartz-feldspathic composition with a minor contribution of other minerals. Whole-rock geochemical data indicate that alteration was strong in each of the three formations studied; chondritic-normalized REE patterns essentially parallel to PAAS, the presence of a negative Eu-anomaly, and Th/Sc and La/Hf ratios point to an average source composition similar to UCC or slightly more felsic. Within the Cerrezuelo Formation, recycling of older volcano-metasedimentary sources is interpreted from Zr/Sc ratios and high Hf, Zr, and REE concentrations. U-Pb detrital zircon age populations of the Cerrezuelo and La Paloma formations indicate that the principal source terranes are of Neoproterozoic age, but include also minor populations derived from Mesoproterozoic and Archean-Paleoproterozoic rocks. A provenance from the Cuchilla Dionisio-Dom Feliciano, Nico Pérez and Piedra Alta terranes of Uruguay and southern Brazil is likely. This study establishes an intracratonic extensional tectonic setting during Durazno time. Considering provenance age sources, regional paleocurrent distributions and the established orogenic history recorded in SW

Climate instability and tipping points in the Late Devonian: Detection of the Hangenberg Event in an open oceanic island arc in the Central Asian Orogenic Belt

Czech Academy of Sciences Publication Activity Database

Carmichael, A.; Waters, J. A.; Batchelor, C. J.; Coleman, D. M.; Suttner, T. J.; Kido, E.; Moore, L. M.; Chadimová, Leona

2016-01-01

Roč. 32, 1 April (2016), s. 213-231 ISSN 1342-937X Institutional support: RVO:67985831 Keywords : Central Asian Orogenic Belt * chemostratigraphy * Devonian-Carboniferous * Hangenberg Event * West Junggar Subject RIV: DB - Geology ; Mineralogy Impact factor: 6.959, year: 2016

Paleomagnetism of Devonian dykes in the northern Kola Peninsula and its bearing on the apparent polar wander path of Baltica in the Precambrian

Science.gov (United States)

Veselovskiy, Roman V.; Bazhenov, Mikhail L.; Arzamastsev, Andrey A.

2016-04-01

Mafic dykes and large alkaline and carbonatite intrusions of Middle-Late Devonian age are widespread on the Kola Peninsula in NE Fennoscandia. These magmatic rocks are well characterized with petrographic, geochemical and geochronological data but no paleomagnetic results have been reported yet. We studied dolerite dykes from the northern part of the Peninsula and isolated three paleomagnetic components in these rocks. A low-temperature component is aligned along the present-day field, while a major constituent of natural remanent magnetization is an intermediate-temperature component (Decl. = 79.6°, Inc. = 78.5°, α95 = 5,9°, N = 17 sites) that is present in most Devonian dykes but is found in some baked metamorphic rocks and Proterozoic dykes too. Finally, a primary Devonian component could be reliably isolated from two dykes only. Rock-magnetic studies point to presumably primary low-Ti titanomagnetite and/or pure magnetite as the main remanence carriers but also reveal alteration of the primary minerals and the formation of new magnetic phases. The directions of a major component differ from the Middle Paleozoic reference data for Baltica but closely match those for the 190 ± 10 Ma interval recalculated from the apparent polar wander path of the craton. We assume that this Early Jurassic component is a low-temperature overprint of chemical origin. The main impact of the new results is not to mid-Paleozoic or Early Mesozoic times but to much older epochs. Analysis of paleomagnetic data shows that the directionally similar remanences are present in objects with the ages ranging from 500 Ma to 2 Ga over entire Fennoscandia. Hence we argue that an Early Jurassic remagnetization is of regional extent but cannot link it to a certain process and a certain tectonic event. If true, this hypothesis necessitates a major revision of the APWP for Baltica over a wide time interval.

A new elasmobranch Karksiodus mirus gen. et sp. nov. from the Burtnieki Regional Stage, Middle Devonian of Estonia

Directory of Open Access Journals (Sweden)

Alexander Ivanov

2011-03-01

Full Text Available Teeth of a new elasmobranch Karksiodus mirus gen. et sp. nov. were discovered on two levels in the sandstones of the Karksi outcrop (South Estonia, corresponding to the Härma Beds, lower part of the Burtnieki Regional Stage (Givetian, Middle Devonian. These teeth differ from all known Palaeozoic elasmobranch teeth in the presence of a unique wide transversal tube-shaped basal canal, in very fine and dense striation of cusps and in an arched base without well-developed extensions. The order and family of this taxon are notspecified.

Devonian conodonts from the Foča–Prača Paleozoic complex (Durmitor Nappe, southeastern Bosnia and Herzegovina

Directory of Open Access Journals (Sweden)

Bogdan Jurkovšek

2011-06-01

Full Text Available Conodont study of the Crna Rijeka borehole CR-17, positioned in the frontal part of the Durmitor Nappe (Foča – Prača Paleozoic complex, SE Bosnia and Herzegovina is presented. The obtained fauna indicates an Early-Middle Devonian age and due to poor preservation an identification at a generic level is possible only. The recovered conodont elements have a high Color Alteration Index (CAI = 6,5–7 indicating a degree of metamorphism corresponding to a temperature interval from 440 °C to 720 °C.

Devonian alkaline magmatism in the northern North China Craton: Geochemistry, SHRIMP zircon U-Pb geochronology and Sr-Nd-Hf isotopes

Directory of Open Access Journals (Sweden)

Dingling Huang

2017-01-01

Full Text Available The Wulanhada pluton is among the rare suite of Devonian alkaline plutons occurring along the northern margin of the North China Craton (NCC. The intrusion is mainly composed of quartz-monzonite. Here we report zircon SHRIMP U-Pb data from this intrusion which shows emplacement age of ca. 381.5 Ma. The rock is metaluminous with high (Na2O + K2O values ranging from 8.46 to 9.66 wt.%. The REE patterns of the rocks do not show any Eu anomaly whereas the primitive-mantle-normalized spider diagram shows strong positive Sr and Ba anomalies. The Wulanhada rocks exhibit high initial values of (87Sr/86Srt = 0.70762–0.70809, low ɛNd(t = −12.76 to −12.15 values and negative values of ɛHf(t = −23.49 to −17.02 with small variations in (176Hf/177Hft (0.281873–0.282049. These geochemical features and quantitative isotopic modeling results suggest that the rocks might have been formed through the partial melting of Neoarchean basic rocks in the lower crust of the NCC. The Wulanhada rocks, together with the Devonian alkaline rocks and mafic-ultramafic complex from neighboring regions, constitute a post-collisional magmatic belt along the northern NCC.

Stratigraphy, palynology and organic geochemistry of the Devonian-Mississippian metasedimentary Albergaria-a-Velha Unit (Porto-Tomar shear zone, W Portugal)

Czech Academy of Sciences Publication Activity Database

Machado, G.; Franců, E.; Vavrdová, Milada; Flores, D.; Fonseca, P. E.; Rocha, F.; Gama Pereira, L. C.; Gomes, A.; Fonseca, M.; Chaminé, H. I.

2011-01-01

Roč. 55, č. 2 (2011), s. 139-164 ISSN 1641-7291. [International Palynological Conference of the International Commission of the Paleozoic Microflora ( CIMP ). Warsaw-Kielce, 13.09.2010-19.09.2010] Institutional research plan: CEZ:AV0Z30130516 Keywords : Mississippian * Late Devonian * Ossa-Morena Zone * Porto-Tomar shear zone * palynology * organic geochemistry * turbidite systems * provenance * phytoplankton Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.844, year: 2011 http://gq.pgi.gov.pl/gq/article/viewFile/7606/pdf_4

ANALYSIS OF DEVONIAN BLACK SHALES IN KENTUCKY FOR POTENTIAL CARBON DIOXIDE SEQUESTRATION AND ENHANCED NATURAL GAS PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Brandon C. Nuttall

2004-08-01

Devonian gas shales underlie approximately two-thirds of Kentucky. In the shale, natural gas is adsorbed on clay and kerogen surfaces. This is analogous to methane storage in coal beds, where CO{sub 2} is preferentially adsorbed, displacing methane. Black shales may similarly desorb methane in the presence of CO{sub 2}. Drill cuttings from the Kentucky Geological Survey Well Sample and Core Library are being sampled to collect CO{sub 2} adsorption isotherms. Sidewall core samples have been acquired to investigate CO{sub 2} displacement of methane. An elemental capture spectroscopy log has been acquired to investigate possible correlations between adsorption capacity and mineralogy. Average random vitrinite reflectance data range from 0.78 to 1.59 (upper oil to wet gas and condensate hydrocarbon maturity range). Total organic content determined from acid-washed samples ranges from 0.69 to 4.62 percent. CO{sub 2} adsorption capacities at 400 psi range from a low of 19 scf/ton in less organic-rich zones to more than 86 scf/ton in the Lower Huron Member of the shale. Initial estimates based on these data indicate a sequestration capacity of 5.3 billion tons of CO{sub 2} in the Lower Huron Member of the Ohio Shale of eastern Kentucky and as much as 28 billion tons total in the deeper and thicker parts of the Devonian shales in Kentucky. Should the black shales of Kentucky prove to be a viable geologic sink for CO{sub 2}, their extensive occurrence in Paleozoic basins across North America would make them an attractive regional target for economic CO{sub 2} storage and enhanced natural gas production.

ANALYSIS OF DEVONIAN BLACK SHALES IN KENTUCKY FOR POTENTIAL CARBON DIOXIDE SEQUESTRATION AND ENHANCED NATURAL GAS PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Brandon C. Nuttall

2005-01-01

Devonian gas shales underlie approximately two-thirds of Kentucky. In the shale, natural gas is adsorbed on clay and kerogen surfaces. This is analogous to methane storage in coal beds, where CO{sub 2} is preferentially adsorbed, displacing methane. Black shales may similarly desorb methane in the presence of CO{sub 2}. Drill cuttings from the Kentucky Geological Survey Well Sample and Core Library were sampled to determine CO{sub 2} and CH{sub 4} adsorption isotherms. Sidewall core samples were acquired to investigate CO{sub 2} displacement of methane. An elemental capture spectroscopy log was acquired to investigate possible correlations between adsorption capacity and mineralogy. Average random vitrinite reflectance data range from 0.78 to 1.59 (upper oil to wet gas and condensate hydrocarbon maturity range). Total organic content determined from acid-washed samples ranges from 0.69 to 14 percent. CO{sub 2} adsorption capacities at 400 psi range from a low of 14 scf/ton in less organic-rich zones to more than 136 scf/ton. Initial estimates based on these data indicate a sequestration capacity of 5.3 billion tons of CO{sub 2} in the Lower Huron Member of the Ohio Shale of eastern Kentucky and as much as 28 billion tons total in the deeper and thicker parts of the Devonian shales in Kentucky. Should the black shales of Kentucky prove to be a viable geologic sink for CO{sub 2}, their extensive occurrence in Paleozoic basins across North America would make them an attractive regional target for economic CO{sub 2} storage and enhanced natural gas production.

Lithosphere evolution during the pre devonian of Uruguay: Prevalence of strike slip faults

International Nuclear Information System (INIS)

Bossi, J.

2010-01-01

The available data about mega shear zones were analyzed. Also the geo chronological trusty data about pre devonian rocks from Uruguay were overlapped. Emphasizing in the basic rocks, four tecto no-stratigraphy c terranes might be recognized. The approximate age of those rocks is known as well as the displacement trend. It can be concluded that the transmazonian age Piedra Alta Terrane (transmazonian age 2000 ± 100 My) is the most ancient block followed by the Tandilla Terrane (ages 2200 ± 100 My) which was joined through 1700 Ma. The Nico Perez Terrane displaced itself towards South generating the continental N10W mega shear fault Sarandi del Yi- Piriapolis towards 1250 My. Finally, the Arachania called continent made tangential collision from SE towards 525 Ma generating the ultramylonites band of the Sierra Ballena share zone. Each one of these terranes have totally different stratigraphy and lithological associations, and the chronological ages did not agree with the arrival of each one of the identified terranes

First Record of Soft Tissue Preservation in the Upper Devonian of Poland

Science.gov (United States)

Zatoń, Michał; Broda, Krzysztof

2015-01-01

Soft tissue preservation is reported from Upper Devonian deposits of the Holy Cross Mountains, central Poland, for the first time. The preserved soft tissues are muscles associated with arthropod cuticle fragments. The muscles are phosphatized with variable states of preservation. Well-preserved specimens display the typical banding of striated muscles. Other muscle fragments are highly degraded and/or recrystallized such that their microstructure is barely visible. The phosphatized muscles and associated cuticle are fragmented, occur in patches and some are scattered on the bedding plane. Due to the state of preservation and the lack of diagnostic features, the cuticle identification is problematic; however, it may have belonged to a phyllocarid crustacean. Taphonomic features of the remains indicate that they do not represent fossilized fecal matter (coprolite) but may represent a regurgitate, but the hypothesis is difficult to test. Most probably they represent the leftover remains after arthropod or fish scavenging. The present study shows that soft tissues, which even earlier were manipulated by scavenger, may be preserved if only special microenvironmental conditions within and around the animal remains are established. PMID:26559060

Sea-level changes vs. organic productivity as controls on Early and Middle Devonian bioevents: Facies- and gamma-ray based sequence-stratigraphic correlation of the Prague Basin, Czech Republic

Czech Academy of Sciences Publication Activity Database

Bábek, O.; Faměra, M.; Šimíček, D.; Weinerová, H.; Hladil, Jindřich; Kalvoda, J.

2018-01-01

Roč. 160, January (2018), s. 75-95 ISSN 0921-8181 R&D Projects: GA ČR GA14-18183S Institutional support: RVO:67985831 Keywords : Devonian * carbonates * sequence stratigraphy * bioevents * eustatic cyclicity * palaeoclimatology Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Paleontology Impact factor: 3.915, year: 2016

ANALYSIS OF DEVONIAN BLACK SHALES IN KENTUCKY FOR POTENTIAL CARBON DIOXIDE SEQUESTRATION AND ENHANCED NATURAL GAS PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Brandon C. Nuttall

2005-04-26

Devonian gas shales underlie approximately two-thirds of Kentucky. In the shale, natural gas is adsorbed on clay and kerogen surfaces. This is analogous to methane storage in coal beds, where CO{sub 2} is preferentially adsorbed, displacing methane. Black shales may similarly desorb methane in the presence of CO{sub 2}. Drill cuttings from the Kentucky Geological Survey Well Sample and Core Library were sampled to determine CO{sub 2} and CH{sub 4} adsorption isotherms. Sidewall core samples were acquired to investigate CO{sub 2} displacement of methane. An elemental capture spectroscopy log was acquired to investigate possible correlations between adsorption capacity and mineralogy. Average random vitrinite reflectance data range from 0.78 to 1.59 (upper oil to wet gas and condensate hydrocarbon maturity range). Total organic content determined from acid-washed samples ranges from 0.69 to 14 percent. CO{sub 2} adsorption capacities at 400 psi range from a low of 14 scf/ton in less organic-rich zones to more than 136 scf/ton. There is a direct correlation between measured total organic carbon content and the adsorptive capacity of the shale; CO{sub 2} adsorption capacity increases with increasing organic carbon content. Initial estimates based on these data indicate a sequestration capacity of 5.3 billion tons of CO{sub 2} in the Lower Huron Member of the Ohio Shale of eastern Kentucky and as much as 28 billion tons total in the deeper and thicker parts of the Devonian shales in Kentucky. Should the black shales of Kentucky prove to be a viable geologic sink for CO{sub 2}, their extensive occurrence in Paleozoic basins across North America would make them an attractive regional target for economic CO{sub 2} storage and enhanced natural gas production.

ANALYSIS OF DEVONIAN BLACK SHALES IN KENTUCKY FOR POTENTIAL CARBON DIOXIDE SEQUESTRATION AND ENHANCED NATURAL GAS PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Brandon C. Nuttall

2005-01-28

Devonian gas shales underlie approximately two-thirds of Kentucky. In the shale, natural gas is adsorbed on clay and kerogen surfaces. This is analogous to methane storage in coal beds, where CO{sub 2} is preferentially adsorbed, displacing methane. Black shales may similarly desorb methane in the presence of CO{sub 2}. Drill cuttings from the Kentucky Geological Survey Well Sample and Core Library were sampled to determine CO{sub 2} and CH{sub 4} adsorption isotherms. Sidewall core samples were acquired to investigate CO{sub 2} displacement of methane. An elemental capture spectroscopy log was acquired to investigate possible correlations between adsorption capacity and mineralogy. Average random vitrinite reflectance data range from 0.78 to 1.59 (upper oil to wet gas and condensate hydrocarbon maturity range). Total organic content determined from acid-washed samples ranges from 0.69 to 14 percent. CO{sub 2} adsorption capacities at 400 psi range from a low of 14 scf/ton in less organic-rich zones to more than 136 scf/ton. There is a direct correlation between measured total organic carbon content and the adsorptive capacity of the shale; CO{sub 2} adsorption capacity increases with increasing organic carbon content. Initial estimates based on these data indicate a sequestration capacity of 5.3 billion tons of CO{sub 2} in the Lower Huron Member of the Ohio Shale of eastern Kentucky and as much as 28 billion tons total in the deeper and thicker parts of the Devonian shales in Kentucky. Should the black shales of Kentucky prove to be a viable geologic sink for CO{sub 2}, their extensive occurrence in Paleozoic basins across North America would make them an attractive regional target for economic CO{sub 2} storage and enhanced natural gas production.

ANALYSIS OF DEVONIAN BLACK SHALES IN KENTUCKY FOR POTENTIAL CARBON DIOXIDE SEQUESTRATION AND ENHANCED NATURAL GAS PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Brandon C. Nuttall

2005-07-29

Devonian gas shales underlie approximately two-thirds of Kentucky. In the shale, natural gas is adsorbed on clay and kerogen surfaces. This is analogous to methane storage in coal beds, where CO{sub 2} is preferentially adsorbed, displacing methane. Black shales may similarly desorb methane in the presence of CO{sub 2}. Drill cuttings from the Kentucky Geological Survey Well Sample and Core Library were sampled to determine CO{sub 2} and CH{sub 4} adsorption isotherms. Sidewall core samples were acquired to investigate CO{sub 2} displacement of methane. An elemental capture spectroscopy log was acquired to investigate possible correlations between adsorption capacity and mineralogy. Average random vitrinite reflectance data range from 0.78 to 1.59 (upper oil to wet gas and condensate hydrocarbon maturity range). Total organic content determined from acid-washed samples ranges from 0.69 to 14 percent. CO{sub 2} adsorption capacities at 400 psi range from a low of 14 scf/ton in less organic-rich zones to more than 136 scf/ton. There is a direct correlation between measured total organic carbon content and the adsorptive capacity of the shale; CO{sub 2} adsorption capacity increases with increasing organic carbon content. Initial estimates based on these data indicate a sequestration capacity of 5.3 billion tons of CO{sub 2} in the Lower Huron Member of the Ohio Shale of eastern Kentucky and as much as 28 billion tons total in the deeper and thicker parts of the Devonian shales in Kentucky. Should the black shales of Kentucky prove to be a viable geologic sink for CO{sub 2}, their extensive occurrence in Paleozoic basins across North America would make them an attractive regional target for economic CO{sub 2} storage and enhanced natural gas production.

Two hundred years of palaeontological discovery: Review of research on the Early to Middle Devonian Bokkeveld Group (Cape Supergroup) of South Africa

Science.gov (United States)

Penn-Clarke, C. R.; Rubidge, B. S.; Jinnah, Z. A.

2018-01-01

Documentation of the palaeontological heritage of the Early to Middle Devonian Bokkeveld Group of South Africa has been recorded as far back as the early nineteenth century with the arrival of the first European settlers, merchants and explorers to the Cape region. Anecdotal evidence suggests that indigenous peoples had knowledge of fossils in the Bokkeveld Group from as early as the Middle-to-Late Stone Age. Within the first hundred years of the expansion of the Cape Colony the first geological maps of the Bokkeveld Group were produced alongside the first description of fossils as well as their Devonian age and marine origin. These early investigations provided a foundation for establishing faunal endemism common to South Africa, South America and the Falkland Islands. During the early twentieth century considerable progress was made in the description of fossil fauna of the Bokkeveld Group, most notably of invertebrates and plants. This research demonstrated that invertebrate fossils from the Bokkeveld Group, as well as those from time equivalents in South America and the Falkland Islands, were distinct from the Devonian Period elsewhere (e.g. Europe and North America). The role of fossils from the Bokkeveld Group proved critical in the formal designation and delineation of a broad region of endemism, the Malvinokaffric Realm that persisted at high subpolar-to-polar palaeolatitudes in southwestern Gondwana and extended from South Africa, Bolivia, Brazil, Argentina, Antarctica and the Falkland Islands with possible elements in Guinea-Bissau, Senegal and Ghana during the Emsian-Eifelian Stages. In the latter half of the twentieth century developments in understanding the sedimentology and stratigraphy of the Bokkeveld Group lead to the premise that the succession accumulated in a storm-and-wave dominated deltaic palaeoenvironment, and enabled inferences on the palaeoecology of the fossil taxa. During this period detailed revisions of numerous invertebrate and plant

The Late Devonian Gogo Formation Lägerstatte of Western Australia: Exceptional Early Vertebrate Preservation and Diversity

Science.gov (United States)

Long, John A.; Trinajstic, Kate

2010-05-01

The Gogo Formation of Western Australia preserves a unique Late Devonian (Frasnian) reef fauna. The exceptional three-dimensional preservation of macrofossils combined with unprecedented soft-tissue preservation (including muscle bundles, nerve cells, and umbilical structures) has yielded a particularly rich assemblage with almost 50 species of fishes described. The most significant discoveries have contributed to resolving placoderm phylogeny and elucidating their reproductive physiology. Specifically, these discoveries have produced data on the oldest known vertebrate embryos; the anatomy of the primitive actinopterygian neurocranium and phylogeny of the earliest actinopterygians; the histology, radiation, and plasticity of dipnoan (lungfish) dental and cranial structures; the anatomy and functional morphology of the extinct onychodonts; and the anatomy of the primitive tetrapodomorph head and pectoral fin.

New Data on Conodonts of the Upper Devonian of the Polar Urals (Ostantsovy Section, Malaya Usa River

Directory of Open Access Journals (Sweden)

M.A. Soboleva

2016-09-01

Full Text Available The main features of the Upper Devonian sediments on the right side of the Ostantsovy Creek (the left tributary of the Malaya Usa River in the eastern part of the Bielsko-Eletskaya structural formational belt on the western slope of the Polar Urals have been considered. The late Frasnian age of these sediments has been determined on the basis of conodonts (the linguiformis zone of the standard conodont scale. The transition from clastic and organic limestones with massive stromatoporoid forms to limestones with fused (reservoir stromatoporoid forms and Palmatolepis biofacies is indicative of the transgressive shift of the linguiformis phase. This transgressive level is an indirect expression of the Upper Kellwasser global event.

New Insights in the Ontogeny and Taphonomy of the Devonian Acanthodian Triazeugacanthus affinis From the Miguasha Fossil-Lagerstätte, Eastern Canada

Directory of Open Access Journals (Sweden)

Marion Chevrinais

2015-12-01

Full Text Available Progressive biomineralization of a skeleton occurs during ontogeny in most animals. In fishes, larvae are poorly mineralized, whereas juveniles and adults display a progressively more biomineralized skeleton. Fossil remains primarily consist of adult specimens because the fossilization of poorly-mineralized larvae and juveniles necessitates exceptional conditions. The Miguasha Fossil-Lagerstätte is renowned for its Late Devonian vertebrate fauna, revealing the exceptional preservation of fossilized ontogenies for 14 of the 20 fish species from this locality. The mineralization of anatomical structures of the acanthodian Triazeugacanthus affinis from Miguasha are compared among larval, juvenile and adult specimens using Energy Dispersive X-ray Spectrometry. Chemical composition of anatomical structures of Triazeugacanthus reveals differences between cartilage and bone. Although the histology and anatomy is well-preserved, Fourier transform infrared spectrometry shows that the original chemical composition of bone is altered by diagenesis; the mineral phase of the bone (i.e., hydroxyapatite is modified chemically to form more stable carbonate-fluorapatite. Fluorination occurring in mineralized skeletal structures of adult Triazeugacanthus is indicative of exchanges between groundwater and skeleton at burial, whereas the preservation of larval soft tissues is likely owing to a rapid burial under anoxic conditions. The exceptional state of preservation of a fossilized ontogeny allowed us to characterize chemically the progressive mineralization of the skeleton in a Devonian early vertebrate.

A new assessment of the Late Devonian antiarchan fish Bothriolepis leptocheira from South Timan (Russia) and the biotic crisis near the Frasnian–Famennian boundary

OpenAIRE

Ervīns Lukševičs; Pavel Beznosov; Valdemārs Stūris

2017-01-01

The species of the Late Devonian, earliest Famennian placoderm fish Bothriolepis jeremejevi has been downranked to subspecies Bothriolepis leptocheira jeremejevi comb. nov. in a result of detailed morphological studies of the type specimens and abundant new material from the type locality of the Sosnogorsk Formation, South Timan, Komi Republic, Russia. This taxon closely resembles Bothriolepis leptocheira leptocheira from Scotland, B. leptocheira curonica from Latvia, and B. leptocheira ssp. ...

Geochemical and palaeontological evidence for the definition of the Silurian/Devonian boundary in the Changwantang Section, Guangxi Province, China

Directory of Open Access Journals (Sweden)

Wen-jin Zhao

2015-02-01

Full Text Available Southern Guangxi Province is one of the important areas for the study of the Silurian/Devonian boundary (SDB in South China. Despite attempts to define the exact level of the SDB in the Yulin (Guangxi Province area using biostratigraphy, no consensus has been reached as the indicator fossils (e.g. graptolite Monograptus uniformis uniformis, conodont Icriodus woschmidti woschmidti and trilobite Warburgella rugulosa rugosa are not coexistent in South China. Since Mann et al. (2001: Dynamics of the Silurian/Devonian boundary sequence: sedimentary cycles vs. organic matter variation. Terra Nostra, 2001, 44–48 reported the first isotope curve based on organic carbon for the SDB at Klonk in the Czech Republic (GSSP, some comparable variation curves of δ13Corg across the SDB have been obtained at several locations including sections in Turkey and China. This distinct variation curve of the isotopic composition of organic carbon across the SDB provides a chemostratigraphic reference for a worldwide correlation of the SDB. In this study, organic geochemistry together with graptolite biostratigraphy is applied as a tool for identifying the SDB at the Changwantang Section in Yulin (Guangxi Province. The results suggest that the variations in some indexes of organic geochemistry can be correlated to the representative curve of the SDB in the Klonk and Esenyali sections. The exact level of the SDB in the Changwantang Section is positioned within the upper part of the Fangcheng Formation, which is consistent with the available palaeontological data from graptolites (e.g. Colonograptus colonus, Plectograptus sp., Monograptus uniformis, M. cf. M. praehercynicus and M. aequabilis.

Devonian to Early Carboniferous magmatic alkaline activity in the Tafilalt Province, Eastearn Morocco: An Eovariscan episode in the Gondwana margin, north of the West African Craton

Science.gov (United States)

Pouclet, André; El Hadi, Hassan; Bardintzeff, Jacques-Marie; Benharref, Mohammed; Fekkak, Abdelilah

2017-05-01

To the eastern edge of the Moroccan Anti-Atlas, the Tafilalt Province is the repository of a Lower Palaeozoic platform and basin sedimentation constrained by a W-E and NW-SE fault network. During the mid-late Devonian, an extensional tectonic activity, demonstrated by sharp changes in sediment thickness and development of syn-sedimentary faults, was contemporaneous with a significant magmatic activity. A great number of doleritic dykes, sills, and laccoliths intruded sedimentary Silurian to Lower Visean strata. The intrusions were linked to sub-water volcanic activities with spilitic lava flows and pyroclastites during two main pulses in the Famennian-Tournaisian and in the Early Visean. The rocks consist of basaltic dolerites, lamprophyric dolerites and analcite-bearing camptonites, sharing a sodic alkaline magma composition. The magma derived from low partial melting degree of the metasome layer of the lithospheric subcontinental mantle, below the spinel-garnet transition zone. This Tafilalt tectono-magmatic activity was coeval with the Eovariscan phase in the Moroccan Meseta, which was responsible for the opening of Western Meseta basins and their transitional to alkaline volcanic activities in the Late Devonian to Early Carboniferous time.

Stratigraphic significance and resolution of spectral reflectance logs in Lower Devonian carbonates of the Barrandian area, Czech Republic; a correlation with magnetic susceptibility and gamma-ray logs

Czech Academy of Sciences Publication Activity Database

Koptíková, Leona; Bábek, O.; Hladil, Jindřich; Kalvoda, J.; Slavík, Ladislav

2010-01-01

Roč. 225, 3/4 (2010), s. 83-98 ISSN 0037-0738 R&D Projects: GA AV ČR IAAX00130702; GA ČR GA205/08/0767 Institutional research plan: CEZ:AV0Z30130516 Keywords : VIS spectral reflectance * cyclostratigraphy * sea -level changes * Lower Devonian * red pelagic carbonates * diagenesis Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.685, year: 2010

Graphic correlation of the Frasnian Upper Devonian Composite

Energy Technology Data Exchange (ETDEWEB)

Klapper, G. (Univ. of Iowa, Iowa City, IA (United States). Dept. of Geology); Kirchgasser, W.T. (Potsdam Coll., NY (United States). Geology Dept.); Baesemann, J.F. (Amoco Production Co., Houston, TX (United States))

1993-03-01

Although statistical solution to the line of correlation (LOC) was advocated by Shaw (1964) when the technique of graphic correlation was introduced, most practioners, including Shaw himself shortly after publication of Time in Stratigraphy, agree that statistical methods for locating the LOC are inappropriate. As a consequence, calculation of the standard error of estimate and other statistical measures of error in order to quantify the resolution of graphic correlation is also inappropriate. Methods for locating the LOC are diverse involving geologic as well as biostratigraphic knowledge, and include positioning it with respect to magnetic reversals, volcanic ash beds, oxygen isotope data, and splitting bases and tops of species so as to cause minimum disruption in known ranges. The LOC for each section with the Composite Standard is a testable hypothesis of stratigraphic correlation. The Frasnian Composite consists of 27 sections in the Montagne Noire (southern France), Alberta Rockies, Hay River - Trout River areas of the Northwest Territories, Canada, the Midcontinent and New York sequences in the US, the Canning Basin, Western Australia, and the Central Devonian Field and Timan-Pechora Basin of the Russian Platform. Through graphic correlation, the Frasnian Stage is divided into 34 composite standard units, using ranges of conodonts and to a lesser extent goniatites. The resulting subdivision is considerably more precise than that achieved by the conventional thirteen-fold zonation based on the Montagne Noire conodont sequence, many zones of which have been replicated in the cited areas outside the Montagne Noire. The Frasnian Composite successfully provides a precise intrazonal method of correlation that uses the ranges of all species from the studies sections in a single biostratigraphic framework, rather than emphasizing a few zonal indices.

Petrogenesis and tectonic implications of Late Devonian arc volcanic rocks in southern Beishan orogen, NW China: Geochemical and Nd-Sr-Hf isotopic constraints

Science.gov (United States)

Guo, Qian-Qian; Chung, Sun-Lin; Xiao, Wen-Jiao; Hou, Quan-Lin; Li, Shan

2017-05-01

Late Devonian (ca. 370 Ma) volcanic rocks provide important information about the nature of magmatism during the tectonic transition between the Early and Late Paleozoic in the Beishan orogen, southern Central Asian Orogenic Belt. They are predominantly an andesitic-dacitic-rhyolitic assemblage, characterized by alkali contents ranging from slightly calcic to slightly alkaline. The rhyolitic rocks are generally ferroan, whereas the andesitic rocks are magnesian. These volcanic rocks exhibit similar trace element characteristics to those of continental arcs. Strongly negative εNd(t) values (- 2.8 to - 3.6) and high Sr isotopic compositions (initial 87Sr/86Sr = 0.7036-0.7108) suggest that they are mainly derived from an ancient crust. However, the positive zircon εHf(t) values (+ 1.4 to + 16.4) support the role of juvenile components in their genesis, indicating the significant input of new mantle-derived magmas. These characteristics imply a hybrid derivation, from an ancient crustal source with the addition of juvenile materials during magma genesis, or perhaps heterogeneous contamination or hybridization during magma emplacement. Combined with the regional geology, our results indicate that the Late Devonian magmatism resulted from a southward retreat of the subduction zone, which records significant continental crustal growth in a transitional arc or an accretionary arc setting. The distinct geochemical compositions, especially the Nd-Hf isotope decoupling of the Dundunshan volcanic rocks, imply a significant change in the geodynamic setting in the Late Paleozoic.

Continental crust melting induced by subduction initiation of the South Tianshan Ocean: Insight from the Latest Devonian granitic magmatism in the southern Yili Block, NW China

Science.gov (United States)

Bao, Zihe; Cai, Keda; Sun, Min; Xiao, Wenjiao; Wan, Bo; Wang, Yannan; Wang, Xiangsong; Xia, Xiaoping

2018-03-01

The Tianshan belt of the southwestern Central Asian Orogenic Belt was generated by Paleozoic multi-stage subduction and final closure of several extinct oceans, including the South Tianshan Ocean between the Kazakhstan-Yili and Tarim blocks. However, the subduction initiation and polarity of the South Tianshan Ocean remain issues of highly debated. This study presents new zircon U-Pb ages, geochemical compositions and Sr-Nd isotopes, as well as zircon Hf isotopic data of the Latest Devonian to Early Carboniferous granitic rocks in the Wusun Mountain of the Yili Paleozoic convergent margin, which, together with the spatial-temporal distributions of regional magmatic rocks, are applied to elucidate their petrogenesis and tectonic linkage to the northward subduction initiation of the South Tianshan Ocean. Our zircon U-Pb dating results reveal that these granites were emplaced at the time interval of 362.0 ± 1.2-360.3 ± 1.9 Ma, suggesting a marked partial melting event of the continental crust in the Latest Devonian to Early Carboniferous. These granites, based on their mineral compositions and textures, can be categorized as monzogranites and K-feldspar granites. Geochemically, both monzogranites and K-feldspar granites have characters of I-type granites with high K2O contents (4.64-4.83 wt.%), and the K-feldspar granites are highly fractionated I-type granites, while the monzogranites have features of unfractionated I-type granites. Whole-rock Sr-Nd isotopic modeling results suggest that ca. 20-40% mantle-derived magmas may be involved in magma mixing with continental crust partial melts to generate the parental magmas of the granites. The mantle-derived basaltic magmas was inferred not only to be a major component of magma mixture but also as an important heat source to fuse the continental crust in an extensional setting, which is evidenced by the high zircon saturation temperatures (713-727 °C and 760-782 °C) of the studied granites. The Latest Devonian to

Characterization and analysis of Devonian shales as related to release of gaseous hydrocarbons. Well V-7 Wetzel County, West Virginia

Energy Technology Data Exchange (ETDEWEB)

Kalyoncu, R.S.; Boyer, J.P.; Snyder, M.J.

1979-08-15

This program was initiated in September 1976, with the objective and scope of determining the relationships between the shale characteristics, hydrocarbon gas contents, and well location, and thereby provide a sound basis for (1) assessing the productive capacity of the Eastern Devonian Gas Shale deposits, and (2) guiding research, development and demonstration projects to enhance the recovery of natural gas from the shale deposits. Included in the scope of the program are a number of elemental tasks as a part of the Resource Inventory and Shale Characterization subprojects of DOE's Eastern Gas Shales Project designed to provide large quantities of support data for current and possibly future needs of the Project.

U-Pb SHRIMP ages of volcanic zircons from the Merrions and Turondale Formations, New South Wales, and the early devonian time-scale: a biostratigraphic and sedimentological assessment

International Nuclear Information System (INIS)

Packham, G.H.

2003-01-01

U-Pb ages for volcanic zircons from the Lower Devonian Turondale and Merrions Formations initially dated by Jagodzinski and Black (1999) have been recalculated by Compston (2000, 2001). The Turondale, Waterbeach and Merrions Formations are, in ascending stratigraphic order, three of the Lower Devonian deep-water formations of the Hill End Trough. The recent discovery of a Lochkovian conodont fauna of the delta zone in derived limestone blocks from the uppermost beds of the Turondale Formation has established a maximum age for that horizon. The principal lithological assemblages of the formations are volcanic (megaturbidite and lavas), epiclastic turbidites and essentially hemipelagic lithologies. The mean zircon ages, determined by Sensitive High-Resolution Ion MicroProbe (SHRIMP), suggest a long duration for the Merrions Formation, 615 m thick and 91% volcanic, and a very much shorter interval for the upper two-thirds of the Turondale Formation, 360 m thick and 34% volcanic, plus the intervening non-volcanic Waterbeach Formation, 512 m thick. A sedimentological model based on scaled depositional rates for the facies has been used to estimate the relative accumulation rates and durations of the succession from the base of the Turondale Formation to the top of the Merrions Formation The model indicates that the Merrions Formation accumulated in a much shorter time than the interval from the top of the lower Turondale Formation to the base of the Merrions Formation. The analytical uncertainties of the Jagodzinski and Black (1999) zircon ages are large enough to be compatible with the sedimentological model, but the smaller analytical uncertainties calculated by Compston (2000, 2001) fall far from the scaled sedimentological model. Grouping together of the lower Merrions Formation and lower Turondale Formation zircon dates in Compston (2000) for a single mid-Lochkovian age is in conflict with the biostratigraphic and sedimentological evidence available and the derived

Rugose corals across the Devonian-Carboniferous boundary in NW Turkey

Directory of Open Access Journals (Sweden)

Julien Denayer

2016-02-01

Full Text Available An uppermost Famennian (Strunian coral assemblage has been recovered in the middle part of the Yılanlı Formation of the Istanbul Zone (Zonguldak and Bartın areas, NW Turkey. In the Bartın area, the studied fossiliferous interval corresponds to a c. 30 m-thick unit of bioclastic to peloidal wackestone to packstone grading to grainstone and including two stromatoporoid biostromes. In the Zonguldak area, 60 km westward, the bioclastic facies is dominant. The rugose corals are mainly solitary taxa belonging to the genera Campophyllum, Bounophyllum, Amplexocarinia, and ?Metriophyllum, and only one colonial genus occurs: Pseudoendophyllum. This fauna is similar to that documented in Europe. The campophyllids and dibunophyllids are the main component of the uppermost Famennian assemblages in S Belgium, N France, W Germany, NW and S Poland. The endophyllids occur in S Poland, Novaya Zemlya, and in the Ural Mountains. The Istanbul Zone is supposed to be situated in the central part of the Palaeotethys Ocean, along the southern margin of Laurussia during the uppermost Devonian and Carboniferous. The rugose corals indicate some relationship with the eastern part of Laurussia, or that both areas were under a common marine influence at this time. The global Hangenberg event was not recognized in the Turkish localities, except for the disappearance of the corals, occurring less than 19 m below the Devonian–Carboniferous boundary based on the foraminifers. There is no major facies change through the boundary and the first Carboniferous corals (small Uralinia and Caninophyllum appear 6 m above the D–C boundary. The new species Caninophyllum charli sp. nov. is described from the upper part of the lower Tournaisian.

Earth’s oldest ‘Bobbit worm’ – gigantism in a Devonian eunicidan polychaete

Science.gov (United States)

Eriksson, Mats E.; Parry, Luke A.; Rudkin, David M.

2017-01-01

Whilst the fossil record of polychaete worms extends to the early Cambrian, much data on this group derive from microfossils known as scolecodonts. These are sclerotized jaw elements, which generally range from 0.1–2 mm in size, and which, in contrast to the soft-body anatomy, have good preservation potential and a continuous fossil record. Here we describe a new eunicidan polychaete, Websteroprion armstrongi gen. et sp. nov., based primarily on monospecific bedding plane assemblages from the Lower-Middle Devonian Kwataboahegan Formation of Ontario, Canada. The specimens are preserved mainly as three-dimensional moulds in the calcareous host rock, with only parts of the original sclerotized jaw walls occasionally present. This new taxon has a unique morphology and is characterized by an unexpected combination of features seen in several different Palaeozoic polychaete families. Websteroprion armstrongi was a raptorial feeder and possessed the largest jaws recorded in polychaetes from the fossil record, with maxillae reaching over one centimetre in length. Total body length of the species is estimated to have reached over one metre, which is comparable to that of extant ‘giant eunicid’ species colloquially referred to as ‘Bobbit worms’. This demonstrates that polychaete gigantism was already a phenomenon in the Palaeozoic, some 400 million years ago. PMID:28220886

Regional geological assessment of the Devonian-Mississippian shale sequence of the Appalachian, Illinois, and Michigan basins relative to potential storage/disposal of radioactive wastes

Energy Technology Data Exchange (ETDEWEB)

Lomenick, T.F.; Gonzales, S.; Johnson, K.S.; Byerly, D.

1983-01-01

The thick and regionally extensive sequence of shales and associated clastic sedimentary rocks of Late Devonian and Early Mississippian age has been considered among the nonsalt geologies for deep subsurface containment of high-level radioactive wastes. This report examines some of the regional and basin-specific characteristics of the black and associated nonblack shales of this sequence within the Appalachian, Illinois, and Michigan basins of the north-central and eastern United States. Principal areas where the thickness and depth of this shale sequence are sufficient to warrant further evaluation are identified, but no attempt is made to identify specific storage/disposal sites. Also identified are other areas with less promise for further study because of known potential conflicts such as geologic-hydrologic factors, competing subsurface priorities involving mineral resources and groundwater, or other parameters. Data have been compiled for each basin in an effort to indicate thickness, distribution, and depth relationships for the entire shale sequence as well as individual shale units in the sequence. Included as parts of this geologic assessment are isopach, depth information, structure contour, tectonic elements, and energy-resource maps covering the three basins. Summary evaluations are given for each basin as well as an overall general evaluation of the waste storage/disposal potential of the Devonian-Mississippian shale sequence,including recommendations for future studies to more fully characterize the shale sequence for that purpose. Based on data compiled in this cursory investigation, certain rock units have reasonable promise for radioactive waste storage/disposal and do warrant additional study.

Regional geological assessment of the Devonian-Mississippian shale sequence of the Appalachian, Illinois, and Michigan basins relative to potential storage/disposal of radioactive wastes

International Nuclear Information System (INIS)

Lomenick, T.F.; Gonzales, S.; Johnson, K.S.; Byerly, D.

1983-01-01

The thick and regionally extensive sequence of shales and associated clastic sedimentary rocks of Late Devonian and Early Mississippian age has been considered among the nonsalt geologies for deep subsurface containment of high-level radioactive wastes. This report examines some of the regional and basin-specific characteristics of the black and associated nonblack shales of this sequence within the Appalachian, Illinois, and Michigan basins of the north-central and eastern United States. Principal areas where the thickness and depth of this shale sequence are sufficient to warrant further evaluation are identified, but no attempt is made to identify specific storage/disposal sites. Also identified are other areas with less promise for further study because of known potential conflicts such as geologic-hydrologic factors, competing subsurface priorities involving mineral resources and groundwater, or other parameters. Data have been compiled for each basin in an effort to indicate thickness, distribution, and depth relationships for the entire shale sequence as well as individual shale units in the sequence. Included as parts of this geologic assessment are isopach, depth information, structure contour, tectonic elements, and energy-resource maps covering the three basins. Summary evaluations are given for each basin as well as an overall general evaluation of the waste storage/disposal potential of the Devonian-Mississippian shale sequence,including recommendations for future studies to more fully characterize the shale sequence for that purpose. Based on data compiled in this cursory investigation, certain rock units have reasonable promise for radioactive waste storage/disposal and do warrant additional study

Analysis of the structural parameters that influence gas production from the Devonian shale. Annual progress report, 1979-1980. Volume II. Data repository and reports published during fiscal year 1979-1980: regional structure, surface structure, surface fractures, hydrology

Energy Technology Data Exchange (ETDEWEB)

Negus-De Wys, J.; Dixon, J. M.; Evans, M. A.; Lee, K. D.; Ruotsala, J. E.; Wilson, T. H.; Williams, R. T.

1980-10-01

This volume comprises appendices giving regional structure data, surface structure data, surface fracture data, and hydrology data. The fracture data covers oriented Devonian shale cores from West Virginia, Ohio, Virginia, Pennsylvania, and Kentucky. The subsurface structure of the Eastern Kentucky gas field is also covered. (DLC)

Effects of ancient porosity and permeability on formation of sedimentary dolomites: Devonian Jefferson Formation (Frasnian), south-central Montana

Energy Technology Data Exchange (ETDEWEB)

Smith, T.M.; Dorobek, S.L.

1987-08-01

Petrographic and geochemical evidence indicates that multiple dolomitization and dolomite stabilization events affected the Devonian Jefferson Formation (Frasnian) in south-central Montana. Several types of dolomite occur, defined by cathodoluminescence: nonzoned, dully luminescent subhedral-anhedral mosaics (most common), euhedral nonzoned and zoned dolomites, zoned dolomite cements, and irregularly luminescent dolomites (dully luminescent with irregularly luminescent regions). The irregularly luminescent fabrics probably represent partial replacement of early dolomite phases with later dolomite phases. Nonzoned, Ca-enriched, euhedral dolomites occur in calcite-cemented, coarse-grained limestone layers. These permeable layers probably were conduits for early meteoric waters, that occluded porosity in the limestones and prevented later dolomite stabilization. Irregularly luminescent dolomites are interpreted as intermediate fabrics in the dolomite stabilization process. Later calcite cements which occlude intercrystalline porosity prevented further dolomite replacement. Total recrystallization of remaining dolomites and formation of final dully luminescent mosaics occurred prior to brecciation and stylolitization.

Checklist of Recent thecideoid brachiopods from the Indian Ocean and Red Sea, with a description of a new species of Thecidellina from Europa Island and a re-description of T. blochmanni Dall from Christmas Island.

Science.gov (United States)

Logan, Alan; Hoffmann, Jana; Lüter, Carsten

2015-09-08

Compilation of a checklist of Recent thecideoid brachiopods from the Indian Ocean and Red Sea indicates that members of this superfamily are represented by a small number of species. The subfamily Lacazellinae is represented by Ospreyella maldiviana from the Maldive Islands but the presence of Lacazella cannot yet be confirmed in the Indian Ocean as the holotype of Lacazella mauritiana from Mauritius is lost. The subfamily Thecidellininae is represented by Thecidellina blochmanni from Christmas Island in the eastern Indian Ocean and the Red Sea while a new species T. europa is here described from Europa Island in the Mozambique Channel. The subfamily Minutellinae is represented by Minutella minuta from Samper Bank and Walters Bank in the south-western Indian Ocean and in the Red Sea. Since the holotype of Thecidellina blochmanni from Flying Fish Cove, Christmas Island is also lost, this species is re-described and illustrated mainly from topotypes in the Museum für Naturkunde, Berlin, from which a suggested neotype has been selected.

Precise position of the Basal Choteč event and evolution of sedimentary environments near the Lower–Middle Devonian boundary: The magnetic susceptibility, gamma-ray spectrometric, lithological, and geochemical record of the Prague Synform (Czech Republic)

Czech Academy of Sciences Publication Activity Database

Koptíková, Leona

2011-01-01

Roč. 304, 1/2 (2011), s. 96-112 ISSN 0031-0182 R&D Projects: GA AV ČR KJB307020602; GA AV ČR IAAX00130702 Institutional research plan: CEZ:AV0Z30130516 Keywords : magnetic susceptibility * Gamma-ray spectrometry * Prague Synform * Lower–Middle Devonian Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.392, year: 2011

Metamorphosis in Craniiformea revisited

DEFF Research Database (Denmark)

Altenburger, Andreas; Wanninger, Andreas; Holmer, Lars E.

2013-01-01

We revisited the brachiopod fold hypothesis and investigated metamorphosis in the craniiform brachiopod Novocrania anomala. Larval development is lecithotrophic and the dorsal (brachial) valve is secreted by dorsal epithelia. We found that the juvenile ventral valve, which consists only of a thin...... brachiopods during metamorphosis to cement their pedicle to the substrate. N. anomala is therefore not initially attached by a valve but by material corresponding to pedicle cuticle. This is different to previous descriptions, which had led to speculations about a folding event in the evolution of Brachiopoda...

Interrogation of distributional data for the End Ordovician crisis interval

DEFF Research Database (Denmark)

Mac Ørum Rasmussen, Christian; Harper, David Alexander Taylor

2011-01-01

The uppermost Ordovician–lowermost Silurian (Upper Katian–Rhuddanian) is surveyed with respect to the a- and ß-diversity of rhynchonelliformean brachiopods. The survey is based on new collections as well as existing literature, compiled in a large, georeferenced database. The brachiopod faunas ar...

