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Emplacement mechanisms and structural influences of a younger granite intrusion into older wall rocks - a principal study with application to the Goetemar and Uthammar granites. Site-descriptive modelling SDM-Site Laxemar  

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The c. 1.80 Ga old bedrock in the Laxemar-Simpevarp area, which is the focus of the site investigation at Oskarshamn, is dominated by intrusive rocks belonging to the c. 1.86-1.65 Ga Transscandinavian Igneous Belt (TIB). However, the site investigation area is situated in between two c. 1.45 Ga old anorogenic granites, the Goetemar granite in the north and the Uthammar granite in the south. This study evaluates the emplacement mechanism of these intrusions and their structural influence on the older bedrock. Field observations and structural measurements indicate that both the Goetemar and the Uthammar granites are discordant and have not imposed any significant ductile deformation on their wall-rocks. The apparent conformity of geological contacts and fabrics in the wall rocks and the southern margin of the Goetemar granite is coincidental and inherited from the pattern of Svecokarelian deformation of the TIB. However, interpretation of regional aeromagnetic data suggests that the granites occur within a broad, NNE-SSW trending linear belt, pointing to deep seated tectonic control on their generation, ascent and emplacement. Thermochronology indicates that the granites were emplaced at depths between 4 and 8 km into brittle wall rocks. The 3-D shape of the Goetemar and Uthammar plutons has been investigated by 2.75D forward modelling of the residual gravity anomalies due to both granites. Both granites are associated with strong residual gravity anomalies of up to -10 mgal. Constraints on the geometry of the plutons at the surface are provided from surface geology maps and several deep boreholes located on or close to the model profiles. A further variable in the gravity modelling is introduced by either allowing the upper contact of the plutons to assume the most suitable orientation to produce the best fit between the modelled and observed gravity ('unconstrained models') or by forcing the near surface orientation of the contacts to be vertical ('constrained models'). The unconstrained model profiles for both plutons are characterized by gently outward dipping upper contacts to depths approx1 km, gently inward dipping lower contacts and a thin, centrally located root extending to depths of 5 to 10 km. However, this geometry is not supported by available boreholes, which do not penetrate the upper contact of the Goetemar pluton as predicted by the models. The constrained models are consistent with borehole data. They characterize the plutons as having vertical contacts in the upper 500 to 1,000 m, a 1,000 to 1,500 m thick mid-level body with outward dipping upper and horizontal and lower contacts, respectively, and broad roots extending to depths of approx4 km. Preliminary observations and gravity modelling results indicate that the Goetemar and Uthammar granites are discordant plutons with geometries most consistent with punched laccoliths, with some modification due to floor subsidence due to root development. Their vertical and lateral dimensions fall in the upper range for laccoliths and lower range for plutons as defined by recent data compilations. Their emplacement required elastic bending and eventual failure of roof rocks that was likely accompanied by reactivation of pre-existing fractures and shear zones and possibly the creation of new brittle fractures. Cooling and crystallization of the granites resulted in thermal resetting of the wall rocks and the establishment of a transient hydrothermal system, now recorded by fracture filling mineral assemblages

Cruden, Alexander R. (Dept. of Geology, Univ. of Toronto (Canada))

2008-12-15

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Emplacement mechanisms and structural influences of a younger granite intrusion into older wall rocks - a principal study with application to the Goetemar and Uthammar granites. Site-descriptive modelling SDM-Site Laxemar  

International Nuclear Information System (INIS)