Recognition of depositional sequences and stacking patterns, Late Devonian (Frasnian) carbonate platforms, Alberta basin

Energy Technology Data Exchange (ETDEWEB)

Anderson, J.H.; Reeckmann, S.A.; Sarg, J.F.; Greenlee, S.M.

1987-05-01

Six depositional sequences bounded by regional unconformities or their correlative equivalents (sequence boundaries) have been recognized in Late Devonian (Frasnian) carbonate platforms in the Alberta basin. These sequences consist of a predictable vertical succession of smaller scale shoaling-upward cycles (parasequences). Parasequences are arranged in retrogradational, aggradational, and progradational stacking patterns that can be modeled as a sediment response to relative changes in sea level. Sequence boundaries are recognized by onlap onto underlying shelf or shelf margin strata. This onlap includes shelf margin wedges and deep marine onlap. In outcrop sections shelf margin wedges exhibit an abrupt juxtaposition of shallow water facies over deeper water deposits with no gradational facies changes at the boundaries. High on the platform, subaerial exposure fabrics may be present. The shelf margin wedges are interpreted to have formed during lowstands in sea level and typically exhibit an aggradational stacking pattern. On the platform, two types of sequences are recognized. A type 1 cycle occurs where the sequence boundary is overlain by a flooding surface and subsequent parasequences exhibit retrogradational stacking. In a type 2 cycle the sequence boundary is overlain by an aggradational package of shallow water parasequences, followed by a retrogradational package. These two types of sequences can be modeled using a sinusoidal eustatic sea level curve superimposed on thermo-tectonic subsidence.

The Hunsrück biota: A unique window into the ecology of Lower Devonian arthropods.

Science.gov (United States)

Rust, Jes; Bergmann, Alexandra; Bartels, Christoph; Schoenemann, Brigitte; Sedlmeier, Stephanie; Kühl, Gabriele

2016-03-01

The approximately 400-million-year old Hunsrück biota provides a unique window into Devonian marine life. Fossil evidence suggests that this biota was dominated by echinoderms and various classes of arthropods, including Trilobita, stem lineage representatives of Euarthropoda, Chelicerata and Eucrustacea, as well as several crown group Chelicerata and Eucrustacea. The Hunsrück biota's exceptional preservation allows detailed reconstructions and description of key-aspects of its fauna's functional morphologies thereby revealing modes of locomotion, sensory perception, and feeding strategies. Morphological and stratigraphic data are used for a critical interpretation of the likely habitats, mode of life and nutritional characteristics of this diverse fauna. Potential predators include pycnogonids and other chelicerates, as well as the now extinct stem arthropods Schinderhannes bartelsi, Cambronatus brasseli and Wingertshellicus backesi. Mainly the deposit feeding Trilobita, Marrellomorpha and Megacheira, such as Bundenbachiellus giganteus, represents scavengers. Possibly, opportunistic scavenging was also performed by the afore-mentioned predators. Most of the studied arthropods appear to have been adapted to living in relatively well-illuminated conditions within the photic zone. Fossil evidence for associations amongst arthropods and other classes of metazoans is reported. These associations provide evidence of likely community structures. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ciliary and mucus-net filter feeding, with special reference to fluid mechanical characteristics

DEFF Research Database (Denmark)

Jørgensen, C.B.; Kiørboe, Thomas; Møhlenberg, F.

1984-01-01

feeding characterized by processing of water at low pressures (.ltoreq. 1 mm H2O). Mechanisms of water processing and particle retention in brachiopods and bivalves are compared. Laminar flow of through-currents and surface-currents in brachiopods is consistent with the hypothesis of capture of suspended...

The hyper-enrichment of V and Zn in black shales of the Late Devonian-Early Mississippian Bakken Formation (USA)

Science.gov (United States)

Scott, Clinton T.; Slack, John F.; Kelley, Karen Duttweiler

2017-01-01

Black shales of the Late Devonian to Early Mississippian Bakken Formation are characterized by high concentrations of organic carbon and the hyper-enrichment (> 500 to 1000s of mg/kg) of V and Zn. Deposition of black shales resulted from shallow seafloor depths that promoted rapid development of euxinic conditions. Vanadium hyper-enrichments, which are unknown in modern environments, are likely the result of very high levels of dissolved H2S (~ 10 mM) in bottom waters or sediments. Because modern hyper-enrichments of Zn are documented only in Framvaren Fjord (Norway), it is likely that the biogeochemical trigger responsible for Zn hyper-enrichment in Framvaren Fjord was also present in the Bakken basin. With Framvaren Fjord as an analogue, we propose a causal link between the activity of phototrophic sulfide oxidizing bacteria, related to the development of photic-zone euxinia, and the hyper-enrichment of Zn in black shales of the Bakken Formation.

New porcellioidean gastropods from early Devonian of Royal Creek area, Yukon Territory, Canada, with notes on their early phylogeny

Science.gov (United States)

Fryda, J.; Blodgett, R.B.; Lenz, A.C.; Manda, S.

2008-01-01

This paper presents a description of new gastropods belonging to the superfamily Porcellioidea (Vetigastropoda) from the richly diverse Lower Devonian gastropod fauna of the Road River Formation in the Royal Creek area, Yukon Territory. This fauna belongs to Western Canada Province of the Old World Realm. The Pragian species Porcellia (Porcellia) yukonensis n. sp. and Porcellia (Paraporcellia) sp. represent the oldest presently known members of subgenera Porcellia (Porcellia) and Porcellia (Paraporcellia). Their simple shell ornamentation fits well with an earlier described evolutionary trend in shell morphology of the Porcellinae. Late Pragian to early Emsian Perryconcha pulchra n. gen. and n. sp. is the first member of the Porcellioidea bearing a row of tremata on adult teleoconch whorls. The occurrence of this shell feature in the Porcellioidea is additional evidence that the evolution of the apertural slit was much more complicated than has been proposed in classical models of Paleozoic gastropod evolution. Copyright ?? 2008, The Paleontological Society.

Devonian paleomagnetism of the North Tien Shan: Implications for the middle-Late Paleozoic paleogeography of Eurasia

Science.gov (United States)

Levashova, Natalia M.; Mikolaichuk, Alexander V.; McCausland, Philip J. A.; Bazhenov, Mikhail L.; Van der Voo, Rob

2007-05-01

The Ural-Mongol belt (UMB), between Siberia, Baltica and Tarim, is widely recognized as the locus of Asia's main growth during the Paleozoic, but its evolution remains highly controversial, as illustrated by the disparate paleogeographic models published in the last decade. One of the largest tectonic units of the UMB is the Kokchetav-North Tien Shan Domain (KNTD) that stretches from Tarim in the south nearly to the West Siberian Basin. The KNTD comprises several Precambrian microcontinents and numerous remnants of Early Paleozoic island arcs, marginal basins and accretionary complexes. In Late Ordovician time, all these structures had amalgamated into a single contiguous domain. Its paleogeographic position is of crucial importance for elucidating the Paleozoic evolution of the UMB in general and of the Urals in particular. The Aral Formation, located in Kyrgyzstan in the southern part of the KNTD, consists of a thick Upper Devonian (Frasnian) basalt-andesite sequence. Paleomagnetic data show a dual-polarity characteristic component (Dec/Inc = 286° / + 56°, α95 = 9°, k = 21, N = 15 sites). The primary origin of this magnetization is confirmed by a positive test on intraformational conglomerates. We combine this result with other Paleozoic data from the KNTD and show its latitudinal motion from the Late Ordovician to the end of the Paleozoic. The observed paleolatitudes are found to agree well with the values extrapolated from Baltica to a common reference point (42.5°N, 73°E) in our sampling area for the entire interval; hence coherent motion of the KNTD and Baltica is strongly indicated for most of the Paleozoic. This finding contradicts most published models of the UMB evolution, where the KNTD is separated from Baltica by a rather wide Ural Ocean containing one or more major plate boundaries. An exception is the model of Şengör and Natal'in [A.M.C. Şengör, B.A. Natal'in, Paleotectonics of Asia: fragments of a synthesis, in: A. Yin and M. Harrison (eds

Iron in the Middle Devonian aquifer system and its removal at Võru County water treatment plants, Estonia

Directory of Open Access Journals (Sweden)

Mariina Hiiob

2012-08-01

Full Text Available Groundwater abstracted from the Middle Devonian aquifer system is the main source of drinking water in South Estonia. High iron and manganese concentrations in groundwater are the greatest problems in this region. The total iron concentrations up to 16 mg L–1 are mainly caused by a high Fe2+ content in water, pointing to the dominance of reducing conditions in the aquifer system. A pilot study was carried out to estimate the effectiveness of 20 groundwater purification plants with eight different water treatment systems (aeration combined with Manganese Greensand, Birm, Nevtraco, Hydrolit-Mn, Magno-Dol and quartz sand filters in Võru County. The results demonstrate that in most cases the systems with pre-aeration effectively purify groundwater from iron, but only 13 out of 20 water treatment plants achieved a reduction of iron concentration to the level fixed in drinking water requirements (0.2 mg L–1. Manganese content decreased below the maximum allowed concentration in only 25% of systems and in cases where the filter media was Birm or quartz sand and pre-oxidation was applied. The study showed that the high level of iron purification does not guarantee effective removal of manganese.

Infiltration-driven metamorphism, New England, USA: Regional CO2 fluxes and implications for Devonian climate and extinctions

Science.gov (United States)

Stewart, E. M.; Ague, Jay J.

2018-05-01

We undertake thermodynamic pseudosection modeling of metacarbonate rocks in the Wepawaug Schist, Connecticut, USA, and examine the implications for CO2 outgassing from collisional orogenic belts. Two broad types of pseudosections are calculated: (1) a fully closed-system model with no fluid infiltration and (2) a fluid-buffered model including an H2O-CO2 fluid of a fixed composition. This fluid-buffered model is used to approximate a system open to infiltration by a water-bearing fluid. In all cases the fully closed-system model fails to reproduce the observed major mineral zones, mineral compositions, reaction temperatures, and fluid compositions. The fluid-infiltrated models, on the other hand, successfully reproduce these observations when the XCO2 of the fluid is in the range ∼0.05 to ∼0.15. Fluid-infiltrated models predict significant progressive CO2 loss, peaking at ∼50% decarbonation at amphibolite facies. The closed-system models dramatically underestimate the degree of decarbonation, predicting only ∼15% CO2 loss at peak conditions, and, remarkably, global warming, sea level rise, and, perhaps, extinction in the mid- to late-Devonian.

Biostratigraphy and biofacies of the Devonian deposits of the Kuh-e-Shorab section (southwest Damghan based on conodont fauna

Directory of Open Access Journals (Sweden)

Mehdi Hoveida

2016-09-01

Full Text Available The studied section located in the Djam-Semnan area 55 kms south west Damghan, at the vicinity of the Amrovan rail way station, in the northern flank of Shorab unassymetric anticline. The section is 440 meters thick, including limestone, dolomitic limestone and sandstone with rich fossils contents (e.g.: trilobite, coral, brachiopod, crinoid segments and vertebrate remains. The lower boundary is covered with the recent alluvial and the upper boundary disconformably overlain by the red marls and sandstones of the Permian Dorud formation. In order to determine biostratigraphy and bifacies of the deposits of Bahram formation in Shorab section, twenty five samples (4-6 kgs were collected and processed with conventional actic/formic acid. Nineteen samples were prolific and totally yielded 340 conodont elements. The extracted conodont elements mainly separated out of the carbonate units. Thirty-one species belong to four genera (Polygnathus, Icriodus, Pelecysgnathus and Ancyrodella were discriminated as: Icriodus excavatus, I. expansus, I. cedarensis, I. subterminus, I. iowaensis, I. alternatus, I. tafilaltensis, I. brevis, I. cf. expansus, I. sp., Polygnathus brevilaminus, Poly. angustidiscus, Poly. pollocki, Poly. cf. webbi, Poly. aspelundi, Poly. politus, Poly. alatus, Poly. webbi, Poly. cf. olgae, Poly. dubius, Poly. xylus, Poly. zinaidae, Poly. sp., Pelekeygnathus inclinathus, Pele. serradentatus, Pele. sp., Ancyrodella pristina, Acny. cf. pristina, Ancy. aff. binodosa, Ancy. sp. Based on the frequency and distribution of the collected elements Late Givetian to Early Famennian age were suggested to the studied interval. Conodonts biofacies (icriodid-polygnathid confirm the deposition of the Bahram formation of the Shorab section in the shallow carbonate condition.

Characteristics of the Late Devonian Tsagaan Suvarga Cu-Mo deposit, Southern Mongolia

Science.gov (United States)

Tungalag, Naidansuren; Jargalan, Sereenen; Khashgerel, Bat-Erdene; Mijiddorj, Chuluunbaatar; Kavalieris, Imants

2018-05-01

The Late Devonian Tsagaan Suvarga deposit (255 Mt at 0.55% Cu, 0.02% Mo) is located on the NW margin of the Tsagaan Suvarga Complex (TSC), which extends ENE over 15 × 10 km and comprises mainly medium-grained equigranular hornblende-biotite quartz monzonite and monzodiorite. Distinct mineralized intrusions are inferred from distribution of Cu-Mo mineralization but are not clearly discernible. The Tsagaan Suvarga Complex is a window within Carboniferous volcanic and sedimentary rocks, and wall rocks to the TSC are not known or exposed in the nearby district. Whole-rock analyses and Sr-Nd isotopes, 87Sr/86Sr0 = 0.7027 to 0.7038 (n = 12) and ɛNd0 = + 4.26 to + 2.77 (n = 12), show that the granitoids are subduction-related I-type, high K-calc-alkaline to shoshonitic series and derived from a mantle source. They exhibit fractionated light rare earth elements, without depleted Eu and depleted middle heavy rare earth elements and Y, typical of oxidized, fertile porphyry magmatic suites. Early porphyry-style quartz veins include A- and B-type. Molybdenite occurs in monomineralic veins (1-5 mm) or A veins. Copper mineralization occurs mainly as chalcopyrite and subordinate bornite, disseminated and associated with quartz-muscovite veins. Pyrite (vol%) content is less than chalcopyrite and bornite combined. Deep oxidation to about 50 m depth has formed zones of malachite and covellite in late fractures. The most important alteration is actinolite-biotite-chlorite-magnetite replacing hornblende and primary biotite. Quartz-K-feldspar alteration is minor. Late albite replaces primary K-feldspar and enhances sodic rims on plagioclase crystals. Quartz-muscovite (or sericitic alteration) overprints actinolite-biotite and porphyry-type quartz veins. Field observations and petrographic studies suggest that the bulk of the chalcopyrite-bornite mineralization at the Tsagaan Suvarga formed together with coarse muscovite alteration.

Carbon isotope chemostratigraphy and precise dating of middle Frasnian (lower Upper Devonian) Alamo Breccia, Nevada, USA

Science.gov (United States)

Morrow, J.R.; Sandberg, C.A.; Malkowski, K.; Joachimski, M.M.

2009-01-01

At Hancock Summit West, Nevada, western USA, uppermost Givetian (upper Middle Devonian) and lower and middle Frasnian (lower Upper Devonian) rocks of the lower Guilmette Formation include, in stratigraphic sequence, carbonate-platform facies of the conodont falsiovalis, transitans, and punctata Zones; the type Alamo Breccia Member of the middle punctata Zone; and slope facies of the punctata and hassi Zones. The catastrophically deposited Alamo Breccia and related phenomena record the ~ 382??Ma Alamo event, produced by a km-scale bolide impact into a marine setting seaward of an extensive carbonate platform fringing western North America. Re-evaluation of conodonts from the lower Guilmette Formation and Alamo Breccia Member, together with regional sedimentologic and conodont biofacies comparisons, now firmly locates the onset of the Johnson et al. (1985) transgressive-regressive (T-R) cycle IIc, which occurred after the start of the punctata Zone, within a parautochthonous megablock low in the Alamo Breccia. Whole-rock carbon isotope analyses through the lower Guilmette Formation and Alamo Breccia Member reveal two positive ??13Ccarb excursions: (1) a small, 3??? excursion, which is possibly correlative with the falsiovalis Event previously identified from sections in Western Europe and Australia, occurs below the breccia in the Upper falsiovalis Zone to early part of the transitans Zone; and (2) a large, multi-part excursion, dominated by a 6??? positive shift, begins above the start of the punctata Zone and onset of T-R cycle IIc and continues above the Alamo Breccia, ending near the punctata- hassi zonal boundary. This large excursion correlates with the punctata Event, a major positive ??13C excursion previously recognized in eastern Laurussia and northern Gondwana. Consistent with previous studies, at Hancock Summit West the punctata Event is apparently not associated with any regional extinctions or ecosystem reorganizations. In the study area, onset of the

The Early Devonian eurypterid Grossopterus overathi (Gross, 1933 from Overath, Germany

Directory of Open Access Journals (Sweden)

J. A. Dunlop

2002-01-01

Full Text Available The holotype and only known specimen of the eurypterid (Chelicerata: Eurypterida Grossopterus overathi (Gross, 1933 from the Early Devonian (Siegennian of Overath, north-west Germany is redescribed. Based on comparisons with other eurypterid taxa we interpret G. overathi as having a well-preserved type B genital appendage, which exhibits two apomorphic character states: (1 a furca fused into a single, spatulate plate and (2 marginal serrations near the distal end of the appendage. Grossopterus is assigned to the family Hughmilleriidae, but its carapace resembles that of the larger Slimonia acuminata (Salter, 1856 (Slimoniidae. A provisional phylogenetic analysis resolves Grossopterus as the sister group of (Slimonia + Pterygotoidea. The large pterygotids, in particular, have been suggested as significant predators on early vertebrates and hypotheses about eurypterid-fish co-evolution are reviewed, in particular Romer's proposal that dermal armour in fish evolved in response to eurypterid predation. Der Holotyp – das einzig bekannte Exemplar – des Eurypteriden (Chelicerata: Eurypterida Grossopterus overathi (Gross, 1933 aus dem frühen Devon (Siegennian von Overath im nordwestlichen Deutschland wird wieder beschrieben. Basierend auf Vergleichen mit anderen Eurypteriden-Taxa interpretieren wir G. overathi als Träger eines Typ B-Anhanges, wobei zwei apomorphe Merkmalszustände vorliegen: (1 die Furca ist zu einer einzigen, spatelförmigen Platte verschmolzen, und (2 der Seitenrand nahe des distalen Endes des Genitalanhanges ist gezähnt. Grossopterus wird zur Familie der Hughmilleriidae gestellt, aber der prosomale Dorsalschild ähnelt der größeren Slimonia acuminata (Salter, 1856 (Slimoniidae. Eine vorläufige phylogenetische Analyse zeigt Grossopterus als Schwesteruppe von (Slimonia + Pterygotoidea auf. Besonders die großen Pterygotiden wurden als signifikante Prädatoren von frühen Vertebraten gehandelt, und Hypothesen zur Eurypteriden

Taphonomy of a thick Terebratula bioherm from the Pliocene of southeastern Spain

Science.gov (United States)

García-Ramos, Diego A.

2015-04-01

Brachiopods were extremely abundant during the Paleozoic era but underwent a dramatic loss of biodiversity at the Permo-Triassic boundary. The comparison of brachiopod and bivalve diversity through geological time shows that the latter were the most successful counterpart at best recovering from mass extinction events. Nonetheless, there are cases where Post-Paleozoic brachiopods stand out as the dominant marine benthos in particular environments, forming paucispecific brachiopod-dominated bioherms. This note describes an example of shallow-water brachiopod bioherm dominated by the terebratulid Terebratula calabra. The shell bed is found in mixed siliciclastic-temperate carbonate deposits of late Early Pliocene age nearby Águilas (southeastern Spain). This unique brachiopod concentration may be helpful to understand the particular success of large-sized brachiopods like Terebratula in Cenozoic environments typically dominated by bivalves. The bioherm attains 1.5 meters in thickness and crops out along a band up to 140 meters wide. The lithology consists of bioturbated fine-grained sands containing poorly sorted bioclasts, mostly fragments of Terebratula. This shell bed also records a diverse fauna, including five brachiopod genera, pectinids (4 genera), oysters (3 genera), in addition to rare gastropods, echinoids, bryozoans, etc. The density and sorting of bioclasts is laterally variable, and the biofabrics range from loosely dispersed to densely-packed, including examples of concave-up vertical stacking and nesting of shells. Most of the fragments of Terebratula preserve the posterior part of the shell only. These fragments generally display corrasion (rounded fractured margins, rounded to completely missing symphytium), bioerosion (prevailing the ichnogenera Entobia, Gnathichnus and Podichnus) and encrustation (mainly by bryozoans, Ancistrocrania, and Pododesmus). The good preservation of Pododesmus contrasts with that of most fragments of Terebratula, although

Carbon and nitrogen isotopic analysis of coral-associated nitrogen in rugose corals of the Middle Devonian, implications for paleoecology and paleoceanography.

Science.gov (United States)

Hickey, A. N.; Junium, C. K.; Uveges, B. T.; Ivany, L. C.; Martindale, R. C.

2017-12-01

The Middle Devonian Appalachian Basin of Central New York hosts an extraordinary diversity of well-studied fossil invertebrates within the shallow marine sequences of the Givetian Age, Hamilton Group. Of particular interest are a series of aerially expansive coral beds with diverse assemblages of rugose corals. These well-preserved specimens provide an excellent opportunity to test the feasibility of δ15N and δ13C analyses in rugose corals in an effort to resolve outstanding issues regarding their paleoecology and ontogeny as well environmental dynamics within the Devonian Appalachian Basin. Here we present carbon and nitrogen isotope analyses of the rugose corals Heliophyllum and Siphonophrentis from the Joshua Coral Bed. Corals were cleaned of the host calcareous shale and sonicated sequentially in deionized water and methanol, and then oxidatively cleaned. Cleaned corals were sectioned into 0.5cm billets to obtain enough residual organic material for analysis. The organic content of the corals is low, but nanoEA allows for serial sampling of 5-10 samples per coral. Coral sections were decarbonated and the residual organic material is filtered and dried prior to analysis. Coral organic matter is analyzed in triplicate using nanoEA, which is a cryo-trapping, capillary focusing technique for δ15N and δ13C. The δ15N of organic matter extracted from rugose corals is, on average, enriched by 2-4‰ relative to the bulk nitrogen in the host rock. As well, the δ13C of organic carbon from the corals is 13C-enriched relative to the bulk rock, but to a lesser degree (no more than 1.5‰). Assuming that the bulk rock carbon and nitrogen are largely representative of the long-term primary production background, the modest enrichment is consistent with a trophic effect, and that rugose corals are likely planktivores. In an individual coral, δ15N ranges by 3-4‰ over its length, and when adjusted for trophic enrichment varies around the average δ15N of bulk

Skarn-mineralized porphyry adakites in the Harlik arc at Kalatage, E. Tianshan (NW China): Slab melting in the Devonian-early Carboniferous in the southern Central Asian Orogenic Belt

Science.gov (United States)

Mao, Qigui; Yu, Mingjie; Xiao, Wenjiao; Windley, Brian F.; Li, Yuechen; Wei, Xiaofeng; Zhu, Jiangjian; Lü, Xiaoqiang

2018-03-01

The geodynamic control of mineralization in the accretionary evolution of the Central Asian Orogenic Belt (CAOB) has long been controversial. Here we report new field, geochemical and geochronological data on recently defined porphyry and skarn-type ore deposits (Devonian-Early Carboniferous) in the Kalatage area in the middle of the Harlik-Dananhu arc, Eastern Tianshan, NW China in the southern CAOB, with the aim of better understanding the accretionary tectonics and genesis of porphyry and skarn-type mineralization. The Yudai porphyry Cu-(Au) deposits and the Xierqu skarn Cu-Fe-(Au) deposits are closely associated with Middle Devonian adakitic diorite porphyries (382-390 Ma), which are calc-alkaline and characterized by high Na2O/K2O ratios and Sr contents (310-1020 ppm), strong depletion of HREE (e.g., Yb = 0.80-1.44 ppm) and Y (7.68-14.50 ppm), and all enriched in Rb, Sr, Ba, K and depleted in Nb and Ti. They are characterized by distinctive Eu positive anomalies, high Na2O contents and MORB-like Sr and Nd isotope signatures (high εNd(t) = +6.1 to +7.0 and low (87Sr/86Sr)i = 0.70412-0.70462). These adakites most likely formed by melting of a young/hot subducted oceanic slab, and adakites in general are important carriers of porphyry Cu ± (Au) deposits. Early Carboniferous adakites in the Tuwu area south of Kalatage are known to have similar features. Therefore, skarn-mineralized porphyry adakites get younger from north to south, suggesting southward migration of the Harlik-Dananhu arc from 390 Ma to 322 Ma. These data indicate that partial melting of hot (and/or young) oceanic crustal slabs were an important mechanism of accretionary crustal growth and mineralization in the southern CAOB.

Equatorial seawater temperatures and latitudinal temperature gradients during the Middle to Late Jurassic: the stable isotope record of brachiopods and oysters from Gebel Maghara, Egypt

Science.gov (United States)

Alberti, Matthias; Fürsich, Franz T.; Abdelhady, Ahmed A.; Andersen, Nils

2017-04-01

The Jurassic climate has traditionally been described as equable, warmer than today, with weak latitudinal temperature gradients, and no polar glaciations. This view changed over the last decades with studies pointing to distinct climate fluctuations and the occasional presence of polar ice caps. Most of these temperature reconstructions are based on stable isotope analyses of fossil shells from Europe. Additional data from other parts of the world is slowly completing the picture. Gebel Maghara in the northern Sinai Peninsula of Egypt exposes a thick Jurassic succession. After a phase of terrestrial sedimentation in the Early Jurassic, marine conditions dominated since the end of the Aalenian. The stable isotope (δ18O, δ13C) composition of brachiopod and oyster shells was used to reconstruct seawater temperatures from the Bajocian to the Kimmeridgian at a palaeolatitude of ca. 3°N. Throughout this time interval, temperatures were comparatively constant aorund an average of 25.7°C. Slightly warmer conditions existed in the Early Bathonian ( 27.0°C), while the Kimmeridgian shows the lowest temperatures ( 24.3°C). The seasonality has been reconstructed with the help of high-resolution sampling of two oyster shells and was found to be very low (temperature gradients. During the Middle Jurassic, this gradient was much steeper than previously expected and comparable to today. During the Kimmeridgian, temperatures in Europe were generally warmer leading to weaker latitudinal gradients. Based on currently used estimates for the δ18O value of seawater during the Jurassic, reconstructed water temperatures for localities above the thermocline in Egypt and Europe were mostly lower than Recent sea-surface temperatures. These results improve our understanding of the Jurassic climate and its influence on marine faunal diversity patterns.

Geology of redbed Cu-U occurrences in the Upper Devonian Catskill Fm., Pennsylvania

International Nuclear Information System (INIS)

Smith, A.T.

1983-01-01

A regional and detailed geologic, petrographic and geochemical study of 40 redbed Cu-U occurrences and the host Upper Devonian Catskill Fm. in Pennsylvania shows that depositional environment and diagenetic processes were the most important controls on the formation of the occurrences. The Catskill Fm. in Pa. has been divided into 4 magnafacies (Mf). In ascending order, Mf-A contains interbedded marine and non-marine shale and fine sandstones; Mf-B contains mainly thick red shales and thin sandstones interpreted to be low-energy fluvial deposits on an inactive coastal plain interrupted by occasional thin transgressive marine sandstones. Mf-C is composed of thick sandstones deposited by braided rivers; and Mf-D is composed of thick fining-up cycles deposited by meandering rivers. The Cu-U occurrences are located in areas of thick Mf-B; they occur in Mf-A, -B and -D. Cu-sulfides formed during diagenesis with chlorite in pockets of plant trash within or below a marine or fluvial sandstones, which contain a greater percentage of ductile grains than similar sandstones are inferred to have been more permeable than non-mineralized sandstones. The Cu-sulfides formed after early hematite, clay coatings and calcite cement. Based on isotopic, textural and compositional evidence, the calcite is considered to have formed near the surface at temperatures of less than 100 0 C from oxidizing waters reduced by plant material. The Cu and U in a typical occurrence could easily have been derived by leaching of 1-3% of the total Cu and U from a volume of sediment equivalent to a cube of 40 m or less on a side. Cu appears to have been mobilized during compaction and was derived from the fine fraction of the sediments by Cl-bearing solutions introduced during marine transgressions

Depositional environments and sequence stratigraphy of the Bahram Formation (middle–late Devonian in north of Kerman, south-central Iran

Directory of Open Access Journals (Sweden)

Afshin Hashmie

2016-09-01

Full Text Available This study is focused on sedimentary environments, facies distribution, and sequence stratigraphy. The facies and sequence stratigraphic analyses of the Bahram Formation (middle–late Devonian in south-central Iran are based on two measured stratigraphic sections in the southern Tabas block. The Bahram Formation overlies red sandstones Padeha Formation in sections Hutk and Sardar and is overlain by Carboniferous carbonate deposits of Hutk Formation paraconformably, with a thickness of 354 and 386 m respectively. Mixed siliciclastic and carbonate sediments are present in this succession. The field observations and laboratory studies were used to identify 14 micro/petrofacies, which can be grouped into 5 depositional environments: shore, tidal flat, lagoon, shoal and shallow open marine. A mixed carbonate-detrital shallow shelf is suggested for the depositional environment of the Bahram Formation which deepens to the east (Sardar section and thins in southern locations (Hutk section. Three 3rd-order cyclic siliciclastic and carbonate sequences in the Bahram Formation and one sequence shared with the overlying joint with Hutk Formation are identified, on the basis of shallowing upward patterns in the micro/pertofacies.

Middle to Late Ordovician faunal studies from central Australia and Tasmania during the Great Ordovician Biodiversification Event

DEFF Research Database (Denmark)

Jakobsen, Kristian Grube

A profound transformation of the marine biosphere took place during the Great Ordovician Biodiversification Event (GOBE), recognized as the longest interval of sustained biodiversification in the history of life. Successions through the Middle Ordovician Stairway Sandstone of the Amadeus Basin......, but the diversity is generally relatively low. The bivalves are the most dominant and diverse group in the central Australian fauna, whereas the brachiopods are the most dominant and diverse group in the Tasmanian fauna. Thirteen trilobite, five brachiopod, four conodont and 22 mollusc taxa have been documented......, but the preservation and low number of specimens prevent formal definition of additional new taxa. Although highly endemic at species level, the investigated brachiopod, trilobite and mollusc faunas display a high degree of overall similarity at generic level with Middle Ordovician faunas from North China. Other...

Geochronology, stratigraphy and geochemistry of Cambro-Ordovician, Silurian and Devonian volcanic rocks of the Saxothuringian Zone in NE Bavaria (Germany)—new constraints for Gondwana break up and ocean-island magmatism

Science.gov (United States)

Höhn, Stefan; Koglin, Nikola; Klopf, Lisa; Schüssler, Ulrich; Tragelehn, Harald; Frimmel, Hartwig E.; Zeh, Armin; Brätz, Helene

2018-01-01

Stratigraphically well-defined volcanic rocks in Palaeozoic volcano-sedimentary units of the Frankenwald area (Saxothuringian Zone, Variscan Orogen) were sampled for geochemical characterisation and U-Pb zircon dating. The oldest rock suite comprises quartz keratophyre, brecciated keratophyre, quartz keratophyre tuff and basalt, formed in Upper Cambrian to Tremadocian time (c. 497-478 Ma). Basaltic volcanism continued until the Silurian. Quartz keratophyre shows post-collisional calc-alkaline signature, the Ordovician-Silurian basalt has alkaline signature typical of continental rift environments. The combined datasets provide evidence of Cambro-Ordovician bimodal volcanism and successive rifting until the Silurian. This evolution very likely resulted from break-up of the northern Gondwana margin, as recorded in many terranes throughout Europe. The position at the northern Gondwana margin is supported by detrital zircon grains in some tuffs, with typical Gondwana-derived age spectra mostly recording ages of 550-750 Ma and minor age populations of 950-1100 and 1700-2700 Ma. The absence of N-MORB basalt in the Frankenwald area points to a retarded break-off of the Saxothuringian terrane along a continental rift system from Uppermost Cambrian to Middle Silurian time. Geochemical data for a second suite of Upper Devonian basalt provide evidence of emplacement in a hot spot-related ocean-island setting south of the Rheic Ocean. Our results also require partial revision of the lithostratigraphy of the Frankenwald area. The basal volcanic unit of the Randschiefer Formation yielded a Tremadocian age and, therefore, should be attributed to the Vogtendorf Formation. Keratophyre of the Vogtendorf Formation, previously assigned to the Tremadoc, is most likely of Upper Devonian age.

Parental Sources of High-Alumina Alkaline Melts: Nd, Sr, Pb, and O Isotopic Evidence from the Devonian Kiya-Shaltyr Gabbro-Urtite Intrusion, South Siberia

Science.gov (United States)

Vrublevskii, V. V.; Gertner, I. F.; Chugaev, A. V.

2018-04-01

The isotope geochemistry (ɛNd( t) 4.8-5.4, 206Pb/204Pb in 18.05-18.36, 207Pb/204Pbin 15.53-15.57, 208Pb/204Pb in 37.59-37.83, 87Sr/86Sr( t) 0.7048-0.7057, δ18OSMOW 8-10.5‰) and trace element composition of the Kiya-Shaltyr gabbro-urtite pluton allow us to suggest a heterogeneous source and complex geodynamic settings of the Devonian alkali magmatism in the Kuznetsk Alatau. It is assumed that its evolution took place under conditions of partial mingling of matter of the depleted (PREMA) and enriched (EM) mantle with crustal contamination of the evolving melt. Such an interaction could have been a result of superposition of a mantle plume and an active margin (OIB and IAB components). In fold belts this led to the formation of hybrid high-alumina foidoite magmas.

New morphological information on, and species of placoderm fish Africanaspis (Arthrodira, Placodermi from the Late Devonian of South Africa.

Directory of Open Access Journals (Sweden)

Robert W Gess

Full Text Available Here we present a new species of placoderm fish, Africanaspis edmountaini sp. nov., and redescribe Africanaspis doryssa on the basis of new material collected from the type locality of Africanaspis. The new material includes the first head shields of Africanaspis doryssa in addition to soft anatomy for both taxa. Hitherto Africanaspis was entirely described from trunk armour and no record of body and fin outlines had been recorded. In addition the first record of embryonic and juvenile specimens of Africanaspis doryssa is presented and provides a growth series from presumed hatchlings to presumed adults. The presence of a greater number of juveniles compared to adults indicates that the Waterloo Farm fossil site in South Africa represents the first nursery site of arthrodire placoderms known from a cold water environment. The preservation of an ontogenetic series demonstrates that variation within the earlier known sample, initially considered to have resulted from ontogenetic change, instead indicates the presence of a second, less common species Africanaspis edmountaini sp. nov. There is some faunal overlap between the Waterloo Farm fossil site and faunas described from Strud in Belgium and Red Hill, Pennsylvania, in north America, supporting the concept of a more cosmopolitan vertebrate fauna in the Famennian than earlier in the Devonian.

New morphological information on, and species of placoderm fish Africanaspis (Arthrodira, Placodermi) from the Late Devonian of South Africa

Science.gov (United States)

2017-01-01

Here we present a new species of placoderm fish, Africanaspis edmountaini sp. nov., and redescribe Africanaspis doryssa on the basis of new material collected from the type locality of Africanaspis. The new material includes the first head shields of Africanaspis doryssa in addition to soft anatomy for both taxa. Hitherto Africanaspis was entirely described from trunk armour and no record of body and fin outlines had been recorded. In addition the first record of embryonic and juvenile specimens of Africanaspis doryssa is presented and provides a growth series from presumed hatchlings to presumed adults. The presence of a greater number of juveniles compared to adults indicates that the Waterloo Farm fossil site in South Africa represents the first nursery site of arthrodire placoderms known from a cold water environment. The preservation of an ontogenetic series demonstrates that variation within the earlier known sample, initially considered to have resulted from ontogenetic change, instead indicates the presence of a second, less common species Africanaspis edmountaini sp. nov. There is some faunal overlap between the Waterloo Farm fossil site and faunas described from Strud in Belgium and Red Hill, Pennsylvania, in north America, supporting the concept of a more cosmopolitan vertebrate fauna in the Famennian than earlier in the Devonian. PMID:28379973

Shallow water mud-mounds of the Early Devonian Buchan Group, East Gippsland, Australia

Science.gov (United States)

Tosolini, A.-M. P.; Wallace, M. W.; Gallagher, S. J.

2012-12-01

The Lower Devonian Rocky Camp Member of the Murrindal Limestone, Buchan Group of southeastern Australia consists of a series of carbonate mud-mounds and smaller lagoonal bioherms. The Rocky Camp mound is the best exposed of the mud-mounds and has many characteristics in common with Waulsortian (Carboniferous) mounds. Detailed paleoecological and sedimentological studies indicate that the mound initially accumulated in the photic zone, in contrast to most of the previously recorded mud-mounds. Five facies are present in the mud-mound: a Dasycladacean Wackestone Facies at the base of the mound represents a moderate energy, shallow water bank environment within the photic zone. A Crinioidal Wackestone Facies was deposited in a laterally equivalent foreslope setting. A Poriferan-Crinoidal Mudstone Facies developed in a quiet, deeper water, lee-side mound setting associated with a minor relative sea-level rise. A Stromatoporoid-Coralline Packstone Facies in the upper part of the mound deposited in a high-energy, fair-weather wave base, mound-front environment. The crest of the mound is represented by a Crinoidal-Receptaculitid Packstone Facies indicative of a moderate-energy mound-top environment in the photic zone, sheltered by the mound-front stromatoporoid-coral communities. A mound flank facies is present on the southern side of the mound and this consists of high-energy crinoidal grainstones. Mud-mound deposition was terminated by a transgression that deposited dark gray, fossil-poor marl of the overlying Taravale Formation. The Rocky Camp mound appears to have originated in shallow water photic zone conditions and grew into a high-energy environment, with the mound being eventually colonized by corals and stromatoporoids. The indications of a high-energy environment during later mound growth (growth form of colonial metazoans and grainstones of the flanking facies) suggest that the micrite in the mound was autochthonous and implies the presence of an energy

Origin of uranium and other metal concentrations in the Helmsdate granite and the Devonian sediments of the north-east of Scotland

Energy Technology Data Exchange (ETDEWEB)

Tweedie, J R

1981-01-01

An examination of the radiometrically anomalous Caledonian Helmsdale granite and certain radiometric localities in the Devonian sediments of Caithness has been undertaken in order to discover the processes of U concentration in the different rock types. The study is based mainly on geochemical examination, with analyses for U, Th, Cu, Zn, Pb, Mo, Zr, Rb, Sr, Bi, Se, P/sub 2/O/sub 5/, and K/sub 2/O being carried out. The granite was found to have a high mean U content (9 ppm), approximately twice that expected from comparison with the world granite average (4 ppm), whilst zones of intense alteration gave U enrichments of up to 71 ppm. These latter have a mineralogy and geochemistry distinct from the normal granite. A limited Cu-Mo stockwork mineralisation was discovered almost coincident with a highly radioactive hydrocarbon vein. The main U concentrations in the Caithness sediments occur in thin phosphatic horizons. In these, U ranges from 100 to 1000 ppm and is paralleled by the phosphate in an approximately linear relationship of 100 ppm U/1% P/sub 2/O/sub 5/. Black shales contain low level U concentrations with anomalously high Zn and/or Mo. (author).

EVIDENCE OF A GUADALUPIAN AGE FOR THE KHUFF FORMATION OF SOUTHEASTERN OMAN: PRELIMINARY REPORT

Directory of Open Access Journals (Sweden)

LUCIA ANGIOLINI

1998-11-01

Full Text Available The Guadalupian succession of the Huqf area (Sultanate of Oman represents a mega-sequence comprising the fluvial terrigenous Gharif Formation and the overlying marine Khuff Formation. The Khuff Fm. is subdivided into four members and is composed of marls and bioclastic limestones. The Khuff Fm. yields a rich fauna of brachiopods, conodonts, foraminifers, bivalves, gastropods, ostracods and cephalopods. The brachiopod fauna of the Khuff Fm. includes strophomenids, productids, orthids and terebratulids. The associated conodont fauna includes Hindeodus excavatus Behnken, Merrilina sp., M. praedivergens Kozur & Mostler, and Sweetina n. sp. (systematic descriptions of conodonts are given in the Paleontological Appendix. Foraminifers are represented by species of Miliolina and Rotaliina. The Khuff Fm. is given a Wordian age, based on brachiopods and conodonts. The depositional environment of the Khuff Fm. of southeastern Oman corresponds to the outer shelf of a large carbonate platform covering most of the Arabian Platform. The Khuff Fm. is interpreted as a major transgressive-regressive cycle related to differential subsidence. 

The Late Devonian Frasnian-Famennian (F/F) biotic crisis: Insights from δ13C carb, δ13C org and 87Sr / 86Sr isotopic systematics

Science.gov (United States)

Chen, Daizhao; Qing, Hairuo; Li, Renwei

2005-06-01

A severe biotic crisis occurred during the Late Devonian Frasnian-Famennian (F/F) transition (± 367 Myr). Here we present δ13C carb, δ13C org and 87Sr / 86Sr isotopic systematics, from identical samples of two sections across F/F boundary in South China, which directly demonstrate large and frequent climatic fluctuations (˜200 kyr) from warming to cooling during the F/F transition. These climate fluctuations are interpreted to have been induced initially by increased volcanic outgassing, and subsequent enhanced chemical weathering linked to the rapid expansion of vascular plants on land, which would have increased riverine delivery to oceans and primary bioproductivity, and subsequent burial of organic matter, thereby resulting in climate cooling. Such large and frequent climatic fluctuations, together with volcanic-induced increases in nutrient (e.g., biolimiting Fe), toxin (sulfide) and anoxic water supply, and subsequent enhanced riverine fluxes and microbial bloom, were likely responsible for the stepwise faunal demise of F/F biotic crisis.

A new assessment of the Late Devonian antiarchan fish Bothriolepis leptocheira from South Timan (Russia and the biotic crisis near the Frasnian–Famennian boundary

Directory of Open Access Journals (Sweden)

Ervīns Lukševičs

2017-03-01

Full Text Available The species of the Late Devonian, earliest Famennian placoderm fish Bothriolepis jeremejevi has been downranked to subspecies Bothriolepis leptocheira jeremejevi comb. nov. in a result of detailed morphological studies of the type specimens and abundant new material from the type locality of the Sosnogorsk Formation, South Timan, Komi Republic, Russia. This taxon closely resembles Bothriolepis leptocheira leptocheira from Scotland, B. leptocheira curonica from Latvia, and B. leptocheira ssp. from Severnaya Zemlya differing only in small deviations of the size, proportions and shape of some plates of the armour. The composition of vertebrate assemblages from Scotland, Latvia, and Severnaya Zemlya containing B. leptocheira demonstrates a reduced diversity of antiarch placoderm, acanthodian, and sarcopterygian fishes; however, the Sosnogorsk assemblage differs in a larger diversity containing very primitive tetrapod and diversified sarcopterygian fishes including dipnoans and porolepiforms but lacking acanthodians. Wide distribution of a single species of Bothriolepis and usually diminished diversity of vertebrates suggest that the earliest Famennian vertebrate assemblages conform the survival faunas of the latest Frasnian–earliest Famennian biotic crisis.

A functional collapse of persistent shell-gravel benthic ecosystem on the California shelf within the last century

Science.gov (United States)

Tomasovych, Adam; Kidwell, Susan M.

2016-04-01

Death assemblages sampled from the muddy seabed of the inner and middle mainland Southern California continental shelf frequently contain dead shells of epifaunal terebratulid brachiopod and large-bodied scallop species that have not been encountered alive during annual surveys of this area over the last four decades. Instead, live-collected shelly benthos is dominated by infaunal species, especially chemosynthetic and deposit-feeding bivalves. Postmortem age-frequency distributions based on 190 individuals of the brachiopod Laqueus show (1) a mode between 100 and 300 years, (2) the absence of shells younger than 100 years old, and (3) the continuous presence of shells older than 300 years, ranging up to six thousands of years old, implying the relatively continuous active production of shells by this brachiopod species over millennia. The localized occurrence of small living populations of this brachiopod and of the scallops Chlamys and Euvola under the reduced sedimentation conditions along the outermost edge of the mainland shelf, and their occurrence on the sandy shelves of the isolated, offshore Channel Islands less affected by natural and anthropogenic runoff, indicates that, up until the last century, the inner and middle mainland shelf had also been characterized by extensive areas of mud-free, shell-gravel habitat. The shift in community structure to the spatially pervasive, infauna-dominated muddy habitats encountered today implies a change to higher siltation and sediment loading due to increased land clearance within recent centuries.

The lower Maastrichtian Hivdskud succession, Møns Klint, Denmark

DEFF Research Database (Denmark)

Jelby, M.E.; Thibault, Nicolas Rudolph; Surlyk, Finn

2014-01-01

with the cored boreholes Stevns-1 (Denmark) and ODP Site 762C (Indian Ocean). Hvidskud encompasses the 405 kyr eccentricity cycles Ma40513 – Ma40511 within magnetochron C31r. A sedimentation rate of 5.0 cm kyr-1 can be inferred from correlation to geochronological tie-points in ODP 762C, suggesting an age of ~70...... Maastrichtian in north-western Europe. Information on palaeo-seawater temperatures can be drawn from oxygen isotope records obtained from bulk rock samples and 24 micromorphic brachiopod specimens (Terebratulina faujasii). The brachiopod data show a clear diagenetic trend but point to an upper range...

NEW PALEOMAGNETIC DATA ON THE SILURIAN AND DEVONIAN SEDIMENTARY ROCKS FROM PODOLIA, SW UKRAINE, AND KINEMATICS OF THE EAST EUROPEAN PLATFORM IN THE MIDDLE PALEOZOIC

Directory of Open Access Journals (Sweden)

V. G. Bakhmutov

2014-01-01

Full Text Available Paleomagnetic data are the priority source of information for global paleotectonic reconstructions representing horizontal movements of the crustal blocks. Upon receipt of new paleomagnetic data, kinematic models of the East European platform in the Paleozoic are regularly revised and improved. The article presents results of the paleomagnetic study of sedimentary gray-colored and red beds of the Silurian and Lower Devonian sequences located in the Dniester river basin, Podolia region, SW Ukraine. The study covered 17 outcrops that are stratigraphically correlated with the Wenlock, Ludlow, Pridoli states of the Sillurian and the Lochkovian stage of the Devon. Over 400 samples of grey limestone, argillite, dolomite, red limestone and sandstone were analyzed, and two components of natural remnant magnetization (NRM were revealed. The first component with SSW declination and negative inclination is revealed in the majority of the samples during AF- and T-magnetic cleaning. Its pole positions, that are calculated separately for each series, are trending to the Permian segment of the apparent polar wander path (APWP published by Torsvik et al. [2012] for Baltica / Stable Europe. Considering its chemical origin, this NRM component is related to formation of authigenic minerals due to rock remagnetization. The second component is revealed only in some samples taken from the red beds (during thermal demagnetization in the range of unblocking temperatures from 590 to 690 °С and in few samples of grey limestone (in AF fields from 30 to 70 mT or in the range of unblocking temperatures from 300 to 460 °С. This component has SW declination and positive inclination, goes to the origin of coordinates of the diagrams, and has all the indicators of primary magnetization of sediments. Calculated positions of the poles (0 ºS and 329 ºE for grey limestone of the Tiverskaya series, 2.3 °S and 338.4 °E for red beds of the Dniestrovskaya series, etc. are well

Comparative morphology, histology and growth of the dental plates of the Devonian dipnoan Chirodipterus.

Science.gov (United States)

Smith, M M; Campbell, K S

1987-10-14

The dental plates of the Devonian lungfish Chirodipterus australis Miles (Osteichthyes; Dipnoi) are shown to have achieved their characteristic morphology by a growth process different from that assumed for the plates of genera such as Dipterus. Each plate was thickened by the addition of layers of bone that also extended the plate labially, thus providing the base on which and into which dentine grew. Distinctive features of the dentition are: (a) labial increase of the dentine mass by the addition of blister-like denticles of simple enamel-covered dentine, which is initially ingrown by pleromic dentine and subsequently resorbed and replaced by petrodentine; (b) increase in the midline by a similar process that results in the addition of one (or possibly two) new ridges; (c) resorption of the posterior edge of the pterygoid plates and the posterior and posteromedial edges of the prearticular plates, with subsequent development over the resorbed surfaces of several generations of simple regenerative dentine; (d) resorption and redeposition of pleromic dentine and bone in a triangular region posteromedially on the pterygoid plates; (e) the formation of tuberosities that simulate teeth at a short distance in from the labial edge, by four processes: formation of an undulating plate margin, differential growth of petrodentine (hard compact dentine) within the pulp cavity, differential wear of the petrodentine and the adjacent bone plus pleromic dentine, and slightly greater growth of the petrodentine towards the occlusal surface relative to the adjacent bone and dentine; (f) expansion of the large flat surfaces of the plates by gradual replacement of the bone and dentine at the proximal ends of the furrows and also by the development of linkages of petrodentine across the furrows; (g) development of isolated tuberosities on the flat posterolateral parts of the plates. The petrodentine of the ridges, tuberosities and plateaus of the plates is indistinguishable

The Frasnian-Famennian boundary (Upper Devonian) in black shale sequences: US Southern Midcontinent, Illinois Basin, and northern Appalachian Basin

Energy Technology Data Exchange (ETDEWEB)

Over, D.J. (State Univ. of New York, Geneseo, NY (United States). Dept. of Geological Sciences)

1994-04-01

The Frasnian-Famennian (F/F) boundary in the Woodford Shale of the US southern Midcontinent, Sweetland Creek Shale of the Illinois Basin, and the Hanover Shale of the northern Appalachian Basin is recognized to a discrete horizon. In each locality the boundary is marked by evidence of a disconformity: phosphate nodules, concentration of conodonts, or coated and corroded grains. The Woodford Shale consists of finely laminated pyritic organic-rich shale containing interbeds of greenish shale and chert. The F/F boundary horizon is marked by a concentration of conodonts and phosphatic nodules. The boundary lag horizon contains Pa. linguliformis, Pa. subperlobtata, Pa. delicatula delicatula, and Pa. triangularis. Underlying laminations contain Ancyrognathus ubiquitus and Pa. triangularis indicating that the disconformity is within the uppermost MN Zone 13 or Lower triangularis Zone. The upper portion of the Type Sweetland Creek Shale consists of dark organic-rich shales. The F/F boundary is located within an interval containing three green shale interbeds. Palmatolepis triangularis in the absence of Frasnian species first occurs in the middle green shale. In the thick Upper Devonian clastic sequence of the northern Appalachian Basin the F/F boundary is within an interval of interbedded pyritic green and organic-rich silty shales of the Hanover Shale. At Irish Gulf strata containing Pa. triangularis overlie finely laminated dark shales containing Pa. bogartensis, Pa. triangularis, Pa. winchell, Ancyrodella curvata, and Icriodus alternatus. The conodont fauna transition is below a conodont-rich laminae containing a Famennian fauna that marks the boundary horizon.

Geochemical constraints on the origin and volume of gas in the New Albany Shale (Devonian-Mississippian), eastern Illinois Basin

Science.gov (United States)

Strapoc, D.; Mastalerz, Maria; Schimmelmann, A.; Drobniak, A.; Hasenmueller, N.R.

2010-01-01

This study involved analyses of kerogen petrography, gas desorption, geochemistry, microporosity, and mesoporosity of the New Albany Shale (Devonian-Mississippian) in the eastern part of the Illinois Basin. Specifically, detailed core analysis from two locations, one in Owen County, Indiana, and one in Pike County, Indiana, has been conducted. The gas content in the locations studied was primarily dependent on total organic carbon content and the micropore volume of the shales. Gas origin was assessed using stable isotope geochemistry. Measured and modeled vitrinite reflectance values were compared. Depth of burial and formation water salinity dictated different dominant origins of the gas in place in the two locations studied in detail. The shallower Owen County location (415-433 m [1362-1421 ft] deep) contained significant additions of microbial methane, whereas the Pike County location (832-860 m [2730-2822 ft] deep) was characterized exclusively by thermogenic gas. Despite differences in the gas origin, the total gas in both locations was similar, reaching up to 2.1 cm3/g (66 scf/ton). Lower thermogenic gas content in the shallower location (lower maturity and higher loss of gas related to uplift and leakage via relaxed fractures) was compensated for by the additional generation of microbial methane, which was stimulated by an influx of glacial melt water, inducing brine dilution and microbial inoculation. The characteristics of the shale of the Maquoketa Group (Ordovician) in the Pike County location are briefly discussed to provide a comparison to the New Albany Shale. Copyright ??2010. The American Association of Petroleum Geologists. All rights reserved.

Lenticellaria and Hillerella, new kraussinoid genera (Kraussinoidea, Brachiopoda) from Indo-Pacific and Red Sea waters: evolution in the subfamily Megerliinae.

Science.gov (United States)

Simon, Eric G; Logan, Alan; Zuschin, Martin; Mainguy, Jerome; Mottequin, Bernard

2016-07-08

Two new kraussinid brachiopod genera, namely Lenticellaria gen. nov. and Hillerella gen. nov. are described from Pacific waters in the sub-equatorial zone in the Indonesian Archipelago, from Indian Ocean waters in Madagascar and from Red Sea waters in Egypt (Gulf of Aqaba) and Sudan. This fills the equatorial gap in the distribution of the superfamily Kraussinoidea, known from higher latitudes in both hemispheres. The micromorphic new material described is an excellent example of homeomorphy in brachiopods. It also provides new information on the distribution of the genus Megerlia sensu stricto and illustrates subtle variations in the evolutionary process of the reduced brachidium in Kraussinoidea.

On the origin of a phosphate enriched interval in the Chattanooga Shale (Upper Devonian) of Tennessee-A combined sedimentologic, petrographic, and geochemical study

Science.gov (United States)

Li, Yifan; Schieber, Juergen

2015-11-01

The Devonian Chattanooga Shale contains an uppermost black shale interval with dispersed phosphate nodules. This interval extends from Tennessee to correlative strata in Kentucky, Indiana, and Ohio and represents a significant period of marine phosphate fixation during the Late Devonian of North America. It overlies black shales that lack phosphate nodules but otherwise look very similar in outcrop. The purpose of this study is to examine what sets these two shales apart and what this difference tells us about the sedimentary history of the uppermost Chattanooga Shale. In thin section, the lower black shales (PBS) show pyrite enriched laminae and compositional banding. The overlying phosphatic black shales (PhBS) are characterized by phosbioclasts, have a general banded to homogenized texture with reworked layers, and show well defined horizons of phosphate nodules that are reworked and transported. In the PhBS, up to 8000 particles of P-debris per cm2 occur in reworked beds, whereas the background black shale shows between 37-88 particles per cm2. In the PBS, the shale matrix contains between 8-16 phosphatic particles per cm2. The shale matrix in the PhBS contains 5.6% inertinite, whereas just 1% inertinite occurs in the PBS. The shale matrix in both units is characterized by flat REE patterns (shale-normalized), whereas Phosbioclast-rich layers in the PhBS show high concentrations of REEs and enrichment of MREEs. Negative Ce-anomalies are common to all samples, but are best developed in association with Phosbioclasts. Redox-sensitive elements (Co, U, Mo) are more strongly enriched in the PBS when compared to the PhBS. Trace elements associated with organic matter (Cu, Zn, Cd, Ni) show an inverse trend of enrichment. Deposited atop a sequence boundary that separates the two shale units, the PhBS unit represents a transgressive systems tract and probably was deposited in shallower water than the underlying PBS interval. The higher phosphate content in the PhBS is

A Silurian-early Devonian slab window in the southern Central Asian Orogenic Belt: Evidence from high-Mg diorites, adakites and granitoids in the western Central Beishan region, NW China

Science.gov (United States)

Zheng, Rongguo; Xiao, Wenjiao; Li, Jinyi; Wu, Tairan; Zhang, Wen

2018-03-01

The Beishan orogenic belt is a key region for deciphering the accretionary processes of the southern Central Asian Orogenic Belt. Here in this paper we present new zircon U-Pb ages, bulk-rock major and trace element, and zircon Hf isotopic data for the Baitoushan, and Bagelengtai plutons in the western Central Beishan region to address the accretionary processes. The Baitoushan pluton consists of quartz diorites, monzonites and K-feldspar granites, with zircon LA-ICP-MS U-Pb ages of 435 Ma, 421 Ma and 401 Ma, respectively. The Baitoushan quartz diorites and quartz monzonites exhibit relatively high MgO contents and Mg# values (63-72), display enrichments in LILEs and LREEs, and exhibit high Ba (585-1415 ppm), Sr (416-570 ppm) and compatible element (such as Cr and Ni) abundances, which make them akin to typical high-Mg andesites. The Baitoushan quartz diorites and quartz monzonites were probably generated by the interaction of subducted oceanic sediment-derived melts and mantle peridotites. The Baitoushan K-feldspar granites are ascribed to fractionated I-type granites with peraluminous and high-K calc-alkaline characteristics. They exhibit positive εHf(t) values (2.43-7.63) and Mesoproterozoic-Neoproterozoic zircon Hf model ages (0.92-1.60 Ga). Those early Devonian granites, including Baitoushan K-feldspar granite and Gongpoquan leucogranites (402 Ma), are derived from melting of the mafic lower crust and/or sediments by upwelling of hot asthenospheric mantle. The Bagelengtai granodiorites exhibit similar geochemical signatures with that of typical adakites, with a zircon SHRIMP U-Pb age of 435 Ma. They exhibit relatively high Sr (502-628 ppm) and Al2O3 (16.40-17.40 wt.%) contents, and low MgO (1.02-1.29 wt.%), Y (3.37-6.94 ppm) and HREEs contents, with relatively high Sr/Y and (La/Yb)N ratios. The Bagelengtai granodiorites were derived from partial melting of subducted young oceanic crust, with significant contributions of subducted sediments, subsequently

The Svalbard Caledonides - a collage of Laurentian, Timanian and exotic terranes assembled by Silurian - Late (?) Devonian transcurrent faulting.

Science.gov (United States)

Andresen, Arild; Gasser, Deta

2014-05-01

New field and geochronological data from NE Greenland and Svalbard indicate that most of the sub-terranes making up the Svalbard Caledonides (Eastern, Northwestern and Southwestern Terranes) are derived from Laurentias eastern margin. The Neoproterozoic deposits of the Eastern Terrane (Nordaustlandet) show an almost one to one correlation with the Late Neoproterozoic Eleonore Bay Supergroup in NE Greenland. Great similarities also exist between the substratum to the Neoproterozoic deposits in the two areas. The "Barentsian plate/continent" is interpreted to be derived from Laurentias eastern margin Lithologic similarities also exist between parts of the Northwestern Terrane and NE Greenland. The geologic evolution of Svalbard`s Southwestern Terrane, with subduction complexes and Late Neoproterozoic intrusives (Timanian ?) is poorly understood. It will, however, be argued that there is no need to invoke considerable right lateral strike-slip movement of the Motalefjellet subduction complex and related rocks from a position in Arctic Canada to their present position within the Southwestern Terrane, as proposed by some authors. The structural grain of the Svalbard Caledonides, oblique to East Greenland and Scandinavian Caledonides, as well as the Ellesmerian Orogen, is interpreted to be due to counter-clockwise rotation (c. 45o) of the Caledonian trend. A counter-clockwise rotation is to be expected when the northward moving terranes reached the E-W trending Franklinian Basin north of Greenland/Laurentia, which in Early Devonian time had not yet started to close. The model predicts that there should be a dramatic change in the Caledonian structural grain somewhere south of Bjørnøya. It is furthermore speculated that the fan-shaped orientation of Late Paleozoic rift basins in the Western Barents Sea is controlled by reactivation of the rotated structural trend (e.g. Billefjorden Fault Zone and Billefjorden Trough).

Stratigraphy, structure, and lithofacies relationships of Devonian through Permian sedimentary rocks: Paradox Basin and adjacent areas - southeastern Utah. Technical report

International Nuclear Information System (INIS)

McCleary, J.; Rogers, T.; Ely, R.

1983-08-01

Geophysical well log analysis, literature review, and field work were conducted to develop isopach, structure contour, outcrop, and facies maps and cross sections for the Devonian through Permian strata of a 14,586-km 2 (5632-square-mile) area in southeastern Utah. The study area includes part of the Paradox Basin, the salt deposits of which are of interest in siting studies for a nuclear waste repository. For this reason hydrologic models of this area are needed. This study, part of which included the development of a three-dimensional stratigraphic computer model utilizing Geographic Information System software, can serve as a base for hydrologic or other models for this area. Within and adjacent to the study area, 730 wells were screened to select the 191 wells analyzed for the study. It was found that the Elbert through Molas formations did not exhibit noticeable facies changes within the study area. The Pinkerton Trail Formation exhibits moderate changes: anhydrite and shale become somewhat more abundant toward the northeast. Facies changes in the Paradox Formation are more dramatic. Thick saline facies deposits are present in the northeast, grading to thinner anhydrite and then to carbonate facies in the south and west. The lithology of the Honaker Trail Formation appears to be fairly uniform throughout the area. Facies changes in the Cutler Group are numerous and sometimes dramatic, and generally correspond to the named formations of the group. Other factors that could affect groundwater flow, such as stratigraphic cover of fine-grained rocks, area of formation outcrops, and fracturing and faulting are discussed and delineated on maps

Hábitos de Vida da Associação “Schuchertella”agassizi – Pthychopteria eschwegei, Formação Maecuru,Devoniano, Bacia do Amazonas, Brasil.

Directory of Open Access Journals (Sweden)

Luiza Corral Martins de Oliveira Ponciano

2007-07-01

Full Text Available The fossils studied came from outcrops of the Maecuru and Curuá rivers, State of Pará, belonging to the upper strata of theMaecuru Formation, Eifelian age. In this formation, two associations of marine benthic invertebrate can be identified, each inferring adistinct paleoenvironment. The association analyzed occurs in medium and coarse sandstones and shows “Schuchertella” agassizi andPtychopeteria eschwegei as predominant organisms. It was idnetified 12 species of brachiopods, 20 species of bivalves, 12 of trilobites,8 of gastropods, 6 of bellerophonts, 3 of crinoids and 3 of tentaculitids in this association. Brachiopods are the most abundant organisms,responsible for approximately 50% of it, followed by tentaculitids and bivalves. Trilobites, gastropods and bellerophonts sum less than10% of the aforementioned association. Crinoids were not included in the quantitative analysis because they are only found as calicinalplates and disarticulated column disks. The brachiopods showed, through their morphofunctional characteristics, suspension feedersrecumbent (free-lying epifaunal life habit or a pedicle attached mode of life. The bivalves showed a predominant suspension feeder semiinfaunalhabit, attached by byssus threads to the substratum, and an infaunal mode of life. All the trilobites showed a predator/scavengerand vagile epifaunal habit. The epifaunal platyceratids represents the gastropods with low mobility (coprophagous/suspension feeders.The bellerophonts showed an epifaunal highly/medium mobility and grazing/predator habit. The tentaculitids having a semi-infaunal,suspension feeder habit. The suspension feeder forms (brachiopods, bivalves and tentaculitids account for over 90% of the organisms, withthe remaining percentage distributed among the predator/scavenger (trilobites, coprophagous/suspension feeders (gastropods, grazers/predators (bellerophonts and deposit feeders (rare bivalves. The predominance of suspension feeder forms

A new psammosteid (Agnatha, Heterostraci from the Amata Regional Stage of the Main Devonian Field and morpho-histological types of discrete micromeric elements in the family Psammosteidae

Directory of Open Access Journals (Sweden)

Vadim N. Glinskiy

2017-05-01

Full Text Available In memory of an outstanding palaeoichthyologist Elga Mark-Kurik The range of diversity of psammosteids from the family Psammosteidae is still poorly known. Here a new species, Psammosteus ramosus sp. nov. Glinskiy, from the Amata Regional Stage of the Main Devonian Field is described. Its morphology, ornamentation, histology of exoskeletal plates, and micromeric elements are compared with those of other representatives of the family Psammosteidae. The comparison shows a close relationship of the new species with Psammosteus falcatus Obruchev, P. kiaeri Halstead Tarlo and P. pectinatus Obruchev, a group of species that is significantly different from other representatives of the genus Psammosteus and constitutes a separate evolutionary lineage. On the basis of morphological and histological features we here differentiate in the fields of tesserae of Psammosteidae the discrete micromeric elements of the ‘basic type’, known in Psammosteus bergi (Obruchev, P. levis Obruchev, P. livonicus Obruchev, P. maeandrinus Agassiz, P. megalopteryx (Trautschold, P. praecursor Obruchev and Karelosteus weberi Obruchev, and micromeric elements of the ‘progressive type’, known in Psammosteus falcatus, P. cf. kiaeri and P. ramosus sp. nov. Glinskiy.

The Lower Devonian of Ouled Abbou (Morocco. Sedimentary organization; diagenetic modes and impact on porosity

Directory of Open Access Journals (Sweden)

Razouani, A.

2007-12-01

Full Text Available The region of Ouled Abbou is characterized by the intercalation of carbonated beds in Silurian-Devonian pelite-sandstones. The series is organized into a succesion of three deposition sequences: SD1, SD2, SD3 of Silurian-Lochkovian, Praguian and Emsian age, respectively, developed in a monoclynal platform-type ramp. The hydrodynamics, in relation to variations in sea level, controlled the formation and distribution of the carbonated facies (bioclastic deposits, slope deposits, etc.. In the carbonate beds, diagenetic analysis reveals the sequence of development of the diagenetic transformations: It is essentially the result of multiple phases of cementing and recrystallization, mainly affecting the granular facies that define the diagenetic history leading to an almost complete lithification, hence their low potential as a possible reservoir. Early dolomitisation appears at the summit of sequences SD2 and SD3, leading to the formation of a crystalline rock (dolomicrosparite followed by a remplacement-recristallisation of calcareous mud. These transformations are later affected by compaction, cracking and tectonic phases of late dolomitisation.La región de Ouled Abbou se caracteriza por la intercalación de niveles carbonatados en pelitas silurico-devónicas. Esta serie está estructurada en una secuencia de tres niveles de depósitos: SD1, SD2, SD3, que son respectivamente de edad siluro-lochkoviense, praguiense y emsiense, desarrollados en una plataforma mixta de typo rampa monoclinal. La hidrodinámica, en relación con las variaciones del nivel del mar, controló la formación y distribución de las facies carbonatadas (depósitos bioclásticos, de pendiente, etc.. El análisis de los niveles carbonatados ha permitido establecer la secuencia de desarrollo de las tranformaciones diagenéticas. Éstas son esencialmente el resultado de múltiples fases de cementación y recristalización, que afectan principalmente a las facies granulares. La

Magmatic record of Late Devonian arc-continent collision in the northern Qiangtang, Tibet: Implications for the early evolution of East Paleo-Tethys Ocean

Science.gov (United States)

Dan, Wei; Wang, Qiang; Zhang, Xiu-Zheng; Zhang, Chunfu; Tang, Gong-Jian; Wang, Jun; Ou, Quan; Hao, Lu-Lu; Qi, Yue

2018-05-01

Recognizing the early-developed intra-oceanic arc is important in revealing the early evolution of East Paleo-Tethys Ocean. In this study, new SIMS zircon U-Pb dating, O-Hf isotopes, and whole-rock geochemical data are reported for the newly-discovered Late Devonian-Early Carboniferous arc in Qiangtang, central Tibet. New dating results reveal that the eastern Riwanchaka volcanic rocks were formed at 370-365 Ma and were intruded by the 360 Ma Gangma Co alkali feldspar granites. The volcanic rocks consist of basalts, andesites, dacites, and rhyodacites, whose geochemistry is similar to that typical of subduction-related volcanism. The basalts and andesites were generated by partial melting of the fluid and sediment-melt metasomatized mantle, respectively. The rhyodacites and dacites were probably derived from the fractional crystallization of andesites and from partial melting of the juvenile underplated mafic rocks, respectively. The Gangma Co alkali feldspar granites are A-type granites, and were possibly derived by partial melting of juvenile underplated mafic rocks in a post-collisional setting. The 370-365 Ma volcanic arc was characterized by basalts with oceanic arc-like Ce/Yb ratios and by rhyodacites with mantle-like or slightly higher zircon δ18O values, and it was associated with the contemporary ophiolites. Thus, we propose that it is the earliest intra-oceanic arc in the East Paleo-Tethys Ocean, and was accreted to the Northern Qiangtang Terrane during 365-360 Ma.

Homeobox gene expression in Brachiopoda

DEFF Research Database (Denmark)

Altenburger, Andreas; Martinez, Pedro; Wanninger, Andreas

2011-01-01

(ectoderm) specification with co-opted functions in notochord formation in chordates and left/right determination in ambulacrarians and vertebrates. The caudal ortholog, TtrCdx, is first expressed in the ectoderm of the gastrulating embryo in the posterior region of the blastopore. Its expression stays......The molecular control that underlies brachiopod ontogeny is largely unknown. In order to contribute to this issue we analyzed the expression pattern of two homeobox containing genes, Not and Cdx, during development of the rhynchonelliform (i.e., articulate) brachiopod Terebratalia transversa...... completion of larval development, which is marked by a three-lobed body with larval setae. Expression starts at gastrulation in two areas lateral to the blastopore and subsequently extends over the animal pole of the gastrula. With elongation of the gastrula, expression at the animal pole narrows to a small...

An exceptionally preserved transitional lungfish from the lower permian of Nebraska, USA, and the origin of modern lungfishes.

Directory of Open Access Journals (Sweden)

Jason D Pardo

Full Text Available Complete, exceptionally-preserved skulls of the Permian lungfish Persephonichthys chthonica gen. et sp. nov. are described. Persephonichthys chthonica is unique among post-Devonian lungfishes in preserving portions of the neurocranium, permitting description of the braincase of a stem-ceratodontiform for the first time. The completeness of P. chthonica permits robust phylogenetic analysis of the relationships of the extant lungfish lineage within the Devonian lungfish diversification for the first time. New analyses of the relationships of this new species within two published matrices using both maximum parsimony and Bayesian inference robustly place P. chthonica and modern lungfishes within dipterid-grade dipnoans rather than within a clade containing Late Devonian 'phaneropleurids' and common Late Paleozoic lungfishes such as Sagenodus. Monophyly of post-Devonian lungfishes is not supported and the Carboniferous-Permian taxon Sagenodus is found to be incidental to the origins of modern lungfishes, suggesting widespread convergence in Late Paleozoic lungfishes. Morphology of the skull, hyoid arch, and pectoral girdle suggests a deviation in feeding mechanics from that of Devonian lungfishes towards the more dynamic gape cycle and more effective buccal pumping seen in modern lungfishes. Similar anatomy observed previously in 'Rhinodipterus' kimberyensis likely represents an intermediate state between the strict durophagy observed in most Devonian lungfishes and the more dynamic buccal pump seen in Persephonichthys and modern lungfishes, rather than adaptation to air-breathing exclusively.

An Exceptionally Preserved Transitional Lungfish from the Lower Permian of Nebraska, USA, and the Origin of Modern Lungfishes

Science.gov (United States)

Pardo, Jason D.; Huttenlocker, Adam K.; Small, Bryan J.

2014-01-01

Complete, exceptionally-preserved skulls of the Permian lungfish Persephonichthys chthonica gen. et sp. nov. are described. Persephonichthys chthonica is unique among post-Devonian lungfishes in preserving portions of the neurocranium, permitting description of the braincase of a stem-ceratodontiform for the first time. The completeness of P. chthonica permits robust phylogenetic analysis of the relationships of the extant lungfish lineage within the Devonian lungfish diversification for the first time. New analyses of the relationships of this new species within two published matrices using both maximum parsimony and Bayesian inference robustly place P. chthonica and modern lungfishes within dipterid-grade dipnoans rather than within a clade containing Late Devonian ‘phaneropleurids’ and common Late Paleozoic lungfishes such as Sagenodus. Monophyly of post-Devonian lungfishes is not supported and the Carboniferous-Permian taxon Sagenodus is found to be incidental to the origins of modern lungfishes, suggesting widespread convergence in Late Paleozoic lungfishes. Morphology of the skull, hyoid arch, and pectoral girdle suggests a deviation in feeding mechanics from that of Devonian lungfishes towards the more dynamic gape cycle and more effective buccal pumping seen in modern lungfishes. Similar anatomy observed previously in ‘Rhinodipterus’ kimberyensis likely represents an intermediate state between the strict durophagy observed in most Devonian lungfishes and the more dynamic buccal pump seen in Persephonichthys and modern lungfishes, rather than adaptation to air-breathing exclusively. PMID:25265394

Temporal-spatial reconstruction of the early Frasnian (Late Devonian) anoxia in NW Africa: new field data from the Ahnet Basin (Algeria)

Science.gov (United States)

Lüning, S.; Wendt, J.; Belka, Z.; Kaufmann, B.

2004-01-01

Anoxic conditions were widespread in NW Africa during the early Frasnian (Late Devonian) that resulted in deposition of organic-rich shales and limestones with total organic carbon (TOC) values of up to 14%. Organic richness and thickness of these sediments vary laterally, and organic-rich vs. organic-poor facies boundaries are likely to have been diachronous. A precise temporal-spatial reconstruction of this anoxic phase in NW Africa is complicated because the organic matter in outcrops is largely oxidised and biostratigraphic resolution in boreholes is generally low due to the lack of recoverable conodonts. This contribution is based on eight outcrop sections at the margin of the central Algerian Ahnet Basin, where detailed spectral gamma-ray measurements were carried out using a handheld instrument. The pre-weathering organic richness in Frasnian outcrop sections is approximated using the characteristic uranium enrichment in the anoxic facies that, based on well studies, is positively correlated with the total organic carbon content. Conodont biostratigraphic results from these sections suggest that the uranium-enriched interval (the anoxic interval) at the basin margin is most common in the basal Frasnian conodont Biozones 1-2, confirming previous results from the Anti Atlas in Morocco. In three of the eight localities studied the basal Frasnian has not been deposited and the Frasnian here commences with distinctly younger uranium-enriched intervals, including Zones 4-11. Well data from the eastern Algerian Berkine Basin is interpreted to indicate a significantly longer anoxic phase there. Million-year-scale diachroneities of the Frasnian anoxia, therefore, clearly exist across the North Africa shelf. It is assumed that the palaeorelief might have been a major factor in controlling the onset, duration, and intensity of anoxia in the region.

Étude palynologique du Dévonien terminal et du Carbonifère inférieur du bassin d'Illizi (Fort-Polignac, Algérie Palynological Study of the Uppermost Devonian and Lower Carboniferous in the Illizi Basin (Fort-Polignac, Algeria

Directory of Open Access Journals (Sweden)

Attar A.

2006-11-01

Full Text Available L'étude de la microflore des formations Djebel llleréne, Issendjel, Assekaïfaf, Oubarakat et El Adeb Larache du bassin d'Illizi (Sahara algérien a permis d'établir, depuis le Dévonien terminal jusqu au Namurien, six palynozones. Une comparaison est faite avec les travaux de Lanzoni et Magloire et de Massa et al. (bassin de Rhadamès, Libye occidentale. A study of microflora from the Djebel Illeréne, Issendjel, Assekaïfaf, Oubarakat und El Adeb Larache formations in the Illizi Basin (Algerian Sahara has enabled six palynozones to be identified in the interval between the uppermost Devonian and the Namurian. The findings are compared with those by Lanzoni and Magloire (Grand Erg Occidental, Algerian Sahara and Massa et al. (Rhadamès Basin, western Libya.

Oxygen-isotope trends and seawater temperature changes across the Late Cambrian Steptoean positive carbon-isotope excursion (SPICE event)

Science.gov (United States)

Elrick, M.; Rieboldt, S.; Saltzman, M.; McKay, R.M.

2011-01-01

The globally recognized Late Cambrian Steptoean positive C-isotope excursion (SPICE) is characterized by a 3???-5??? positive ??13C shift spanning SPICE represents a widespread ocean anoxic event leading to enhanced burial/preservation of organic matter (Corg) and pyrite. We analyzed ??18O values of apatitic inarticulate brachiopods from three Upper Cambrian successions across Laurentia to evaluate paleotemperatures during the SPICE. ??18O values range from ~12.5??? to 16.5???. Estimated seawater temperatures associated with the SPICE are unreasonably warm, suggesting that the brachiopod ??18O values were altered during early diagenesis. Despite this, all three localities show similar trends with respect to the SPICE ??13C curve, suggesting that the brachiopod apatite preserves a record of relative ??18O and temperature changes. The trends include relatively high ??18O values at the onset of the SPICE, decreasing and lowest values during the main event, and an increase in values at the end of the event. The higher ??18O values during the global extinction at the onset of the SPICE suggests seawater cooling and supports earlier hypotheses of upwelling of cool waters onto the shallow shelf. Decreasing and low ??18O values coincident with the rising limb of the SPICE support the hypothesis that seawater warming and associated reduced thermohaline circulation rates contributed to decreased dissolved O2 concentrations, which enhanced the preservation/burial of Corg causing the positive ??13C shift. ?? 2011 Geological Society of America.

Brachiopodové fauny triasu a jury v oblasti Salzkammergut v Rakousku

Czech Academy of Sciences Publication Activity Database

Siblík, Miloš

2007-01-01

Roč. 2006, - (2007), s. 166-167 ISSN 0514-8057 Institutional research plan: CEZ:AV0Z30130516 Keywords : brachiopods * Triassic * Jurassic Subject RIV: EG - Zoology http://www.geology.cz/zpravy/obsah/2006/2006-str.166-167.pdf

Stratigraphy and macrofauna of the Lower Jurassic (Toarcian) Marrat Formation, central Saudi Arabia

Science.gov (United States)

El-Sorogy, Abdelbaset S.; Gameil, Mohamed; Youssef, Mohamed; Al-Kahtany, Khaled M.

2017-10-01

The stratigraphy and macrofaunal content of the Lower Jurassic (Toarcian) Marrat Formation was studied at Khashm adh Dhibi, central Saudi Arabia. The studied succession is dominated by limestones and dolomites, with subordinate occurrences of sandstones, siltstones and claystones. The formation is highly fossiliferous with brachiopods, gastropods, bivalves, ammonites and echinoids, particularly the lower and upper members. Twenty nine species are identified, they include 7 species of brachiopods, 8 gastropods, 8 bivalves, 4 ammonites and 2 echinoids. Many of the identified fauna are correlated with Jurassic equivalents in Jordan, Italy, Morocco, Egypt and India. Three gastropod species: Globularia subumbilicata, Ampullospira sp., Purpuroidea peristriata and seven bivalve species: Palaeonucula lateralis, Chlamys (Radulopecten) fibrosa, Eligmus weiri, E.integer, E. asiaticus, Musculus somaliensis and Pholadomya orientalis were recognized for the first time in the Lower Jurassic deposits of Saudi Arabia.

Giving perspective to cliff exposures with ground penetrating radar: Devonian lacustrine shore zone architecture

Science.gov (United States)

Andrews, Steven; Moreau, Julien; Archer, Stuart

2015-04-01

The orbitally-controlled cyclic lacustrine successions of the Middle Devonian in Northern Scotland contains repeated developments of shore zone sandstones. However, due to the cliff-forming nature of the succession and the attitude of the sections through these sandstones, interpretation of this facies has been problematic. To better understand the shore zone systems, we carried out very high resolution sedimentary logging and constructed photo-panels which were combined with high resolution GPR profiling (250 MHz). To ensure close ties between the sedimentary logs and the GPR data, the cliffs were accessed using rope access techniques while GPR grids were shot directly above. The profiles were shot mainly in the strike direction of what was thought to be the shore elongation every 5-10 m and every 20-30 m in the dip direction. Shore zone systems of 3 different sequences have been imaged for a total of 1155 m of GPR profile collected. This configuration has allowed 3D visualisation of the architecture of the shore zone systems and, in combination with detailed sedimentology, provided insights into the generation of the dynamic shore zone environments. The coastal cliffs of northern Scotland expose sedimentary cycles on average 16-m-thick which record deep lake, perennial lake and playa environments. The shore zone deposits reach 2 to 3.5 m in thickness. Loading and discrete channel forms are recognised in both the GPR data and sedimentary logs through the lower portion of the lake shore zone successions. Up-section the sandstone beds appear to become amalgamated forming subtle low angle accretionary bar complexes which although visible in outcrop, after careful investigation, can be fully visualised and examined in the GPR data. The 3D visualisation allowed mapping the architecture and distribution of the bars . The orientation of these features, recognised from the survey, is consistent with extensive palaeocurrent measurements from oscillation ripples. Further

Time-temperature-burial significance of Devonian anthracite implies former great (approx.6.5 km) depth of burial of Catskill Mountains, New York

International Nuclear Information System (INIS)

Friedman, G.M.; Sanders, J.E.

1982-01-01

Specimens of coalified plant debris in Tully-correlative strata of the Gilboa Formation (uppermost Middle Devonian) within the eastern Catskill Mountains of New York State have been converted to anthracite having a vitrinite reflectance of 2.5%. This implies a level of organic metamorphism (LOM) of 16. The specimens are about 350 m.y. old; if 200 m.y. is taken as the duration of the time of exposure to the maximum geothermal temperature, then the LOM of 16 and other thermal indicators imply a maximum temperature of 190 0 C. Using a geothermal gradient of 26 0 C.km -1 (17 0 F.1,000 ft -1 ), a former depth of burial of 6.5 km is implied. Such former deep burial is not usually inferred for the Catskills, but it is consistent with the idea that the thick (about 6.4 km or 21,000 ft) Carboniferous strata of northeastern Pennsylvania formerly extended northeast far enough to bury the Catskills. The lack of metamorphism of the Paleozoic strata lying about 4.5 km beneath the Tully-correlative rocks and exposed in the adjacent Hudson Valley places low limits on the former geothermal gradient; this supports the concept of great depth of former burial of the Catskills. For example, 6.5 km of former burial and a geothermal gradient of 26 0 C.km -1 imply a temperature of 307 0 C for the base of the Paleozoic. By contrast, only 1 km of former burial requires a geothermal gradient of 170 0 C.km -1 , which would have subjected the base of the Paleozoic to a temperature of 955 0 GAMMA, which is far higher than the 600 to 650 0 C recently inferred for the Acadian-age metamorphism of the Taconic allochthon in southwestern Massachusetts and adjoining areas

Geology of the Cupsuptic quadrangle, Maine

Science.gov (United States)

Harwood, David S.

1966-01-01

The Cupsuptic quadrangle, in west-central Maine, lies in a relatively narrow belt of pre-Silurian rocks extending from the Connecticut River valley across northern New Hampshire to north-central Maine. The Albee Formation, composed of green, purple, and black phyllite with interbedded-quartzite, is exposed in the core of a regional anticlinorium overlain to the southeast by greenstone of the Oquossoc Formation which in turn is overlain by black slate of the Kamankeag Formation. In the northern part of the quadrangle the Albee Formation is overlain by black slate, feldspathic graywacke, and minor greenstone of the Dixville Formation. The Kamankeag Formation is dated as 1-ate Middle Ordovician by graptolites (zone 12) found near the base of the unit. The Dixville Formation is correlated with the Kamankeag Formation and Oquossoc Formation and is considered to be Middle Ordovician. The Albee Formation is considered to be Middle to Lower Ordovician from correlations with similar rocks in northeastern and southwestern Vermont. The Oquossoc and Kamankeag Formations are correlated with the Amonoosuc and Partridge Formations of northern New Hampshire. The pre-Silurian rocks are unconformably overlain by unnamed rocks of Silurian age in the southeast, west-central, and northwest ninths of the quadrangle. The basal Silurian units are boulder to cobble polymict conglomerate and quartz-pebble conglomerate of late Lower Silurian (Upper Llandovery) age. The overlying rocks are either well-bedded slate and quartzite, silty limestone, or arenaceous limestone. Thearenaceous limestone contains Upper Silurian (Lower Ludlow) brachiopods. The stratified rocks have been intruded by three stocks of biotite-muscovite quartz monzonite, a large body of metadiorite and associated serpentinite, smaller bodies of gabbro, granodiorite, and intrusive felsite, as well as numerous diabase and quartz monzonite dikes. The metadiorite and serpentinite, and possibly the gabbro and granodiorite are Late

Invertebrates and Plants :: NOAA Fisheries

Science.gov (United States)

Invertebrates & Plants Species of Concern Threatened & Endangered Health & Stranding Marine Mammals Chart Partnerships Fisheries Home » Protected Resources » Species Invertebrates and Plants White Marine Sanctuary Mollusks, corals, and brachiopods are three groups of marine invertebrates. To view ESA

An early 'handwritten' shell exchange catalogue of the Leiden Museum, with notes on the collectors Rethaan Macaré and Tischbein

NARCIS (Netherlands)

Bruggen, van A.C.

2013-01-01

A ‘handwritten’ (lithographed) shell exchange catalogue of the National Museum of Natural History, Leiden (The Netherlands), dated 1850 and containing 864 nominal taxa (861 molluscs and 3 brachiopods), is discussed in the context of the history of the museum. This catalogue must have been

The geology of Burnsville Cove, Bath and Highland Counties, Virginia

Science.gov (United States)

Swezey, Christopher; Haynes, John T.; Lambert, Richard A.; White, William B.; Lucas, Philip C.; Garrity, Christopher P.

2015-01-01

Burnsville Cove is a karst region in Bath and Highland Counties of Virginia. A new geologic map of the area reveals various units of limestone, sandstone, and siliciclastic mudstone (shale) of Silurian through Devonian age, as well as structural features such as northeast-trending anticlines and synclines, minor thrust faults, and prominent joints. Quaternary features include erosional (strath) terraces and accumulations of mud, sand, and gravel. The caves of Burnsville Cove are located within predominantly carbonate strata above the Silurian Williamsport Sandstone and below the Devonian Oriskany Sandstone. Most of the caves are located within the Silurian Tonoloway Limestone, rather than the Silurian-Devonian Keyser Limestone as reported previously.

The highest-latitude Foliomena Fauna (Upper Ordovician, Portugal) and its palaeogeographical and palaeoecological significance

DEFF Research Database (Denmark)

Colmenar Lallena, Jorge; Pereira, Sofia; Sá, Artur Abreu

2017-01-01

of the Portuguese Buçaco-Penacova region (Central Iberian Zone). The three studied localities have yielded different associations, composed of 15 species of brachiopods and two trilobites, including both key elements of the deep water Foliomena Fauna and taxa typically from shallower benthic biotas, e...

Mass extinctions: Ecological selectivity and primary production

Science.gov (United States)

Rhodes, Melissa Clark; Thayer, Charles W.

1991-09-01

If mass extinctions were caused by reduced primary productivity, then extinctions should be concentrated among animals with starvation-susceptible feeding modes, active lifestyles, and high-energy budgets. The stratigraphic ranges (by stage) of 424 genera of bivalves and 309 genera of articulate brachiopods suggest that there was an unusual reduction of primary productivity at the Cretaceous/Tertiary (K/T) boundary extinction. For bivalves at the K/T, there were (1) selective extinction of suspension feeders and other susceptible trophic categories relative to deposit feeders and other resistant categories, and (2) among suspension feed-ers, selective extinction of bivalves with active locomotion. During the Permian-Triassic (P/Tr) extinction and Jurassic background time, extinction rates among suspension feeders were greater for articulate brachiopods than for bivalves. But during the K/T event, extinction rates of articulates and suspension-feeding bivalves equalized, possibly because the low-energy budgets of articulates gave them an advantage when food was scarce.

Unravelling Orbital Climatic Cycles from Devonian Magnetic Susceptibility Signal - The Quest for a Better Age Model for the Lochkovian and Pragian Stages (Czech Republic)

Science.gov (United States)

da Silva, A. C.; Chadimova, L.; Hladil, J.; Slavik, L.; Hilgen, F. J.; Dekkers, M. J.

2015-12-01

The uncertainties on the Devonian stage boundaries are currently in the order of several millions of years. When shown to reflect a detrital signal, which is influenced by climatic variations, Magnetic Susceptibility (MS) has been proven as a useful tool for identifying climatic cycles; which can subsequently be used to improve the time scale. Here, we focus on two sections from the Prague Synform (Czech Republic) cutting through the Lochkovian, Pragian and the lower part of the Emsian. Sedimentation is rhythmic, dominated by slightly clayey offshore limestones, being mostly calciturbidites and hemipelagites. We provide hysteresis analysis in order to get insight into the nature and the origin of the magnetic minerals driving the variation in the MS signal. The results point to a MS signal mostly carried by clay minerals. Subsequently, to improve estimation of the duration of the stages, we apply different spectral analysis techniques on this MS signal. From the Continuous Wavelet Transform (CWT), Evolutive Harmonic Analysis (EHA) and field observations, we subdivide the section into portions with a steady sedimentation rate (a first estimate of this rate is also delivered by these analyzes). Then, we apply Multitaper Method (MTM) and Multitaper harmonic Analysis (F-test) and extract the frequencies reaching 95% Confidence Level. These frequencies are then implemented into the Average Spectral Misfit procedures (ASM) which enables comparison with orbital targets. By combining these different techniques, 405 kyr cyclicty is identifed, a powerful duration paleochronometer. These new results indicate a duration of 7.7 ± 2 Myr for the Lochkovian stage and of 1.7 Myr ± 1.4 for the Pragian stage (compared to respectively 8.4 ± 6 Myr and 3.2 ± 5.4 Myr in the 2012 Geological Time Scale).

Review of oil families and their petroleum systems of the Williston Basin

Science.gov (United States)

Lillis, Paul G.

2013-01-01

The petroleum system concept was first applied in 1974 (Dow/Williams) to identify three oil systems in the Williston Basin, and recent studies have expanded the number to at least nine. This paper reviews the petroleum geochemistry, oil-oil, and oil-source correlations of the oil systems of the Williston Basin, providing a new perspective and some new findings. Petroleum systems with a known source (documented oil-source correlation) include the Red River (Ordovician), Winnipegosis (Devonian), Bakken (Devonian-Mississippian), Madison (Mississippian), and Tyler (Pennsylvanian) systems. Petroleum systems with an identified source rock but no documented oil-source correlation are considered hypothetical and include the Winnipeg (Ordovician), Duperow (Devonian), and Birdbear (Devonian). The Deadwood (Cambrian-Ordovician) petroleum system is speculative because a good oil-prone source rock has not been identified. The stratigraphic distribution of the oil families from each system is generally limited to the same formation from which they were sourced due to efficient seals and a paucity of vertical migration pathways, but some notable exceptions do occur.

Gas storage in the Upper Devonian-Lower Mississippian Woodford Shale, Arbuckle Mountains, Oklahoma: how much of a role do the cherts play?

Science.gov (United States)

Fishman, Neil S.; Ellis, Geoffrey S.; Paxton, Stanley T.; Abbott, Marvin M.; Boehlke, Adam

2010-01-01

How gas is stored in shale-gas systems is a critical element in characterizing these potentially prolific, low-porosity/permeability reservoirs. An integrated mineralogic, geochemical, and porosity/permeability study is of the Upper Devonian-Lower Mississippian Woodford Shale, Arbuckle Mountains, southern Oklahoma, at locations previously described through detailed stratigraphic and spectral gamma surveys, was undertaken to provide insights into possible mechanisms by which natural gas might be stored in Woodford reservoirs in the adjacent Anadarko Basin. The outcrops in the Arbuckle Mountains are an ideal location to study the Woodford because here the formation is immature or marginally mature for oil generation (Comer and Hinch, 1987; Lewan, 1987), so deep burial and thermal maturation are much less pronounced than is the case for the Woodford in the basin, and as such the samples we studied are not overprinted by possible alterations resulting from deep burial and heating. Rock types studied in the Woodford Shale are broadly divided into chert (n = 8) and mudstone (n = 10) lithologies that display different characteristics from the outcrop to thin section scales. Woodford cherts, based on quantitative X-ray diffraction (XRD), contain >85 weight (wt) % quartz, green algae). Quartz in mudstones is both detrital and authigenic, with unequivocal authigenic quartz occurring as monocrystalline “grains” that can partly or even completely infill Tasmanites; as in the case of the cherts, authigenic quartz in mudstones must have precipitated soon after deposition before significant burial and collapse of the soft, delicate Tasmanites cysts. MICP analyses (at 50% Hg saturation) reveal that, with one exception, mudstones have (1) porosities ranging from 1.97-6.31%, (2) low calculated permeabilities (0.011-0.089 D), and (3) small mean pore apertures (6.2-17.8 nm). Porosity in the mudstones occurs as (1) “slots” between clay mineral grains or plates, (2) micropores

Ventastega curonica and the origin of tetrapod morphology.

Science.gov (United States)

Ahlberg, Per E; Clack, Jennifer A; Luksevics, Ervīns; Blom, Henning; Zupiņs, Ivars

2008-06-26

The gap in our understanding of the evolutionary transition from fish to tetrapod is beginning to close thanks to the discovery of new intermediate forms such as Tiktaalik roseae. Here we narrow it further by presenting the skull, exceptionally preserved braincase, shoulder girdle and partial pelvis of Ventastega curonica from the Late Devonian of Latvia, a transitional intermediate form between the 'elpistostegids' Panderichthys and Tiktaalik and the Devonian tetrapods (limbed vertebrates) Acanthostega and Ichthyostega. Ventastega is the most primitive Devonian tetrapod represented by extensive remains, and casts light on a part of the phylogeny otherwise only represented by fragmentary taxa: it illuminates the origin of principal tetrapod structures and the extent of morphological diversity among the transitional forms.

Semiplanus (Productida, Brachiopoda) from the Carboniferous limestone of Kotaki, Niigata Prefecture, central Japan

OpenAIRE

Ibaraki, Yousuke; Sato, Kiichi

2013-01-01

An Early Carboniferous large–sized productid brachiopod species, Semiplanus semiplanus (Schwetzow, 1922), is described from the Tsuchikurazawa Limestone (upper Visean–Serpukhovian), a limestone block within a Permian accretionary complex, distributed in the Kotaki area, Itoigawa City, Niigata Prefecture, central Japan. This is the first record of Semipanus species from Japan.

A Systems Approach to Identifying Exploration and Development Opportunities in the Illinois Basin: Digital Portifolio of Plays in Underexplored Lower Paleozoic Rocks [Part 1 of 2

Energy Technology Data Exchange (ETDEWEB)

Seyler, Beverly; Harris, David; Keith, Brian; Huff, Bryan; Lasemi, Yaghoob

2008-06-30

This study examined petroleum occurrence in Ordovician, Silurian and Devonian reservoirs in the Illinois Basin. Results from this project show that there is excellent potential for additional discovery of petroleum reservoirs in these formations. Numerous exploration targets and exploration strategies were identified that can be used to increase production from these underexplored strata. Some of the challenges to exploration of deeper strata include the lack of subsurface data, lack of understanding of regional facies changes, lack of understanding the role of diagenetic alteration in developing reservoir porosity and permeability, the shifting of structural closures with depth, overlooking potential producing horizons, and under utilization of 3D seismic techniques. This study has shown many areas are prospective for additional discoveries in lower Paleozoic strata in the Illinois Basin. This project implemented a systematic basin analysis approach that is expected to encourage exploration for petroleum in lower Paleozoic rocks of the Illinois Basin. The study has compiled and presented a broad base of information and knowledge needed by independent oil companies to pursue the development of exploration prospects in overlooked, deeper play horizons in the Illinois Basin. Available geologic data relevant for the exploration and development of petroleum reservoirs in the Illinois Basin was analyzed and assimilated into a coherent, easily accessible digital play portfolio. The primary focus of this project was on case studies of existing reservoirs in Devonian, Silurian, and Ordovician strata and the application of knowledge gained to future exploration and development in these underexplored strata of the Illinois Basin. In addition, a review of published reports and exploration in the New Albany Shale Group, a Devonian black shale source rock, in Illinois was completed due to the recent increased interest in Devonian black shales across the United States. The New

Hydrology, water quality, and effects of drought in Monroe County, Michigan

Science.gov (United States)

Nicholas, J.R.; Rowe, Gary L.; Brannen, J.R.

1996-01-01

Monroe County relies heavily on its aquifers and streams for drinking water, irrigation, and other ~ses; however, increased water use, high concentrations of certain constituents in ground water, and droughts may limit the availability of water resources. Although the most densely populated parts of the county use water from the Great Lakes, large amounts of ground water are withdrawn for quarry dewatering, domestic supply, and irrigation.Unconsolidated deposits and bedrock of Silurian and Devonian age underlie Mon_roe County. The unconsolidated deposits are mostly clayey and less than 50 feet thick. Usable amounts of ground water generally are obtained from thin, discontinuous surficial sand deposits or, in the northwestern part of the county, from deep glaciofluvial deposits. In most of the county, however, ground water in unconsolidated deposits is highly susceptible to effects of droughts and to contamination.The bedrock is mostly carbonate rock, and usable quantities of ground water can be obtained from fractures and other secondary openings throughout the county. Transmissivities of the Silurian-Devonian aquifer range from 10 to 6,600 feet squared per day. Aquifer tests and historical informati.on indicate that the Silurian-Devonian aquifer is confmed throughout most of the county. The major recharge area for the Silurian-Devonian aquifer in Monroe County is in the southwest, and groundwater flow is mostly southeastward toward Lake Erie. In the northeastern and southeastern parts of the county, the potentiometric surface of the SilurianDevonian aquifers has been lowered by pumpage to below the elevation of Lake Erie.Streams and artificial drains in Monroe County are tributary to Lake Erie. Most streams are perennial because of sustained discharge from the sand aquifer and the Silurian-Devonian aquifer; however, the lower reaches of River Raisin and Plum Creek lost water to the Silurian-Devonian aquifer in July 1990.The quality of ground water and of

Cope's Rule and Romer's theory: patterns of diversity and gigantism in eurypterids and Palaeozoic vertebrates

Science.gov (United States)

Lamsdell, James C.; Braddy, Simon J.