The c. 1.80 Ga old bedrock in the Laxemar-Simpevarp area, which is the focus of the site investigation at Oskarshamn, is dominated by intrusive rocks belonging to the c. 1.86-1.65 Ga Transscandinavian Igneous Belt (TIB). However, the site investigation area is situated in between two c. 1.45 Ga old anorogenic granites, the Goetemar granite in the north and the Uthammar granite in the south. This study evaluates the emplacement mechanism of these intrusions and their structural influence on the older bedrock. Field observations and structural measurements indicate that both the Goetemar and the Uthammar granites are discordant and have not imposed any significant ductile deformation on their wall-rocks. The apparent conformity of geological contacts and fabrics in the wall rocks and the southern margin of the Goetemar granite is coincidental and inherited from the pattern of Svecokarelian deformation of the TIB. However, interpretation of regional aeromagnetic data suggests that the granites occur within a broad, NNE-SSW trending linear belt, pointing to deep seated tectonic control on their generation, ascent and emplacement. Thermochronology indicates that the granites were emplaced at depths between 4 and 8 km into brittle wall rocks. The 3-D shape of the Goetemar and Uthammar plutons has been investigated by 2.75D forward modelling of the residual gravity anomalies due to both granites. Both granites are associated with strong residual gravity anomalies of up to -10 mgal. Constraints on the geometry of the plutons at the surface are provided from surface geology maps and several deep boreholes located on or close to the model profiles. A further variable in the gravity modelling is introduced by either allowing the upper contact of the plutons to assume the most suitable orientation to produce the best fit between the modelled and observed gravity ('unconstrained models') or by forcing the near surface orientation of the contacts to be vertical ('constrained models'). The unconstrained model profiles for both plutons are characterized by gently outward dipping upper contacts to depths ?1 km, gently inward dipping lower contacts and a thin, centrally located root extending to depths of 5 to 10 km. However, this geometry is not supported by available boreholes, which do not penetrate the upper contact of the Goetemar pluton as predicted by the models. The constrained models are consistent with borehole data. They characterize the plutons as having vertical contacts in the upper 500 to 1,000 m, a 1,000 to 1,500 m thick mid-level body with outward dipping upper and horizontal and lower contacts, respectively, and broad roots extending to depths of ?4 km. Preliminary observations and gravity modelling results indicate that the Goetemar and Uthammar granites are discordant plutons with geometries most consistent with punched laccoliths, with some modification due to floor subsidence due to root development. Their vertical and lateral dimensions fall in the upper range for laccoliths and lower range for plutons as defined by recent data compilations. Their emplacement required elastic bending and eventual failure of roof rocks that was likely accompanied by reactivation of pre-existing fractures and shear zones and possibly the creation of new brittle fractures. Cooling and crystallization of the granites resulted in thermal resetting of the wall rocks and the establishment of a transient hydrothermal system, now recorded by fracture filling mineral assemblages

3

Contribution to uranium geochemistry in intrusive granites  

International Nuclear Information System (INIS)

This work aims to define the position of a certain number of French granitic deposits within the field of the geochemistry of granites in general, and of the geochemistry of uranium in particular. The regions concerned are: - 3 French Hercynian ranges, in the Vendee, in Brittany and in the Morvan, - 1 African range, probably precambrian, of the Hoggar. For each range, the petrochemical framework is first of all determined and then the degree of chemical homogeneity of the rocks is evaluated. In the petrochemical groups thus obtained the geochemical behaviour of the uranium is studied. From a point of view of the geochemistry of the granites under investigation, a comparison of the laws of distribution of the major elements in the 4 ranges shows up a convergence of average composition which was not anticipated by geological and petrographic considerations alone. The statistical and geochemical distribution laws of the total uranium as a function of the petrochemical variations are established. A study of the chemical forms of uranium in the rocks has drawn an attention to the qualitative and quantitative importance of the fraction of this uranium soluble in dilute acids. We have therefore reconsidered on the one hand, the laws of distribution of the insoluble uranium, which represents essentially the uranium fixed in crystalline structures (zircon, allanite...), and we have justified on the other hand the interest presented by the soluble uranium: this, although more complex in character, presents a geochemical unity in post magmatic phenomena which makes possible to find a genetic connection between the uraniferous deposits and the intrusive massifs. Finally we have given a plan of the geochemical cycle of uranium, in which we hope to have provided some more accurate data on the igneous phase. (author)

4

Petrogenesis of selected A-type granitic intrusions from Central Eastern Desert of Egypt  

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The Pan-African orogeny in the Arabian-Nubian Shield was terminated by intrusion of A-type granites (~ 595 Ma; Greenberg, 1981) and its volcanic equivalents. Subsequent to the intrusions of these granitic bodies the shield was exhumed. Eroded A-type granite pebbles were found in the molasse sediments that were deposited in intermountain basins. Therefore the A-type granites provide information about the last stage of the Pan-African geochemical system. Preliminary whole-rock geochemical data of three granitic intrusions (Kadabora, Um Naggat and El shiekh Salem) from the Central Eastern Desert of Egypt; indicate that all of them are peraluminous and with A-type characteristics. These intrusions show low CaO content (average 0.43 %wt), high FeOT/MgO ratio (10.46-121.88), high Na2O+K2O (average 8.04 %wt), marked enrichment of high field strength elements (Y, Nb and Ga except Zr), depletion in MgO (0.01-0.11 %wt) and with low concentration of Sr and Ba. The studied granitoids were emplaced in within plate tectonic regime. References: Greenberg, J.K. (1981): Characteristic and origin of Egyptian younger granites. Bull. Geol. Soc. Am. Part 1, v.92: 224-232.