2010-01-01

Gigantism is widespread among Palaeozoic arthropods, yet causal mechanisms, particularly the role of (abiotic) environmental factors versus (biotic) competition, remain unknown. The eurypterids (Arthropoda: Chelicerata) include the largest arthropods; gigantic predatory pterygotids (Eurypterina) during the Siluro-Devonian and bizarre sweep-feeding hibbertopterids (Stylonurina) from the Carboniferous to end-Permian. Analysis of family-level originations and extinctions among eurypterids and Palaeozoic vertebrates show that the diversity of Eurypterina waned during the Devonian, while the Placodermi radiated, yet Stylonurina remained relatively unaffected; adopting a sweep-feeding strategy they maintained their large body size by avoiding competition, and persisted throughout the Late Palaeozoic while the predatory nektonic Eurypterina (including the giant pterygotids) declined during the Devonian, possibly out-competed by other predators including jawed vertebrates. PMID:19828493

Terrestrial-style feeding in a very early aquatic tetrapod is supported by evidence from experimental analysis of suture morphology

OpenAIRE

Markey, Molly J.; Marshall, Charles R.

2007-01-01

There is no consensus on when in the fish-tetrapod transition suction feeding, the primary method of prey capture in the aquatic realm, evolved into the direct biting on prey typical of terrestrial animals. Here, we show that differences in the morphology of selected cranial sutures between species that span the fish–tetrapod transition (the Devonian osteolepiform fish Eusthenopteron, the aquatic Devonian tetrapod Acanthostega, and the Permian terrestrial tetrapod Phonerpeton) can be used to ...

Ventastega curonica and the origin of tetrapod morphology

OpenAIRE

Ahlberg, Per; Clack, Jennifer; Luksevics, Ervins; Blom, Henning; Zupins, Ivars

2008-01-01

The gap in our understanding of the evolutionary transition from fish to tetrapod is beginning to close thanks to the discovery of new intermediate forms such as Tiktaalik roseae. Here we narrow it further by presenting the skull, exceptionally preserved braincase, shoulder girdle and partial pelvis of Ventastega curonica from the Late Devonian of Latvia, a transitional intermediate form between the 'elpistostegids' Panderichthys and Tiktaalik and the Devonian tetrapods (limbed vertebrates) A...

Flood-dominated fluvio-deltaic system: a new depositional model for the Devonian Cabeças Formation, Parnaíba Basin, Piauí, Brazil

Directory of Open Access Journals (Sweden)

Luiza Corral M.O. Ponciano

2009-12-01

Full Text Available The depositional model of the Cabeças Formation is re-evaluated in the context of the Devonian paleogeography of the Parnaíba Basin, and with particular reference to similarities between the formation's facies associations on the eastern border of the basin and the flood-dominated fluvio-deltaic system facies that have been discussed in recent literature. The widespread occurrence and nature of sigmoidal clinoforms (with asymptotic cross-stratification and climbing ripples of the Cabeças Formation are here considered as strong evidence of flood-influenced depositional settings. Sandy strata of the Passagem Member, in the vicinity of Pimenteiras and Picos (Piauí State, are interpreted as the distal part of fine-grained mouth-bar deposits interbedded with delta-front sandstone lobes showing hummocky cross-stratification. Richly fossiliferous levels, with diverse megainvertebrates and plant cuticles, occur within the delta-front lobes and the distal mouth-bar deposits, reflecting continuation of shallow marine conditions.O modelo deposicional da Formação Cabeças é reinterpretado no presente estudo com base no contexto paleogeográfico da Bacia do Parnaíba durante o Devoniano e na similaridade entre as fácies encontradas na Formação Cabeças com as fácies características dos sistemas flúvio-deltaicos dominados por inundações. O tipo das clinoformas sigmoidais (com estratificação cruzada assintótica e laminação cruzada cavalgante, e a sua predominância na Formação Cabeças, são consideradas como as principais evidências da influência de inundações nesta unidade. Depósitos do Membro Passagem, localizados nos arredores das cidades de Pimenteiras e Picos, são interpretados como o componente distal de um tipo de barra de desembocadura com a predominância de arenitos finos a conglomeráticos, intercalados com lobos arenosos tabulares de frente deltaica com estratificação cruzada hummocky. Diversos intervalos fossil

Lipid and fatty acid fractions in Lingula anatina (Brachiopoda): an intertidal benthic fauna in the West Bengal-Orissa coast, India

OpenAIRE

Samaresh Samanta; Tapas Kumar Das; Amalesh Choudhury; Susanta Kumar Chakraborty

2014-01-01

Objective: To record the fractional components of lipid and polyunsaturated fatty acids of Lingula anatina (L. anatina), a Precambrian intertidal benthic brachiopod, giving emphasis on -ω series group especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) alongside assessing their biotransformation within the population and mangrove-estuarine associated community. Methods: Different biological samples after being collected from three contrasting study sites viz. ...

Frasnian

OpenAIRE

Coen-Aubert, M.; Boulvain, Frédéric

2006-01-01

The name Frasnian, which comes from the locality of Frasnes near Couvin in Belgium, was introduced by Gosselet in 1879 and was formally retained for the lower stage of the Upper Devonian by the Subcommission on Devonian Stratigraphy in 1981. The modern definition of the Frasnian is based on conodonts and the historical background of the stage is developed in detail herein. Data about the lithostratigraphy, sedimentology, biostratigraphy, chronostratigraphy and absolute age of the Frasnian can...

GIVETIAN–FRASNIAN BOUNDARY CONODONTS FROM KERMAN PROVINCE, CENTRAL IRAN

OpenAIRE

GHOLAMALIAN, HOSSEIN; HAIRAPETIAN, VACHIK; BARFEHEI, NAHID; MANGELIAN, SOHEYLA; FARIDI, PARVANEH

2013-01-01

The Middle - Late Devonian boundary is investigated based on twenty-two conodont species and subspecies from three sections in the north and west of Kerman, southeastern central Iran. Upper Givetian - lower Frasnian carbonates of the basal part of the Bahram Formation transgressively overlie the sandstone beds of the top of (?) Early - Middle Devonian Padeha Formation. These massive skeletal limestones encompass the G-F boundary. The base of Frasnian is identified by the appearance of early f...

Paleogeographic features of Zhiguli arch development in the Frasnian century

Energy Technology Data Exchange (ETDEWEB)

Yaroslavtsev, G.A.

1984-01-01

The absence of terrigenous masses of the Devonian on the Pokrovskiy apex of the Zhiguli arch is linked by many researchers with the existence here of an island mass. The unsoundness of this hypothesis is substantiated. The absence of terrigenous masses of the Devonian and the occurrence of offshore carbonate deposits of Voronezh age with discordance on the underlying masses is substantiated by the underwater erosion of underlaying masses and recessive accumulation of carbonate Voronezh formations.

Late Paleozoic SEDEX deposits in South China formed in a carbonate platform at the northern margin of Gondwana

Science.gov (United States)

Qiu, Wenhong Johnson; Zhou, Mei-Fu; Liu, Zerui Ray

2018-05-01

SEDEX sulfide deposits hosted in black shale and carbonate are common in the South China Block. The Dajiangping pyrite deposit is the largest of these deposits and is made up of stratiform orebodies hosted in black shales. Sandstone interlayered with stratiform orebodies contains detrital zircon grains with the youngest ages of 429 Ma. Pyrite from the orebodies has a Re-Os isochron age of 389 ± 62 Ma, indicative of formation of the hosting strata and syngenetic pyrite ores in the mid-late Devonian. The hosting strata is a transgression sequence in a passive margin and composed of carbonaceous limestone in the lower part and black shales in the upper part. The ore-hosting black shales have high TOC (total organic carbon), Mo, As, Pb, Zn and Cd, indicating an anoxic-euxinic deep basin origin. The high redox proxies, V/(V + Ni) > 0.6 and V/Cr > 1, and the positive correlations of TOC with Mo and V in black shales are also consistent with an anoxic depositional environment. The Dajiangping deposit is located close to the NE-trending Wuchuan-Sihui fault, which was active during the Devonian. The mid-late Devonian mineralization age and the anoxic-euxinic deep basinal condition of this deposit thus imply that the formation of this deposit was causally linked to hydrothermal fluid exhalation in an anoxic fault-bounded basin that developed in a carbonate platform of the South China Block. The regional distribution of many Devonian, stratiform, carbonaceous sediment-hosted sulfide deposits along the NE-trending fault-bounded basins in South China, similar to the Dajiangping deposit, indicates that these deposits formed at a basin developed in the passive margin setting of the South China Block during the Devonian. This environment was caused by the break-up and northward migration of the South China Block from Gandwana.

Preandean geological configuration of the eastern North Patagonian Massif, Argentina

Directory of Open Access Journals (Sweden)

Daniel A. Gregori

2013-11-01

Full Text Available The Preandean geological configuration of the eastern North Patagonian Massif is established through the use of geological and geophysical analysis. The positive gravity anomalies located near the Atlantic coast are due to 535 and 540 Ma old rocks belonging to the Pampean Orogeny (Precambrian–middle Cambrian, which are widely recognized in central and northern Argentina. The Famatinian Cycle (Ordovician–Devonian is represented by a Silurian–Devonian marine basin equivalent to those of eastern-central Argentina and South Africa, and which was deformed at the end of the Devonian by an ∼E–W to WNW–ESE compressional event, part of the Famatinian Orogeny. Containing strong gravity gradients, the NW–SE belt is coincident with fault zones which were originated during the Gondwanide Orogeny. This event also produced NW–SE overthrusting of the Silurian–Devonian sequences and strike-slip faults that displaced blocks in the same direction. This deformation event belongs to the Gondwanide Orogeny that includes movements related to a counterclockwise rotation of blocks in northern Patagonia. The strong negative anomalies located in the western part of the area stem from the presence of rocks of the Jurassic Cañadón Asfalto basin interbedded in the Marifil Complex. These volcaniclastic sequences show mild deformation of accommodation zones in a pre-Jurassic paleorelief.

Paleozoic subduction complex and Paleozoic-Mesozoic island-arc volcano-plutonic assemblages in the northern Sierra terrane

Science.gov (United States)

Hanson, Richard E.; Girty, Gary H.; Harwood, David S.; Schweickert, Richard A.

2000-01-01

This field trip provides an overview of the stratigraphic and structural evolution of the northern Sierra terrane, which forms a significant part of the wall rocks on the western side of the later Mesozoic Sierra Nevada batholith in California. The terrane consists of a pre-Late Devonian subduction complex (Shoo Fly Complex) overlain by submarine arc-related deposits that record the evolution of three separate island-arc systems in the Late Sevonian-Early Mississippian, Permian, and Late Triassic-Jurassic. The two Paleozoic are packages and the underlying Shoo Fly Complex have an important bearing on plate-tectonic processes affecting the convergent margin outboard of the Paleozoic Cordilleran miogeocline, although their original paleogeographic relations to North America are controversial. The third arc package represents an overlap assemblage that ties the terrane to North America by the Late Triassic and helps constrain the nature and timing of Mesozoic orogenesis. Several of the field-trip stops examine the record of pre-Late Devonian subduction contained in the Shoo Fly Complex, as well as the paleovolcanology of the overlying Devonian to Jurassic arc rocks. Excellent glaciated exposures provide the opportunity to study a cross section through a tilted Devonian volcano-plutonic association. Additional stops focus on plutonic rocks emplaced during the Middle Jurassic arc magmatism in the terrane, and during the main pulse of Cretaceous magmatism in the Sierra Nevada batholith to the east.

Study seeks to boost Appalachian gas recovery

International Nuclear Information System (INIS)

Land, R.

1992-01-01

Ashland Exploration Inc. and the Gas Research Institute (GRI) are trying to find ways to increase gas recovery in the Appalachian basin. They are working together to investigate Mississippian Berea sandstone and Devonian shale in a program designed to achieve better understanding and improved performance of tight natural gas formations in the area. This paper reports that three wells on Ashland Exploration acreage in Pike County, Ky., are involved in the research program. Findings from the first two wells will be used to optimize evaluation and completion of the third well. The first two wells have been drilled. Drilling of the third well was under way at last report. Ashland Exploration has been involved with GRI's Devonian shale research since 1988. GRI's initial focus was on well stimulation because Devonian shale wells it reviewed had much lower recoveries than could be expected, based on estimated gas in place. Research during the past few years was designed to improve the execution and quality control of well stimulation

Additional Gigantoproductus species from the upper Visean-Namurian limestone of Kotaki, central Japan

OpenAIRE

Ibaraki, Yousuke; Tazawa, Jun-ichi; Nakamura, Yukio

2010-01-01

A large productid brachiopod species, Gigantoproductus aurita (Bolkhovitinova, 1938), is described from the Tsuchikurazawa Limestone (upper Visean-Namurian), a large limestone block within a Permian accretionary complex of Kotaki, Itoigawa City, Niigata Prefecture, central Japan. This is the fourth described Gigantoproductus species from the Tsuchikurazawa Limestone. The range of G. aurita may extend to late Visean on the basis of the previous fossil records of the limestone.

Investigation on the upper Paleozoic Strata in Tang-e-Zakeen, and introducing Zakeen formation, Kuh-e Faraghan Zagros Basin, South Iran

International Nuclear Information System (INIS)

Ghavidel-Syooki, M.

1998-01-01

A thick clastic sequence is well-developed in Tang-e-Zakeen, Kuh-e-Faraghan, being situated approximately 80 Km north of Bandar Abbas. The sequence is 340 m. thick and mainly consists of sandstone, siltstone, shale and subordinate dolomitic beds. So far, this clastic sequence has been called Faraghan Formation. This rock unit lacks marine fauna and based on stratigraphic position, it was assigned to the Early Permian (Szabo and Kheradpir, 1978). Since then, a detailed palynological study has been carried out on the Faraghan Formation by the author. These studies resulted identification of numerous palynomorph taxa, including miospore and acritarch species. The known palynomorph taxa indicated that, a major part of Faraghan Formation belongs to the Devonian Period, while the rest is Early Permian. As a result, the National Iranian Stratigraphic Committee decided and agreed upon to divide the Faraghan Formation into two rock units, namely, the Zakeen Formation, embracing the Devonian strata, and Faraghan Formation for the Early Permian sequence in the Zagros Basin respectively. The Zakeen Formation derives from the Zakeen Village which is located in the southern flank of Kuh-e-Faraghan, about 80 km north of Bandar Abbas. The type section of Zakeen Formation attains a thickness of 285m. in Tang-e-Zakeen, Kuh-e-Faraghan, approximately 23 Km from the Zakeen village. It disconformably rests on the Sarchahan Formation, while it too, disconformably overlain by the Faraghan Formation. A total of 100 samples from the Zakeen Formation were selected and treated in the palynological laboratory of the Exploration Division of National Iranian Oil Company. 63 palynomorph taxa were encountered from the Zakeen Formation. The known species were arranged in five local stratigraphic assemblage zones. Zones I and II occur in a thickness of 96 m. of the Zakeen Formation, in ascending order, suggesting the Early Devonian whereas Zones III and IV occur Within 156 m. interval of the Zakeen

The Role of Terrestrial N along a Frasnian/Famennian Boundary Transect of the Appalachian Basin

Science.gov (United States)

Tuite, Michael; Macko, Stephen

2010-05-01

A causal link between the Late Devonian emergence of forest ecosystems and episodic black shale deposition has been proposed by several authors. Most attribute increases in epicontinental basin productivity to elevated rates of terrestrial phosphorus weathering facilitated by the co-evolution of root systems and soils. Two reasons to suspect that an increase in the P weathering flux was not the primary cause of organic-rich shale deposition are as follows. First, most Late Devonian black shales were deposited during sea level transgressions, periods when riverine fluxes of sediment and mineral nutrients such as P to marine basins were diminished. Second, Late Devonian forests were restricted to warm, moist lowlands where P was sequestered in soils as inorganic, occluded forms. However, the export flux of reactive N from these forests to adjacent epeiric seas by riverine and atmospheric deposition was enhanced by the warm, wet climate and expanding areal extent of forests. Abundant terrestrial reactive N primed the marine eutrophication pump by extending the residence time of P in the photic zone, permitting extensive growth of primary biomass. The consequent flux of organic matter to the sea floor created anoxic bottom waters that, in turn, allowed for the remobilization of P into the water column. Based on abundance and isotopic analyses of organic and inorganic C, N, P, and S from terrestrial and marine environments within and adjacent to the Late Devonian Appalachian Basin, this latter scenario is supported.

Late Frasnian-Famennian climates based on palynomorph analyses and the question of the Late Devonian glaciations

Science.gov (United States)

Streel, Maurice; Caputo, Mário V.; Loboziak, Stanislas; Melo, José Henrique G.

2000-11-01

Palynomorph distribution in Euramerica and western Gondwana, from the Latest Givetian to the Latest Famennian, may be explained, to some extent, by climatic changes. Detailed miospore stratigraphy dates accurately the successive steps of these changes. Interpretation is built on three postulates which are discussed: Euramerica at slightly lower latitudes than generally accepted by most paleomagnetic reconstructions; a conodont time-scale accepted as the most used available subdivision of time; and Late Devonian sea-level fluctuations mainly governed by glacio-eustasy. The Frasnian-Famennian timescale is also evaluated. The comparison, based on conodont correlations, between Givetian and most of the Frasnian miospore assemblages from, respectively, northern and southern Euramerica demonstrates a high taxonomic diversity in the equatorial belt and much difference between supposed equatorial and (sub) tropical vegetations. On the contrary, a similar vegetation pattern and therefore probably compatible climatic conditions were present from tropical to subpolar areas. A rather hot climate culminated during the Latest Frasnian when equatorial miospore assemblages reached their maximum width. The miospore diversity shows also a rather clear global Late Frasnian minimum which is also recorded during the Early and Middle Famennian but only in low latitude regions while, in high latitude, very cold climates without perennial snow may explain the scarcity of miospores and so, of vegetation. The Early and Middle Famennian conspicuous latitudinal gradient of the vegetation seems to attenuate towards the Late and Latest Famennian but this might be above all the result of the development, of cosmopolitan coastal lowland vegetations (downstream swamps) depending more on the moisture and equable local microclimates than on the probably adverse climates of distant hinterland areas. During that time, periods of cold climate without perennial snow cover and with rare vegetation may

Revison of an Atheloptic Visean Trilobite Association in the Moravian Karst (Czech Republic

Directory of Open Access Journals (Sweden)

Rak Štěpán

2015-01-01

Full Text Available Recently two new trilobite occurrences were discovered during geological mapping of fossiliferous shales of the Březina Formation around the village of Březina in the Moravian Karst (Czech Republic. The newly discovered localities are extraordinary because of the unexpected occurrence of articulated trilobite exoskeletons associated with brachiopods including supporting spines. The new atheloptic association of Mississippian trilobites is described for the first time from the Moravian Karst.

Isotopic and elemental proxies in mollusc and brachiopod calcite

DEFF Research Database (Denmark)

Ullmann, Clemens Vinzenz

composition of the oceans have changed. These changes of environmental conditions and seawater composition are primarily caused by plate tectonic processes, the cyclic variations of the Earth’s orbital parameters and living organisms, actively causing, and passively adapting to shifting conditions...

Fennoscandia in the Phanerozoic: Paleogeodynamic Reconstructions Based on the New Paleomagnetic and Geochronological Data from the Kola Magmatic Province (kola Peninsula, Russia)

Science.gov (United States)

Veselovskiy, R. V.; Arzamastsev, A. A.

2013-12-01

During last four years we studied more than 100 dolerite and alkaline dykes, which are widely spread on the Kola Peninsula and belong to the Devonian magmatic province. Within the scope of our researches some of these dykes have been dated and their precise isotopic ages (Ar/Ar, Sm-Nd, Rb-Sr) lie in the range of 390-360 Ma (Veselovskiy et al., 2013). The age of other sampled dykes can be considered as Devonian due to similarity of their paleomagnetic, geochemical and petrological characteristics to the dated ones. Paleomagnetic directions have been obtained from more than 80 dykes. Almost all dykes yielded (a) a low-temperature component that is aligned along the present-day field and is likely of viscous origin; (b) a well defined dual-polarity intermediate-temperature component with steep eastward directions that accounts for a main part of the NRM and often decays to the origin on orthogonal plots; and (c) a dual-polarity high-temperature component with shallow inclinations and ENE declinations of presumed primary origin. The presence of the primary high-temperature component makes us possible to calculate preliminary Baltica's paleomagnetic pole for the Middle-Late Devonian. In view of the obtained microprobe data we believe that intermediate component is a result of unknown hydrothermal process, which age can be estimated from the comparison of corresponding paleomagnetic pole with the Baltica's APWP as Jurassic. We believe that both mentioned episodes of endogenous activity within the large stable craton were connected with plume-lithospheric interaction in the Devonian and Jurassic. In this presentation we use the obtained paleomagnetic, petrological and geochronological data to determine the paleogeography of Baltica in the Devonian and Jurassic times and to find its position within the global paleotectonic and geodynamic reconstructions. This study was funded by grants RFBR # 12-05-00216, 13-05-12021, 13-05-12030 and grant MK-3383.2012.5.

Bedrock geologic map of the Nashua South quadrangle, Hillsborough County, New Hampshire, and Middlesex County, Massachusetts

Science.gov (United States)

Walsh, Gregory J.; Jahns, Richard H.; Aleinikoff, John N.

2013-01-01

The bedrock geology of the 7.5-minute Nashua South quadrangle consists primarily of deformed Silurian metasedimentary rocks of the Berwick Formation. The metasedimentary rocks are intruded by a Late Silurian to Early Devonian diorite-gabbro suite, Devonian rocks of the Ayer Granodiorite, Devonian granitic rocks of the New Hampshire Plutonic Suite including pegmatite and the Chelmsford Granite, and Jurassic diabase dikes. The bedrock geology was mapped to study the tectonic history of the area and to provide a framework for ongoing hydrogeologic characterization of the fractured bedrock of Massachusetts and New Hampshire. This report presents mapping by G.J. Walsh and R.H. Jahns and zircon U-Pb geochronology by J.N. Aleinikoff. The complete report consists of a map, text pamphlet, and GIS database. The map and text pamphlet are only available as downloadable files (see frame at right). The GIS database is available for download in ESRITM shapefile and Google EarthTM formats, and includes contacts of bedrock geologic units, faults, outcrops, structural geologic information, photographs, and a three-dimensional model.

Petrogenesis of the Mairupt microgranite: A witness of an Uppermost Silurian magmatism in the Rocroi Inlier, Ardenne Allochton

Science.gov (United States)

Cobert, Corentin; Baele, Jean-Marc; Boulvais, Philippe; Poujol, Marc; Decrée, Sophie

2018-03-01

Magmatism in the Rocroi inlier (Ardenne Allochton, southeastern Avalonia during eo-Hercynian times) consists of a swarm of bimodal dykes (diabase and/or microgranite) emplaced in Middle to Upper Cambrian siliciclastics (Revin Group). Felsic volcanites interbedded within the Upper Silurian/Lower Devonian transgressive strata on the eastern edge of the inlier were interpreted as belonging to the same magmatic event. This was subsequently invalidated by zircon U-Pb dating of the Mairupt and Grande Commune magmatic rocks, which yielded an Upper Devonian age. Here we report a reevaluation of the age of the Mairupt microgranite based on LA-ICP-MS in situ U-Pb zircon geochronology, which yields a concordant age of 420.5 ± 2.9 Ma (Late Silurian/Early Devonian). This new dating restores the consistency between the different magmatic occurrences in the Rocroi inlier. The geochemical and petrographical data furthermore indicate a major crustal contribution, which fits well within the context of crust thinning of the Ardenne margin (southeastern Avalonia) in the transtensional Rheno-Hercynian back-arc basin.

A review of the petroleum geochemistry of the Precaspian Basin

Energy Technology Data Exchange (ETDEWEB)

Pairazian, V.V. [All-Russian Geological Oil Research and Prospecting Inst. (VNIGNI), Moscow (Russian Federation); ENI-AGIP, San Donato Milanese (Italy)

1999-11-01

On the territory of the former Soviet Union more than 30- oil and gas-bearing basins have been defined. Among them the Precaspian basin is one of the most prolific in terms of oil and gas exploration and production. The basin is situated in the southeastern part of the East European Platform and covers an areas of about 500 000 km{sup 2}. There are a number of source rocks of different ages, among which the principal ones are Lower Permian, Middle Carboniferous and Middle Devonian marine shales and carbonates. The post-salt Mesozoic sources are of less significance. Geological and geochemical data interpretation allows the main oil/gas accumulation zones and new exploration prospects to be defined. Two main petroleum systems are recognised in the Palaeozoic sequence of the basin, containing 90% of the recoverable hydrocarbon resources: Lower Permian-Middle Carboniferous and Lower Carboniferous-Upper Devonian. The new exploration targets are deep Middle Devonian clastic reservoirs on the passive continental margins and Middle Carboniferous (Bashkirian) carbonates in the Caspian offshore part of the basin. (Author)

Biofacies and habitats of Brereton Limestone member (Carbondale Formation, Middle Pennsylvanian), Southwestern Illinois

Energy Technology Data Exchange (ETDEWEB)

O' Connell, D.B.; Utgaard, J.

1983-09-01

The Brereton Limestone is a shallow-water, open-marine carbonate deposited over peat or delta-plain muds after delta abandonment and a marine transgression. Data on autecology, lithology, insoluble residue content, and thickness were used to interpret the habitats of each biofacies. Biofacies V, a low-diversity biofacies dominated by brachiopods and ostracods, occupied turbid-water, mud- or shelly mud-bottom areas during influxes of detrital clays late in the abandonment of the Herrin delta and, also, early in the construction of the Jamestown delta. Low-relief carbonate mud mounds accumulated within and around baffles provided by thickets of phylloid algae and foraminifers, are capped locally by biofacies VI, a low-diversity biofacies dominated by ostracods. Biofacies VI, occupied the high subtidal to supratidal crests of algal mud mounds which had a stressed (possibly hypersaline) environment. Deeper water mud mounds were occupied by either Biofacies III, a crinoid-mixed fossil biofacies, or by Biofacies IV, which is dominated by fusulinids, strophomenids, and trilobites. Biofacies II, dominated by sponges, mollusks, and impunctate brachiopods, generally occurred on the flanks of the shallow-water mounds. Biofacies I, III, and IV also occurred in broad, muddy intermound areas and Biofacies III in narrow, winnowed intermound areas.

Body Size Preference of Marine Animals in Relation to Extinction Selectivity

Science.gov (United States)

Sriram, A.; Idgunji, S.; Heim, N. A.; Payne, J.

2014-12-01

Our project encompasses an extremely specific aspect in relation to the five mass extinctions in geologic history. We asked ourselves whether larger or smaller body sizes would be better suited for surviving a mass extinction. To conduct research for our project, we used the body sizes of 17,172 marine animal genera as our primary data. These animals include echinoderms, arthropods, chordates, mollusks, and brachiopods. These creatures are perfect model organisms in terms of finding data on them because they have an excellent fossil record, and are well documented. We focused on the mean body size of these animals before and after each of the five mass extinctions (end-Ordovician, Late Devonian, end-Permian, end-Triassic, and end-Cretaceous). Our hypothesis was that the average biovolume of animals increased after each of the extinctions, with the mean size being greater after than it was before. Our size data is from the Ellis & Messina Catalogue of Ostracoda and the Treatise on Invertebrate Paleontology. We obtained stratigraphic range data The Treatise and Sepkoski (2002). In our analyses, we compared the mean size of the different animal genera before and after each extinction event. We further partitioned size change across mass extinction boundaries into three categories: the surviving genera, the extinct genera, and the newly originating genera that came about after the extinction. According to our analyses, the mean sizes did not change significantly from the genera living during the stages before the extinctions and after the extinctions. From our results, we can assume that there were not enough major increases in the overall volume of the organisms to warrant a definite conclusion that extinctions lead to larger body sizes. Further support for our findings came from the T-tests in our R code. Only the Cretaceous period showed true evidence for size changing because of the extinction; in this case, the mean size decreased. T-tests for the Cretaceous

Re Os depositional ages and seawater Os estimates for the Frasnian Famennian boundary: Implications for weathering rates, land plant evolution, and extinction mechanisms

Science.gov (United States)

Turgeon, Steven C.; Creaser, Robert A.; Algeo, Thomas J.

2007-09-01

Four TOC-rich shale intervals spanning the Frasnian-Famennian (F-F) boundary were recovered in a drillcore (West Valley NX-1) from western New York (USA) and radiometrically dated using Re-Os. Two of the black shale intervals (WVC785 from ˜ 2.9 m below, and WVC754 from ˜ 6.4 m above the F-F boundary, respectively) yielded statistically overlapping ages with uncertainties of initial 187Os/ 188Os (0.45 to 0.47), reflecting contemporaneous seawater Os values, are low but similar to the value of 0.42 reported for the Exshaw Fm (Canada) at the Devonian-Mississippian boundary (ca. 361 Ma) [Selby D., Creaser R.A., 2005. Direct radiometric dating of the Devonian-Mississippian time-scale boundary using the Re-Os black shale geochronometer. Geology 33, 545-548]. This may suggest fairly constant and low global continental weathering rates during the Late Devonian, although in view of the short residence time of Os in seawater (˜ 1-4 × 10 4 yr), further measurements are needed to assess potential short-term variation in seawater Os ratios. Owing to low Os and Re abundances at the F-F boundary, our data are inconsistent with long-term volcanism and bolide impact as potential Late Devonian mass extinction mechanisms. In addition, the Frasnian-Famennian ocean appears to have been depleted with respect to Re, possibly indicating an exhaustion of the Re seawater reservoir owing to high burial rates of redox-sensitive elements under dysoxic/anoxic conditions leading up to the F-F boundary.

Prolonged Permian–Triassic ecological crisis recorded by molluscan dominance in Late Permian offshore assemblages

OpenAIRE

Clapham, Matthew E.; Bottjer, David J.

2007-01-01

The end-Permian mass extinction was the largest biotic crisis in the history of animal life, eliminating as many as 95% of all species and dramatically altering the ecological structure of marine communities. Although the causes of this pronounced ecosystem shift have been widely debated, the broad consensus based on inferences from global taxonomic diversity patterns suggests that the shift from abundant brachiopods to dominant molluscs was abrupt and largely driven by the catastrophic effec...

A new species of Conchicolites (Cornulitida, Tentaculita from the Wenlock of Gotland, Sweden

Directory of Open Access Journals (Sweden)

Olev Vinn

2014-08-01

Full Text Available A new cornulitid species, Conchicolites crispisulcans sp. nov., is described from the Wenlock of Gotland, Sweden. The undulating edge of C. crispisulcans sp. nov. peristomes is unique among the species of Conchicolites. This undulating peristome edge may reflect the position of setae at the tube aperture. The presence of the undulating peristome edge supports the hypothesis that cornulitids had setae and were probably related to brachiopods.

Devonian micritic limestones used in the historic production of Prague hydraulic lime (‘pasta di Praga’: characterization of the raw material and experimental laboratory burning

Directory of Open Access Journals (Sweden)

Kozlovcev, P.

2015-09-01

Full Text Available The Devonian micritic limestones from the Prague Basin (Barrandian area, Bohemian Massif, Czech Republic, which were the primary raw material used for natural hydraulic lime burned in Prague, exhibit a feebly to eminently hydraulic character. Based on a laboratory experimental study, the burned product is composed of dominant free-lime (CaO and/or portlandite (Ca(OH2, larnite-belite (bicalcium silicate 2CaO.SiO2, and quartz (SiO2 - i.e. phases formed due to the decomposition of carbonate and quartz, present in the original limestones. Proportions of the newly formed phases depend on: the composition of the raw material, maximum burning temperature (the highest amount of larnite-belite appearing at a burning temperature of 1200 °C, and the granulometry of the experimental batches (a coarsely-ground batch exhibited a higher amount of larnite-belite compared to the finely-ground one. The presence of minor phyllosilicates in the raw material contributed to the formation of gehlenite, brownmillerite, wollastonite, calcium aluminate, and/or spurrite.Las calizas micríticas devonianas provenientes de la Cuenca de Praga (área de Barrand, macizo de Bohemia, República checa que fueron la principal materia prima utilizada para la producción de la cal hidráulica natural calcinada en Praga, presentan un carácter hidráulico desde débil hasta alto. El estudio experimental de laboratorio, ha determinado que el producto calcinado está compuesto de cal viva (CaO como componente predominante y/o cal hidratada (Ca(OH2, larnita-belita (silicato bicálcico 2CaO.SiO2 y cuarzo (SiO2 – es decir, fases formadas como resultado de la descomposición de carbonato y cuarzo presentes en las calizas originales. Las proporciones de las nuevas fases formadas dependen de: la composición de la materia prima, temperatura máxima de calcinación (la mayor cantidad de larnita-belita se produce a la temperatura de calcinación de 1200 °C, y la granulometría de las

Retrowedge-related Carboniferous units and coeval magmatism in the northwestern Neuquén province, Argentina

Science.gov (United States)

Zappettini, Eduardo O.; Chernicoff, Carlos J.; Santos, Joao O. S.; Dalponte, Marcelo; Belousova, Elena; McNaughton, Neal

2012-11-01

The studied Carboniferous units comprise metasedimentary (Guaraco Norte Formation), pyroclastic (Arroyo del Torreón Formation), and sedimentary (Huaraco Formation) rocks that crop out in the northwestern Neuquén province, Argentina. They form part of the basement of the Neuquén Basin and are mostly coeval with the Late Paleozoic accretionary prism complex of the Coastal Cordillera, south-central Chile. U-Pb SHRIMP dating of detrital zircon yielded a maximum depositional age of 374 Ma (Upper Devonian) for the Guaraco Norte Formation and 389 Ma for the Arroyo del Torreón Formation. Detrital magmatic zircon from the Guaraco Norte Formation are grouped into two main populations of Devonian and Ordovician (Famatinian) ages. In the Arroyo del Torreón Formation, zircon populations are also of Devonian and Ordovician (Famatinian), as well as of Late Neoproterozoic and Mesoproterozoic ages. In both units, there is a conspicuous population of Devonian magmatic zircon grains (from 406 ± 4 Ma to 369 ± 5 Ma), indicative of active magmatism at that time range. The ɛHf values of this population range between -2.84 and -0.7, and the TDM-(Hf) are mostly Mesoproterozoic, suggesting that the primary sources of the Devonian magmatism contained small amounts of Mesoproterozoic recycled crustal components. The chemical composition of the Guaraco Norte Formation corresponds to recycled, mature polycyclic sediment of mature continental provenance, pointing to a passive margin with minor inputs from continental margin magmatic rocks. The chemical signature of the Huaraco Formation indicates that a magmatic arc was the main provenance for sediments of this unit, which is consistent with the occurrence of tuff—mostly in the Arroyo del Torreón Formation and very scarcely in the Huaraco Formation—with a volcanic-arc signature, jointly indicating the occurrence of a Carboniferous active arc magmatism during the deposition of the two units. The Guaraco Norte Formation is interpreted

Facies and age of the Oso Ridge Member (new), Abo Formation, Zuni Mountains, New Mexico

Science.gov (United States)

Armstrong, A.K.; Stamm, R.G.; Kottlowski, F.E.; Mamet, B.L.; Dutro, J.T.; Weary, D.J.

1994-01-01

The Oso Ridge Member (new), at the base of the Abo Formation, nonconformably overlies Proterozoic rocks. The member consists of some 9m of conglomerate and arkose composed principally of fragments of the underlying Proterozoic metamorphic rocks; thin, fossiliferous limestone lenses are interbedded with the arkose. Biota from the lenses include a phylloid alga, foraminifers, conodonts, brachiopods, and molluscs. The age of the Oso Ridge Member is Virgilian Late Pennsylvanian) to Wolfcampian (Early Permian). -from Authors

An early (1850) 'handwritten' shell exchange catalogue of the Leiden Museum, with notes on the collectors Rethaan Macaré and Tischbein

OpenAIRE

Bruggen, van, A.C.

2013-01-01

A ‘handwritten’ (lithographed) shell exchange catalogue of the National Museum of Natural History, Leiden (The Netherlands), dated 1850 and containing 864 nominal taxa (861 molluscs and 3 brachiopods), is discussed in the context of the history of the museum. This catalogue must have been distributed in a limited edition to shell collectors interested in the exchange of specimens. Among the exchange partners of the museum were the well-known 19th century Dutch collector Lady (later Dowager) F...

Geometry, kinematics and tectonic models of the Kazakhstan Orocline, Central Asian Orogenic Belt

Science.gov (United States)

Li, Pengfei; Sun, Min; Rosenbaum, Gideon; Yuan, Chao; Safonova, Inna; Cai, Keda; Jiang, Yingde; Zhang, Yunying

2018-03-01

The Central Asian Orogenic Belt (CAOB) is one of the largest accretionary orogens on Earth and is characterized by the occurrence of tight oroclines (Kazakhstan and Tuva-Mongolian oroclines). The origin of these large-scale orogenic curvatures is not quite understood, but is fundamentally important for understanding crustal growth and tectonic evolution of the CAOB. Here we provide an outline of available geological and paleomagnetic data around the Kazakhstan Orocline, with an aim of clarifying the geometry, kinematics and geodynamic origin of the orocline. The Kazakhstan Orocline is evident in a total magmatic image, and can be traced by the continuation of high magnetic anomalies associated with the Devonian Volcanic Belt and the Late Devonian to Carboniferous Balkhash-Yili arc. Paleomagnetic data show ∼112-126° clockwise rotation of the northern limb relative to the southern limb in the Late Devonian to Early Carboniferous, as well as ∼15-28° clockwise rotation of the northern limb and ∼39-40° anticlockwise rotation of the southern limb relative to the hinge of the orocline during the Late Carboniferous to Permian. We argue that the Kazakhstan Orocline experienced two-stage bending with the early stage of bending (Late Devonian to Early Carboniferous; ∼112-126°) driven by slab rollback, and the later stage (Late Carboniferous to Permian; 54-68°) possibly associated with the amalgamation of the Siberian, Tarim and Baltic cratons. This new tectonic model is compatible with the occurrence of rift basins, the spatial migration of magmatic arc, and the development of large-scale strike-slip fault systems during oroclinal bending.

Aquifer Characteristics Data Report for the Weldon Spring Site chemical plant/raffinate pits and vicinity properties for the Weldon Spring Site Remedial Action Project, Weldon Spring, Missouri

International Nuclear Information System (INIS)

1990-11-01

This report describes the procedures and methods used, and presents the results of physical testing performed, to characterize the hydraulic properties of the shallow Mississippian-Devonian aquifer beneath the Weldon Spring chemical plant, raffinate pits, and vicinity properties. The aquifer of concern is composed of saturated rocks of the Burlington-Keokuk Limestone which constitutes the upper portion of the Mississippian-Devonian aquifer. This aquifer is a heterogeneous anisotropic medium which can be described in terms of diffuse Darcian flow overlain by high porosity discrete flow zones and conduits. Average hydraulic conductivity for all wells tested is 9.6E-02 meters/day (3.1E-01 feet/day). High hydraulic conductivity values are representative of discrete flow in the fractured and weathered zones in the upper Burlington-Keokuk Limestone. They indicate heterogeneities within the Mississippian-Devonian aquifer. Aquifer heterogeneity in the horizontal plane is believed to be randomly distributed and is a function of fracture spacing, solution voids, and preglacial weathering phenomena. Relatively high hydraulic conductivities in deeper portions of the aquifer are though to be due to the presence of widely spaced fractures. 44 refs., 27 figs., 9 tabs

Marcellus shale gas potential in the southern tier of New York

Energy Technology Data Exchange (ETDEWEB)

Faraj, B. [Talisman Energy Inc., Calgary, AB (Canada); Duggan, J. [Hunt Oil Canada, Calgary, AB (Canada)

2008-07-01

Marcellus shale is a significant, underexplored, shale gas target in the Appalachian Basin. Gas-in-place estimates in the Marcellus shale range from 200 to 100 billion cubic feet (bcf). The Devonian shales have favorable attributes such as high total organic content (TOC), high gas content, favorable mineralogy and over-pressured. Land owned by Fortuna Energy in the northern Appalachian Basin may contain significant shale gas with unrisked gas-in-place in excess of 10 trillion cubic feet. Unlocking the true shale gas potential requires innovative drilling and completion techniques. This presentation discussed Marcellus shale gas potential in the southern tier and a test program being conducted by Fortuna to test the potential. Several photographs were shown, including Taughannock Falls, Finger Lakes and the Ithaca Shale, Sherburne Sandstone, and Geneseo Shale; two orthogonal fracture sets in the Upper Devonian Geneseo Shale; and two orthogonal fracture sets in the Upper Devonian Rocks, near Corning, New York. Figures that were presented included the supercontinent Pangaea in the early Triassic; undiscovered gas resources in the Appalachian Basin; stratigraphy; and total gas production in New York since 1998. Fortuna's work is ongoing in the northern Appalachian Basin. tabs., figs.

The Cambrian to Devonian odyssey of the Brabant Massif within Avalonia: A review with new zircon ages, geochemistry, Sm-Nd isotopes, stratigraphy and palaeogeography

Science.gov (United States)

Linnemann, Ulf; Herbosch, Alain; Liégeois, Jean-Paul; Pin, Christian; Gärtner, Andreas; Hofmann, Mandy

2012-05-01

signature (ɛNd - 4/- 5) and TDM model ages (1.3-1.7 Ga) for Brabant magmatic rocks indicate an old recycled component. Megasequence 3 (uppermost Ordovician to lowermost Devonian; > 3.5 km thick) includes the onset of a Silurian foreland basin that reflects the tectonic inversion of the core of the massif (Brabantian orogeny) in response to the Baltica-Avalonia-Laurentia collision. Finally, the comparison with the strikingly similar Cambrian successions of the Harlech Dome (Wales, Avalonia) and the Meguma terrane (Nova Scotia, peri-Gondwana) allows the construction of a new Early Cambrian palaeogeographic model for the whole Avalonia microplate, in which the Meguma terrane is included.

Patterns of fossil distributions within their environmental context from the Middle Triassic in South Canyon, Central Nevada, USA

Directory of Open Access Journals (Sweden)

Pedro M. Monarrez

2014-01-01

Full Text Available The Middle Triassic records the return of diverse marine communities after the severe effects of the end-Permian mass extinction. This diversification leads to the Mesozoic/modern adaptive radiation resulting in substantial changes in marine communities in comparison to their Paleozoic predecessors. This analysis focuses on the faunal abundance, ecological patterns, and environmental interpretation of a Middle Triassic section in Central Nevada. Twelve bulk samples were collected. Visible fossils were identified and tallied from hand samples and thin-sections were used to aid in environmental interpretation. Beginning in the Late Anisian, we observed an ammonoid dominated to flat-clam, epifaunal dominated benthic community within a muddy, quiet, inner shelf depositional environment. Through time, epifaunal bivalves dominate within a middle shelf environment followed by an increase in infaunalization and shell-thickness. During this time the presence of oncoids and the reported finding of corals suggest the middle shelf environment gave way to a higher energy patch reef shelf edge environment. Finally, we observe epifaunal brachiopods communities at the top of our section deposited in a middle shelf environment. In sum, we observe the dominance of modern taxa (i.e., bivalves with Paleozoic ecologies (i.e., epifaunal, followed by the dominance of modern taxa with Modern ecologies (i.e., infaunal, thick shells and then a return to Paleozoic taxa (i.e., brachiopods and Paleozoic ecologies within an overall transgressive environment.

Embryonic chirality and the evolution of spiralian left–right asymmetries

Science.gov (United States)

2016-01-01

The group Spiralia includes species with one of the most significant cases of left–right asymmetries in animals: the coiling of the shell of gastropod molluscs (snails). In this animal group, an early event of embryonic chirality controlled by cytoskeleton dynamics and the subsequent differential activation of the genes nodal and Pitx determine the left–right axis of snails, and thus the direction of coiling of the shell. Despite progressive advances in our understanding of left–right axis specification in molluscs, little is known about left–right development in other spiralian taxa. Here, we identify and characterize the expression of nodal and Pitx orthologues in three different spiralian animals—the brachiopod Novocrania anomala, the annelid Owenia fusiformis and the nemertean Lineus ruber—and demonstrate embryonic chirality in the biradial-cleaving spiralian embryo of the bryozoan Membranipora membranacea. We show asymmetric expression of nodal and Pitx in the brachiopod and annelid, respectively, and symmetric expression of Pitx in the nemertean. Our findings indicate that early embryonic chirality is widespread and independent of the cleavage programme in the Spiralia. Additionally, our study illuminates the evolution of nodal and Pitx signalling by demonstrating embryonic asymmetric expression in lineages without obvious adult left–right asymmetries. This article is part of the themed issue ‘Provocative questions in left–right asymmetry’. PMID:27821523

Abiotic and biotic responses to Milankovitch-forced megamonsoon and glacial cycles recorded in South China at the end of the Late Paleozoic Ice Age

Science.gov (United States)

Fang, Qiang; Wu, Huaichun; Hinnov, Linda A.; Tian, Wenqian; Wang, Xunlian; Yang, Tianshui; Li, Haiyan; Zhang, Shihong

2018-04-01

At the end of the Late Paleozoic Ice Age (LPIA) from late Early Permian to early Late Permian, the global climate was impacted by a prevailing megamonsoon and Gondwanan deglaciation. To better understand the abiotic and biotic responses to Milankovitch-forced climate changes during this time period, multi-element X-ray fluorescence (XRF) geochemistry analyses were conducted on 948 samples from the late Early-late Middle Permian Maokou Formation at Shangsi, South China. The Fe/Ti, S/Ti, Ba/Ti and Ca time series, which were calibrated with an existing "floating" astronomical time scale (ATS), show the entire suite of Milankovitch rhythms including 405 kyr long eccentricity, 128 and 95 kyr short eccentricity, 33 kyr obliquity and 20 kyr precession. Spectral coherency and cross-phase analysis reveals that chemical weathering (monitored by Fe/Ti) and upwelling (captured by S/Ti and Ba/Ti) are nearly antiphase in the precession band, which suggests a contrast between summer and winter monsoon intensities. Strong obliquity signal in the Ba/Ti series is proposed to derive from changes in thermohaline circulation intensity from glaciation dynamics in southern Gondwana. The abundance of foraminifer, brachiopod and ostracod faunas within the Maokou Formation were mainly controlled by the 1.1 Myr obliquity modulation cycle. The obliquity-forced high-nutrient and oxygen-depleted conditions generally produced a benthic foraminifer bloom, but threatened the brachiopod and ostracod faunas.

Hirnantia sagittifera (Brachiopoda and Mucronaspis mucronata s.l. (Trilobita in the Upper Ordovician of the East Baltic: taxonomy and distribution

Directory of Open Access Journals (Sweden)

Linda Hints

2012-05-01

Full Text Available The brachiopod Hirnantia sagittifera (M’Coy and trilobite morphs of the genus Mucronaspis from the topmost Ordovician Porkuni Stage of the central East Baltic are described and compared with those from the Hirnantian Stage of other regions. These important Hirnantian taxa occur in the Livonian Tongue of the Central Baltoscandian Facies Belt of the Baltic Basin, where the Porkuni Stage is represented by the non-graptolitic Kuldiga and Saldus formations. Hirnantia sagittifera appears in the lowermost part of the Porkuni Stage and is rather widely distributed in the basin in spite of its rare finds in each locality. Our study of trilobites of the genus Mucronaspis has enabled us to observe morphological changes in its exoskeleton in time and to identify a succession of five morphotypes (morphs. In some characteristics these morphs are similar to those of different alleged species of the genus Mucronaspis (M. olini, M. danai, M. ganabina, M. mucronata but they cannot be definitely assigned to any of these species due to some variances. However, here for the first time a stratigraphically ordered collection is presented, which deserves attention in revising the taxonomy of highly variable Mucronaspis. The described brachiopods and trilobites occur mainly in the strata correlated with the Normalograptus extraordinarius graptolite Biozone. However, the uppermost finds of both taxa come from strata correlated with the N. persculptus Biozone.

Geochemistry of the brachiopod Hemithiris psittacea from the Canadian Arctic

DEFF Research Database (Denmark)

Ullmann, Clemens V.; Korte, Christoph; Bitner, M. Aleksandra

2017-01-01

Fossil shell material from high palaeo-latitudes is increasingly studied for environmental forcings specific to these latitudes and as sensitive archives of climate change. However, more detailed studies of modern analogues are necessary for putting findings into global and high latitude perspect...

Sequences, stratigraphy and scenarios: what can we say about the fossil record of the earliest tetrapods?

Science.gov (United States)

Friedman, Matt; Brazeau, Martin D

2011-02-07

Past research on the emergence of digit-bearing tetrapods has led to the widely accepted premise that this important evolutionary event occurred during the Late Devonian. The discovery of convincing digit-bearing tetrapod trackways of early Middle Devonian age in Poland has upset this orthodoxy, indicating that current scenarios which link the timing of the origin of digited tetrapods to specific events in Earth history are likely to be in error. Inspired by this find, we examine the fossil record of early digit-bearing tetrapods and their closest fish-like relatives from a statistical standpoint. We find that the Polish trackways force a substantial reconsideration of the nature of the early tetrapod record when only body fossils are considered. However, the effect is less drastic (and often not statistically significant) when other reliably dated trackways that were previously considered anachronistic are taken into account. Using two approaches, we find that 95 per cent credible and confidence intervals for the origin of digit-bearing tetrapods extend into the Early Devonian and beyond, spanning late Emsian to mid Ludlow. For biologically realistic diversity models, estimated genus-level preservation rates for Devonian digited tetrapods and their relatives range from 0.025 to 0.073 per lineage-million years, an order of magnitude lower than species-level rates for groups typically considered to have dense records. Available fossils of early digited tetrapods and their immediate relatives are adequate for documenting large-scale patterns of character acquisition associated with the origin of terrestriality, but low preservation rates coupled with clear geographical and stratigraphic sampling biases caution against building scenarios for the origin of digits and terrestrialization tied to the provenance of particular specimens or faunas.

Late to the table: diversification of tetrapod mandibular biomechanics lagged behind the evolution of terrestriality.

Science.gov (United States)

Anderson, Philip S L; Friedman, Matt; Ruta, Marcello

2013-08-01

The origin of digit-bearing tetrapods in the Middle to Late Devonian (ca. 393-360 Mya) and their subsequent invasion of land represent a classic case of a major evolutionary radiation driven by new ecological opportunities. In this and other examples, exploration of new eco-space is hypothesized to correlate with functional innovation and adaptive divergence of phenotypes. Simultaneous changes in all morphofunctional systems are rare in major evolutionary transitions and may be non-existent. Here, we focus on the mandibles of early tetrapods and their kin as a model system to test whether shifts in functional innovation were coeval with some major events in tetrapod history. To this end, we quantified mechanical variation in the mandibles of tetrapodomorphs ranging in age from Early Devonian to earliest Permian. Biomechanical disparity is stable from the Devonian to the Early Pennsylvanian, even though the origin of weight-bearing, digited limbs, and the initial phases of the colonization of land occurred during this interval. An appreciable increase in functional variation is detected in the latest Pennsylvanian and earliest Permian, when stem and crown amniotes began to explore new regions of mechanical morphospace, a pattern partly attributable to the origin of herbivory. We find no difference in the rate of functional change between tetrapodomorph "fish" and early digited tetrapods, although two independent shifts are detected among Devonian stem tetrapods more crownward than Acanthostega. Instead, the most profound shifts in evolutionary rate are nested well within the tetrapod crown and are associated with amniotes (particularly diadectomorphs and some synapsids). The substantial temporal gap between the origin of postcranial features associated with terrestriality, such as limbs with functional elbow/knee and wrist/ankle joints capable of weight-bearing, and the onset of divergence in jaw biomechanics provides a compelling example of "functional modularity

GIVETIAN–FRASNIAN BOUNDARY CONODONTS FROM KERMAN PROVINCE, CENTRAL IRAN

Directory of Open Access Journals (Sweden)

HOSSEIN GHOLAMALIAN

2013-07-01

Full Text Available The Middle - Late Devonian boundary is investigated based on twenty-two conodont species and subspecies from three sections in the north and west of Kerman, southeastern central Iran. Upper Givetian - lower Frasnian carbonates of the basal part of the Bahram Formation transgressively overlie the sandstone beds of the top of (? Early - Middle Devonian Padeha Formation. These massive skeletal limestones encompass the G-F boundary. The base of Frasnian is identified by the appearance of early forms of Ancyrodella rotundiloba . It helps to compare our biozones to those of global stratotype in southern France. A new species, Polygnathus hojedki n. sp. is described here. New range is suggested for P. praepolitus .

Significance of detrital zircons in upper Devonian ocean-basin strata of the Sonora allochthon and Lower Permian synorogenic strata of the Mina Mexico foredeep, central Sonora, Mexico

Science.gov (United States)

Poole, F.G.; Gehrels, G.E.; Stewart, John H.

2008-01-01

U-Pb isotopic dating of detrital zircons from a conglomeratic barite sandstone in the Sonora allochthon and a calciclastic sandstone in the Mina Mexico foredeep of the Minas de Barita area reveals two main age groups in the Upper Devonian part of the Los Pozos Formation, 1.73-1.65 Ga and 1.44-1.42 Ga; and three main age groups in the Lower Permian part of the Mina Mexico Formation, 1.93-1.91 Ga, 1.45-1.42 Ga, and 1.1-1.0 Ga. Small numbers of zircons with ages of 2.72-2.65 Ga, 1.30-1.24 Ga, ca. 2.46 Ga, ca. 1.83 Ga, and ca. 0.53 Ga are also present in the Los Pozos sandstone. Detrital zircons ranging in age from 1.73 to 1.65 Ga are considered to have been derived from the Yavapai, Mojave, and Mazatzal Provinces and their transition zones of the southwestern United States and northwestern Mexico. The 1.45-1.30 Ga detrital zircons were probably derived from scattered granite bodies within the Mojave and Mazatzal basement rocks in the southwestern United States and northwestern Mexico, and possibly from the Southern and Eastern Granite-Rhyolite Provinces of the southern United States. The 1.24-1.0 Ga detrital zircons are believed to have been derived from the Grenville (Llano) Province to the east and northeast or from Grenvilleage intrusions or anatectites to the north. Several detrital zircon ages ranging from 2.72 to 1.91 Ga were probably derived originally from the Archean Wyoming Province and Early Paleoproterozoic rocks of the Lake Superior region. These older detrital zircons most likely have been recycled one or more times into the Paleozoic sandstones of central Sonora. The 0.53 Ga zircon is believed to have been derived from a Lower Cambrian granitoid or meta-morphic rock northeast of central Sonora, possibly in New Mexico and Colorado, or Oklahoma. Detrital zircon geochronology suggests that most of the detritus in both samples was derived from Laurentia to the north, whereas some detritus in the Permian synorogenic foredeep sequence was derived from the

Fossil record of stem groups employed in evaluating the chronogram of insects (Arthropoda: Hexapoda)

Science.gov (United States)

Wang, Yan-hui; Engel, Michael S.; Rafael, José A.; Wu, Hao-yang; Rédei, Dávid; Xie, Qiang; Wang, Gang; Liu, Xiao-guang; Bu, Wen-jun

2016-01-01

Insecta s. str. (=Ectognatha), comprise the largest and most diversified group of living organisms, accounting for roughly half of the biodiversity on Earth. Understanding insect relationships and the specific time intervals for their episodes of radiation and extinction are critical to any comprehensive perspective on evolutionary events. Although some deeper nodes have been resolved congruently, the complete evolution of insects has remained obscure due to the lack of direct fossil evidence. Besides, various evolutionary phases of insects and the corresponding driving forces of diversification remain to be recognized. In this study, a comprehensive sample of all insect orders was used to reconstruct their phylogenetic relationships and estimate deep divergences. The phylogenetic relationships of insect orders were congruently recovered by Bayesian inference and maximum likelihood analyses. A complete timescale of divergences based on an uncorrelated log-normal relaxed clock model was established among all lineages of winged insects. The inferred timescale for various nodes are congruent with major historical events including the increase of atmospheric oxygen in the Late Silurian and earliest Devonian, the radiation of vascular plants in the Devonian, and with the available fossil record of the stem groups to various insect lineages in the Devonian and Carboniferous. PMID:27958352

Natural gas production verification tests

International Nuclear Information System (INIS)

1992-02-01

This Environmental Assessment (EA) has been prepared by the Department of Energy (DOE) in compliance with the requirements of the National Environmental Policy Act of 1969. The Department of Energy (DOE) proposes to fund, through a contract with Petroleum Consulting Services, Inc. of Canton, Ohio, the testing of the effectiveness of a non-water based hydraulic fracturing treatment to increase gas recovery from low-pressure, tight, fractured Devonian Shale formations. Although Devonian Shales are found in the Appalachian, Michigan, and Illinois Basins, testing will be done only in the dominant, historical five state area of established production. The objective of this proposed project is to assess the benefits of liquid carbon dioxide (CO 2 )/sand stimulations in the Devonian Shale. In addition, this project would evaluate the potential nondamaging (to the formation) properties of this unique fracturing treatment relative to the clogging or chocking of pores and fractures that act as gas flow paths to the wellbore in the target gas-producing zones of the formation. This liquid CO 2 /sand fracturing process is water-free and is expected to facilitate gas well cleanup, reduce the time required for post-stimulation cleanup, and result in improved production levels in a much shorter time than is currently experienced

Microfossils in the Ordovician erratic boulders from South-western Finland

Directory of Open Access Journals (Sweden)

Nõlvak, J.

1995-12-01

Full Text Available Chitinozoans, ostracods and acritarchs found in four glacially transported limestone boulders from the south-western coast of Finland have been studied in order to test the usefulness of these microfossil groups in age determinations. Also rare specimens of conodonts, inarticulated brachiopods and foraminifers were found. Baltic limestone (or Östersjö limestone was the most problematic, because only fossils with calcitic or phosphatic shells are preserved. It is concluded that the boulders identified correlate with the Uhaku and Rakvere stages of the Middle Ordovician.

Conodont succession and reassessment of major events around the Permian-Triassic boundary at the Selong Xishan section, southern Tibet, China

Science.gov (United States)

Yuan, Dong-Xun; Zhang, Yi-Chun; Shen, Shu-Zhong

2018-02-01

A major discrepancy for the age of the Selong Group from middle Cisuralian (Early Permian) to Changhsingian resulted from previous reports of Sakmarian, Kungurian and Guadalupian (Middle Permian) conodonts and Lopingian (Late Permian) brachiopods. Recently, Cisuralian and Guadalupian conodonts were reported again from the Selong Group and the basal part of the Kangshare Formation at the Selong section, but the age discrepancy remains. We present our conodont materials based on large samples collected from the Selong Group and our interpretation based on identifications using a sample population approach. Three conodont zones are recognized in our re-investigation of the upper part of the Selong Group. They include the Vjalovognathus sp., the Mesogondolella hendersoni, and the M. sheni zones, in ascending order. These zones are overlain by the basal Triassic Hindeodus parvus Zone and the Otoceras woodwardi Zone. Our reassessment of conodonts reported by previous studies from Selong and nearby sections suggest that all specimens consistently point to a Lopingian age; the upper part of the Selong Group is latest Changhsingian in age based on the presence of Clarkina orchardi and Mesogondolella sheni. Previously reported early Cisuralian and Guadalupian conodonts are misidentified using a form species concept. A hiatus may be present at the erosional surface between the Selong Group and the Waagenites Bed of the basal part of the Kangshare Formation. However, the hiatus is minimal because conodont and brachiopod assemblages above and below this surface are very similar, and it results from a latest Changhsingian transgression just before the extinction that follows a global latest Changhsingian regression. There is a distinct rapid end-Permian mass extinction at Selong within the Waagenites Bed, as indicated by the disappearances of all benthic brachiopods, rugose corals and Permian bryozoans. The burst of Clarkina species in the Waagenites Bed and throughout the

Microbialites in the shallow-water marine environments of the Holy Cross Mountains (Poland) in the aftermath of the Frasnian-Famennian biotic crisis

Science.gov (United States)

Rakociński, Michał; Racki, Grzegorz

2016-01-01

Microbial carbonates, consisting of abundant girvanellid oncoids, are described from cephalopod-crinoid and crinoid-brachiopod coquinas (rudstones) occurring in the lowermost Famennian of the Holy Cross Mountains, Poland. A Girvanella-bearing horizon (consist with numerous girvanellid oncoids) has been recognised at the Psie Górki section, and represents the northern slope succession of the drowned Dyminy Reef. This occurrence of microbialites in the aftermath of the Frasnian-Famennian event is interpreted as the result of opportunistic cyanobacteria blooms, which, as 'disaster forms', colonised empty shallow-water ecological niches during the survival phase following the Frasnian metazoan reef collapse, due to collapsed activity of epifaunal, grazing, and/or burrowing animals. The anachronistic lithofacies at Psie Górki is linked with catastrophic mass mortality of the cephalopod and crinoid-brachiopod communities during the heavy storm events. This mass occurrence of girvanellid oncoids, along with Frutexites-like microbial shrubs and, at least partly, common micritisation of some skeletal grains, records an overall increase in microbial activity in eutrophic normal marine environments. Microbial communities in the Holy Cross Mountains are not very diverse, being mainly represented by girvanellid oncoids, and stand in contrast to the very rich microbial communities known from the Guilin area (China), Canning Basin (Australia) and the Timan-northern Ural area (Russia). The association from Poland is similar to more diverse microbial communities represented by oncoids, trombolites and stromatolites, well known from the Canadian Alberta basin.

Geochemical characterization and miospore biochronostratigraphy of the Frasnian anoxic event in the Parnaiba basin, Northeast Brazil

International Nuclear Information System (INIS)

Rodrigues, R.; De Melo, J.H.G.; Alves, D.B.; Loboziak, S.

1995-01-01

Radioactive shales of Frasnian age in the Parnaiba Basin present high concentrations of organic matter. They correspond to a condensed section related to the Devonian maximum marine transgression. Combined geochemical, palynological and clay mineral data point out to a dominant algal contribution in the composition of the organic matter, as well as to anoxic depositional settings. This radioactive shale interval corresponds to the onset of a long-lasting, global anoxic event which was to be intensified in the Late Frasnian, and thus can be regarded as a marker for chronostratigraphic correlations. It includes the main source rocks of Devonian age in the Palaeozoic basins of north Brazil, and therefore represents a target of potential interest for hydrocarbon exploration. (authors). 16 refs., 10 figs., 1 tab., 17 photos

Geochemical characterization and miospore biochronostratigraphy of the Frasnian anoxic event in the Parnaiba basin, Northeast Brazil

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, R.; De Melo, J.H.G.; Alves, D.B. [Universidade Federal, Rio de Janeiro, RJ (Brazil); Loboziak, S. [Lille-1 Univ., 59 - Villeneuve-d`Ascq (France)

1995-12-31

Radioactive shales of Frasnian age in the Parnaiba Basin present high concentrations of organic matter. They correspond to a condensed section related to the Devonian maximum marine transgression. Combined geochemical, palynological and clay mineral data point out to a dominant algal contribution in the composition of the organic matter, as well as to anoxic depositional settings. This radioactive shale interval corresponds to the onset of a long-lasting, global anoxic event which was to be intensified in the Late Frasnian, and thus can be regarded as a marker for chronostratigraphic correlations. It includes the main source rocks of Devonian age in the Palaeozoic basins of north Brazil, and therefore represents a target of potential interest for hydrocarbon exploration. (authors). 16 refs., 10 figs., 1 tab., 17 photos.

Uranium and selected trace elements in granites from the Caledonides of East Greenland

International Nuclear Information System (INIS)

Steenfelt, A.

1982-01-01

The Caledonian fold belt of East Greenland contains calc-alkaline granite (sensu lato) intrusions with ages ranging from c.2000 Ma to c.350 Ma. The Proterozoic granites have low U contents and the pre-Devonian Caledonian granites contents of U corresponding to the clarke value for U in granites. Some aspects of the geochemistry of U are discussed using U-K/Rb, U-Sr, U-Zr, and U-Th diagrams. Secondary enrichment and mineralization occurs in fractured and hydrothermally altered granites and rhyolites situated in or near a major NNE fault zone. The U is associated with iron oxides or hydrocarbons. It is suggested that the source of the mineralization was Devonian acid magma, which also acted as a heat source for circulating hydrothermal fluids. (author)

Jurassic animals and algae in the flooring of Our Lady of Sorrows Church in Poznań

Directory of Open Access Journals (Sweden)

Antczak Mateusz

2015-12-01

Full Text Available The flooring of Our Lady of Sorrows Church in Poznań is made of Jurassic rocks from the Świętokrzyskie Mountains (also known as Holy Cross Mountains and contain abundant marine invertebrate fossils: sponges, bivalves, brachiopods, various families of cephalopods, etc. Some of them can be identified to the genus level. The fossils make it possible to describe the environment and ecosystem of the Jurassic sea and biostratigraphy of the sediment. There are also some significant inorganic structures, which suggest post-diagenetic tectonic movements.

Precisely locating the Ordovician equator in Laurentia

DEFF Research Database (Denmark)

Jin, Jisuo; Harper, David A. T.; Cocks, L. Robin M.

2013-01-01

The Late Ordovician equatorial zone, like the zone today, had few hurricane-grade storms within 100 of the equator, as emphasized by the preservation of massive-bedded Thalassinoides ichnofacies in a trans-Laurentian belt more than 6000 km long, from the southwestern United States to North...... Greenland. That belt also includes nonamalgamated shell beds dominated by the brachiopod Proconchidium, which would not have been preserved after hurricane-grade storms. The belt lacks such storm-related sedimentary features as rip-up clasts, hummocky cross-stratification, or large channels. In contrast...

Palaeoenvironmental changes in the Late Triassic (Rhaetian) of the Northern Calcareous Alps

DEFF Research Database (Denmark)

Mette, Wolfgang; Elsler, Armin; Korte, Christoph

2012-01-01

in the Kössen Formation and determine their significance for environmental and climatic conditions in the Rhaetian sea of the Eiberg Basin (Northern Calcareous Alps). For this purpose 60 δ 18O measurements on 43 articulate brachiopods samples from 8 different horizons were carried out. The results indicate...... to the lowest unit 3 of the Eiberg Member that parallels oxygen isotopes. This positive δ 13C trend is interrupted by a sudden ~1.5‰ negative excursion in the late Rhaetian (Late Rhaetian Event), a time span when the oxygen isotopes remain heavy....

Early to Middle Jurassic palaeoenvironmental changes: High resolution δ13C and δ18O records from the UK

DEFF Research Database (Denmark)

Korte, Christoph; Hesselbo, Stephen; Ullmann, Clemens Vinzenz

Low-Mg-calcite fossils, such as bivalves, belemnites and brachiopods, and bulk rocks have been extensively utilized to reconstruct past seawater chemistry and paleoenviron¬mental changes. Recent work on major bioevents demonstrated that particularly higher resolution stable isotope records...... are necessary to reveal short-term paleoenviron¬mental fluctuations and, in addition, to discover its causes. Here we present a new high resolution carbon and oxygen isotope dataset generated from low-Mg-calcite fossils, fossil wood and bulk rocks collected from Early to Middle Jurassic marine successions...

Late Ordovician (post-Sardic) rifting branches in the North Gondwanan Montagne Noire and Mouthoumet massifs of southern France

DEFF Research Database (Denmark)

Javier Álvaro, J.; Colmenar Lallena, Jorge; Monceret, Eric

2016-01-01

, and the subsequent Middle-Ordovician stratigraphic gap is related to the Sardic phase. Upper Ordovician sedimentation started in the rifting branches of Cabrières and Mouthoumet with deposition of basaltic lava flows and lahar deposits (Roque de Bandies and Villerouge formations) of continental tholeiite signature...... (CT), indicative of continental fracturing.The infill of both rifting branches followed with the onset of (1) Katian (Ka1-Ka2) conglomerates and sandstones (Glauzy and Gascagne formations), which have yielded a new brachiopod assemblage representative of the Svobodaina havliceki Community; (2) Katian...

Geochemical and strontium isotope characterization of produced waters from Marcellus Shale natural gas extraction.

Science.gov (United States)

Chapman, Elizabeth C; Capo, Rosemary C; Stewart, Brian W; Kirby, Carl S; Hammack, Richard W; Schroeder, Karl T; Edenborn, Harry M

2012-03-20

Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters with other waters in the Appalachian Basin in the event of an accidental release, and to provide information about the source of the dissolved solids. Strontium isotopic ratios of Marcellus produced waters collected over a geographic range of ~375 km from southwestern to northeastern Pennsylvania define a relatively narrow set of values (ε(Sr)(SW) = +13.8 to +41.6, where ε(Sr) (SW) is the deviation of the (87)Sr/(86)Sr ratio from that of seawater in parts per 10(4)); this isotopic range falls above that of Middle Devonian seawater, and is distinct from most western Pennsylvania acid mine drainage and Upper Devonian Venango Group oil and gas brines. The uniformity of the isotope ratios suggests a basin-wide source of dissolved solids with a component that is more radiogenic than seawater. Mixing models indicate that Sr isotope ratios can be used to sensitively differentiate between Marcellus Formation produced water and other potential sources of TDS into ground or surface waters.

Uranium project GEO 2 attachment: cronostratigraphy aplied to Uranium research; Proyecto Uranio anexo GEO 2: cronoestratigrafia aplicada a la investigacion de Uranio

Energy Technology Data Exchange (ETDEWEB)

NONE

1983-07-01

In the article, different sources of information about Uranium stratigraphy from Uruguay have been reviewed. Some results have been presented in Upper Cambrian period and Precambrian era, specially Devonian, Carboniferous and Silurian period.

Uranium project GEO 2 attachment: cronostratigraphy aplied to Uranium research

International Nuclear Information System (INIS)

1983-01-01

In the article, different sources of information about Uranium stratigraphy from Uruguay have been reviewed. Some results have been presented in Upper Cambrian period and Precambrian era, specially Devonian, Carboniferous and Silurian period

Palaeozoic synorogenic sedimentation in central and northern Australia: a review of distribution and timing with implications for the evolution of intracontinental orogens

International Nuclear Information System (INIS)

Haines, P.W.; Hand, M.; Sandiford, M.

2001-01-01

The Palaeozoic Alice Springs Orogeny was a major intraplate tectonic event in central and northern Australia. The sedimentological, structural and isotopic effects of the Alice Springs Orogeny have been well documented in the northern Amadeus Basin and adjacent exhumed Arunta lnlier, although the full regional extent of the event, as well as lateral variations in timing and intensity are less well known. Because of the lack of regional isotopic data, we take a sedimentological approach towards constraining these parameters, compiling the location and age constraints of inferred synorogenic sedimentation across a number of central and northern Australian basins. Such deposits are recorded from the Amadeus, Ngalia, Georgina, Wiso, Eastern Officer and, possibly, Warburton Basins. Deposits are commonly located adjacent to areas of significant basement uplift related to north-south shortening. In addition, similar aged orogenic deposits occur in association with strike-slip tectonism in the Ord and southern Bonaparte Basins of northwest Australia. From a combination of sedimentological and isotopic evidence it appears that localised convergent deformation started in the Late Ordovician in the eastern Arunta lnlier and adjacent Amadeus Basin. Synorogenic style sedimentation becomes synchronously widespread in the late Early Devonian and in most areas the record terminates abruptly close to the end of the Devonian. A notable exception is the Ngalia Basin in which such sedimentation continued until the mid-Carboniferous. In the Ord and Bonaparte Basins there is evidence of two discrete pulses of transcurrent activity in the Late Devonian and Carboniferous. The sedimentological story contrasts with the isotopic record from the southern Arunta lnlier, which has generally been interpreted in terms of continuous convergent orogenic activity spanning most of the Devonian and Carboniferous, with a suggestion that rates of deformation increased in the mid-Carboniferous. Either

Lower Paleozoic deep-water facies of the Medfra area, central Alaska: A section in Geologic studies in Alaska by the U.S. Geological Survey, 1997

Science.gov (United States)

Dumoulin, Julie A.; Bradley, Dwight C.; Harris, Anita G.; Repetski, John E.

1999-01-01

Deep-water facies, chiefly hemipelagic deposits and turbidites, of Cambrian through Devonian age are widely exposed in the Medfra and Mt. McKinley quadrangles. These strata include the upper part of the Telsitna Formation (Middle-Upper Ordovician) and the Paradise Fork Formation (Lower Silurian-Lower Devonian) in the Nixon Fork terrane, the East Fork Hills Formation (Upper Cambrian-Lower Devonian) in the East Fork subterrane of the Minchumina terrane, and the chert and argillite unit (Ordovician) and the argillite and quartzite unit (Silurian- Devonian? and possibly older) in the Telida subterrane of the Minchumina terrane.In the western part of the study area (Medfra quadrangle), both hemipelagic deposits and turbidites are largely calcareous and were derived from the Nixon Fork carbonate platform. East- ern exposures (Mt. McKinley quadrangle; eastern part of the Telida subterrane) contain much less carbonate; hemipelagic strata are mostly chert, and turbidites contain abundant rounded quartz and lesser plagioclase and potassium feldspar. Deep-water facies in the Medfra quadrangle correlate well with rocks of the Dillinger terrane exposed to the south (McGrath quadrangle), but coeval strata in the Mt. McKinley quadrangle are compositionally similar to rocks to the northeast (Livengood quadrangle). Petrographic data thus suggest that the Telida subterranes presently defined is an artificial construct made up of two distinct sequences of disparate provenance.Restoration of 90 and 150 km of dextral strike-slip on the Iditarod and Farewell faults, respectively, aligns the deep-water strata of the Minchumina and Dillinger terranes in a position east of the Nixon Fork carbonate platform. This restoration supports the interpretation that lower Paleozoic rocks in the Nixon Fork and Dillinger terranes, and in the western part of the Minchumina terrane (East Fork subterrane and western part of the Telida subterrane), formed along a single continental margin. Rocks in the

The greatest step in vertebrate history: a paleobiological review of the fish-tetrapod transition.

Science.gov (United States)

Long, John A; Gordon, Malcolm S

2004-01-01

Recent discoveries of previously unknown fossil forms have dramatically transformed understanding of many aspects of the fish-tetrapod transition. Newer paleobiological approaches have also contributed to changed views of which animals were involved and when, where, and how the transition occurred. This review summarizes major advances made and reevaluates alternative interpretations of important parts of the evidence. We begin with general issues and concepts, including limitations of the Paleozoic fossil record. We summarize important features of paleoclimates, paleoenvironments, paleobiogeography, and taphonomy. We then review the history of Devonian tetrapods and their closest stem group ancestors within the sarcopterygian fishes. It is now widely accepted that the first tetrapods arose from advanced tetrapodomorph stock (the elpistostegalids) in the Late Devonian, probably in Euramerica. However, truly terrestrial forms did not emerge until much later, in geographically far-flung regions, in the Lower Carboniferous. The complete transition occurred over about 25 million years; definitive emergences onto land took place during the most recent 5 million years. The sequence of character acquisition during the transition can be seen as a five-step process involving: (1) higher osteichthyan (tetrapodomorph) diversification in the Middle Devonian (beginning about 380 million years ago [mya]), (2) the emergence of "prototetrapods" (e.g., Elginerpeton) in the Frasnian stage (about 372 mya), (3) the appearance of aquatic tetrapods (e.g., Acanthostega) sometime in the early to mid-Famennian (about 360 mya), (4) the appearance of "eutetrapods" (e.g., Tulerpeton) at the very end of the Devonian period (about 358 mya), and (5) the first truly terrestrial tetrapods (e.g., Pederpes) in the Lower Carboniferous (about 340 mya). We discuss each of these steps with respect to inferred functional utility of acquired character sets. Dissociated heterochrony is seen as the most

Andoma segment of southeastern margin of fennoscandian shield: Structure and evolution

Science.gov (United States)

Kolodyazhny, S. Yu.; Baluev, A. S.; Terekhov, E. N.

2016-07-01

The components of deformation related to endogenic (tectonic) and exogenic (glaciotectonic, gravitational sliding) factors are considered in the sedimentary platform cover by a study of Andoma dislocations in the Upper Devonian sedimentary rocks of the Lake Onega district. These structures are localized in the eponymous segment of the southeastern margin of the Fennoscandian (Baltic) Shield; indications of high tectonic activity are noted along this margin. As has been shown by a structural study, the development of the Andoma structure is caused by long-term (Late Devonian-Quaternary) multistage deformations related to tectonic factors and, to a lesser degree, glaciotectonics. The consecutive stages of synsedimentation normal faulting and landsliding, bedding-plane gliding, various forms of shear flow in a regime of transpression, glaciotectonic thrusting, and neotectonic transpression are recognized in the deformation history.

Post-early cretaceous landform evolution along the western margin of the banca~nnia trough, western nsw

Science.gov (United States)

Gibson, D.L.

2000-01-01

Previously undated post-Devonian sediments outcropping north of Fowlers Gap station near the western margin of the Bancannia Trough are shown by plant macro- and microfossil determinations to be of Early Cretaceous (most likely Neocomian and/or Aptian) age, and thus part of the Eromanga Basin. They are assigned to the previously defined Telephone Creek Formation. Study of the structural configuration of this unit and the unconformably underlying Devonian rocks suggests that the gross landscape architecture of the area results from post-Early Cretaceous monoclinal folding along blind faults at the western margin of the trough, combined with the effects of differential erosion. This study shows that, while landscape evolution in the area has been dynamic, the major changes that have occurred are on a geological rather than human timescale.

Paleozoic stratigraphy of two areas in southwestern Indiana

International Nuclear Information System (INIS)

Droste, J.B.

1976-09-01

Two areas recommended for evaluation as solid waste disposal sites lie along the strike of Paleozoic rocks in southwestern Indiana. Thin Pennsylvanian rocks and rocks of the upper Mississippian are at the bedrock surface in maturely dissected uplands in both areas. The gross subsurface stratigraphy beneath both areas is the same, but facies and thickness variation in some of the subsurface Paleozoic units provide for some minor differences between the areas. Thick middle Mississippi carbonates grade downward into clastics of lower Mississippian (Borden Group) and upper Devonian (New Albany Shale) rocks. Middle Devonian and Silurian rocks are dominated by carbonate lithologies. Upper Ordovician (Maquoketa Group) overly carbonates of middle Ordovician age. Thick siltstone and shale of the Borden Group-New Albany Shale zone and Maquoketa Group rocks should be suitable for repository development

Geologická stavba propasti Macocha v Moravském krasu na základě strukturních a stratigrafických výzkumů

Czech Academy of Sciences Publication Activity Database

Barák, P.; Poul, I.; Geršl, M.; Hladil, Jindřich; Pukaj, M.

2011-01-01

Roč. 18, č. 2 (2011), s. 88-93 ISSN 1212-6209 Institutional research plan: CEZ:AV0Z30130516 Keywords : Moravian Karst * Macocha Abyss * Macocha Formation * Devonian * structural geology Subject RIV: DB - Geology ; Mineralogy

Caolines Program. N1 area prospective soundings

International Nuclear Information System (INIS)

Coronel, N.; Mari, C.

1984-01-01

This work is about The Caolines program. After several stages was designed a network of drilling to be developed in prospective areas. The support of this network was a geological cartography performed in a devonian region.

Training course about reserves and resources calculation

International Nuclear Information System (INIS)

Techera, J.; Arrighetti, R.; Coronel, N.; Heinzen, W.; Pena, S.; Rossi, P.; Spoturno, J.; Tabo, F.; Vaz, N.

1981-01-01

This work shows the basic information to carry out the hydrogeologic investigation about the devonian aquifers in Uruguay. As the time the information obtained will be used to drill well of water in poor p oblations

Some problematic shallow-marine structures

NARCIS (Netherlands)

Manten, A.A.

The lowermost Devonian beds in Gotland (Sweden) were deposited in a very shallow marine environment, close to the coast. In these beds three structures were observed, whose mode of formation cannot be explained by the author.

Prolonged Permian Triassic ecological crisis recorded by molluscan dominance in Late Permian offshore assemblages.

Science.gov (United States)

Clapham, Matthew E; Bottjer, David J

2007-08-07

The end-Permian mass extinction was the largest biotic crisis in the history of animal life, eliminating as many as 95% of all species and dramatically altering the ecological structure of marine communities. Although the causes of this pronounced ecosystem shift have been widely debated, the broad consensus based on inferences from global taxonomic diversity patterns suggests that the shift from abundant brachiopods to dominant molluscs was abrupt and largely driven by the catastrophic effects of the end-Permian mass extinction. Here we analyze relative abundance counts of >33,000 fossil individuals from 24 silicified Middle and Late Permian paleocommunities, documenting a substantial ecological shift to numerical dominance by molluscs in the Late Permian, before the major taxonomic shift at the end-Permian mass extinction. This ecological change was coincident with the development of fluctuating anoxic conditions in deep marine basins, suggesting that numerical dominance by more tolerant molluscs may have been driven by variably stressful environmental conditions. Recognition of substantial ecological deterioration in the Late Permian also implies that the end-Permian extinction was the climax of a protracted environmental crisis. Although the Late Permian shift to molluscan dominance was a pronounced ecological change, quantitative counts of 847 Carboniferous-Cretaceous collections from the Paleobiology Database indicate that it was only the first stage in a stepwise transition that culminated with the final shift to molluscan dominance in the Late Jurassic. Therefore, the ecological transition from brachiopods to bivalves was more protracted and complex than their simple Permian-Triassic switch in diversity.

Prolonged Permian–Triassic ecological crisis recorded by molluscan dominance in Late Permian offshore assemblages

Science.gov (United States)

Clapham, Matthew E.; Bottjer, David J.

2007-01-01

The end-Permian mass extinction was the largest biotic crisis in the history of animal life, eliminating as many as 95% of all species and dramatically altering the ecological structure of marine communities. Although the causes of this pronounced ecosystem shift have been widely debated, the broad consensus based on inferences from global taxonomic diversity patterns suggests that the shift from abundant brachiopods to dominant molluscs was abrupt and largely driven by the catastrophic effects of the end-Permian mass extinction. Here we analyze relative abundance counts of >33,000 fossil individuals from 24 silicified Middle and Late Permian paleocommunities, documenting a substantial ecological shift to numerical dominance by molluscs in the Late Permian, before the major taxonomic shift at the end-Permian mass extinction. This ecological change was coincident with the development of fluctuating anoxic conditions in deep marine basins, suggesting that numerical dominance by more tolerant molluscs may have been driven by variably stressful environmental conditions. Recognition of substantial ecological deterioration in the Late Permian also implies that the end-Permian extinction was the climax of a protracted environmental crisis. Although the Late Permian shift to molluscan dominance was a pronounced ecological change, quantitative counts of 847 Carboniferous–Cretaceous collections from the Paleobiology Database indicate that it was only the first stage in a stepwise transition that culminated with the final shift to molluscan dominance in the Late Jurassic. Therefore, the ecological transition from brachiopods to bivalves was more protracted and complex than their simple Permian–Triassic switch in diversity. PMID:17664426

Phylogeny and mitochondrial gene order variation in Lophotrochozoa in the light of new mitogenomic data from Nemertea

Directory of Open Access Journals (Sweden)

von Döhren Jörn

2009-08-01

Full Text Available Abstract Background The new animal phylogeny established several taxa which were not identified by morphological analyses, most prominently the Ecdysozoa (arthropods, roundworms, priapulids and others and Lophotrochozoa (molluscs, annelids, brachiopods and others. Lophotrochozoan interrelationships are under discussion, e.g. regarding the position of Nemertea (ribbon worms, which were discussed to be sister group to e.g. Mollusca, Brachiozoa or Platyhelminthes. Mitochondrial genomes contributed well with sequence data and gene order characters to the deep metazoan phylogeny debate. Results In this study we present the first complete mitochondrial genome record for a member of the Nemertea, Lineus viridis. Except two trnP and trnT, all genes are located on the same strand. While gene order is most similar to that of the brachiopod Terebratulina retusa, sequence based analyses of mitochondrial genes place nemerteans close to molluscs, phoronids and entoprocts without clear preference for one of these taxa as sister group. Conclusion Almost all recent analyses with large datasets show good support for a taxon comprising Annelida, Mollusca, Brachiopoda, Phoronida and Nemertea. But the relationships among these taxa vary between different studies. The analysis of gene order differences gives evidence for a multiple independent occurrence of a large inversion in the mitochondrial genome of Lophotrochozoa and a re-inversion of the same part in gastropods. We hypothesize that some regions of the genome have a higher chance for intramolecular recombination than others and gene order data have to be analysed carefully to detect convergent rearrangement events.

Hirnantian (latest Ordovician bio- and chemostratigraphy of the Stirnas-18 core, western Latvia

Directory of Open Access Journals (Sweden)

Hints, Linda

2010-03-01

Full Text Available Integrated study of the uppermost Ordovician Porkuni Stage in the Stirnas-18 core, western Latvia, has revealed one of the most complete Hirnantian successions in the eastern Baltic region. The interval is characterized by two shallowing upwards depositional sequences that correspond to the Kuldiga and Saldus formations. The whole-rock carbon stable isotope curve indicates a long rising segment of the Hirnantian carbon isotope excursion, with the highest peak in the upper part of the Kuldiga Formation. The bioclast carbon and oxygen curves fit well with the whole-rock carbon data. Micro- and macrofossil data enabled seven combined associations to be distinguished within the Hirnantian strata. The early Porkuni fauna of the Spinachitina taugourdeaui Biozone, with pre-Hirnantian affinities, is succeeded by an interval with a Hindella–Cliftonia brachiopod association, a specific polychaete fauna, the chitinozoan Conochitina scabra, and the conodont Noixodontus girardeauensis. The middle part of the Kuldiga Formation is characterized by a low-diversity Dalmanella testudinaria brachiopod association, high diversity of scolecodonts, and the occurrence of the chitinozoan Lagenochitina prussica. From the middle part of the Kuldiga Formation the youngest occurrence yet known of the conodont Amorphognathus ordovicicus is reported. Also typical of the Kuldiga Formation is the occurrence of the trilobite Mucronaspis mucronata. The uppermost Hirnantian Saldus Formation contains no shelly fauna, but yields redeposited conodonts and at least partly indigenous chitinozoans and scolecodonts. Palaeontological criteria and stable isotope data enable correlation of the Stirnas section with other Hirnantian successions in the Baltic region and elsewhere.

First record of chambered hexactinellid sponges from the Palaeozoic

Czech Academy of Sciences Publication Activity Database

Nose, M.; Vodrážka, Radek; Fernández, L.-P.; Méndez-Bedia, I.

2014-01-01

Roč. 59, č. 4 (2014), s. 985-996 ISSN 0567-7920 Institutional support: RVO:67985831 Keywords : Hexactinellida * Hexactinosida * chambered sponges * mud mounds * Devonian * Northern Spain Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.866, year: 2014

Devonian granitoids and their hosted mafic enclaves in the Gorny Altai terrane, northwestern Central Asian Orogenic Belt: crust-mantle interaction in a continental arc setting

Science.gov (United States)

Chen, Ming; Sun, Min

2016-04-01

of the Yaloman intrusive complex. Our data imply that mantle-derived melts not only provided heat to melt the pre-existing Neoproterozoic crustal materials but also served as an important component in controlling the geochemical diversity of the granitoids. The mineral assemblages and compositions suggest that the Yaloman intrusive complex was possibly crystallized from a relatively oxidizing and water-enriched magma chamber, indicative of a continental-arc related tectonic setting in stead of a collisional origin as previously proposed. Collectively, our study suggests that the widespread Devonian granitoids within the Gorny Altai terrane signify significant vertical crustal growth and differentiation via underplating of subduction-related mafic melts. Acknowledgement This study is financially supported by the Major Research Project of the Ministry of Science and Technology of China (2014CB44801 and 2014CB448000), Hong Kong Research Grant Council (HKU705311P and HKU704712P) and National Science Foundation of China (41273048).

Evidence for an extensive Phanerozoic sediment cover on the Canadian and Fenno-Scandian shields

Energy Technology Data Exchange (ETDEWEB)

Laine, E.P.; Dickson, S.M.

1985-01-01

Examination of the age and diameter of 75 terrestrial meteorite impact craters taken from platform and shield regions throughout the world suggest that both the Canadian and Fenno-Scandian Shields were covered by a sedimentary blanket during a portion of the Phanerozoic. Subsequent erosion, fostered perhaps by a combination of glacial and tectonic processes, has exposed both of these shields to reveal an anomalous distribution of craters through time. The primary evidence for sedimentary cover and subsequent erosion is in the form of a 280 Myr gap in the record of craters less than 15 km in diameter. Small craters of Cambrian, Ordovician and Silurian age are found in shield regions, suggesting either a thin or non-existent sediment cover during this period. However, there is no record of small diameter craters on either shield of Devonian, Carboniferous, Permian, Triassic, or Jurassic age (400 to 120 Myr). This 280 Myr gap suggests that the shields were protected from smaller body impacts by a sedimentary cover. In contrast, the record of impacts on platform sediments implies no such hiatus in the infall of cosmic bodies to the earth's surface between the Devonian and the Early Cretaceous. Subsequent erosion, perhaps by Early Cretaceous time, exposed the shields to further bombardment. In addition, pre-Devonian craters became exhumed. Thus, the record of impact craters suggests that the Canadian and Fenno-Scandian Shields were covered by sediments while part of Pangaea.

Tabasosphaera pustulosa nov. gen., nov. sp., a microproblematicum (foraminifer? from the Upper Triassic (Norian-Rhaetian reef limestone of Nayban Formation (NE Iran

Directory of Open Access Journals (Sweden)

Baba Senowbari-Daryan

2004-09-01

Full Text Available A microproblematicum with calcaerous test, Tabasosphaera pustulosa nov. gen., nov. sp., a hollow spherical microfossil with pustule-like elements on the outer surface, is described from Upper Triassic (Norian-Rhaetian reef limestones exposed near the town of Ali-Abad, south of Tabas (northeast Iran. Tabasosphaera is an endobiotic organism living within the cavities of other organisms, such as brachiopods, worm tubes, or in sponge spongocoels. The systematic position of Tabasosphaera, its interspecific association and the fossil assemblage of which it makes part is discussed. Most probably Tabasosphaera represents a foraminifer belonging to the group Lagenina.

Phanerozoic pO2 and the early evolution of terrestrial animals.

Science.gov (United States)

Schachat, Sandra R; Labandeira, Conrad C; Saltzman, Matthew R; Cramer, Bradley D; Payne, Jonathan L; Boyce, C Kevin

2018-01-31

Concurrent gaps in the Late Devonian/Mississippian fossil records of insects and tetrapods (i.e. Romer's Gap) have been attributed to physiological suppression by low atmospheric p O 2 Here, updated stable isotope inputs inform a reconstruction of Phanerozoic oxygen levels that contradicts the low oxygen hypothesis (and contradicts the purported role of oxygen in the evolution of gigantic insects during the late Palaeozoic), but reconciles isotope-based calculations with other proxies, like charcoal. Furthermore, statistical analysis demonstrates that the gap between the first Devonian insect and earliest diverse insect assemblages of the Pennsylvanian (Bashkirian Stage) requires no special explanation if insects were neither diverse nor abundant prior to the evolution of wings. Rather than tracking physiological constraint, the fossil record may accurately record the transformative evolutionary impact of insect flight. © 2018 The Author(s).

Biogenic hardparts: Difficult archives of the geological past (Invited)

Science.gov (United States)

Immenhauser, A.; Schone, B. R.; Hoffmann, R.; Niedermayr, A.

2013-12-01

Biomineralized exo- or endoskeletons of fossil marine invertebrates are widespread and diverse components of the Phanerozoic rock record of Earth's past and present oceans. Exoskeletons serve as protection against environmental pressure or predators, whilst endoskeletons can act as support or serve as an attachment for muscles and ligaments and hence as a mechanism for transmitting muscular forces. Biogenic hard parts represent sophisticated products resulting from the hierarchical interaction of inorganic minerals (95%) and macromolecular organic matrices, forming commonly less than 5%. The significance of many biogenic carbonate archives lies in the time-resolved growth patterns and their ability to record ambient environmental conditions in the form of multiple geochemical properties (multi-proxy archives) that have been widely used to assess past oceanic seawater properties. Here, we compile and review published work dealing with crystallization pathways of skeletal hard parts secreted by mollusks (i.e., bivalves and cephalopods) as well as brachiopods as widely used archives of ancient neritic epeiric settings. Bivalves and cephalopods (e.g., extinct ammonoids and belemnites and extant Sepia, Nautilus and Spirula) all form accretionary calcitic, aragonitic or vateritic skeletal hard parts. Despite the fact that mollusks and brachiopods form part of very different branches of the animal phylogenetic tree, their biomineralization strategies are surprisingly similar. Our main focus lies in a critical assessment of the complex pathways of ions and aquo-complexes from their source (seawater) to the final product (biomineral). We do this as an attempt to critically test the commonly held hypothesis that many fossil hard parts precipitated (under favorable conditions and pending subsequent diagenetic alteration) in equilibrium with seawater. Two main observations stand out: (1) the present knowledge on pathways and mechanisms (e.g., ion channel trans-membrane or

Rostrokonchy z devonských sedimentů moravskoslezské pánve

Czech Academy of Sciences Publication Activity Database

Weinerová, Hedvika; Weiner, Tomáš; Hladil, Jindřich

2017-01-01

Roč. 50, č. 1 (2017), s. 153-157 ISSN 0514-8057 R&D Projects: GA ČR GA14-18183S Institutional support: RVO:67985831 Keywords : Rostroconchia * Mollusca * Devonian * Moravo-Silesian Basin Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Paleontology

Carbonate rocks of the Seward Peninsula, Alaska: Their correlation and paleogeographic significance

Science.gov (United States)

Dumoulin, Julie A.; Harris, Alta; Repetski, John E.

2014-01-01

Paleozoic carbonate strata deposited in shallow platform to off-platform settings occur across the Seward Peninsula and range from unmetamorphosed Ordovician–Devonian(?) rocks of the York succession in the west to highly deformed and metamorphosed Cambrian–Devonian units of the Nome Complex in the east. Faunal and lithologic correlations indicate that early Paleozoic strata in the two areas formed as part of a single carbonate platform. The York succession makes up part of the York terrane and consists of Ordovician, lesser Silurian, and limited, possibly Devonian rocks. Shallow-water facies predominate, but subordinate graptolitic shale and calcareous turbidites accumulated in deeper water, intraplatform basin environments, chiefly during the Middle Ordovician. Lower Ordovician strata are mainly lime mudstone and peloid-intraclast grainstone deposited in a deepening upward regime; noncarbonate detritus is abundant in lower parts of the section. Upper Ordovician and Silurian rocks include carbonate mudstone, skeletal wackestone, and coral-stromatoporoid biostromes that are commonly dolomitic and accumulated in warm, shallow to very shallow settings with locally restricted circulation. The rest of the York terrane is mainly Ordovician and older, variously deformed and metamorphosed carbonate and siliciclastic rocks intruded by early Cambrian (and younger?) metagabbros. Older (Neoproterozoic–Cambrian) parts of these units are chiefly turbidites and may have been basement for the carbonate platform facies of the York succession; younger, shallow- and deep-water strata likely represent previously unrecognized parts of the York succession and its offshore equivalents. Intensely deformed and altered Mississippian carbonate strata crop out in a small area at the western edge of the terrane. Metacarbonate rocks form all or part of several units within the blueschist- and greenschist-facies Nome Complex. The Layered sequence includes mafic meta¬igneous rocks and

Formation and inversion of transtensional basins in the western part of the Lachlan Fold Belt, Australia, with emphasis on the Cobar Basin

Science.gov (United States)

Glen, R. A.

The Palaeozoic history of the western part of the Lachlan Fold Belt in New South Wales was dominated by strike-slip tectonics. In the latest Silurian to late Early Devonian, an area of crust >25,000 km 2 lying west of the Gilmore Suture underwent regional sinistral transtension, leading to the development of intracratonic successor basins, troughs and flanking shelves. The volcaniclastic deep-water Mount Hope Trough and Rast Trough, the siliciclastic Cobar Basin and the volcanic-rich Canbelego-Mineral Hill Belt of the Kopyje Shelf all were initiated around the Siluro-Devonian boundary. They all show clear evidence of having evolved by both active syn-rift processes and passive later post-rift (sag-phase) processes. Active syn-rift faulting is best documented for the Cobar Basin and Mount Hope Trough. In the former case, the synchronous activity on several fault sets suggests that the basin formed by sinistral transtension in response to a direction of maximum extension oriented NE-SW. Structures formed during inversion of the Cobar Basin and Canbelego-Mineral Hill Belt indicate closure under a dextral transpressive strain regime, with a far-field direction of maximum shortening oriented NE-SW. In the Cobar Basin, shortening was partitioned into two structural zones. A high-strain zone in the east was developed into a positive half-flower structure by re-activation of early faults and by formation of short-cut thrusts, some with strike-slip movement, above an inferred steep strike-slip fault. Intense subvertical cleavage, a steep extension lineation and variably plunging folds are also present. A lower-strain zone to the west developed by syn-depositional faults being activated as thrusts soling into a gently dipping detachment. A subvertical cleavage and steep extension lineation are locally present, and variably plunging folds are common. Whereas Siluro-Devonian basin-opening appeared to be synchronous in the western part of the fold belt, the different period of

18 CFR 270.101 - General definitions.

Science.gov (United States)

2010-04-01

..., DEPARTMENT OF ENERGY PROCEDURES GOVERNING DETERMINATIONS FOR TAX CREDIT PURPOSES DETERMINATION PROCEDURES... gas produced from coal seams means naturally occurring natural gas released from entrapment from the fractures, pores and bedding planes of coal seams. (7) Natural gas produced from Devonian shale means...

Structural analysis of superposed fault systems of the Bornholm horst block, Tornquist Zone, Denmark

DEFF Research Database (Denmark)

Graversen, Ole

2009-01-01

The Bornholm horst block is composed of Precambrian crystalline basement overlain by Palaeozoicand Mesozoic cover rocks. The cover intervals are separated by an angular unconformity and a hiatus spanning the Devonian through Middle Triassic interval. Late Palaeozoic faulting of the Early Palaeozo...

Progressive drowning of carbonate platform in the Moravo-Silesian Basin (Czech Republic) before the Frasnian/Famennian event: facies, compositional variations and gamma-ray spectrometry

Czech Academy of Sciences Publication Activity Database

Bábek, O.; Přikryl, T.; Hladil, Jindřich

2007-01-01

Roč. 53, č. 2 (2007), s. 293-316 ISSN 0172-9179 Institutional research plan: CEZ:AV0Z30130516 Keywords : Devonian carbonate platform drowning * Frasnian/Famennian extinction * carbonate platform drowning Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.989, year: 2007

Larval Myogenesis in the Articulate Brachiopod Argyrotheca cordata (Risso, 1826)

DEFF Research Database (Denmark)

Altenburger, Andreas; Wanninger, Andreas Wilhelm Georg

2008-01-01

Brachiopoda is a metazoan phylum with a fossil record dating back to the lower Cambrium and comprises over 12,000 extinct and 400 recent species. Despite some recent progress using mainly palaeontological and molecular datasets, the discussion concerning the phylogenetic position of Brachiopoda r...

Strontium isotopes test long-term zonal isolation of injected and Marcellus formation water after hydraulic fracturing.

Science.gov (United States)

Kohl, Courtney A Kolesar; Capo, Rosemary C; Stewart, Brian W; Wall, Andrew J; Schroeder, Karl T; Hammack, Richard W; Guthrie, George D

2014-08-19

One concern regarding unconventional hydrocarbon production from organic-rich shale is that hydraulic fracture stimulation could create pathways that allow injected fluids and deep brines from the target formation or adjacent units to migrate upward into shallow drinking water aquifers. This study presents Sr isotope and geochemical data from a well-constrained site in Greene County, Pennsylvania, in which samples were collected before and after hydraulic fracturing of the Middle Devonian Marcellus Shale. Results spanning a 15-month period indicated no significant migration of Marcellus-derived fluids into Upper Devonian/Lower Mississippian units located 900-1200 m above the lateral Marcellus boreholes or into groundwater sampled at a spring near the site. Monitoring the Sr isotope ratio of water from legacy oil and gas wells or drinking water wells can provide a sensitive early warning of upward brine migration for many years after well stimulation.

Three-dimensional geometry of the structural front between Berland River and Smoky River, central Alberta Foothills

Energy Technology Data Exchange (ETDEWEB)

Liu, S.; Lawton, D. C.; Spratt, D. A. [Calgary Univ., AB (Canada). Dept. of Geology and Geophysics

1996-06-01

Geometry of the triangle zone and its variations in the region lying between the Berland River and the Smoky River in the central Alberta Foothills was described by drawing closely spaced balanced structural cross-sections, constrained by seismic data interpretation and well-log analysis. The stratigraphic sequence (Devonian to Tertiary in the northwest, or Mississipian to Tertiary in the southeast) was found to have been divided into three structural packages by three detachments. In the northwest, the lower detachment lies in the Lower Devonian Woodbend Group, the middle detachment in the Shaftesbury Formation, and the upper detachment in the upper Kaskapau Formation. Each of these detachment combined with the foreland-verging thrust sheet beneath them to form the triangle zone structure. Based on the peculiarities of the geology, it is suspected that the higher triangle zone was formed before the lower triangle zone. 31 refs., 10 figs.

The largest Silurian vertebrate and its palaeoecological implications

Science.gov (United States)

Choo, Brian; Zhu, Min; Zhao, Wenjin; Jia, Liaotao; Zhu, You'an

2014-01-01

An apparent absence of Silurian fishes more than half-a-metre in length has been viewed as evidence that gnathostomes were restricted in size and diversity prior to the Devonian. Here we describe the largest pre-Devonian vertebrate (Megamastax amblyodus gen. et sp. nov.), a predatory marine osteichthyan from the Silurian Kuanti Formation (late Ludlow, ~423 million years ago) of Yunnan, China, with an estimated length of about 1 meter. The unusual dentition of the new form suggests a durophagous diet which, combined with its large size, indicates a considerable degree of trophic specialisation among early osteichthyans. The lack of large Silurian vertebrates has recently been used as constraint in palaeoatmospheric modelling, with purported lower oxygen levels imposing a physiological size limit. Regardless of the exact causal relationship between oxygen availability and evolutionary success, this finding refutes the assumption that pre-Emsian vertebrates were restricted to small body sizes. PMID:24921626

Upper Paleozoic Marine Shale Characteristics and Exploration Prospects in the Northwestern Guizhong Depression, South China

Science.gov (United States)

Zhu, Zhenhong; Yao, Genshun; Lou, Zhanghua; Jin, Aimin; Zhu, Rong; Jin, Chong; Chen, Chao

2018-05-01

Multiple sets of organic-rich shales developed in the Upper Paleozoic of the northwestern Guizhong Depression in South China. However, the exploration of these shales is presently at a relatively immature stage. The Upper Paleozoic shales in the northwestern Guizhong Depression, including the Middle Devonian Luofu shale, the Nabiao shale, and the Lower Carboniferous Yanguan shale, were investigated in this study. Mineral composition analysis, organic matter analysis (including total organic carbon (TOC) content, maceral of kerogen and the vitrinite reflection (Ro)), pore characteristic analysis (including porosity and permeability, pore type identification by SEM, and pore size distribution by nitrogen sorption), methane isothermal sorption test were conducted, and the distribution and thickness of the shales were determined, Then the characteristics of the two target shales were illustrated and compared. The results show that the Upper Paleozoic shales have favorable organic matter conditions (mainly moderate to high TOC content, type I and II1 kerogen and high to over maturity), good fracability potential (brittleness index (BI) > 40%), multiple pore types, stable distribution and effective thickness, and good methane sorption capacity. Therefore, the Upper Paleozoic shales in the northern Guizhong Depression have good shale gas potential and exploration prospects. Moreover, the average TOC content, average BI, thickness of the organic-rich shale (TOC > 2.0 wt%) and the shale gas resources of the Middle Devonian shales are better than those of the Lower Carboniferous shale. The Middle Devonian shales have better shale gas potential and exploration prospects than the Lower Carboniferous shales.

Paleozoic unconformities favorable for uranium concentration in northern Appalachian basin

International Nuclear Information System (INIS)

Dennison, J.M.

1986-01-01

Unconformities can redistribute uranium from protore rock as ground water moves through poorly consolidated strata beneath the erosion surface, or later moves along the unconformity. Groundwater could migrate farther than in present-day lithified Paleozoic strata in the Appalachian basin, now locally deformed by the Taconic and Allegheny orogenies. Several paleoaquifer systems could have developed uranium geochemical cells. Sandstone mineralogy, occurrences of fluvial strata, and reduzate facies are important factors. Other possibilities include silcrete developed during desert exposure, and uranium concentrated in paleokarst. Thirteen unconformities are evaluated to determine favorable areas for uranium concentration. Cambrian Potsdam sandstone (New York) contains arkoses and possible silcretes just above crystalline basement. Unconformities involving beveled sandstones and possible fluvial strata include Cambrian Hardyston sandstone (New Jersey), Cambrian Potsdam Sandstone (New York), Ordovician Oswego and Juniata formations (Pennsylvania and New York), Silurian Medina Group (New York), and Silurian Vernon, High Falls, and Longwood formations (New York and New Jersey). Devonian Catskill Formation is beveled by Pennsylvanian strata (New York and Pennsylvania). The pre-Pennsylvanian unconformity also bevels Lower Mississippian Pocono, Knapp, and Waverly strata (Pennsylvania, New York, and Ohio), truncates Upper Mississippian Mauch Chunk Formation (Pennsylvania), and forms paleokarst on Mississippian Loyalhanna Limestone (Pennsylvania) and Maxville Limestone (Ohio). Strata associated with these unconformities contain several reports of uranium. Unconformities unfavorable for uranium concentration occur beneath the Middle Ordovician (New York), Middle Devonian (Ohio and New York), and Upper Devonian (Ohio and New York); these involve marine strata overlying marine strata and probably much submarine erosion

Unique growth strategy in the Earth's first trees revealed in silicified fossil trunks from China.

Science.gov (United States)

Xu, Hong-He; Berry, Christopher M; Stein, William E; Wang, Yi; Tang, Peng; Fu, Qiang

2017-11-07

Cladoxylopsida included the earliest large trees that formed critical components of globally transformative pioneering forest ecosystems in the Mid- and early Late Devonian (ca. 393-372 Ma). Well-known cladoxylopsid fossils include the up to ∼1-m-diameter sandstone casts known as Eospermatopteris from Middle Devonian strata of New York State. Cladoxylopsid trunk structure comprised a more-or-less distinct cylinder of numerous separate cauline xylem strands connected internally with a network of medullary xylem strands and, near the base, externally with downward-growing roots, all embedded within parenchyma. However, the means by which this complex vascular system was able to grow to a large diameter is unknown. We demonstrate-based on exceptional, up to ∼70-cm-diameter silicified fossil trunks with extensive preservation of cellular anatomy from the early Late Devonian (Frasnian, ca. 374 Ma) of Xinjiang, China-that trunk expansion is associated with a cylindrical zone of diffuse secondary growth within ground and cortical parenchyma and with production of a large amount of wood containing both rays and growth increments concentrically around individual xylem strands by normal cambia. The xylem system accommodates expansion by tearing of individual strand interconnections during secondary development. This mode of growth seems indeterminate, capable of producing trees of large size and, despite some unique features, invites comparison with secondary development in some living monocots. Understanding the structure and growth of cladoxylopsids informs analysis of canopy competition within early forests with the potential to drive global processes. Published under the PNAS license.

Cretacic tectonics in Uruguay

International Nuclear Information System (INIS)

Gomez Rifas, C.

2012-01-01

This work is about Cretacic tectonics in Uruguay, this formation is characterized by high level cortex because the basament is cratonized since Middle Devonian. There were formed two main grabens such as Santa Lucia and Mirim-Pelotas which are filled with basalt and sediments.

Geological analysis of paleozoic large-scale faulting in the south-central Pyrenees

NARCIS (Netherlands)

Speksnijder, A.

1986-01-01

Detailed structural and sedimentological analysis reveals the existence of an east-west directed fundamental fault zone in the south-central Pyrenees, which has been intermittently active from (at least) the Devonian on. Emphasis is laid on the stUdy of fault-bounded post-Variscan

Style and timing of salt tectonics in the Dniepr-Donets Basin (Ukraine): implications for triggering and driving mechanisms of salt movement in sedimentary basins.

NARCIS (Netherlands)

Stovba, S.M.; Stephenson, R.A.

2003-01-01

The Ukrainian Dniepr-Donets Basin (DDB) is a Late Palaeozoic intracratonic rift basin, with sedimentary thicknesses up to 19 km, displaying the effects of salt tectonics during its entire history of formation, from Late Devonian rifting to the Tertiary. Hundreds of concordant and discordant salt

Limits in the evolution of biological form: a theoretical morphologic perspective.

Science.gov (United States)

McGhee, George R

2015-12-06

Limits in the evolution of biological form can be empirically demonstrated by using theoretical morphospace analyses, and actual analytic examples are given for univalved ammonoid shell form, bivalved brachiopod shell form and helical bryozoan colony form. Limits in the evolution of form in these animal groups can be shown to be due to functional and developmental constraints on possible evolutionary trajectories in morphospace. Future evolutionary-limit research is needed to analyse the possible existence of temporal constraint in the evolution of biological form on Earth, and in the search for the possible existence of functional alien life forms on Titan and Triton that are developmentally impossible for Earth life.

Geological analysis of paleozoic large-scale faulting in the south-central Pyrenees

NARCIS (Netherlands)

Speksnijder, A.

1986-01-01

Detailed structural and sedimentological analysis reveals the existence of an east-west directed fundamental fault zone in the south-central Pyrenees, which has been intermittently active from (at least) the Devonian on. Emphasis is laid on the stUdy of fault-bounded post-Variscan (StephanoPermian)

New Famennian colonial coral (Rugosa) from the Holy Cross Mountains (Poland): an example of local evolution after Frasnian-Famennian extinction

Science.gov (United States)

Berkowski, Błażej; Zapalski, Mikołaj K.; Wrzołek, Tomasz

2016-04-01

Colonial rugose corals are extremely rare in the fossil record after the Late Devonian (Frasnian-Famennian) extinction event. Here, we report a new genus and species, Famastraea catenata, from the late Famennian of the western part of the Holy Cross Mountains (Kowala) in Poland. Although this taxon is colonial, it displays many morphological characters very close to the typically late Famennian solitary species Palaeosmilia aquisgranensis (Frech, 1885), described earlier from the same locality. Hence, we postulate that F. catenata is derived from P. aquisgranensis. In contrast to other Famennian colonial rugose corals, the new taxon represents an example of local evolution within the group of so-called `Strunian' corals. Consequently, we postulate that the new taxon represents a new colonial rugose fauna, which, however, did not survive the subsequent Late Devonian crisis (i.e. Hangenberg event). F. catenata most probably inhabited deeper water settings, possibly near the boundary between the euphotic and dysphotic zones, as inferred from many other benthic taxa described from this locality.

Comparison of Magnetic and Moessbauer Results Obtained for Palaeozoic Rocks of Hornsund, Southern Spitsbergen, Arctic

International Nuclear Information System (INIS)

Szlachta, K.; Galazka-Friedman, J.; Michalski, K.; Brzozka, K.; Gorka, B.

2008-01-01

This analysis was performed as a part of the palaeomagnetic project focused on the reconstruction of the palaeogeographic position of the Svalbard Archipelago and adjacent crustal units (European Arctic) in the Palaeozoic and Mesozoic. Three rock formations | Cambrian, Devonian and Carboniferous were sampled in the area of Hornsund, southern Spitsbergen. The main aim of the presented study is to identify ferromagnetic minerals (sensu lato) - the carriers of the natural remanent magnetisation in the investigated rocks. A wide range of magnetic methods were used: the Lowrie tests, unblocking temperatures determinations and the measurement of coercivity spectra as well as the Moessbauer studies. In Devonian and Carboniferous samples all applied methods indicate the domination of the hematite natural remanent magnetisation carrier. In Cambrian rocks magnetic measurements reveal a mixture of ferromagnetic (sensu lato) minerals with varying coercivities and unblocking temperatures. The Moessbauer data improve the identification, suggesting that in Cambrian rocks the carrier of the dominating natural remanent magnetisation component is maghemite. (authors)

Factors controlling Li concentration and isotopic composition in formation waters and host rocks of Marcellus Shale, Appalachian Basin

Science.gov (United States)

Phan, Thai T.; Capo, Rosemary C; Stewart, Brian W.; Macpherson, Gwen; Rowan, Elisabeth L.; Hammack, Richard W.

2015-01-01

In this study, water and whole rock samples from hydraulically fractured wells in the Marcellus Shale (Middle Devonian), and water from conventional wells producing from Upper Devonian sandstones were analyzed for lithium concentrations and isotope ratios (δ7Li). The distribution of lithium concentrations in different mineral groups was determined using sequential extraction. Structurally bound Li, predominantly in clays, accounted for 75-91 wt. % of total Li, whereas exchangeable sites and carbonate cement contain negligible Li (shale in Greene Co., Pennsylvania, and Tioga Co., New York, ranged from -2.3 to + 4.3‰, similar to values reported for other shales in the literature. The δ7Li values in shale rocks with stratigraphic depth record progressive weathering of the source region; the most weathered and clay-rich strata with isotopically light Li are found closest to the top of the stratigraphic section. Diagenetic illite-smectite transition could also have partially affected the bulk Li content and isotope ratios of the Marcellus Shale.

Feeding biomechanics in Acanthostega and across the fish-tetrapod transition.

Science.gov (United States)

Neenan, James M; Ruta, Marcello; Clack, Jennifer A; Rayfield, Emily J

2014-04-22

Acanthostega is one of the earliest and most primitive limbed vertebrates. Its numerous fish-like features indicate a primarily aquatic lifestyle, yet cranial suture morphology suggests that its skull is more similar to those of terrestrial taxa. Here, we apply geometric morphometrics and two-dimensional finite-element analysis to the lower jaws of Acanthostega and 22 other tetrapodomorph taxa in order to quantify morphological and functional changes across the fish-tetrapod transition. The jaw of Acanthostega is similar to that of certain tetrapodomorph fish and transitional Devonian taxa both morphologically (as indicated by its proximity to those taxa in morphospace) and functionally (as indicated by the distribution of stress values and relative magnitude of bite force). Our results suggest a slow tempo of morphological and biomechanical changes in the transition from Devonian tetrapod jaws to aquatic/semi-aquatic Carboniferous tetrapod jaws. We conclude that Acanthostega retained a primitively aquatic lifestyle and did not possess cranial adaptations for terrestrial feeding.

Feeding biomechanics in Acanthostega and across the fish–tetrapod transition

Science.gov (United States)

Neenan, James M.; Ruta, Marcello; Clack, Jennifer A.; Rayfield, Emily J.

2014-01-01

Acanthostega is one of the earliest and most primitive limbed vertebrates. Its numerous fish-like features indicate a primarily aquatic lifestyle, yet cranial suture morphology suggests that its skull is more similar to those of terrestrial taxa. Here, we apply geometric morphometrics and two-dimensional finite-element analysis to the lower jaws of Acanthostega and 22 other tetrapodomorph taxa in order to quantify morphological and functional changes across the fish–tetrapod transition. The jaw of Acanthostega is similar to that of certain tetrapodomorph fish and transitional Devonian taxa both morphologically (as indicated by its proximity to those taxa in morphospace) and functionally (as indicated by the distribution of stress values and relative magnitude of bite force). Our results suggest a slow tempo of morphological and biomechanical changes in the transition from Devonian tetrapod jaws to aquatic/semi-aquatic Carboniferous tetrapod jaws. We conclude that Acanthostega retained a primitively aquatic lifestyle and did not possess cranial adaptations for terrestrial feeding. PMID:24573844

A study of secondary fabrics in rocks from the lizard Peninsula and adjacent areas in southwest cornwall, england

Science.gov (United States)

Rathore, Jaswant Singh

1980-09-01

Magnetic susceptibility anisotropy techniques were applied to samples taken in selected areas of the Lizard Peninsula in order to study secondary fabrics due to: (1) the intrusion of granites into sediments; (2) the compression in the sediments to the north of the Lizard thrust boundary; and (3) the intrusion of serpentine into hornblende schists of the Lizard metamorphic block. The magnetic fabric around the Carnmenellis and Godolphin granite masses shows a strong compressional fabric, tending to suggest that the Devonian sediments were compressed radially as the granites intruded them. The high degree of anisotropy observed at the Lizard boundary falls, with increasing distance from the thrust, systematically down to low values in the Devonian sediments. The distinct changes in the fabric parameters at the north end of Church Cove-Landewednack and the southern end of Cadgwith Cove appear to be the remnant secondary fabrics due to the intrusion of serpentine into hornblende schists.

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

In Late Devonian and Early-to-Late Triassic times, the southern continental margin of the Eastern European Platform was the site of a basaltic volcanism in the Donbas and Fore-Caucasus areas respectively. Both volcanic piles rest unconformably upon Paleoproterozoic and Late Paleozoic units respectively, and emplaced ...

The influence of hurricanes upon the quiet depositional conditions in the Lower Emsian La Vid shales of Colle (NW Spain)

NARCIS (Netherlands)

Stel, Jan H.

1976-01-01

The author supposes that the fossil content of thin carbonate units in the Upper La Vid shales (Lower Devonian) of Colle was influenced by heavy storms like hurricanes. Apart from microplankton (Cramer, 1964) no fossils are found in the shales. Together with the very well developed fissility of the

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Simulation of the Tornado Event of 22 March, 2013 over Brahmanbaria, Bangladesh using WRF Model with 3DVar DA techniques ..... Graphical user interface (GUI) software has been developed using MATLAB 7.5 to generalize ... Evolution process of the Late Silurian–Late Devonian tectonic environment in Qimantagh in ...

Evaporite karst of northern lower Michigan

Science.gov (United States)

Black, T.J.

1997-01-01

Michigan has three main zones of evaporite karst: collapse breccia in Late Silurian deposits of the Mackinac Straits region; breccia, collapse sinks, and mega-block collapse in Middle Devonian deposits of Northern Lower Michigan, which overlaps the preceding area; and areas of soil swallows in sinks of Mississippian deposits between Turner and Alabaster in Arenac and Iosco counties, and near Grand Rapids in Kent County. The author has focused his study on evaporite karst of the Middle Devonian deposits. The Middle Devonian depos its are the Detroit River Group: a series consisting of limestone, dolomite, shale, salt, gypsum, and anhydrite. The group occurs from subcrop, near the surface, to nearly 1400 feet deep from the northern tip of the Southern Peninsula to the south edge of the "solution front" Glacial drift is from zero to 350 feet thick. Oil and gas exploration has encountered some significant lost-circulation zones throughout the area. Drilling without fluid returns, casing-seal failures, and lost holes are strong risks in some parts of the region. Lost fluid returns near the top of the group in nearby areas indicate some karst development shortly after deposition. Large and irregular lost-circulation zones, linear and patch trends of large sink holes, and 0.25 mile wide blocks of down-dropped land in the northern Lower Peninsula of Michigan were caused by surface- and ground-water movement along faults into the Detroit River Group. Glaciation has removed some evidence of the karst area at the surface. Sinkhole development, collapse valleys, and swallows developed since retreat of the glacier reveal an active solution front in the Detroit River Group.

PETRO- AND PALEOMAGNETIC STUDIES OF BASALTS OF THE UPPER DEVONIAN APPAINSKAYA SUITE (WESTERN YAKUTIA

Directory of Open Access Journals (Sweden)

К. M. Konstantinov

2016-01-01

Full Text Available Introduction. One of the main tasks of paleomagnetic studies is to obtain a framework of reference poles for calculating the kinematic characteristics of lithospheric taxones as a basis for geodynamic reconstructions. Each paleomagnetic reference point must have a precise (±10 Ma geochronological dating and a maximum paleomagnetic reliability index. A correct paleomagnetic pole (PMP can be obtained from the data of geochronological and paleomagnetic studies conducted in one and the same geological object, such as a suite, an intrusive complex etc. In the Yakutian diamondiferous province (YDP, such objects include basalt nappes of the Upper Devonian Appainskaya suite, which stratigraphic position is undoubted (Fran, 385–375 Ma.Geological setting (in brief. In the eastern segments of the Siberian platform, a powerful cycle of tectonic and magmatic activity in the Middle Paleozoic produced transgressive and sheet intrusions, volcanic pipes, lava and tuff formations comprised of basites, as well as all the currently known industrial diamondiferous kimberlite bodies. Magmatic activity of basites was associated with formation of paleorift systems, including the largest one, Viluyi paleorift (Fig. 1. In the Middle Paleozoic, the geodynamic setting for magmatism and rifting was determined by the plume-lithosphere interaction. The rise of the plume’s matter underneath the thinned lithosphere was accompanied by decompression melting and formation of basaltic magmas in large volumes.We have studied basalts of the Appainskaya suite which were sampled from the Ygyatta and Markha river valleys (Fig. 2. In the coastal outcrops at the Ygyatta river, two nappes are observed, a (stratigraphically lower outcrop 17÷23/10 containing plagiophyre palagonite basalts (upper five meters are outcropped, and an upper outcrop 16/10 containing olivinophyric palagonite basalts (upper three meters are outcropped. In the coastal outcrops of the Markha river, from the

Origin and geochemistry of saline spring waters in the Athabasca oil sands region, Alberta, Canada

International Nuclear Information System (INIS)

Gue, Anita E.; Mayer, Bernhard; Grasby, Stephen E.

2015-01-01

Highlights: • Saline groundwater enters the Athabasca and Clearwater rivers in the AOSR via springs. • High TDS is due to subsurface dissolution of Devonian evaporites and carbonates. • Low δ 18 O values, and 3 H and 14 C data suggest some Laurentide glacial meltwater input. • Bacterial sulfate reduction, methanogenesis, and CH 4 oxidation were identified. • Metal and PAH contents are reported; bitumen does not appear to be major influence. - Abstract: The geochemistry of saline spring waters in the Athabasca oil sands region (AOSR) in Alberta (Canada) discharging from Devonian carbonate rocks into the Athabasca and Clearwater rivers was characterized for major ions, trace elements, dissolved gases, and polycyclic aromatic hydrocarbons (PAHs). In addition, stable isotope analyses of H 2 O, SO 4 , dissolved inorganic carbon (DIC), Sr, and CH 4 were used to trace the sources of spring waters and their dissolved solutes, and to identify subsurface processes affecting water chemistry. The spring waters had δ 18 O values as low as −23.5‰, suggesting they are composed of up to 75% Laurentide glacial meltwater. Tritium and radiocarbon age-dating results, analyzed for three spring waters, supported a glacial origin. The high salinity of the spring waters (TDS 7210–51,800 mg/L) was due to dissolution of Devonian evaporite and carbonate deposits in the subsurface. Spring waters were affected by bacterial (dissimilatory) sulfate reduction, methanogenesis, and methane oxidation. Trace elements were present in spring waters at varying concentrations, with only one spring containing several predominant oil sands metals (As, Fe, Mo, Ni, Se, Zn) suggesting bitumen as a source. Five springs contained elements (Al, As, B, Fe, Se) at concentrations exceeding water quality guidelines for the protection of aquatic life. Seven PAHs were detected in spring waters (total PAH concentrations ranged from 7.3 to 273.6 ng/L), but most springs contained a maximum of two PAHs

A Field-Based Biomimicry Exercise Helps Students Discover Connections among Biodiversity, Form and Function, and Species Conservation during Earth's Sixth Extinction

Science.gov (United States)

Soja, Constance M.

2014-01-01

In a first-year seminar on mass extinctions, a field-based, paleontology-focused exercise promotes active learning about Earth's biodiversity, form and function, and the biomimicry potential of ancient and modern life. Students study Devonian fossils at a local quarry and gain foundational experience in describing anatomy and relating form to…

The tectonic and stratigraphic history of the Cardaño area, Cantabrian mountains, Northwest Spain

NARCIS (Netherlands)

Veen, van J.

1965-01-01

The Devonian and Carboniferous rock-sequence in the Cantabrian Mountains is developed in two different facies which are separated by an E-W tectonic line, the León Line, and called the Leonide and Palentian facies, respectively to the S and N. The Leonide facies is widely exposed throughout the

Nineteenth-century collapse of a benthic marine ecosystem on the open continental shelf.

Science.gov (United States)

Tomašových, Adam; Kidwell, Susan M

2017-06-14

The soft-sediment seafloor of the open continental shelf is among the least-known biomes on Earth, despite its high diversity and importance to fisheries and biogeochemical cycling. Abundant dead shells of epifaunal suspension-feeding terebratulid brachiopods ( Laqueus ) and scallops on the now-muddy mainland continental shelf of southern California reveal the recent, previously unsuspected extirpation of an extensive offshore shell-gravel ecosystem, evidently driven by anthropogenic siltation. Living populations of attached epifauna, which formerly existed in a middle- and outer-shelf mosaic with patches of trophically diverse muds, are restricted today to rocky seafloor along the shelf edge and to the sandier shelves of offshore islands. Geological age-dating of 190 dead brachiopod shells shows that (i) no shells have been produced on the mainland shelf within the last 100 years, (ii) their shell production declined steeply during the nineteenth century, and (iii) they had formerly been present continuously for at least 4 kyr. This loss, sufficiently rapid (less than or equal to 100 years) and thorough to represent an ecosystem collapse, coincides with intensification of alluvial-plain land use in the nineteenth century, particularly livestock grazing. Extirpation was complete by the start of twentieth-century urbanization, warming, bottom fishing and scientific surveys. The loss of this filter-feeding fauna and the new spatial homogeneity and dominance of deposit- and detritus-feeders would have altered ecosystem functioning by reducing habitat heterogeneity and seawater filtering. This discovery, attesting to the power of this geological approach to recent ecological transitions, also strongly increases the spatial scope attributable to the negative effects of siltation, and suggests that it has been under-recognized on continental shelves elsewhere as a legacy of coastal land use. © 2017 The Author(s).

Aspectos gerais sobre a alimentação do cangulo, Balistes vetula Linnaeus, 1758 (Pisces - Balistidae no estado de Pernambuco - Brasil

Directory of Open Access Journals (Sweden)

Técio Luiz Macêdo Costa

1987-01-01

Full Text Available The Balistidae, especially Balistes vetula are commom fishes in tropical waters from Northeastern Brazil. Studies about these fishes captured at the coastal area of Recife between Pina; Boa Viagem, Piedade and Candeias beaches were carried out in order to determine the diet, and to verify a possible diet diversification between the sexes, and times of the year. Males and females had a food diet consisting mostly of molluscs belonging the classes Scaphopoda, Bivalvia, Gastropoda and crustaceans and fishes. Echinoderms, foraminifera, bryozoa, sponges, polychaete worms, coelenterates and brachiopods were also observed in smaller proportions. Both males and females had a carnivorous benthic diet. Growth and changes in the seasons were not reflected by changes in the diet.

What fossils can tell us about the evolution of viviparity and placentation

DEFF Research Database (Denmark)

Carter, A M

2008-01-01

Recently a fossil of one of the earliest jawed fishes was found with a fetal skeleton and the remains of a cord. It was from the Devonian period and takes the history of vertebrate placentation back to 380 million years ago. This and later fossil evidence for viviparity in marine reptiles and early...

Bedrock geologic map of the Miles Pond and Concord quadrangles, Essex and Caledonia Counties, Vermont, and Grafton County, New Hampshire

Science.gov (United States)

Rankin, Douglas W.

2018-04-20

The bedrock geologic map of the Miles Pond and Concord quadrangles covers an area of approximately 107 square miles (276 square kilometers) in east-central Vermont and adjacent New Hampshire, north of and along the Connecticut River. This map was created as part of a larger effort to produce a new bedrock geologic map of Vermont through the collection of field data at a scale of 1:24,000. The majority of the map area consists of the Bronson Hill anticlinorium, a post-Early Devonian structure that is cored by metamorphosed Cambrian to Silurian sedimentary, volcanic, and plutonic rocks. A major feature on the map is the Monroe fault, interpreted to be a west-directed, steeply dipping Late Devonian (Acadian) thrust fault. To the west of the Monroe fault, rocks of the Connecticut Valley-Gaspé trough dominate and consist primarily of metamorphosed Silurian and Devonian sedimentary rocks. To the north, the Victory pluton intrudes the Bronson Hill anticlinorium. The Bronson Hill anticlinorium consists of the metamorphosed Albee Formation, the Ammonoosuc Volcanics, the Comerford Intrusive Complex, the Highlandcroft Granodiorite, and the Joselin Turn tonalite. The Albee Formation is an interlayered, feldspathic metasandstone and pelite that is locally sulfidic. Much of the deformed metasandstone is tectonically pinstriped. In places, one can see compositional layering that was transposed by a steeply southeast-dipping foliation. The Ammonoosuc Volcanics are lithologically complex and predominantly include interlayered and interfingered rhyolitic to basaltic volcanic and volcaniclastic rocks, as well as lesser amounts of siltstone, phyllite, graywacke, and grit. The Comerford Intrusive Complex crops out east of the Monroe fault and consists of metamorphosed gabbro, diorite, tonalite, aplitic tonalite, and crosscutting diabase dikes. Abundant mafic dikes from the Comerford Intrusive Complex intruded the Albee Formation and Ammonoosuc Volcanics east of the Monroe fault. The

Linking the southern West Junggar terrane to the Yili Block: Insights from the oldest accretionary complexes in West Junggar, NW China

Science.gov (United States)

Ren, Rong; Han, Bao-Fu; Guan, Shu-Wei; Liu, Bo; Wang, Zeng-Zhen

2018-06-01

West Junggar is known to tectonically correlate with East Kazakhstan; however, the tectonic link of the southern West Junggar terrane to adjacent regions still remains uncertain. Here, we examined the oldest accretionary complexes, thus constraining its tectonic evolution and link during the Early-Middle Paleozoic. They have contrasting lithologic, geochemical, and geochronological features and thus, provenances and tectonic settings. The Laba Unit was derived from the Late Ordovician-Early Devonian continental arc system (peaking at 450-420 Ma) with Precambrian substrate, which formed as early as the Early Devonian and metamorphosed during the Permian; however, the Kekeshayi Unit was accumulated in an intra-oceanic arc setting, and includes the pre-Late Silurian and Late Silurian subunits with or without Precambrian sources. Integrated with the regional data, the southern West Junggar terrane revealed a tectonic link to the northern Yili Block during the Late Silurian to Early Devonian, as suggested by the comparable Precambrian zircon age spectra between the southern West Junggar terrane and the micro-continents in the southern Kazakhstan Orocline, the proximal accumulation of the Laba Unit in the continental arc atop the Yili Block, and the sudden appearance of Precambrian zircons in the Kekeshayi Unit during the Late Silurian. This link rejects the proposals of the southern West Junggar terrane as an extension of the northern Kazakhstan Orocline and the Middle Paleozoic amalgamation of West Junggar. A new linking model is thus proposed, in which the southern West Junggar terrane first evolved individually, and then collided with the Yili Block to constitute the Kazakhstan continent during the Late Silurian. The independent and contrasting intra-oceanic and continental arcs also support the Paleozoic archipelago-type evolution of the Central Asian Orogenic Belt.

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Earth System Science; Volume 116; Issue 6. Volume 116, Issue 6. December 2007, pages 465-597. pp 465-467. Editorial · T N Narasimhan · More Details Fulltext PDF. pp 469-495. Late Devonian and Triassic basalts from the southern continental margin of the East European Platform, tracers of ...

Geophysical records of dispersed weathering products on the Frasnian carbonate platform and early Famennian ramps in Moravia, Czech Republic: proxies for eustasy and palaeoclimate

Czech Academy of Sciences Publication Activity Database

Hladil, Jindřich

2002-01-01

Roč. 181, 1-3 (2002), s. 213-250 ISSN 0031-0182 R&D Projects: GA AV ČR IAA3013209; GA AV ČR IAA3013809 Institutional research plan: CEZ:AV0Z3013912 Keywords : gamma-ray spectrometry * magnetic susceptibility * Devonian carbonate platforms Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.497, year: 2002

The human centrifuge

NARCIS (Netherlands)

van Loon, J.J.W.A.

2009-01-01

Life on Earth has developed at unit gravity, 9.81 m/s2, which was a major factor especially when vertebrates emerged from water onto land in the late Devonian, some 375 million years ago. But how would nature have evolved on a larger planet? We are able to address this question simply in experiments

Subdivision of the Lochkovian Stage based on conodont faunas from the stratotype area (Prague Synform, Czech Republic)

Czech Academy of Sciences Publication Activity Database

Slavík, Ladislav; Carls, P.; Hladil, Jindřich; Koptíková, Leona

2012-01-01

Roč. 47, č. 6 (2012), s. 616-631 ISSN 0072-1050 R&D Projects: GA ČR GA205/09/0703 Institutional research plan: CEZ:AV0Z30130516 Keywords : Lochkovian subdivision * conodont biostratigraphy * Lower Devonian * stratigraphic correlation * Barrandian area * conodont zonation Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.659, year: 2012

Quantitative allochem compositional analysis of Lochkovian-Pragian boundary sections in the Prague Basin (Czech Republic)

Czech Academy of Sciences Publication Activity Database

Weinerová, Hedvika; Hron, K.; Bábek, O.; Šimíček, D.; Hladil, Jindřich

2017-01-01

Roč. 354, JUN 1 (2017), s. 43-59 ISSN 0037-0738 R&D Projects: GA ČR GA14-18183S Institutional support: RVO:67985831 Keywords : compositional analysis * carbonate petrography * multivariate statistics * log-ratio coordinates * Prague Basin * Lower Devonian Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 2.373, year: 2016

Density characteristics in the upper part of the platform of the Pripyatskiy Basin

Energy Technology Data Exchange (ETDEWEB)

Bulyga, V.K.; Anpilogov, A.P.; Ksenofontov, V.A.; Ur' yev, I.I.

1981-01-01

Density characteristics are examined for the Devonian (upper saline and suprasaline), Carboniferous, Permian, Mesozoic and Cenozoic deposits of the Pripyatskiy Basin. Maps are compiled for isodensities, variability is established in the average values of density both in a regional sense and on local elevations which are characterized for the most part by density minimums.

The Fossil Fauna of the Islands Region of Western Lake Erie.

Science.gov (United States)

Bowe, Lulu M., Comp.

The islands of western Lake Erie are rock-bound isles that abound in rocky outcrops and quarries. The rocks of these islands are of two distinct types, Silurian dolomites and Devonian limestones. The dolomites, exposed in the Bass Islands and Sister Islands are virtually devoid of fossils. Conversely, the limestones of Johnson Island, Marblehead,…

Siberia, the wandering northern terrane, and its changing geography through the Palaeozoic

Science.gov (United States)

Cocks, L. Robin M.; Torsvik, Trond H.

2007-05-01

The old terrane of Siberia occupied a very substantial area in the centre of today's political Siberia and also adjacent areas of Mongolia, eastern Kazakhstan, and northwestern China. Siberia's location within the Early Neoproterozoic Rodinia Superterrane is contentious (since few if any reliable palaeomagnetic data exist between about 1.0 Ga and 540 Ma), but Siberia probably became independent during the breakup of Rodinia soon after 800 Ma and continued to be so until very near the end of the Palaeozoic, when it became an integral part of the Pangea Supercontinent. The boundaries of the cratonic core of the Siberian Terrane (including the Patom area) are briefly described, together with summaries of some of the geologically complex surrounding areas, and it is concluded that all of the Palaeozoic underlying the West Siberian Basin (including the Ob-Saisan Surgut area), Tomsk Terrane, Altai-Sayan Terranes (including Salair, Kuznetsk Alatau, Batenov, Kobdin and West Sayan), Ertix Terrane, Barguzin Terrane, Tuva-Mongol Terrane, Central Mongolia Terrane Assemblage, Gobi Altai and Mandalovoo Terranes, Okhotsk Terrane and much of the Verkhoyansk-Kolyma region all formed parts of peri-Siberia, and thus rotated with the main Siberian Craton as those areas were progressively accreted to the main Siberian Terrane at various times during the latest Neoproterozoic and Palaeozoic. The Ertix Terrane is a new term combining what has been termed the "Altay Terrane" or "NE Xinjiang" area of China, and the Baytag, Baaran and Bidz terranes of Mongolia. The Silurian Tuvaella brachiopod fauna is restricted only to today's southern parts of peri-Siberia. Thus, allowing for subsequent rotation, the fauna occurs only in the N of the Siberian Terrane, and, as well as being a helpful indicator of what marginal terranes made up peri-Siberia, is distinctive as being the only Silurian fauna known from northern higher latitudes globally. In contrast, the other terranes adjacent to peri

REE geochemistry and genesis of Daxin uranium deposit

International Nuclear Information System (INIS)

Li Zhixing; Qi Fucheng; He Zhongbo; Zhang Zilong

2011-01-01

Through the analysis on typical REE parameters,chondrite-normalized REE patterns and hierarchical cluster analysis of rocks in the structural-geochemical zonation in Daxin uranium deposit, the paper discusses the uranium source and genesis. The study shows that the uranium source mainly came from Cambrian System. The Devonian System is maily as the favorable room for saving ores in addition to pre-concentrated room for uranium. Underground water resulted from early and late Yanshanian movement and the heating of volcanic rock was turned into geothermal water and it was moved upward by the force of tectonic movement. The geothermal water mainly extracted active uranium from the Cambrian rocks, then moved upward along main regional fault (F2) connecting the Cambrian rocks and the Devonian rocks until it arrived in structural fracture zone which was controlled by secondary faults (F13, F23, F33). At last, the uranium element in geothermal water was precipitated and concentrated into the uranium deposit in reducing environment of enriched organic material and pyrite. (authors)

Bedrock Geologic Map of the Old Lyme Quadrangle, New London and Middlesex Counties, Connecticut

Science.gov (United States)

Walsh, Gregory J.; Scott, Robert B.; Aleinikoff, John N.; Armstrong, Thomas R.

2009-01-01

The bedrock geology of the Old Lyme quadrangle consists of Neoproterozoic and Permian gneisses and granites of the Gander and Avalon terranes, Silurian metasedimentary rocks of the Merrimack terrane, and Silurian to Devonian metasedimentary rocks of uncertain origin. The Avalon terrane rocks crop out within the Selden Neck block, and the Gander terrane rocks crop out within the Lyme dome. The Silurian to Devonian rocks crop out between these two massifs. Previous mapping in the Old Lyme quadrangle includes the work by Lawrence Lundgren, Jr. Lundgren's work provides an excellent resource for rock descriptions and detailed modal analyses of rock units that will not be duplicated in this current report. New research that was not covered in detail by Lundgren is the focus of this report and includes (1) evaluation of the rocks in the core of the Lyme dome in an effort to subdivide units in this area; (2) structural analysis of foliations and folds in and around the Lyme dome; (3) geochronology of selected units within the Lyme dome; and (4) analysis of joints and the fracture properties of the rocks.

Seven 365-Million-Year-Old Trilobites Moulting within a Nautiloid Conch

Science.gov (United States)

Zong, Rui-Wen; Fan, Ruo-Ying; Gong, Yi-Ming

2016-10-01

A nautiloid conch containing many disarticulated exoskeletons of Omegops cornelius (Phacopidae, Trilobita) was found in the Upper Devonian Hongguleleng Formation of the northwestern margin of the Junggar Basin, NW China. The similar number of cephala, thoraces and pygidia, unbroken thoraces, explicit exuviae, and lack of other macrofossils in the conch, indicate that at least seven individual trilobites had moulted within the nautiloid living chamber, using the vacant chamber of a dead nautiloid as a communal place for ecdysis. This exuvial strategy manifests cryptic behaviour of trilobites, which may have resulted from the adaptive evolution induced by powerful predation pressure, unstable marine environments, and competition pressure of organisms occupying the same ecological niche in the Devonian period. The unusual presence of several trilobites moulting within a nautiloid conch is possibly associated with social behaviours in face of a serious crisis. New materials in this study open a window for understanding the survival strategy of marine benthic organisms, especially predator-prey interactions and the behavioural ecology of trilobites in the middle Palaeozoic.

Speculative petroleum systems of the Punta del Este Basin (offshore Uruguay

Directory of Open Access Journals (Sweden)

Ethel Morales

Full Text Available ABSTRACT: The Uruguayan continental margin was generated as the result of the breakup of Gondwana and, later, the opening of the South Atlantic Ocean, which began in the Jurassic. Three major areas of Meso-Cenozoic sedimentation are located in the Uruguayan offshore: the Punta del Este Basin, the southernmost sector of the Pelotas Basin and the Oriental del Plata Basin. These basins share the classical stages of tectono-sedimentary evolution of the other Atlantic basins, including the prerift (Paleozoic, rift (Jurassic-Early Cretaceous, transition (Barremian-Aptian and postrift (Aptian-present phases. Based on the analysis of basin evolution through seismic sections and well data as well as on the establishment of analogies with productive Atlantic basins, four speculative petroleum systems are proposed for the Punta del Este Basin: 1 Marine petroleum system of the prerift stage: Devonian/Permian-Devonian/Permian(?, 2 Lacustrine petroleum system of the synrift stage: Neocomian-Neocomian(?, 3 Marine petroleum system of the Cretaceous postrift: Aptian-Late Cretaceous(?, 4 Marine petroleum system of the Cenozoic postrift: Paleocene-Paleogene/Neogene(?.

Composition and genesis of the Konevinsky gold deposit, Eastern Sayan, Russia

Science.gov (United States)

Damdinov, B. B.; Zhmodik, S. M.; Roshchektaev, P. A.; Damdinova, L. B.

2016-03-01

The Konevinsky gold deposit in southeast Eastern Sayan is distinguished from most known deposits in this region (Zun-Kholba, etc.) by the geological setting and composition of mineralization. To elucidate the cause of the peculiar mineralization, we have studied the composition, formation conditions, and origin of this deposit, which is related to the Ordovician granitoid pluton 445-441 Ma in age cut by intermediate and basic dikes spatially associated with metavolcanic rocks of the Devonian-Carboniferous Ilei Sequence. Four mineral assemblages are recognized: (1) quartz-pyrite-molybdenite, (2) quartz-gold-pyrite, (3) gold-polysulfide, and (4) telluride. Certain indications show that the ore was formed as a result of the superposition of two distinct mineral assemblages differing in age. The first stage dated at ~440 Ma is related to intrusions generating Cu-Mo-Au porphyry mineralization and gold-polysulfide veins. The second stage is controlled by dikes pertaining to the Devonian-Carboniferous volcanic-plutonic association. The second stage is characterized by gain of Hg and Te and formation of gold-mercury-telluride paragenesis.

Characterization of the Helderberg Group as a geologic seal for CO 2 sequestration

Science.gov (United States)

Lewis, J.E.; McDowell, R.R.; Avary, K.L.; Carter, K.M.

2009-01-01

The Midwest Regional Carbon Sequestration Partnership recognizes that both the Devonian Oriskany Sandstone and the Silurian Salina Group offer potential for subsurface carbon dioxide storage in northern West Virginia. The Silurian-Devonian Helderberg Group lies stratigraphically between these two units, and consequendy, its potential as a geologic seal must be evaluated. Predominantly a carbonate interval with minor interbedded siliciclastics and chert, the Helderberg Group was deposited in an ancient epeiric sea. Although most previous investigations of this unit have concentrated on outcrops in eastern West Virginia, new information is available from an injection well drilled along the Ohio River at First Energy's R. E. Burger electric power plant near Shadyside, Ohio. Geophysical, seismic, and core data from this well have been combined with existing outcrop information to evaluate the Helderberg Group's potential as a seal. The data collected suggest that only secondary porosity remains, and permeability, if it exists, most likely occurs along faults or within fractures. ?? 2009. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Geological map of Uruguay Esc 1,100,000. Melo Sheet D-15

International Nuclear Information System (INIS)

Ferrando, L.; Andreis, R.

1990-01-01

This work is about the geological map of Uruguay Esc.1.100.000 (Melo) and the explanatory memoranda which describes the geological , lithological and sedimentological characteristics soils belong to the pre devonian period in Melo, Buena Vista Yaguari and Tres islas formations. These metamorphic rocks would be compared with the orogenic cycle of the east and southeast groups

Bedrock geologic map of the Lisbon quadrangle, and parts of the Sugar Hill and East Haverhill quadrangles, Grafton County, New Hampshire

Science.gov (United States)

Rankin, Douglas W.

2018-04-20

The bedrock geologic map of the Lisbon quadrangle, and parts of the Sugar Hill and East Haverhill quadrangles, Grafton County, New Hampshire, covers an area of approximately 73 square miles (189 square kilometers) in west-central New Hampshire. This map was created as part of a larger effort to produce a new bedrock geologic map of Vermont through the collection of field data at a scale of 1:24,000. A large part of the map area consists of the Bronson Hill anticlinorium, a post-Early Devonian structure that is cored by metamorphosed Cambrian to Devonian sedimentary, volcanic, and plutonic rocks.The Bronson Hill anticlinorium is the apex of the Middle Ordovician to earliest-Silurian Bronson Hill magmatic arc that contains the Ammonoosuc Volcanics, Partridge Formation, and Oliverian Plutonic Suite, and extends from Maine, through western New Hampshire (down the eastern side of the Connecticut River), through southern New England to Long Island Sound. The deformed and partially eroded arc is locally overlain by a relatively thin Silurian section of metasedimentary rocks (Clough Quartzite and Fitch Formation) that thickens to the east. The Silurian section near Littleton is disconformably overlain by a thicker, Lower Devonian section that includes mostly metasedimentary and minor metavolcanic rocks of the Littleton Formation. The Bronson Hill anticlinorium is bisected by a series of northeast-southwest trending Mesozoic normal faults. Primarily among them is the steeply northwest-dipping Ammonoosuc fault that divides older and younger units (lower and upper sections) of the Ammonoosuc Volcanics. The Ammonoosuc Volcanics are lithologically complex and predominantly include interlayered and interfingered rhyolitic to basaltic volcanic and volcaniclastic rocks, as well as lesser amounts of slate, phyllite, ironstone, chert, sandstone, and pelite. The Albee Formation underlies the Ammonoosuc Volcanics and is predominantly composed of interbedded metamorphosed sandstone

Lost Terranes of Zealandia: possible development of late Paleozoic and early Mesozoic sedimentary basins at the southwest Pacific margin of Gondwanaland, and their destination as terranes in southern South America Terrenos perdidos de Zealandia: posible desarrollo de cuencas sedimentarias del Paleozoico tardío y Mesozoico temprano en el margen suroccidental del Pacífico de Gondwana y su destino como terrenos en el sur de América del Sur

Directory of Open Access Journals (Sweden)

Christopher J Adams

2010-07-01

Full Text Available Latest Precambrian to Ordovician metasedimentary successions and Cambrian-Ordovician and Devonian-Carboniferous granitoids form the major part of the basement of southern Zealandia and adjacent sectors of Antarctica and southeast Australia. Uplift/cooling ages of these rocks, and local Devonian shallow-water cover sequences suggest that final consolidation of the basement occurred through Late Paleozoic time. A necessary consequence of this process would have been contemporaneous erosion and the substantial development of marine sedimentary basins at the Pacific margin of Zealandia. These are found nowhere at the present day, suggesting that the basins have been lost by tectonic erosion, perhaps in a margin-parallel dextral translation similar to late Paleozoic-Mesozoic suspect terranes of New Zealand. Aprobable detrital zircon age pattern is assembled for these lost Zealandia sediments, and then compared with those of pre-Jurassic (probable Triassic to Devonian metasedimentary rocks in the Chilean archipelago. Significant Mesoproterozoic, latest Neoproterozoic-Cambrian and Devonian-Carboniferous detrital zircon age components are common to both, thus supporting a possible Chilean terrane destination for these 'lost terranes of Zealandia'.Las sucesiones metasedimentarias del Precámbrico tardío al Ordovícico y granitoides del Cámbrico-Ordovícico y Devónico-Carbonífero constituyen la mayor parte del basamento del sur de Zealandia y sectores adyacentes de la Antartica y el sudeste de Australia. Las edades de enfriamiento/alzamiento de estas rocas y la cobertura local de secuencias de aguas someras del Devónico, sugieren que la consolidación definitiva del basamento se produjo durante el Paleozoico tardío. Una consecuencia necesaria de este proceso habría sido la erosion contemporánea y el desarrollo sustancial de cuencas sedimentarias marinas en el margen del Pacífico de Zealandia. Estas no se encuentran en ninguna parte en la

Subsurface example of a dolomitized middle Guadalupian (Permian) reef from west Texas

Energy Technology Data Exchange (ETDEWEB)

Longacre, S.A.

1983-01-01

A middle Guadalupian organic buildup was cored in the North McElroy Unit (NMU No. 3713 well) in Upton County, W. Texas. Fusulinid control indicates the buildup is equivalent to the Goat Seep reef that crops out in the Guadalupe Mt. The organic buildup at North McElroy consists of boundstones and associated flank grainstones. The reef biota is dominated by ramose and encrusting bryozoans, numerous types of calcareous sponges, the problematic encrusting organism Tubiphytes, encrusting algae, crinoids, brachiopods, and trilobites. Among the more significant aspects of diagenesis are mechanical degradation and biologic degradation, leaching, gypsum-anhydrite transformations, cementation, replacement of all calcite by dolomite, cementation and replacement by baroque dolomite, fracturing, and replacement of carbonate by anhydrite. 17 references.

Early Middle Frasnian platform reef strata in the Moravian Karst interpreted as recording the atmospheric dust changes: the key to understanding perturbations in the punctata conodont zone

Czech Academy of Sciences Publication Activity Database

Hladil, Jindřich; Koptíková, Leona; Galle, Arnošt; Sedláček, Václav; Pruner, Petr; Schnabl, Petr; Langrová, Anna; Bábek, O.; Frána, Jaroslav; Hladíková, J.; Otava, J.; Geršl, M.

2009-01-01

Roč. 84, č. 1 (2009), s. 75-106 ISSN 1214-1119 R&D Projects: GA AV ČR IAAX00130702; GA AV ČR IAA300130702 Institutional research plan: CEZ:AV0Z30130516; CEZ:AV0Z10480505 Keywords : mineral dust * platform reef * stromatactis * Devonian * Alamo impact Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.983, year: 2009

Rb-Sr Autunian age of cordierite-bearing migmatites from northern Cevennes (French Massif Central)

International Nuclear Information System (INIS)

Chenevoy, M.; Gay, M.; Duthou, J.L.

1995-01-01

On the basis of whole rock Rb-Sr data, an Autunian age (287 ± 6 Ma) is ascribed to the cordierite-bearing migmatites occurring south of Mt Pilat. The related anatexis is therefore linked with the low pressure metamorphism, and is distinct from the Devonian anatexis with gave rise to the Barrovian cordierite migmatites in the Lyonnais area. (authors). 34 refs., 2 figs

Transition elements in tabulate coral skeletons: seawater vs. sediment

Czech Academy of Sciences Publication Activity Database

Hladil, Jindřich; Voltr, J.

2003-01-01

Roč. 7, 9th International Symposium on Fossil Cnidaria and Porifera Abstracts. (2003), s. 36 ISSN 1608-8166. [International Symposium on Fossil Cnidaria and Porifera /9./. 03.08.2003-07.08.2003, Graz] R&D Projects: GA AV ČR IAA3013209 Institutional research plan: CEZ:AV0Z3013912 Keywords : transition elements * coral increments * Devonian Subject RIV: DB - Geology ; Mineralogy

Geological Structure of the Basement of Western and Eastern Parts of the West-Siberian Plain

Science.gov (United States)

Ivanov, Kirill S.; Erokhin, Yuriy V.; Ponomarev, Vladimir S.; Pogromskaya, Olga E.; Berzin, Stepan V.

2016-01-01

The U-Pb dating (SHRIMP-II on zircon) was obtained for the first time from the basement of the West Siberian Plain in the Western half of the region. It is established that a large part of the protolith of the metamorphic depth in the Shaim-Kuznetsov meganticlinorium contained sedimentary late- and middle-Devonian rocks (395-358 million years).…

National Uranium Resource Evaluation, Scranton Quadrangle, Pennsylvania, New York, and New Jersey

International Nuclear Information System (INIS)

Baillieul, T.A.; Indelicato, G.J.; Penley, H.M.

1980-11-01

Reconnaissance and detailed geologic and radiometric investigations were conducted throughout the Scranton Quadrangle, Pennsylvania, New York, and New Jersey, to evaluate uranium favorability using National Uranium Resource Evaluation criteria. Surface and subsurface studies were augmented by aerial radiometric, hydrogeochemical and stream sediment reconnaissance, and emanometry surveys. Results of the investigations indicate four environments favorable for uranium deposits: In the Precambrian metamorphic terrain of the Reading Prong, magmatic-hydrothermal and anatectic deposits may occur in the northwestern massif; contact metasomatic deposits may occur in a portion of the southeastern massif. The alluvial-fan environment at the base of the Upper Devonian Catskill Formation appears favorable for deposits in peneconcordant channel controlled sandstones. Seven environments are considered unfavorable for uranium deposits: the southeastern massif of the Reading Prong, exclusive of that portion denoted as a favorable contact metasomatic environment; the lower Paleozoic sedimentary units; the Beemerville nepheline syenite complex; the Upper Devonian Catskill Formation, exclusive of the favorable basal alluvial-fan facies; Mississippian and Pennsylvanian units; and peat bogs. Two environments were not evaluated: the Spechty Kopf Formation, because of paucity of exposure and lack of sufficient data; and the Newark Basin, because of cultural density and inadequate subsurface information

Factors controlling Li concentration and isotopic composition in formation waters and host rocks of Marcellus Shale, Appalachian Basin

Science.gov (United States)

Phan, Thai T.; Capo, Rosemary C; Stewart, Brian W.; Macpherson, Gwen; Rowan, Elisabeth L.; Hammack, Richard W.

2015-01-01

In this study, water and whole rock samples from hydraulically fractured wells in the Marcellus Shale (Middle Devonian), and water from conventional wells producing from Upper Devonian sandstones were analyzed for lithium concentrations and isotope ratios (δ7Li). The distribution of lithium concentrations in different mineral groups was determined using sequential extraction. Structurally bound Li, predominantly in clays, accounted for 75-91 wt. % of total Li, whereas exchangeable sites and carbonate cement contain negligible Li (< 3%). Up to 20% of the Li is present in the oxidizable fraction (organic matter and sulfides). The δ7Li values for whole rock shale in Greene Co., Pennsylvania, and Tioga Co., New York, ranged from -2.3 to + 4.3‰, similar to values reported for other shales in the literature. The δ7Li values in shale rocks with stratigraphic depth record progressive weathering of the source region; the most weathered and clay-rich strata with isotopically light Li are found closest to the top of the stratigraphic section. Diagenetic illite-smectite transition could also have partially affected the bulk Li content and isotope ratios of the Marcellus Shale.

Metallogenic relationships to tectonic evolution - the Lachlan Orogen, Australia

Science.gov (United States)

Bierlein, Frank P.; Gray, David R.; Foster, David A.

2002-08-01

Placing ore formation within the overall tectonic framework of an evolving orogenic system provides important constraints for the development of plate tectonic models. Distinct metallogenic associations across the Palaeozoic Lachlan Orogen in SE Australia are interpreted to be the manifestation of interactions between several microplates and three accretionary complexes in an oceanic back-arc setting. In the Ordovician, significant orogenic gold deposits formed within a developing accretionary wedge along the Pacific margin of Gondwana. At the same time, major porphyry Cu-Au systems formed in an oceanic island arc outboard of an evolved magmatic arc that, in turn, gave rise to granite-related Sn-W deposits in the Early Silurian. During the ongoing evolution of the orogen in the Late Silurian to Early Devonian, sediment-hosted Cu-Au and Pb-Zn deposits formed in short-lived intra-arc basins, whereas a developing fore-arc system provided the conditions for the formation of several volcanogenic massive sulphide deposits. Inversion of these basins and accretion to the Australian continental margin triggered another pulse of orogenic gold mineralisation during the final consolidation of the orogenic belt in the Middle to Late Devonian.

The paleozoic of Amazonas basin south edge: Tapajos river, Para state; O paleozoico da borda sul da bacia do Amazonas: rio Tapajos, estado do Para

Energy Technology Data Exchange (ETDEWEB)

Matsuda, Nilo Siguehiko [Petrobras E e P, Rio de Janeiro, RJ (Brazil). Exploracao. Estratigrafia e Sedimentologia Geologia Aplicada a Exploracao], E-mail: nilo@petrobras.com.br; Winter, Wilson Rubem [Petrobras, Campoas dos Goytacases, RJ (Brazil). Exploracao. Sedimentologia e Estratigrafia], E-mail: winter@petrobras.com.br; Wanderley Filho, Joaquim Ribeiro; Cacela, Alessandra Suzely Moda [Petrobras, Manaus, AM (Brazil). Exploracao. Unidade de Operacoes de Exploracao e Producao da Amazonia], Emails: jwand@petrobras.com.br, alessandra.suzely@petrobras.com.br

2009-11-15

The intracratonic Amazonas Basin covers an area close to 500.000km{sup 2} shared between the Amazonas and Para states. The phanerozoic stratigraphic framework is up to 6.000m thick and may be subdivided into two, first order depositional sequences: the Paleozoic sequence, intruded by diabase dikes and sills and the Mesozoic-Cenozoic sequence. Analyzing the stratigraphic framework, the great tectonic influence on the basin development can be appreciated. The mainly NW-SE structural directions of the basement, which mark the boundaries of the geochronological provinces of the Amazonas, are clearly identified along the Tapajos River. The Paleozoic sequence outcrops on the southern border of the Amazonas Basin embraces potential source rocks, reservoirs and seal rocks. They can be subdivided in three, second order sequences, limited by regional unconformities, as: the Ordovician/Devonian, which corresponds to the Pitinga lithostratigraphic formation; the Devonian-Tournaisian, which corresponds to the Maecuru, Erere, Barreirinha and Curiri formations and, the Pensylvanian-Permian that are represented by the Monte Alegre and Itaituba formations. This field trip guide presents these classic lithostratigraphic outcrop units, together with a brief sedimentological description and an analysis of their positioning related to sequence stratigraphical concepts. (author)

A widespread devonian methamorphic episode in northern Patagonia, Argentina

International Nuclear Information System (INIS)

Ostera, H.A.; Linares, E; Haller, M.J; Cagnoni, M.C.; Lopez de Luchi, M

2001-01-01

One of the greatest difficulties in Rb-Sr dating on metamorphic rocks is the lack of evidences of complete re-homogenization and the assumption of a common initial ratio for all the samples analyzed. The redistribution of parent-daughter elements and the concomitant partial or complete equilibration of the isotopic system could occur on mineral or regional size domains. This fact led to many authors to discard or disapprove the use of this method in metamorphic terranes. However, recent papers suggested that this opinion has been premature and that additional information could be obtained by the Rb-Sr method despite the difficulties that it implies (Patel et al., 1999). Many reports on well fitted Rb-Sr isochrons giving the age of metamorphism in regionally metamorphosed rocks, suggest that the Sr isotopic equilibrium can take place at different scales. This paper presents data and the Rb-Sr system behaviour from a metamorphic unit (Cushamen Formation) in the Northern Patagonia, as a contribution to elucidate the evolution of the North Patagonian Massif (au)

Pressure-Coring of the Gas-bearing Devonian Black Shales

Energy Technology Data Exchange (ETDEWEB)

Zielinski, R. E.; Dixon, J. A.; McIver, R. D.

1979-10-01

A Christensen model pressure-retaining core barrel is being used in the drilling of two EGSP research wells. This effort supported by two other techniques is designed to evaluate the most effective technique to provide meaningful resource assessments. One well has been successfully drilled and the accumulated samples are currently being evaluated. The second well is currently being drilled.

Late Devonian and Triassic basalts from the southern continental ...

Indian Academy of Sciences (India)

continental margin of the East European Platform, tracers of a single heterogeneous ... Areas of Precambrian consolidation within the Late Paleozoic orogen; 3. Areas of ...... and hydrocarbon accumulations; J. Petroleum Geology. 16 183–196.

A phylogenomic profile of hemerythrins, the nonheme diiron binding respiratory proteins

Directory of Open Access Journals (Sweden)

Mizuguchi Kenji

2008-09-01

Full Text Available Abstract Background Hemerythrins, are the non-heme, diiron binding respiratory proteins of brachiopods, priapulids and sipunculans; they are also found in annelids and bacteria, where their functions have not been fully elucidated. Results A search for putative Hrs in the genomes of 43 archaea, 444 bacteria and 135 eukaryotes, revealed their presence in 3 archaea, 118 bacteria, several fungi, one apicomplexan, a heterolobosan, a cnidarian and several annelids. About a fourth of the Hr sequences were identified as N- or C-terminal domains of chimeric, chemotactic gene regulators. The function of the remaining single domain bacterial Hrs remains to be determined. In addition to oxygen transport, the possible functions in annelids have been proposed to include cadmium-binding, antibacterial action and immunoprotection. A Bayesian phylogenetic tree revealed a split into two clades, one encompassing archaea, bacteria and fungi, and the other comprising the remaining eukaryotes. The annelid and sipunculan Hrs share the same intron-exon structure, different from that of the cnidarian Hr. Conclusion The phylogenomic profile of Hrs demonstrated a limited occurrence in bacteria and archaea and a marked absence in the vast majority of multicellular organisms. Among the metazoa, Hrs have survived in a cnidarian and in a few protostome groups; hence, it appears that in metazoans the Hr gene was lost in deuterostome ancestor(s after the radiata/bilateria split. Signal peptide sequences in several Hirudinea Hrs suggest for the first time, the possibility of extracellular localization. Since the α-helical bundle is likely to have been among the earliest protein folds, Hrs represent an ancient family of iron-binding proteins, whose primary function in bacteria may have been that of an oxygen sensor, enabling aerophilic or aerophobic responses. Although Hrs evolved to function as O2 transporters in brachiopods, priapulids and sipunculans, their function in

Survey of the upper Frasnian reefs: a priority exploratory operation in the Volgograd Oblast

Energy Technology Data Exchange (ETDEWEB)

Shakhnovskii, I.M.; Nikishin, A.G.; Lezhnev, V.M.

1978-01-01

A description is given of the first oil fields - the Kotov and Miroshnikov, identified in the upper Frasnian structures of reef origin in the western rim of the Umetov--Linev depression. An identification is made of survey criteria that can be used in the exploration of upper Devonian structures of reef origin. Substantiation is offered for further exploratory and survey operations in the Volgograd Oblast. 2 figures.

FRASNIAN AND VISEAN-NAMURIAN CONODONT FAUNAS AT PRAPROTNO, SLOVENIA

OpenAIRE

KOLAR-JURKOVSEK, TEA; JURKOVSEK, BOGDAN

2017-01-01

Conodont faunas from the limestone pebbles of the Upper Paleozoic Conglomerate at Praprotno, Slovenia demonstrate the presence of two faunas. The older fauna, marked by Palmatolepis surecta and Polygnathus decorosus is indicative of the Frasnian stage (Upper Devonian). The younger fauna is dominated by Gnathodus bilineatus and contains Lochriea commutata and L. nodosa. This fauna is characteristic of the Late Visean-Namurian (Lower Carboniferous).

Magnetic susceptibility correlation of km-thick Eifelian–Frasnian sections (Ardennes and Moravia)

Czech Academy of Sciences Publication Activity Database

Boulvain, F.; da Silva, A.C.; Mabille, C.; Hladil, Jindřich; Geršl, M.; Koptíková, Leona; Schnabl, Petr

2010-01-01

Roč. 13, č. 4 (2010), s. 309-318 ISSN 1374-8505 R&D Projects: GA AV ČR IAA300130702; GA AV ČR IAAX00130702 Institutional research plan: CEZ:AV0Z30130516 Keywords : Devonian limestone * magnetic susceptibility * Moravian Karst * Ardennes Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.645, year: 2010 http://popups.ulg.ac.be/Geol/docannexe.php?id=3181

Geometry of the neoproterozoic and paleozoic rift margin of western Laurentia: Implications for mineral deposit settings

Science.gov (United States)

Lund, K.

2008-01-01

The U.S. and Canadian Cordilleran miogeocline evolved during several phases of Cryogenian-Devonian intracontinental rifting that formed the western mangin of Laurentia. Recent field and dating studies across central Idaho and northern Nevada result in identification of two segments of the rift margin. Resulting interpretations of rift geometry in the northern U.S. Cordillera are compatible with interpretations of northwest- striking asymmetric extensional segments subdivided by northeast-striking transform and transfer segments. The new interpretation permits integration of miogeoclinal segments along the length of the western North American Cordillera. For the U.S. Cordillera, miogeoclinal segments include the St. Mary-Moyie transform, eastern Washington- eastern Idaho upper-plate margin, Snake River transfer, Nevada-Utah lower-plate margin, and Mina transfer. The rift is orthogonal to most older basement domains, but the location of the transform-transfer zones suggests control of them by basement domain boundaries. The zigzag geometry of reentrants and promontories along the rift is paralleled by salients and recesses in younger thrust belts and by segmentation of younger extensional domains. Likewise, transform transfer zones localized subsequent transcurrent structures and igneous activity. Sediment-hosted mineral deposits trace the same zigzag geometry along the margin. Sedimentary exhalative (sedex) Zn-Pb-Ag ??Au and barite mineral deposits formed in continental-slope rocks during the Late Devonian-Mississippian and to a lesser degree, during the Cambrian-Early Ordovician. Such deposits formed during episodes of renewed extension along miogeoclinal segments. Carbonate-hosted Mississippi Valley- type (MVT) Zn-Pb deposits formed in structurally reactivated continental shelf rocks during the Late Devonian-Mississippian and Mesozoic due to reactivation of preexisting structures. The distribution and abundance of sedex and MVT deposits are controlled by the

Geochemical characteristics and tectonic setting of the Tuerkubantao mafic-ultramafic intrusion in West Junggar, Xinjiang, China

Directory of Open Access Journals (Sweden)

Yufeng Deng

2015-03-01

Full Text Available Mineral chemistry, whole-rock major oxide, and trace element compositions have been determined for the Tuerkubantao mafic-ultramafic intrusion, in order to understand the early Paleozoic tectonic evolution of the West Junggar orogenic belt at the southern margin of the Central Asian orogenic belt. The Tuerkubantao mafic-ultramafic intrusion is a well-differentiated complex comprising peridotite, olivine pyroxenite, gabbro, and diorite. The ultramafic rocks are mostly seen in the central part of the intrusion and surrounded by mafic rocks. The Tuerkubantao intrusive rocks are characterized by enrichment of large ion lithophile elements and depleted high field strength elements relative to N-MORB. In addition, the Tuerkubantao intrusion displays relatively low Th/U and Nb/U (1.13–2.98 and 2.53–7.02, respectively and high La/Nb and Ba/Nb (1.15–4.19 and 37.7–79.82, respectively. These features indicate that the primary magma of the intrusion was derived from partial melting of a previously metasomatized mantle source in a subduction setting. The trace element patterns of peridotites, gabbros, and diorite in the Tuerkubantao intrusion have sub-parallel trends, suggesting that the different rock types are related to each other by differentiation of the same primary magma. The intrusive contact between peridotite and gabbro clearly suggest that the Tuerkubantao is not a fragment of an ophiolite. However, the Tuerkubantao intrusion displays many similarities with Alaskan-type mafic-ultramafic intrusions along major sutures of Phanerozoic orogenic belts. Common features include their geodynamic setting, internal lithological zoning, and geochemistry. The striking similarities indicate that the middle Devonian Tuerkubantao intrusion likely formed in a subduction-related setting similar to that of the Alaskan-type intrusions. In combination with the Devonian magmatism and porphyry mineralization, we propose that subduction of the oceanic slab has

Breathing air in air: in what ways might extant amphibious fish biology relate to prevailing concepts about early tetrapods, the evolution of vertebrate air breathing, and the vertebrate land transition?

Science.gov (United States)

Graham, Jeffrey B; Lee, Heather J

2004-01-01

The air-breathing fishes have heuristic importance as possible models for the Paleozoic evolution of vertebrate air breathing and the transition to land. A recent hypothesis about this transition suggests that the diverse assemblage of marine amphibious fishes occurring primarily in tropical, high intertidal zone habitats are analogs of early tetrapods and that the intertidal zone, not tropical freshwater lowlands, was the springboard habitat for the Devonian land transition by vertebrates. Here we argue that selection pressures imposed by life in the intertidal zone are insufficient to have resulted in the requisite aerial respiratory capacity or the degree of separation from water required for the vertebrate land transition. The extant marine amphibious fishes, which occur mainly on rocky shores or mudflats, have reached the limit of their niche expansion onto land and remain tied to water by respiratory structures that are less efficient in air and more vulnerable to desiccation than lungs. We further argue that evolutionary contingencies actuated by the Devonian origin of the tetrapods marked a critical point of divergence for a way of life in which selection pressures would operate on the physiology, morphology, and natural history of the different vertebrate groups. While chronically hypoxic and shallow water conditions in the habitats of some primitive bony fishes and some amphibians appear similar to the conditions that prevailed in the Devonian, markedly different selection pressures have operated on other amphibians and bony fishes over the 300 million years since the vertebrate land transition. For example, both egg development and larval metamorphosis in extant amphibians are geared mainly toward compensating for the uncertainty of habitat water quality or even the absence of water by minimizing the time required to develop there. In contrast, reproduction by most intertidal (and amphibious) fishes, all of which are teleosts, remains dependent on a

The giant Carlin gold province: A protracted interplay of orogenic, basinal, and hydrothermal processes above a lithospheric boundary

Science.gov (United States)

Emsbo, P.; Groves, D.I.; Hofstra, A.H.; Bierlein, F.P.

2006-01-01

Northern Nevada hosts the only province that contains multiple world-class Carlin-type gold deposits. The first-order control on the uniqueness of this province is its anomalous far back-arc tectonic setting over the rifted North American paleocontinental margin that separates Precambrian from Phanerozoic subcontinental lithospheric mantle. Globally, most other significant gold provinces form in volcanic arcs and accreted terranes proximal to convergent margins. In northern Nevada, periodic reactivation of basement faults along this margin focused and amplified subsequent geological events. Early basement faults localized Devonian synsedimentary extension and normal faulting. These controlled the geometry of the Devonian sedimentary basin architecture and focused the discharge of basinal brines that deposited syngenetic gold along the basin margins. Inversion of these basins and faults during subsequent contraction produced the complex elongate structural culminations that characterize the anomalous mineral deposit "trends." Subsequently, these features localized repeated episodes of shallow magmatic and hydrothermal activity that also deposited some gold. During a pulse of Eocene extension, these faults focused advection of Carlin-type fluids, which had the opportunity to leach gold from gold-enriched sequences and deposit it in reactive miogeoclinal host rocks below the hydrologic seal at the Roberts Mountain thrust contact. Hence, the vast endowment of the Carlin province resulted from the conjunction of spatially superposed events localized by long-lived basement structures in a highly anomalous tectonic setting, rather than by the sole operation of special magmatic or fluid-related processes. An important indicator of the longevity of this basement control is the superposition of different gold deposit types (e.g., Sedex, porphyry, Carlin-type, epithermal, and hot spring deposits) that formed repeatedly between the Devonian and Miocene time along the trends

Lophotrochozoan mitochondrial genomes

Energy Technology Data Exchange (ETDEWEB)

Valles, Yvonne; Boore, Jeffrey L.

2005-10-01

Progress in both molecular techniques and phylogeneticmethods has challenged many of the interpretations of traditionaltaxonomy. One example is in the recognition of the animal superphylumLophotrochozoa (annelids, mollusks, echiurans, platyhelminthes,brachiopods, and other phyla), although the relationships within thisgroup and the inclusion of some phyla remain uncertain. While much ofthis progress in phylogenetic reconstruction has been based on comparingsingle gene sequences, we are beginning to see the potential of comparinglarge-scale features of genomes, such as the relative order of genes.Even though tremendous progress is being made on the sequencedetermination of whole nuclear genomes, the dataset of choice forgenome-level characters for many animals across a broad taxonomic rangeremains mitochondrial genomes. We review here what is known aboutmitochondrial genomes of the lophotrochozoans and discuss the promisethat this dataset will enable insight into theirrelationships.

Cornulitids (tubeworms) from the Late Ordovician Hirnantia fauna of Morocco

Science.gov (United States)

Gutiérrez-Marco, Juan Carlos; Vinn, Olev

2018-01-01

Two species of cornulitids, Cornulites gondwanensis sp. nov. and C. aff. shallochensis Reed are described from the Hirnantian of Morocco, within an assemblage representative of the Hirnantia brachiopod fauna occurring near the Ordovician South Pole. The dominance of aggregated and solitary free forms could be explained by particular sedimentary environments preceding the Hirnantian glaciation and the latest Ordovician Extinction Event. The diversity of cornulitids in the Late Ordovician of Gondwana and related terranes was relatively low, and less diverse than the cornulitids of Laurentia and Baltica. Hirnantian cornulitids from Morocco do not resemble Late Ordovician cornulitids of Baltica and Laurentia. Moroccan cornulitids seem to be closely allied to some older Gondwanan cornulitids, especially Sardinian ones. They resemble species described from the Late Ordovician and Llandovery of Scotland suggesting a palaeobiogeographic link.

New data on internal morphology of exceptionally preserved Nannirhynchia pygmaea (Morris, 1847 from the Lusitanian Basin (Brachiopoda, Early Jurassic, Portugal

Directory of Open Access Journals (Sweden)

M. Schemm-Gregory

2012-08-01

Full Text Available Pyritized internal moulds of articulated shells of the Early Jurassic brachiopod taxon Nannirhynchia pygmaea were found in beds closely below the early Toarcian oceanic anoxic event in the Polymorphum Zone in Portugal. The material allows a detailed study of the outline of the muscle fields, the length and direction of the crura, and the orientation of the cardinalia, which are hitherto undescribed. Three-dimensional reconstructions of articulated shells of N. pygmaea occurring in a single horizon were produced to show the orientation and length of arcuiform crura. The preservation of internal moulds together with the three-dimensional reconstruction of the internal shell morphology allow a more precise description of the internal morphology of this taxon than it is possible with articulated shells and serial sections. doi:10.1002/mmng.201200005

Impact Theory of Mass Extinctions and the Invertebrate Fossil Record

Science.gov (United States)

Alvarez, Walter; Kauffman, Erle G.; Surlyk, Finn; Alvarez, Luis W.; Asaro, Frank; Michel, Helen V.

1984-03-01

There is much evidence that the Cretaceous-Tertiary boundary was marked by a massive meteorite impact. Theoretical consideration of the consequences of such an impact predicts sharp extinctions in many groups of animals precisely at the boundary. Paleontological data clearly show gradual declines in diversity over the last 1 to 10 million years in various invertebrate groups. Reexamination of data from careful studies of the best sections shows that, in addition to undergoing the decline, four groups (ammonites, cheilostomate bryozoans, brachiopods, and bivalves) were affected by sudden truncations precisely at the iridium anomaly that marks the boundary. The paleontological record thus bears witness to terminal-Cretaceous extinctions on two time scales: a slow decline unrelated to the impact and a sharp truncation synchronous with and probably caused by the impact.

The mitochondrial genome of phoronis architecta--Comparisons demonstrate that phoronids are lophotrochozoan protostomes

Energy Technology Data Exchange (ETDEWEB)

Helfenbein, Kevin G.; Boore, Jeffrey L.

2004-01-31

The proper reconstruction of the relationships among the animal phyla is central to interpreting patterns of animal evolution from the genomic level to the morphological level. This is true not only of the more speciose phyla, but also of smaller groups. We report here the nearly complete DNA sequence of the mitochondrial genome of the phoronid Phoronis architecta, which has a gene arrangement remarkably similar to that of a protostome animal, the chiton Katharina tunicata. Evolutionary analysis of both gene arrangements and inferred amino acid sequences of these taxa, along with those of three brachiopods and other diverse animals, strongly supports the hypothesis that lophophorates are part of the large group that includes mollusks and annelids, i.e., the Lophotrochozoa, and solidly refutes the alternative of their being deuterostomes.

Bedrock geologic map of the Littleton and Lower Waterford quadrangles, Essex and Caledonia Counties, Vermont, and Grafton County, New Hampshire

Science.gov (United States)

Rankin, Douglas W.

2018-06-13

The bedrock geologic map of the Littleton and Lower Waterford quadrangles covers an area of approximately 107 square miles (277 square kilometers) north and south of the Connecticut River in east-central Vermont and adjacent New Hampshire. This map was created as part of a larger effort to produce a new bedrock geologic map of Vermont through the collection of field data at a scale of 1:24,000. A large part of the map area consists of the Bronson Hill anticlinorium, a post-Early Devonian structure that is cored by metamorphosed Cambrian to Devonian sedimentary, volcanic, and plutonic rocks. The northwestern part of the map is divided by the Monroe fault which separates Early Devonian rocks of the Connecticut Valley-Gaspé trough from rocks of the Bronson Hill anticlinorium.The Bronson Hill anticlinorium is the apex of the Middle Ordovician to earliest-Silurian Bronson Hill magmatic arc that contains the Ammonoosuc Volcanics, Partridge Formation, and Oliverian Plutonic suite, and extends from Maine, down the eastern side of the Connecticut River in New Hampshire, to Long Island Sound. The deformed and partially eroded arc is locally overlain by a relatively thin Silurian section of metasedimentary rocks (Clough Quartzite and Fitch Formation) that thickens to the east. The Silurian section near Littleton is disconformably overlain by a thicker, Lower Devonian section that includes mostly metasedimentary rocks and minor metavolcanic rocks of the Littleton Formation. The Bronson Hill anticlinorium is bisected by a series of northeast-southwest trending Mesozoic normal faults. Primarily among them is the steeply northwest-dipping Ammonoosuc fault that divides older and younger units (upper and lower sections) of the Ammonoosuc Volcanics. The Ammonoosuc Volcanics are lithologically complex and predominantly include interlayered and interfingered rhyolitic to basaltic volcanic and volcaniclastic rocks, as well as lesser amounts of metamorphic and metasedimentary rocks

Fertile Prototaxites taiti: a basal ascomycete with inoperculate, polysporous asci lacking croziers

OpenAIRE

Honegger, R.; Edwards, Dianne; Axe, Lindsey; Strullu-Derrien, C.

2018-01-01

The affinities of Prototaxites have been debated ever since its fossils, some attaining tree-trunk proportions, were discovered in Canadian Lower Devonian rocks in 1859. Putative assignations include conifers, red and brown algae, liverworts and fungi (some lichenised). Detailed anatomical investigation led to the reconstruction of the type species, P. logani, as a giant sporophore (basidioma) of an agaricomycete (= holobasidiomycete), but evidence for its reproduction remained elusive. Tissu...

Genesis of zoned granite plutons in the Iapetus Suture Zone: new constraints from high-precision micro-analysis of accessory minerals

OpenAIRE

Miles, Andrew James

2013-01-01

The Trans-Suture Suite (TSS) of granitic plutons located in Northern Britain span the Iapetus Suture and represent a particularly enigmatic stage of post-Caledonian Devonian magmatism. Despite calc-alkaline affinities, proximity to the Iapetus Suture precludes a direct relationship to active subduction. Furthermore, the absence of inherited zircons distinguishes the TSS from plutons of a similar age throughout the Scottish Highlands, and is not easily reconciled with the abunda...

Warming or cooling in the Pragian? Sedimentary record and petrophysical logs across the Lochkovian-Pragian boundary in the Spanish Central Pyrenees

Czech Academy of Sciences Publication Activity Database

Slavík, Ladislav; Valenzuela-Ríos, J. I.; Hladil, Jindřich; Chadimová, Leona; Liao, J.-Ch.; Hušková, Aneta; Calvo, H.; Hrstka, Tomáš

2016-01-01

Roč. 449, May (2016), s. 300-321 ISSN 0031-0182 R&D Projects: GA ČR GA14-18183S Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100131201 Institutional support: RVO:67985831 Keywords : climate change * correlation * Early Devonian * gamma-ray spectrometry * magnetic susceptibility * Pyrenees Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.578, year: 2016

Thixotropic Properties of Latvian Illite Containing Clays

OpenAIRE

Lakevičs, Vitālijs; Stepanova, Valentīna; Niedra, Santa; Dušenkova, Inga; Ruplis, Augusts

2015-01-01

Thixotropic properties of Latvian Devonian and Quaternary clays were studied. Dynamic viscosity of the water clay suspensions were measured with a rotating viscometer. Influence of concentration, pH and modifiers on the thixotropic clay properties was analyzed. It was found that Latvian clays have thixotropic properties. Stability of clay suspensions is described with the thixotropy hysteresis loop. Increasing the speed of the viscometer rotation, dynamic viscosity of the clay suspension decr...

Morphology, Taxonomy and Interrelationships of Tristichopterid Fishes (Sarcopterygii, Tetrapodomorpha)

OpenAIRE

Snitting, Daniel

2008-01-01

Tristichopterids (Sarcopterygii, Tetrapodomorpha) form a monophyletic group of exclusively Devonian fishes. This thesis consists of descriptions of new material of tristichopterids and closely related taxa, as well as new interpretations and descriptions of previously figured material. Redescribed specimens were originally figured as far back as 1861, and publications as old as this are almost always of limited use as anatomical and systematical references, in addition to being difficult to a...

Late Ordovician brachiopod distribution and ecospace partitioning in the Tvären crater system, Sweden

DEFF Research Database (Denmark)

Frisk, Åsa M.; Harper, David Alexander Taylor

2013-01-01

of the guild structure of the fauna permits explanation of a local biodiversity hotspot in otherwise low-diversity strata elsewhere in the Scandinavian region. The Tvaren impact event had an important palaeobiologic effect upon the fossil record as it served as a local pump and reservoir for biodiversity....... Moreover the development of new community types and narrowly-defined niches helped further drive both a and p biodiversity during a critical phase of the Great Ordovician Biodiversification Event (C) 2012 Elsevier B.V. All rights reserved....

Synchrotron radiation X-ray tomographic microscopy (SRXTM) of brachiopod shell interiors for taxonomy: Preliminary report

OpenAIRE

Motchurova-Dekova Neda; Harper David A.T.

2010-01-01

Synchrotron radiation X-ray tomographic microscopy (SRXTM) is a non-destructive technique for the investigation and visualization of the internal features of solid opaque objects, which allows reconstruction of a complete three-dimensional image of internal structures by recording of the differences in the effects on the passage of waves of energy reacting with those structures. Contrary to X-rays, produced in a conventional X-ray tube, the intense synchrot...

Biogeographic and bathymetric determinants of brachiopod extinction and survival during the Late Ordovician mass extinction

DEFF Research Database (Denmark)

Finnegan, Seth; Mac Ørum Rasmussen, Christian; Harper, David A. T.

2016-01-01

–Early Silurian genus extinctions and evaluate which extinction drivers are best supported by the data. The first (latest Katian) pulse of the LOME preferentially affected genera restricted to deeper waters or to relatively narrow (less than 35°) palaeolatitudinal ranges. This pattern is only observed...... in the latest Katian, suggesting that it reflects drivers unique to this interval. Extinction of exclusively deeper-water genera implies that changes in water mass properties such as dissolved oxygen content played an important role. Extinction of genera with narrow latitudinal ranges suggests that interactions...... between shifting climate zones and palaeobiogeography may also have been important. We test the latter hypothesis by estimating whether each genus would have been able to track habitats within its thermal tolerance range during the greenhouse–icehouse climate transition. Models including these estimates...

Analysis on uranium mineralization-formation condition and prospecting potential in Xidamingshan metallogenic belt

International Nuclear Information System (INIS)

Li Zhixing; Qi Fucheng; He Zhongbo; Zhang Zilong

2012-01-01

There are many different opinions about the source of uranium and metallogenic mechanism in Xidamingshan metallogenic belt. therefore it blocked uranium resources potential evaluation and ore exploration. Through absorb in- formation and investigate Daxin deposit and systematic analysis on samples. It is believed that uranium source mainly came from Cambrian System, a little came from the deep. The Devonian System is favorable room for saving ores in addition to be pre-concentrated room for uranium. Also, there are new cognition about uranium metallogenic mechanism, establish ore-forming series of Xidamingshan metallogenic belt, It is proposed that uranium mineralization have experienced 4 stages; It is cleared that hydrothermal fluid superposition transform type uranium deposit is main genetic type, ancient karst accumulate type is secondary genetic type, the later is formed by leaching the former and then precipitate, enrichment in ancient karst congeries, which is formed nearby faults and with the movement of Xishan structural movement. It is proven that metallogenic potential of Xidamingshan metallogenic belt is good. Tectonic rock controlled by subsidiary fracture nearby regional main fault, which connected with the Cambrian System and the Devonian System, and the deep of the deposit is guideline of mineral prospecting next stage. (authors)

Task 8: Evaluation of hydrocarbon potential

International Nuclear Information System (INIS)

Cashman, P.H.; Trexler, J.H. Jr.

1994-01-01

Our studies focus on the stratigraphy of Late Devonian to early Pennsylvanian rocks at the NTS, because these are the best potential hydrocarbon source rocks in the vicinity of Yucca Mountain. In the last year, our stratigraphic studies have broadened to include the regional context for both the Chainman and the Eleana formations. New age data based on biostratigraphy constrain the age ranges of both Chainman and Eleana; accurate and reliable ages are essential for regional correlation and for regional paleogeographic reconstructions. Source rock analyses throughout the Chainman establish whether these rocks contained adequate organic material to generate hydrocarbons. Maturation analyses of samples from the Chainman determine whether the temperature history has been suitable for the generation of liquid hydrocarbons. Structural studies are aimed at defining the deformation histories and present position of the different packages of Devonian - Pennsylvanian rocks. This report summarizes new results of our structural, stratigraphic and hydrocarbon source rock potential studies at the Nevada Test Site and vicinity. Stratigraphy is considered first, with the Chainman Shale and Eleana Formation discussed separately. New biostratigraphic results are included in this section. New results from our structural studies are summarized next, followed by source rock and maturation analyses of the Chainman Shale. Directions for future work are included where appropriate

The Paleozoic ichthyofauna of the Amazonas and Parnaíba basins, Brazil

Science.gov (United States)

Figueroa, Rodrigo Tinoco; Machado, Deusana Maria da Costa

2018-03-01

The Brazilian Paleozoic ichthyofauna from the Parnaíba and Amazonas basins regard a sparsely known diversity, including chondrichthyans and acanthodians, besides some osteichthyan remains. This work proposes a revision of the fossil material from these two sedimentary basins and synthesizes the morphological aspect of such material trying to understand the influences of those fossils to the paleontology of the region, comparing the Brazilian fossils with other gondwanan faunas. The Brazilian Paleozoic fish fauna shows great resemblance to those of Bolivia, especially during the Devonian. Many of the Acanthodian spines from the Manacapuru Formation (Amazonas Basin), and the Pimenteira Formation (Parnaíba Basin), are comparable to the taxa found in Bolivia. The lack of more Placoderm remains in the Brazilian outcrops is similar to the low diversity of this group in Bolivia, when compared to other South American and Euramerican localities. The most diverse Brazilian ichthyofauna is encountered in the Permian Pedra de Fogo Formation where numerous chondrichthyans and 'paleopterygians' remains are found, together with dipnoans and actinistians. Despite the apparent lack of more representative Paleozoic ichthyofaunas in Brazil, the available material that ranges from Lower Devonian to early Permian from Brazil bears important taxa that could address valuable taxonomic and biogeographic informations.

Combined oxygen- and carbon-isotope records through the Early Jurassic: multiple global events and two modes of carbon-cycle/temperature coupling

DEFF Research Database (Denmark)

Hesselbo, Stephen P.; Korte, Christoph

2010-01-01

, to the extent that meaningful comparisons between these events can begin to be made. Here we present new carbon and oxygen isotope data from mollusks (bivalves and belemnites) and brachiopods collected through the marine Early Jurassic succession of NE England, including the Sinemurian-Plienbachian boundary...... GSSP. All materials have been screened by chemical analysis and scanning electron microscopy to check for diagenetic alteration. Analysis of carbon isotopes from marine calcite is supplemented by analysis of carbon-isotope values from fossil wood collected through the same section. It is demonstrated...... that both long-term and short-term carbon-isotope shifts from the UK Early Jurassic represent global changes in carbon cycle balances. The Sinemurian-Pliensbachian boundary event is an event of global significance and shows several similarities to the Toarcian OAE (relative sea-level change, carbon-isotope...

Seven 365-Million-Year-Old Trilobites Moulting within a Nautiloid Conch

OpenAIRE

Zong, Rui-Wen; Fan, Ruo-Ying; Gong, Yi-Ming

2016-01-01

A nautiloid conch containing many disarticulated exoskeletons of Omegops cornelius (Phacopidae, Trilobita) was found in the Upper Devonian Hongguleleng Formation of the northwestern margin of the Junggar Basin, NW China. The similar number of cephala, thoraces and pygidia, unbroken thoraces, explicit exuviae, and lack of other macrofossils in the conch, indicate that at least seven individual trilobites had moulted within the nautiloid living chamber, using the vacant chamber of a dead nautil...

The Caledonian tectonomagmatic evolution of the Orkney Islands, Scotland

OpenAIRE

Bjerga, Audun Dalene

2017-01-01

The geology of the Orkney Islands is dominated by well-studied Devonian sedimentary rocks deposited in the Orcadian basin. However, on the islands of Mainland Orkney and Graemsay there are small, relatively poorly studied outcrops of the underlying basement. Based on comparison with rocks in mainland Scotland this basement has been suggested to comprise pre-Caledonian para-gneisses and Caledonian granites. This has, however, never been documented. Here the contact relationships in the basemen...

Geology and total petroleum systems of the Paradox Basin, Utah, Colorado, New Mexico, and Arizona

Science.gov (United States)

Whidden, Katherine J.; Lillis, Paul G.; Anna, Lawrence O.; Pearson, Krystal M.; Dubiel, Russell F.

2014-01-01

The geological model for the development of the Total Petroleum Systems (TPSs) within the Paradox Basin formed the foundation of the recent U.S. Geological Survey assessment of undiscovered, technically recoverable resources in the basin. Five TPSs were defined, of which three have known production and two are hypothetical. These TPSs are based on geologic elements of the basin and the potential development of Precambrian, Devonian, Pennsylvanian, Permian-Mississippian, and Cretaceous source rock intervals.

Early Carboniferous adakite-like and I-type granites in central Qiangtang, northern Tibet: Implications for intra-oceanic subduction and back-arc basin formation within the Paleo-Tethys Ocean

Science.gov (United States)

Liu, Jin-Heng; Xie, Chao-Ming; Li, Cai; Wang, Ming; Wu, Hao; Li, Xing-Kui; Liu, Yi-Ming; Zhang, Tian-Yu

2018-01-01

Recent studies have proposed that the Late Devonian ophiolites in the central Qiangtang region of northern Tibet were formed in an oceanic back-arc basin setting, which has led to controversy over the subduction setting of the Longmucuo-Shuanghu-Lancangjiang Suture Zone (LSLSZ) during the Late Devonian to Early Carboniferous. In this paper we present new data about a suite of granite plutons that intrude into ophiolite in central Qiangtang. Our aim was to identify the type of subduction and to clarify the existence of an intra-oceanic back-arc basin in the LSLSZ during the Late Devonian to Early Carboniferous. The suite of granites consists of monzogranites, syenogranites, and granodiorites. Our laser ablation-inductively coupled plasma-mass spectrometry zircon U-Pb data yielded Early Carboniferous crystallization ages of 357.2 Ma, 357.4 Ma and 351.1 Ma. We subsequently investigated the petrogenesis and tectonic setting of these granites based on their geochemical and Hf isotopic characteristics. First, we divided the granites into high Sr/Y (HSG) and low Sr/Y granites (LSG). The HSG group contains monzogranites and granodiorites that have similar geochemical characteristics to adakites (i.e., high Sr/Y and La/Yb ratios, low MgO, Y, and Yb contents, and no pronounced negative Eu anomaly), although they have slightly lower Sr and Al2O3 contents, caused by crystal fractionation during late magmatic evolution. Therefore, we define the HSG group as adakite-like granites. The study of the HSG shows that they are adakite-like granites formed by partial melting of oceanic crust and experience fractional crystallization process during late evolution. However, some differences between the monzogranites and granodiorites indicate that there are varying degree contributions of subducted sediments during diagenesis. The LSG group contains syenogranites that have distinct negative correlations between their P2O5 and SiO2 contents, and Y and Th contents have significant positive

Devonian lacustrine shore zone architecture imaged with ground penetrating radar

DEFF Research Database (Denmark)

Andrews, Steven D.; Moreau, Julien; Archer, Stuart

. The shore zone sandstones overlie playa facies which contain abundant desiccation horizons, reflecting the most arid phase in the climatically controlled lacustrine cycle. As climatic conditions ameliorated the rejuvenation of fluvial systems resulted in the transport of sand out into the basin. Initial...... deposition was limited to intermittent events where sediment was laid down on a water saturated substrate. Some of these may have occurr­­­ed subaqueously as small scale turbidity flows. High resolution fluctuations in lake level resulted in periodic short lived reworking events along the lake margin which...

Dissolved methane in New York groundwater, 1999-2011

Science.gov (United States)

Kappel, William M.; Nystrom, Elizabeth A.

2012-01-01

New York State is underlain by numerous bedrock formations of Cambrian to Devonian age that produce natural gas and to a lesser extent oil. The first commercial gas well in the United States was dug in the early 1820s in Fredonia, south of Buffalo, New York, and produced methane from Devonian-age black shale. Methane naturally discharges to the land surface at some locations in New York. At Chestnut Ridge County Park in Erie County, just south of Buffalo, N.Y., several surface seeps of natural gas occur from Devonian black shale, including one behind a waterfall. Methane occurs locally in the groundwater of New York; as a result, it may be present in drinking-water wells, in the water produced from those wells, and in the associated water-supply systems (Eltschlager and others, 2001). The natural gas in low-permeability bedrock formations has not been accessible by traditional extraction techniques, which have been used to tap more permeable sandstone and carbonate bedrock reservoirs. However, newly developed techniques involving horizontal drilling and high-volume hydraulic fracturing have made it possible to extract previously inaccessible natural gas from low-permeability bedrock such as the Marcellus and Utica Shales. The use of hydraulic fracturing to release natural gas from these shale formations has raised concerns with water-well owners and water-resource managers across the Marcellus and Utica Shale region (West Virginia, Pennsylvania, New York and parts of several other adjoining States). Molofsky and others (2011) documented the widespread natural occurrence of methane in drinking-water wells in Susquehanna County, Pennsylvania. In the same county, Osborn and others (2011) identified elevated methane concentrations in selected drinking-water wells in the vicinity of Marcellus gas-development activities, although pre-development samples were not available for comparison. In order to manage water resources in areas of gas-well drilling and hydraulic

Discovery of a Triassic magmatic arc source for the Permo-Triassic Karakaya subduction complex, NW Turkey

Science.gov (United States)

Ayda Ustaömer, Petek; Ustaömer, Timur; Gerdes, Axel; Robertson, Alastair H. F.; Zulauf, Gernold

2014-05-01

The Permo-Triassic Karakaya Complex is well explained by northward subduction of Palaeotethys but until now no corresponding magmatic arc has been identified in the region. With the aim of determining the compositions and ages of the source units, ten sandstone samples were collected from the mappably distinct Ortaoba, Hodul, Kendirli and Orhanlar Units. Zircon grains were extracted from these sandstones and >1300 were dated by the U-Pb method and subsequently analysed for the Lu-Hf isotopic compositions by LA-MC-ICPMS at Goethe University, Frankfurt. The U-Pb-Hf isotope systematics are indicative of two different sediment provenances. The first, represented by the Ortaoba, Hodul and Kendirli Units, is dominated by igneous rocks of Triassic (250-220 Ma), Early Carboniferous-Early Permian (290-340 Ma) and Early to Mid-Devonian (385-400 Ma) ages. The second provenance, represented by the Orhanlar Unit, is indicative of derivation from a peri-Gondwanan terrane. In case of the first provenance, the Devonian and Carboniferous source rocks exibit intermediate eHf(t) values (-11 to -3), consistent with the formation at a continental margin where juvenile mantle-derived magmas mixed with (recycled) old crust having Palaeoproterozoic Hf model ages. In contrast, the Triassic arc magma exhibits higher eHf(t) values (-6 to +6), consistent with the mixing of juvenile mantle-derived melts with (recycled) old crust perhaps somewhat rejuvanated during the Cadomian period. We have therefore identified a Triassic magmatic arc as predicted by the interpretation of the Karakaya Complex as an accretionary complex related to northward subduction (Carboniferous and Devonian granites are already well documented in NW Turkey). Possible explanations for the lack of any outcrop of the source magmatic arc are that it was later subducted or the Karakaya Complex was displaced laterally from its source arc (both post 220 Ma). Strike-slip displacement (driven by oblique subduction?) can also

A comparative study of detrital zircon ages from river sediment and rocks of the Karoo Supergroup (Late Carboniferous to Jurassic), Eastern Cape Province, South Africa : implications for the tectono-sedimentary evolution of Gondwanaland’s southern continental margin

OpenAIRE

2014-01-01

M.Sc. (Geology) The Mzimvubu River, situated in the Eastern Cape Province of South Africa, drains essentially strata of the Late Carboniferous to Jurassic Karoo Supergroup with minor intersection of the underlying Devonian Msikaba Formation near the mouth of the river at Port St. Johns. Rock- and river sediment samples were collected at specific points from within the Mzimvubu River drainage basin, based on changes in the geology through which the rivers flow. Detrital zircon age populatio...

Geological analysis of paleozoic large-scale faulting in the south-central Pyrenees

OpenAIRE

Speksnijder, A.

1986-01-01

Detailed structural and sedimentological analysis reveals the existence of an east-west directed fundamental fault zone in the south-central Pyrenees, which has been intermittently active from (at least) the Devonian on. Emphasis is laid on the stUdy of fault-bounded post-Variscan (StephanoPermian) sedimentary basins, and the influence of Late Paleozoic faulting on the underlying Variscan basement. The present structure of the basement is rather complex as it results from multiple Variscan an...

Macroinvertebrate palaeo-communities from the Jurassic succession of Gebel Maghara (Sinai, Egypt)

Science.gov (United States)

Abdelhady, Ahmed Awad; Fürsich, Franz Theodor

2014-09-01

Macrobenthic palaeo-communities of the Middle and Upper Jurassic strata of G. Maghara, Egypt, were investigated to identify relationships with environmental parameters and to trace the temporal changes of the ecosystem associated with sea-level fluctuations. The quantitative analysis of a data matrix comprising 198 macrobenthic taxa in 138 samples collected from four sections identified nine associations and three assemblages, interpreted to be representative of their original environment. Non-Metric Multidimensional Scaling (NMDS) delineated the same degree of habitat partitioning as hierarchical clusters with very little overlap. Detrended Correspondence Analysis (DCA) identified water depth as the primary environmental gradient controlling the distribution of the fauna, while Axis 2 reflects substrate consistency. Community structure is related to the various ramp environments. Based on diversities, the associations and assemblages have been divided into two major groups, low-stress polyspecific associations and high-stress paucispecific associations. The low-stress polyspecific associations were interpreted to represent two different habitats, a high-energy, firm substrate habitat, in which epifaunal bivalves and brachiopods in addition to solitary corals dominated during advanced stages of transgression, and a low-energy, soft substrate habitat dominated by infaunal bivalves during the maximum flooding. The high-stress paucispecific associations are dominated by one or few taxa and occurred (1) in an oligotrophic setting that developed during episodes of sediment starvation in restricted inner ramp environments or during early transgression, (2) in a setting characterized by high sedimentation rates which developed during advanced regression, (3) in a distal prodelta setting with soft substrate and dysoxia during sea-level lowstand, and (4) in a high-energy shoal environment during peak regression. A combined stress involving a shortage in food supply

Multigene analysis of lophophorate and chaetognath phylogenetic relationships.

Science.gov (United States)

Helmkampf, Martin; Bruchhaus, Iris; Hausdorf, Bernhard

2008-01-01

Maximum likelihood and Bayesian inference analyses of seven concatenated fragments of nuclear-encoded housekeeping genes indicate that Lophotrochozoa is monophyletic, i.e., the lophophorate groups Bryozoa, Brachiopoda and Phoronida are more closely related to molluscs and annelids than to Deuterostomia or Ecdysozoa. Lophophorates themselves, however, form a polyphyletic assemblage. The hypotheses that they are monophyletic and more closely allied to Deuterostomia than to Protostomia can be ruled out with both the approximately unbiased test and the expected likelihood weights test. The existence of Phoronozoa, a putative clade including Brachiopoda and Phoronida, has also been rejected. According to our analyses, phoronids instead share a more recent common ancestor with bryozoans than with brachiopods. Platyhelminthes is the sister group of Lophotrochozoa. Together these two constitute Spiralia. Although Chaetognatha appears as the sister group of Priapulida within Ecdysozoa in our analyses, alternative hypothesis concerning chaetognath relationships could not be rejected.

The post-Laramide clastic deposits of the Sierra de Guanajuato: Compositional implications on the tectono-sedimentary and paleographic evolution

Energy Technology Data Exchange (ETDEWEB)

Miranda-Aviles, R.; Puy-Alquiza, M.J.; OmaNa, L.; Loza-Aguirre, I.

2016-07-01

This article presents the results of the study on sedimentation, sedimentary environments, tectono-sedimentary and paleogeographic evolution of post-Laramide clastic deposits and pre-volcanism of the Sierra Madre Occidental in the Sierra de Guanajuato, central Mexico. The Eocene Duarte Conglomerate and Guanajuato Conglomerate were deposited in the middle and distal parts of alluvial fans. The studied rocks are composed of limestone clasts, granite, andesite, metasediments, diorite, and pyroxenite, indicating the erosion of uplifted blocks of the basal complex of the Sierra de Guanajuato (Arperos basin). The petrographic and compositional analysis of limestone shows a textural variation from basin limestones and shallow platform limestones. The shallow platform limestone contain bivalves, brachiopods, gastropods, echinoderms and benthic foraminifera from the Berriasian-Valanginian. The shallow-water limestone corresponds to the boundary of the Arperos basin whose original outcrops currently not outcrop in the Sierra de Guanajuato. (Author)

Terrestrial-style feeding in a very early aquatic tetrapod is supported by evidence from experimental analysis of suture morphology.

Science.gov (United States)

Markey, Molly J; Marshall, Charles R

2007-04-24

There is no consensus on when in the fish-tetrapod transition suction feeding, the primary method of prey capture in the aquatic realm, evolved into the direct biting on prey typical of terrestrial animals. Here, we show that differences in the morphology of selected cranial sutures between species that span the fish-tetrapod transition (the Devonian osteolepiform fish Eusthenopteron, the aquatic Devonian tetrapod Acanthostega, and the Permian terrestrial tetrapod Phonerpeton) can be used to infer when terrestrial feeding first appeared. Our approach consists of defining a sutural morphospace, assigning functional fields to that morphospace based on our previous measurements of suture function made during feeding in the living fish Polypterus, inferring the functions of the fossil sutures based on where they fall in the morphospace, and then using the correlation between feeding mode and the patterns of inferred suture function across the skull roof in taxa where feeding mode is unambiguous to infer the feeding mode practiced by Acanthostega. Using this procedure, we find that the suture morphologies of Acanthostega are inconsistent with the hypothesis that it captured prey primarily by means of suction, which suggests that it may have bitten directly on prey at or near the water's edge. Thus, our data strongly support the hypothesis that the terrestrial mode of feeding first emerged in aquatic taxa.

Life history of the stem tetrapod Acanthostega revealed by synchrotron microtomography.

Science.gov (United States)

Sanchez, Sophie; Tafforeau, Paul; Clack, Jennifer A; Ahlberg, Per E

2016-09-15

The transition from fish to tetrapod was arguably the most radical series of adaptive shifts in vertebrate evolutionary history. Data are accumulating rapidly for most aspects of these events, but the life histories of the earliest tetrapods remain completely unknown, leaving a major gap in our understanding of these organisms as living animals. Symptomatic of this problem is the unspoken assumption that the largest known Devonian tetrapod fossils represent adult individuals. Here we present the first, to our knowledge, life history data for a Devonian tetrapod, from the Acanthostega mass-death deposit of Stensiö Bjerg, East Greenland. Using propagation phase-contrast synchrotron microtomography (PPC-SRμCT) to visualize the histology of humeri (upper arm bones) and infer their growth histories, we show that even the largest individuals from this deposit are juveniles. A long early juvenile stage with unossified limb bones, during which individuals grew to almost final size, was followed by a slow-growing late juvenile stage with ossified limbs that lasted for at least six years in some individuals. The late onset of limb ossification suggests that the juveniles were exclusively aquatic, and the predominance of juveniles in the sample suggests segregated distributions of juveniles and adults at least at certain times. The absolute size at which limb ossification began differs greatly between individuals, suggesting the possibility of sexual dimorphism, adaptive strategies or competition-related size variation.

The volcanic rocks construction of the late paleozoic era and uranium mineralization in Beishan area of Gansu province

International Nuclear Information System (INIS)

An Zhengchang; Luo Xiaoqiang

2010-01-01

Late Paleozoic volcanic rocks in Beishan area are the favorable constructions of hydrothermal type and volcanic type deposit. From the distribution of volcanic rocks, the volcanic compositions, the volcanic facies, volcanic eruption method and rhythm, chemical and trace elements compositions, and so on, it discusses the characteristics of the Late Devonian volcanic construction in this area and its relationship with uranium mineralization, analyzes the role of volcanic ore-control mechanism, and summarizes uranium ore forming regularity of volcanic construction in Late Paleozoic. (authors)

Reevaluation of the Piermont-Frontenac allochthon in the Upper Connecticut Valley: Restoration of a coherent Boundary Mountains–Bronson Hill stratigraphic sequence

Science.gov (United States)

Rankin, Douglas W.; Tucker, Robert D.; Amelin, Yuri

2013-01-01

The regional extent and mode and time of emplacement of the Piermont-Frontenac allochthon in the Boundary Mountains–Bronson Hill anticlinorium of the Upper Connecticut Valley, New Hampshire–Vermont, are controversial. Moench and coworkers beginning in the 1980s proposed that much of the autochthonous pre–Middle Ordovician section of the anticlinorium was a large allochthon of Silurian to Early Devonian rocks correlated to those near Rangeley, Maine. This ∼200-km-long allochthon was postulated to have been transported westward in the latest Silurian to Early Devonian as a soft-sediment gravity slide on a hypothesized Foster Hill fault. New mapping and U-Pb geochronology do not support this interpretation. The undisputed Rangeley sequence in the Bean Brook slice is different from the disputed sequence in the proposed larger Piermont-Frontenac allochthon, and field evidence for the Foster Hill fault is lacking. At the type locality on Foster Hill, the postulated “fault” is a stratigraphic contact within the Ordovician Ammonoosuc Volcanics. The proposed Foster Hill fault would place the Piermont-Frontenac allochthon over the inverted limb of the Cornish(?) nappe, which includes the Emsian Littleton Formation, thus limiting the alleged submarine slide to post-Emsian time. Mafic dikes of the 419 Ma Comerford Intrusive Complex intrude previously folded strata attributed to the larger Piermont-Frontenac allochthon as well as the autochthonous Albee Formation and Ammonoosuc Volcanics. The Lost Nation pluton intruded and produced hornfels in previously deformed Albee strata. Zircons from an apophysis of the pluton in the hornfels have a thermal ionization mass spectrometry 207Pb/206Pb age of 444.1 ± 2.1 Ma. Tonalite near Bath, New Hampshire, has a zircon sensitive high-resolution ion microprobe 206Pb/238U age of 492.5 ± 7.8 Ma. The tonalite intrudes the Albee Formation, formerly interpreted as the Silurian Perry Mountain Formation of the proposed allochthon

Middle to Late Devonian–Carboniferous collapse basins on the Finnmark Platform and in the southwesternmost Nordkapp basin, SW Barents Sea

Directory of Open Access Journals (Sweden)

J.-B. P. Koehl

2018-03-01

Full Text Available The SW Barents Sea margin experienced a pulse of extensional deformation in the Middle–Late Devonian through the Carboniferous, after the Caledonian Orogeny terminated. These events marked the initial stages of formation of major offshore basins such as the Hammerfest and Nordkapp basins. We mapped and analyzed three major fault complexes, (i the Måsøy Fault Complex, (ii the Rolvsøya fault, and (iii the Troms–Finnmark Fault Complex. We discuss the formation of the Måsøy Fault Complex as a possible extensional splay of an overall NE–SW-trending, NW-dipping, basement-seated Caledonian shear zone, the Sørøya–Ingøya shear zone, which was partly inverted during the collapse of the Caledonides and accommodated top–NW normal displacement in Middle to Late Devonian–Carboniferous times. The Troms–Finnmark Fault Complex displays a zigzag-shaped pattern of NNE–SSW- and ENE–WSW-trending extensional faults before it terminates to the north as a WNW–ESE-trending, NE-dipping normal fault that separates the southwesternmost Nordkapp basin in the northeast from the western Finnmark Platform and the Gjesvær Low in the southwest. The WNW–ESE-trending, margin-oblique segment of the Troms–Finnmark Fault Complex is considered to represent the offshore prolongation of a major Neoproterozoic fault complex, the Trollfjorden–Komagelva Fault Zone, which is made of WNW–ESE-trending, subvertical faults that crop out on the island of Magerøya in NW Finnmark. Our results suggest that the Trollfjorden–Komagelva Fault Zone dies out to the northwest before reaching the western Finnmark Platform. We propose an alternative model for the origin of the WNW–ESE-trending segment of the Troms–Finnmark Fault Complex as a possible hard-linked, accommodation cross fault that developed along the Sørøy–Ingøya shear zone. This brittle fault decoupled the western Finnmark Platform from the southwesternmost Nordkapp basin and merged with the

Tectonic setting of synorogenic gold deposits of the Pacific Rim

Science.gov (United States)

Goldfarb, R.J.; Phillips, G.N.; Nokleberg, W.J.

1998-01-01

More than 420 million oz of gold were concentrated in circum-Pacific synorogenic quartz loades mainly during two periods of continental growth, one along the Gondwanan margin in the Palaeozoic and the other in the northern Pacific basin between 170 and 50 Ma. These ores have many features in common and can be grouped into a single type of lode gold deposit widespread throughout clastic sedimentary-rock dominant terranes. The auriferous veins contain only a few percent sulphide minerals, have gold:silver ratios typically greater than 1:1, show a distinct association with medium grade metamorphic rocks, and may be associated with large-scale fault zone. Ore fluids are consistently of low salinity and are CO2-rich. In the early and middle Palaeozoic in the southern Pacific basin, a single immense turbidite sequence was added to the eastern margin of Gondwanaland. Deformation of these rocks in southeastern Australia was accompanied by deposition of at least 80 million oz of gold in the Victorian sector of the Lachlan fold belt mainly during the Middle and Late Devonian. Lesser Devonian gold accumulations characterized the more northerly parts of the Gondwanan margin within the Hodgkinson-Broken River and Thomson fold belts. Additional lodes were emplaced in this flyschoid sequence in Devonian or earlier Palaeozoic times in what is now the Buller Terrane, Westland, New Zealand. Minor post-Devonian growth of Gondwanaland included terrane collision and formation of gold-bearing veins in the Permian in Australia's New England fold belt and in the Jurassic-Early Cretaceous in New Zealand's Otago schists. Collision and accretion of dozens of terranes for a 100-m.y.-long period against the western margin of North America and eastern margin of Eurasia led to widespread, lattest Jurassic to Eocene gold veining in the northern Pacific basin. In the former location, Late Jurassic and Early Cretaceous veins and related placer deposits along the western margin of the Sierra Nevada

The glacial geology and landscape of Strathmore and adjoining offshore zone, with especial reference to 1:10 000 scale Sheet NO76NW

OpenAIRE

Golledge, N.R.; Stoker, M.S.

2004-01-01

This report describes the Bedrock and Superficial Geology of 1:10 000 Sheet NO76NW (Craig of Garvock) within the Strathmore area of eastern Scotland. It forms part of the revision of Montrose 1:50 000 Geological Sheet (57E). Strathmore forms a low vale bounded to the north by the Highland Boundary Fault (HBF), and to the south by the Sidlaw Hills. NO76NW is underlain by a Devonian sedimentary sequence with interdigitating contemporaneous igneous sheets. The northern edge of the field-ma...

Pre-Carboniferous sedimentary sequences of the northeastern flank of the Parana basin and southwestern of the Parnaiba basin and its uraniferous possibilites

International Nuclear Information System (INIS)

Andrade, S.M. de; Camarco, P.E.N.

1982-01-01

The analyses of the already existent geological data of the northeastern flank of the Parana Basin and the Southwestern flank of the Parnaiba Basin, added to new data from drilling and geological mapping allowed a better knowledge of the stratigraphy of the pre-carboniferous sedimentary sequences (silurian and devonian ages) as well as provided subsidies for the definition of its uranium possibilites. Besides the already known uranium deposits of the Ponta Grossa Formation, is should be considered as worth while of prospecting the Pimenteiras Formation. (Author) [pt

Assessment of water and proppant quantities associated with petroleum production from the Bakken and Three Forks Formations, Williston Basin Province, Montana and North Dakota, 2016

Science.gov (United States)

Haines, Seth; Varela, Brian A.; Hawkins, Sarah J.; Gianoutsos, Nicholas J.; Thamke, Joanna N.; Engle, Mark A.; Tennyson, Marilyn E.; Schenk, Christopher J.; Gaswirth, Stephanie B.; Marra, Kristen R.; Kinney, Scott A.; Mercier, Tracey J.; Martinez, Cericia D.

2017-06-23

The U.S. Geological Survey (USGS) has completed an assessment of water and proppant requirements and water production associated with the possible future production of undiscovered oil and gas resources in the Three Forks and Bakken Formations (Late Devonian to Early Mississippian) of the Williston Basin Province in Montana and North Dakota. This water and proppant assessment is directly linked to the geology-based assessment of the undiscovered, technically recoverable continuous oil and gas resources that is described in USGS Fact Sheet 2013–3013.

Germanium and uranium in coalified wood from upper Devonian black shale

Energy Technology Data Exchange (ETDEWEB)

Breger, I A; Schopf, J M

1955-02-01

Spectrographic analyses were performed on carbonaceous material and shale samples from the Chattanooga shale in Tennessee and the Cleveland member of the Ohio shale in Ohio with particular emphasis on U and Ge. Semiquantitative analyses for 29 elements (Fe, Si, Ge, Al, Ca, V, Ni, U, Mg, Cu, Ti, Cr, Mo, Na, Sr, B, Y, Pb, Ba, Co, Sn, Zr, Mn, Zn, Yb, Ga, Sc, Be) were performed on both ash specimens and whole sample. The analyses showed unusually high percentages of Ge (1 to 5%) U (0.1 to 1%), V (1 to 5%), and Ni (0.1 to 1%) in the ash of coal from the Chattanooga and Ohio shales. Quantitative chemical analysis for U, Ge, V, and Ni in the whole coal and ash were done to check the results of the semiquantitative analyses. Ash content from the proximate analyses indicated that the coal samples tested were similar to vitrain in ash percentage. Because of the unusually high percentages of U and Ge and the low ash of the coals tested, the author felt that the U and Ge might be associated wire also observed with lower radiation doses (200 and 400 rad).

A NEW DAONELLA FROM THE LADINIAN PLATFORM OF THE ESINO LIMESTONE (SOUTHERN ALPS, ITALY

Directory of Open Access Journals (Sweden)

CRISTIANO LARGHI

2006-03-01

Full Text Available The bivalve Daonella Mojsisovics, 1874 is very common in the Middle Triassic pelagic facies, whereas the record of this genus from shallow water limestones is rare. In the present paper a new species of Daonella, named D. pseudograbensis, is described from the Esino Limestone, a Ladinian (Middle Triassic carbonate platform in the central Southern Alps. The species is described from Brembana Valley, where the Esino Limestone is rather rich in bioclastic lenses yielding faunas with bivalves, cephalopods, gastropods, brachiopods, corals and calcareous algae. Daonella pseudograbensis n. sp. is based on very well preserved specimens, which are often articulated and closed, all coming from the same locality. The new species shows a narrow range of intraspecific and ontogenetic morphologic variations. It is easy distinguishable from the other species of the genus for the outline and ornamentation; it therefore differs from D. grabensis Kittl, 1912, the most similar species, for the longer anterior dorsal margin.Pdf

Geochemical Aspects of Formation of Large Oil Deposits in the Volga-Ural Sedimentary Basin

Science.gov (United States)

Plotnikova, I.; Nosova, F.; Pronin, N.; Nosova, J.; Budkevich, T.

2012-04-01

The study of the rocks domanikoid type in the territory of the Ural-Volga region has an almost century-long history, beginning with the first studies of A.D. Archangelsky in the late 20's of last century. But nevertheless the question of the source of oil that formed the industrial deposits of Volga-Ural oil and gas province (OGP), where Romashkinskoye oil field occupies a special place, remains unresolved and topical. According to the sedimentary-migration theory of origin of oil and gas, it is supposed that the primary source of hydrocarbons in this area are the deposits of domanikoid type that contain a large ammount of sapropel organic matter (OM). Semiluki (domanik) horizon of srednefranski substage of the Upper Devonian is considered to be a typical domanikoid stratum. Investigation of the OM of the rocks and oils of the sedimentary cover on the basis of chromato-mass spectrometry method allows us to study the correlations between rock and oil and to assess the location (or absence) of the sources of hydrocarbons in the Paleozoic sedimentary cover. The results of geochemical study of dispersed organic matter (DOM) of rocks from Semiluksky horizon of the Upper Devonian and of the oil from Pashiysky horizon of the Middle Devonian form the basis of this paper. The objectives of this study were the following: to determine the original organic matter of the rocks, which would indicate the conditions of sedimentation of the supposed rock-oil sources; the study of chemofossils (biomarkers) in oil from Pashiyskiy horizon; and the identification of genetic association of DOM rocks from Semiluksky horizon with this oil on the basis of the oil-DOM correlation. The study of biomarkers was carried out with the help of chromato-mass spectrometry in the Laboratory of Geochemistry of Fossil Fuels (Kazan Federal University). In this study we used several informative parameters characterizing the depositional environment, the type of source OM and its maturity: STER / PENT, h

Geochemistry and Cyclostratigraphy of Magnetic Susceptibility data from the Frasnian-Famennian event interval in western Canada: Insights in the pattern and timing of a biotic crisis

Science.gov (United States)

Whalen, M. T.; De Vleeschouwer, D.; Sliwinski, M. G.; Claeys, P. F.; Day, J. E.

2012-12-01

Cyclostratigraphic calibration of magnetic susceptibility data along with stable isotopic and geochemical proxy data for redox, productivity, and detrital input from western Canada provide insight into the pace and timing of the Late Devonian, Frasnian-Famennian (F-F) biotic crisis. Two organic-rich shales that, in much of the world, display geochemical anomalies indicating low oxygen conditions and carbon burial characterize the F-F event. These events, referred to as the Lower and Upper Kellwasser events (LKE & UKE), have been linked to the evolutionary expansion of deeply rooted terrestrial forests and the concomitant changes in soil development and chemical weathering and changes in Late Devonian climate. Our geochemical data record relatively high levels of redox sensitive trace metals (Mo, U, V), proxies for biological productivity (Ba, Cu, Ni, Zn), and detrital input (Al, Si, Ti, Zr) during both events. C stable isotopic data generated from organic matter records a 3-4‰ positive excursion during both events. Each event is recorded in lowstand and/or early transgressive facies. These data corroborate hypotheses about enhanced biological productivity, driven by heightened terrestrial detrital input, leading to low oxygen conditions and decreases in biotic diversity during during relatively low stands of Late Devonian sea level. Age dating of such events in deep time is problematic due to insufficient biochronologic control. Each event is within one conodont biostratigraphic zone, with durations on the order of 0.5-1.0 Ma. Time series analysis of high-resolution magnetic susceptibility data identified 16 long eccentricity cycles (405 ky) during the Frasnian stage and one in the earliest Famennian stage. The geochemical anomalies associated with the LKE and UKE are recorded over 7 and 14 m of stratigraphic section respectively. These strata represent only a portion of a 405 ky long eccentricity cycle and astronomical tuning implies that the LKE likely occurred

Geochemistry and origin of regional dolomites

International Nuclear Information System (INIS)

Hanson, G.N.; Meyers, W.J.

1989-12-01

The major goal of the carbonate research program at Stony Brook is to better understand the conditions and processes leading to regional diagenesis of carbonate rocks. Our research focuses on studies of ancient, massive dolostones, but we are also studying limestone diagenesis for its own importance, and as it relates to dolomitization. Our approach has been to carry out a very detailed petrographic and geochemical case study to the Mississippian Burlington-Keokuk Fms. of Iowa, Illinois and Missouri, and to develop this as a testing ground for new geochemical and modelling techniques, and for testing various models for regional dolomitization in epicontinental carbonates. The ideas and techniques developed in our Burlington-Keokuk studies are being expanded and applied to carbonate sequences of other ages (Devonian to Neogene), and other tectono-sedimentary settings. The emphasis of this report will be on new developments and results on the Burlington-Keokuk studies and on our diagenetic studies of other strata. Recent research on Burlington-Keokuk rocks include development and application of boron isotopes and the U--Th--Pb system to dolomite studies, investigations of porosity and permeability in the dolostones. Projects on other strata include dolomitization and limestones diagenesis of Devonian carbonates of Alberta and Western Australia, Miocene reefal carbonates of Spain, Neogene carbonates of Curacao and Bonaire, Waulsortian limestones of Ireland, modelling of trace elements and stable isotopes, and experimental growth of calcites to investigate crystallographic controls of trace element incorporation. 118 refs., 46 figs

Productivity Contribution of Paleozoic Woodlands to the Formation of Shale-Hosted Massive Sulfide Deposits in the Iberian Pyrite Belt (Tharsis, Spain)

Science.gov (United States)

Fernández-Remolar, David C.; Harir, Mourad; Carrizo, Daniel; Schmitt-Kopplin, Philippe; Amils, Ricardo

2018-03-01

The geological materials produced during catastrophic and destructive events are an essential source of paleobiological knowledge. The paleobiological information recorded by such events can be rich in information on the size, diversity, and structure of paleocommunities. In this regard, the geobiological study of late Devonian organic matter sampled in Tharsis (Iberian Pyrite Belt) provided some new insights into a Paleozoic woodland community, which was recorded as massive sulfides and black shale deposits affected by a catastrophic event. Sample analysis using TOF-SIMS (Time of Flight Secondary Ion Mass Spectrometer), and complemented by GC/MS (Gas Chromatrograph/Mass Spectrometer) identified organic compounds showing a very distinct distribution in the rock. While phytochemical compounds occur homogeneously in the sample matrix that is composed of black shale, the microbial-derived organics are more abundant in the sulfide nodules. The cooccurrence of sulfur bacteria compounds and the overwhelming presence of phytochemicals provide support for the hypothesis that the formation of the massive sulfides resulted from a high rate of vegetal debris production and its oxidation through sulfate reduction under suboxic to anoxic conditions. A continuous supply of iron from hydrothermal activity coupled with microbial activity was strictly necessary to produce this massive orebody. A rough estimate of the woodland biomass was made possible by accounting for the microbial sulfur production activity recorded in the metallic sulfide. As a result, the biomass size of the late Devonian woodland community was comparable to modern woodlands like the Amazon or Congo rainforests.

Homogenity of geological units with respect to the radon risk in the Walloon region of Belgium.

Science.gov (United States)

Tondeur, François; Cinelli, Giorgia; Dehandschutter, Boris

2014-10-01

In the process of mapping indoor radon risk, an important step is to define geological units well-correlated with indoor radon. The present paper examines this question for the Walloon region of Belgium, using a database of more than 18,000 indoor radon measurements. With a few exceptions like the Carboniferous (to be divided into Tournaisian, Visean and Namurian-Westphalian) and the Tertiary (in which all Series may be treated together), the Series/Epoch stratigraphic level is found to be the most appropriate geological unit to classify the radon risk. A further division according to the geological massif or region is necessary to define units with a reasonable uniformity of the radon risk. In particular, Paleozoic series from Cambrian to Devonian show strong differences between different massifs. Local hot-spots are also observed in the Brabant massif. Finally, 35 geological units are defined according to their radon risk, 6 of which still present a clear weak homogeneity. In the case of 4 of these units (Jurassic, Middle Devonian of Condroz and of Fagne-Famenne, Ordovician of the Stavelot massif) homogeneity is moderate, but the data are strongly inhomogeneous for Visean in Condroz and in the Brabant massif. The 35 geological units are used in an ANOVA analysis, to evaluate the part of indoor radon variability which can be attributed to geology. The result (15.4-17.7%) agrees with the values observed in the UK. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Relaciones isotópicas Sm/Nd en rocas graníticas y miloníticas de Sierras Pampeanas del noroeste Argentino

Directory of Open Access Journals (Sweden)

Kawashita, K.

2005-04-01

Full Text Available The Velasco, Copacabana and Paimán Ranges in Sierras Pampeanas, are constituted mainly by paleozoic plutonic bodies of the Famatinian cycle (Huaco, Antinaco and Paimán and for mylonitic rocks (TIPA Shear Zone, originated as a consequence of dynamic events happening during the Upper Ordovician-Devonian. The last magmatic event of the area would probably have of devonian age (Granite San Blas. Model-ages of two stages were calculated based on 147Sm/144Nd relationships; the obtained values are closely grouped at around 1594 Ma. and the more plausible interpretation seems to be a reworking of an Early Proterozoic protolith.Las sierras de Velasco, Copacabana y Paimán, en el ambiente de Sierras Pampeanas, están constituidas principalmente por cuerpos plutónicos del Paleozoico inferior, relacionados con el ciclo Famatiniano (Granitos Huaco, Antinaco y Paimán y por rocas miloníticas (Faja Milonítica TiPA, originadas a partir de estos protolitos como consecuencia de eventos dinámicos acaecidos durante el Ordovícico superior-Devónico. El último evento magmático del área es de edad probablemente devónica (Granito San Blas. Se calcularon edades modelos de «dos estadios» en base a relaciones 147Sm/144Nd; los valores obtenidos se presentan estrechamente agrupadas en torno a 1594 Ma. y se interpretan a este basamento como un protolito del Proterozoico medio retrabajado.

Uranium geology and prospecting in Greenland

International Nuclear Information System (INIS)

Steenfelt, A.; Neilson, B.L.; Secher, K.

1977-01-01

The Geological Survey of Greenland is responsible for most of the uranium and thorium prospecting activity in Greenland, which involves airborne gamma spectrometry and scintillometry, geochemical sampling, geological investigations and ground scintillometry. Since 1971 large areas of east and west Greenland have been investigated by aerial surveys, geochemical sampling and most of the detailed scintillometric work having been restricted to small areas in east Greenland. Anomalous radioactivity in west Greenland is recorded from carbonatite intrusions, and from units in Proterozoic and Archaean gneisses. No mineralization has been found to date. In south Greenland investigations have been centred on the uranium and thorium deposit at Kvanefjeld, which is situated in a corner of the Ilimaussaq alkaline intrusion. The coincidence of favourable conditions during the differentiation and crystallization of the magma led to an extreme enrichment of uranium and thorium in the rocks that were last formed - the lujavrites. The deposit comprises parts of the lujavrites and a secondary enrichment zone in the contact between lujavrite and basaltic cover rocks. Reasonably assured reserves are 5800 t U with a grade of 310 ppm U. In the Caledonides of east Greenland some gneisses in basement cores, a dark siltstone in late Precambrian sediments and the Devonian acid magmatic rocks are characterized by a higher radiation level. A number of small mineral occurrences have been found, the majority of which are associated with the Devonian acid magmatic rocks. (author)

Application of apatite fission tract analysis to problems of Mississippi Valley-type Pb-Zn ore genesis

International Nuclear Information System (INIS)

Arne, D.C.; Duddy, I.R.; Green, P.F.; Lambert, I.B.

1987-01-01

Epigenetic, carbonate-hosted Pb-Zn mineralization of the Mississippi Valley-Type (MVT) is considered to form from warm basinal brines in the temperature range 50-200 deg.C. A variety of genetic fluid flow models have been proposed to explain MVT mineralization, but all suffer from a lack of constraint concerning the timing of ore formation. Fission tracks in apatite resulting from the spontaneous decay of trace amounts of 238 U are thermally unstable over the range of temperatures proposed for MVT ore formation, and may therefore record thermal events related to Pb-Zn mineralization provided sufficient time is allowed for track annealing to occur. Zinc mineralization in Devonian carbonates of the Lennard Shelf, northwest Australia is also considered to be of the Mississippi Valley-type. Mean apatite ages from Precambrian basement and from Devonian carbonates generally average 300Ma. Studies of well sequences indicate a period of uplift for the Lennard Shelf area around the Late Triassic/Early Jurassic. For carbonate outcrop samples, a thermal history is proposed involving burial in the Late Paleozoic/Early Mesozoic followed by uplift and cooling from peak temperatures around 70 deg.C. No difference in apatite annealing effects are observed in the vicinity of zinc mineralization. Coupled with other evidence, this suggests that the mineralizing episode was of short duration given temperatures of ore formation in the range 70-110 deg.C indicated by fluid inclusion homogenization temperatures. 3 refs

Cathodoluminescence, fluid inclusions and trace element data for the syntaxial quartz cementation in the sandstones of Ora Formation, northern Iraq

DEFF Research Database (Denmark)

Omer, Muhamed Fakhri; Friis, Henrik

2018-01-01

Quartz cements of the quartz arenitic sandstones from the Chalky Nasara and Ora section of the (Devonian-Carboniferous) Ora Formation in northern Iraq have been studied. A combination of Hot-Cathodoluminescence (CL), LA-ICP-MS and fluid inclusions microthermometry revealed three syntaxial quartz......-bedded sandstones than in the6 thickly-bedded sandstones filling most of remaining pore space during mesogenesis. The Q3 was formed during early telogenesis stage fully cementing the sandstones and the fractures were filled by hydrothermal chlorite and sulfides. Significant amount of trace elements Al, Li, Ge...

Hunton Group core workshop and field trip

Energy Technology Data Exchange (ETDEWEB)

Johnson, K.S. [ed.

1993-12-31

The Late Ordovician-Silurian-Devonian Hunton Group is a moderately thick sequence of shallow-marine carbonates deposited on the south edge of the North American craton. This rock unit is a major target for petroleum exploration and reservoir development in the southern Midcontinent. The workshop described here was held to display cores, outcrop samples, and other reservoir-characterization studies of the Hunton Group and equivalent strata throughout the region. A field trip was organized to complement the workshop by allowing examination of excellent outcrops of the Hunton Group of the Arbuckle Mountains.

A paleozoic pangaea.

Science.gov (United States)

Boucot, A J; Gray, J

1983-11-11

Paleozoic paleogeographies should be consistent with all available, reliable data. However, comparison of three different Devonian paleogeographies that are based largely or wholly on the data of remanent magnetism show them to be inconsistent in many regards. When these three paleogeographies are provided with possible ocean surface current circulation patterns, and have added to them lithofacies and biogeographic data, they also are shown to be inconsistent with such data. A pangaeic reconstruction positioned in the Southern Hemisphere permits the lithofacies and biogeographical data to be reconciled in a plausible manner.

Geology of Paleozoic Rocks in the Upper Colorado River Basin in Arizona, Colorado, New Mexico, Utah, and Wyoming, Excluding the San Juan Basin

Science.gov (United States)

Geldon, Arthur L.

2003-01-01

The geology of the Paleozoic rocks in the Upper Colorado River Basin in Arizona, Colorado, New Mexico, Utah, and Wyoming, was studied as part of the U.S. Geological Survey's Regional Aquifer-System Analysis Program to provide support for hydrogeological interpretations. The study area is segmented by numerous uplifts and basins caused by folding and faulting that have recurred repeatedly from Precambrian to Cenozoic time. Paleozoic rocks in the study area are 0-18,000 feet thick. They are underlain by Precambrian igneous, metamorphic, and sedimentary rocks and are overlain in most of the area by Triassic formations composed mostly of shale. The overlying Mesozoic and Tertiary rocks are 0-27,000 feet thick. All Paleozoic systems except the Silurian are represented in the region. The Paleozoic rocks are divisible into 11 hydrogeologic units. The basal hydrogeologic unit consisting of Paleozoic rocks, the Flathead aquifer, predominantly is composed of Lower to Upper Cambrian sandstone and quartzite. The aquifer is 0-800 feet thick and is overlain gradationally to unconformably by formations of Cambrian to Mississippian age. The Gros Ventre confining unit consists of Middle to Upper Cambrian shale with subordinate carbonate rocks and sandstone. The confining unit is 0-1,100 feet thick and is overlain gradationally to unconformably by formations of Cambrian to Mississippian age. The Bighom aquifer consists of Middle Cambrian to Upper Ordovician limestone and dolomite with subordinate shale and sandstone. The aquifer is 0-3,000 feet thick and is overlain unconformably by Devonian and Mississipplan rocks. The Elbert-Parting confining unit consists of Lower Devonian to Lower Mississippian limestone, dolomite, sandstone, quartzite, shale, and anhydrite. It is 0-700 feet thick and is overlain conformably to unconformably by Upper Devonian and Mississippian rocks. The Madison aquifer consists of two zones of distinctly different lithology. The lower (Redwall-Leadville) zone

Brackish to hypersaline lake dolostones of the Mississippian

Science.gov (United States)

Bennett, Carys; Kearsey, Timothy; Davies, Sarah; Millward, David; Marshall, John

2016-04-01

Flat-lying ferroan dolomite beds are common in the Mississippian and occur along the southern margin of Laurassia, from Kentucky USA to Poland. These rocks are important as they record shallow marine to coastal plain environments that may have acted as a pathway or refugia for animals that were radiating into freshwaters such as tetrapods, fish, molluscs and arthropods. This study is a contribution to the TW:eed Project (Tetrapod World: early evolution and diversification), that examines the rebuilding of Carboniferous ecosystems following a mass extinction at the end of the Devonian. The project focuses on the Tournaisian Ballagan Formation of Scotland, which contains rare fish and tetrapod fossils. The formation is characterised by an overbank facies association of siltstone, sandstone and palaeosols, interbedded with dolostone and evaporite units, and cut by fluvial sandstone facies associations of fining-upwards conglomerate lags, cross-bedded sandstone and rippled siltstone. Two sites are used as a case study to describe the sedimentological, faunal and ichnofaunal diversity of these dolostones. More than 270 dolostone beds are recorded in each of the 500 metre depth Norham Core (near Berwick-upon-Tweed) and from a 520 metre thick field section at Burnmouth. The beds are laterally extensive, over ˜1 km, although individual units do not appear to correlate between the core and the field site. In the Norham Core dolostones comprise up to 14% of the succession. 17% of the beds contain marginal marine fossils: Spirorbis, rare orthocones, brachiopods and putative marine sharks. More common fauna include ostracods, bivalves, plants, eurypterids, gastropods and sarcopterygian fish, which are interpreted as brackish to freshwater tolerant. Bioturbation is fairly common with Serpula colonies within dolostone beds and Chondrites burrowing down from the base of dolostone beds. Some rare units in the field section have a bulbous bed surface and preserve tree root traces

A review of the Late Cambrian (Furongian) palaeogeography in the western Mediterranean region, NW Gondwana

Science.gov (United States)

Álvaro, J. Javier; Ferretti, Annalisa; González-Gómez, Cristina; Serpagli, Enrico; Tortello, M. Franco; Vecoli, Marco; Vizcaïno, Daniel

2007-11-01

, onchonotinids, and pagodiids), linguliformean brachiopods (acrotretids, obolids, scaphelasmatids, siphonotretids, and zhanatellids), echinoderms (mitrates, glyptocystitid cystoids, and stromatocystoids), and conodonts belonging to the lower Peltura Zone; and (iii) the subsequent input of new trilobites (asaphids, calymenids, catillicephalids, nileids and remopleurids), which marks the base of the Proteuloma geinitzi Zone, associated with pelmatozoan holdfasts ( Oryctoconus), and a distinct input of late Tremadocian conodonts ( Paltodus deltifer Zone). The biogeographic distribution of latest Middle and Late Cambrian trilobites supports brachiopod data indicating strong affinities between the western Mediterranean region, East Gondwana (North China/Korea, South China, Australia, and Antarctica) and Kazakhstania during the late Languedocian, which became significantly stronger during the Late Cambrian. This major shift may suggest modification in oceanic circulation patterns throughout Gondwana across the Middle-Late Cambrian transition.

Geology and undiscovered resource assessment of the potash-bearing Pripyat and Dnieper-Donets Basins, Belarus and Ukraine

Science.gov (United States)

Cocker, Mark D.; Orris, Greta J.; Dunlap, Pamela; Lipin, Bruce R.; Ludington, Steve; Ryan, Robert J.; Słowakiewicz, Mirosław; Spanski, Gregory T.; Wynn, Jeff; Yang, Chao

2017-08-03

Undiscovered potash resources in the Pripyat Basin, Belarus, and Dnieper-Donets Basin, Ukraine, were assessed as part of a global mineral resource assessment led by the U.S. Geological Survey (USGS). The Pripyat Basin (in Belarus) and the Dnieper-Donets Basin (in Ukraine and southern Belarus) host stratabound and halokinetic Upper Devonian (Frasnian and Famennian) and Permian (Cisuralian) potash-bearing salt. The evaporite basins formed in the Donbass-Pripyat Rift, a Neoproterozoic continental rift structure that was reactivated during the Late Devonian and was flooded by seawater. Though the rift was divided, in part by volcanic deposits, into the separate Pripyat and Dnieper-Donets Basins, both basins contain similar potash‑bearing evaporite sequences. An Early Permian (Cisuralian) sag basin formed over the rift structure and was also inundated by seawater resulting in another sequence of evaporite deposition. Halokinetic activity initiated by basement faulting during the Devonian continued at least into the Permian and influenced potash salt deposition and structural evolution of potash-bearing salt in both basins.Within these basins, four areas (permissive tracts) that permit the presence of undiscovered potash deposits were defined by using geological criteria. Three tracts are permissive for stratabound potash-bearing deposits and include Famennian (Upper Devonian) salt in the Pripyat Basin, and Famennian and Cisuralian (lower Permian) salt in the Dnieper-Donets Basin. In addition, a tract was delineated for halokinetic potash-bearing Famennian salt in the Dnieper-Donets Basin.The Pripyat Basin is the third largest source of potash in the world, producing 6.4 million metric tons of potassium chloride (KCl) (the equivalent of about 4.0 million metric tons of potassium oxide or K2O) in 2012. Potash production began in 1963 in the Starobin #1 mine, near the town of Starobin, Belarus, in the northwestern corner of the basin. Potash is currently produced from

Stratigraphic variation of complex impurities in platform limestones and possible significance of atmospheric dust: a study with emphasis on gamma-ray spectrometry and magnetic susceptibility outcrop logging (Eifelian-Frasnian, Moravia, Czech Republic)

Science.gov (United States)

Hladil, J.; Gersl, M.; Strnad, L.; Frana, J.; Langrova, A.; Spisiak, J.

2006-07-01

Mineral dust and other constituents of Devonian atmospheric aerosols together with certain amounts of aquatic suspensions of riverine detrital origin, colloidal particle dispersions and seawater solutes were embedded in ~95-98% (or purer) limestones on a consistently subsiding isolated carbonate platform where they formed very complex impurity systems. Very low Th/U values, relative abundance of Fe but a slight excess of K typically characterize these ultrafine impurities which are mineralogically dominated by smectite-illite and mica (sericite) together with goethite. In vertical section, these impurities are arranged like incremental series of light and dense bands. The combined method of natural gamma-ray spectrometric and magnetic susceptibility measurements (GRS-MS) together with background of major and trace element analyses provided first systematic insights into fine-scale variability of these impurities in a pile of pure carbonate platform beds, mostly in inner platform Amphipora limestone facies. These carbonates were deposited close to sea level but far from river mouths, and they represented a certain sort of a relatively “independent” medium that was primarily sensitive to climatically (and by rare events) controlled input of atmospheric dust. A remarkable similarity of MS stratigraphic patterns that reflect the quantity and quality of embedded impurities in very distant and paleogeographically separated Devonian basins might be seen as supporting this viewpoint. A long composite stratigraphic section of the Moravian Karst ranges from mid-Eifelian to end-Frasnian levels and yields a number of time characterizing GRS-MS variations that can potentially serve as templates for high-resolution stratigraphic correlations over long distances.

Microbes and mass extinctions: paleoenvironmental distribution of microbialites during times of biotic crisis.

Science.gov (United States)

Mata, S A; Bottjer, D J

2012-01-01

Widespread development of microbialites characterizes the substrate and ecological response during the aftermath of two of the 'big five' mass extinctions of the Phanerozoic. This study reviews the microbial response recorded by macroscopic microbial structures to these events to examine how extinction mechanism may be linked to the style of microbialite development. Two main styles of response are recognized: (i) the expansion of microbialites into environments not previously occupied during the pre-extinction interval and (ii) increases in microbialite abundance and attainment of ecological dominance within environments occupied prior to the extinction. The Late Devonian biotic crisis contributed toward the decimation of platform margin reef taxa and was followed by increases in microbialite abundance in Famennian and earliest Carboniferous platform interior, margin, and slope settings. The end-Permian event records the suppression of infaunal activity and an elimination of metazoan-dominated reefs. The aftermath of this mass extinction is characterized by the expansion of microbialites into new environments including offshore and nearshore ramp, platform interior, and slope settings. The mass extinctions at the end of the Triassic and Cretaceous have not yet been associated with a macroscopic microbial response, although one has been suggested for the end-Ordovician event. The case for microbialites behaving as 'disaster forms' in the aftermath of mass extinctions accurately describes the response following the Late Devonian and end-Permian events, and this may be because each is marked by the reduction of reef communities in addition to a suppression of bioturbation related to the development of shallow-water anoxia. © 2011 Blackwell Publishing Ltd.