Hassan, Tharwat; Asran, Asran; Amron, Taha; Hauzenberger, Christoph

2014-05-01

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Characteristics and significance of uranium bearing pan african younger granite in the eastern desert, Egypt  

International Nuclear Information System (INIS)

Surficial uranium mineralization was discovered in four pan african younger granite plutons in the eastern desert of egypt. The present study revealed great similarity between these plutons both in petrography and geochemistry. They are two-feldspar, two-mica peraluminous granites which have been formed by melting of crustal materials and emplaced during the late stage stage of a late proterozoic orogenic cycle. Radiometric and geochemical investigations indicate that these granites are fertile with respect to U and form a potential target for primary uranium deposits. Four models are suggested to explain the source and mechanism of the surficial uranium mineralization in these granites. The most applicable model is the oxidation of U+4 found in minute disseminated uraninite grains and its subsequent mobilization. This is supported by petrographic and autoradiographic studies. The bearings of the present study on further exploration for uranium deposits in granites of the arabian- Nubian shield in general are discussed

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Emplacement and magnetic fabrics of rapakivi granite intrusions within Wiborg and Åland rapakivi granite batholiths in Finland  

Science.gov (United States)

Anisotropy of magnetic susceptibility (AMS) studies were carried out in two areas in Finland: the Ruotsinpyhtää intrusion within the Wiborg rapakivi granite batholith and the Saltvik intrusions within the Åland rapakivi granite batholith. The main aim of this study was to understand the emplacement history of these mid-Proterozoic rapakivi granites. Aeromagnetic images reveal structures of ca. 5-10 km intrusions that build up the large rapakivi granite batholiths of Åland and Wiborg. Magnetic susceptibility data from the database of the Geological Survey of Finland, including more than 1700 samples from the Wiborg rapakivi batholith and almost 900 samples from the Åland rapakivi batholith, were compared with measurements from the present study. The mean susceptibility is ca. 1500 ?SI for the Wiborg batholith and ca. 10,000 ?SI for the Åland batholith. Samples taken for this study demonstrate that the mean value for the Ruotsinpyhtää intrusion is ca. 1200 ?SI and for the Saltvik intrusions ca. 24,000 ?SI. Thermomagnetic measurements reveal that the magnetic susceptibility is mainly derived either from paramagnetic minerals or from magnetite. The absence of solid-state deformation features such as breccia or contact deformation indicates a cauldron-type subsidence emplacement. The AMS measurements from Ruotsinpyhtää confirm these proposals, with concentric gently dipping magnetic foliations that support a ring complex structure above a piston-type subsidence system. The Saltvik area consists of a number of smaller elliptical intrusions of different rapakivi granites forming a multiple intrusive complex. The magnetic fabric shows a general westward dipping of the pyterlite and eastward dipping of the contiguous even-grained rapakivi granite, which indicates a central inflow of magma batches towards the east and west resulting from a laccolitic emplacement of magma batches, while the main mechanism for space creation was derived from subsidence.

Karell, Fredrik; Ehlers, Carl; Airo, Meri-Liisa

2014-02-01

7

Uranium in the Niger-Nigeria younger granite province  

International Nuclear Information System (INIS)

In Niger, uranium occurs in upper Palaeozoic and lower Mesozoic continental sedimentary basins west of the Air Mountains, but the source of the uranium had not been identified. Geochemical studies and fission-track observations on alkaline ignimbrites preserved in two Palaeozoic anorogenic centres in Air show that uranium is concentrated in the matrix and on secondary iron-oxide coatings surrounding lithic and crystal fragments. Based on variable Th/U ratios and degree of oxidation, it is concluded that the original ignimbrite field was enriched in uranium, but that a considerable proportion was leached during the weathering of the volcanic pile. Tectonic uplift, anorogenic magmatism, followed by weathering and erosion of the volcanic cover, with sedimentation in nearby continental basins, have all contributed to the development of uranium mineralization in Niger. The petrological and geochemical similarities between the Palaeozoic ring complexes in Niger and the Nigerian Mesozoic ring structures suggest that sedimentary uranium deposits may also be found in Nigeria if the tectonic and sedimentological controls were favourable. Enriched concentrations of uranium have been discovered in the exposed granitic roof zones of the Nigerian subvolcanic centres, with Th/U ratios approaching unity. (author)

8

Three Paleoproterozoic A-type granite intrusions and associated dykes from Kainuu, East Finland  

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Mafic and felsic intrusive rocks aged 2.5–2.4 Ga have been observed over a large area in eastern and northern Finland, as well as in adjacent northwestern Russia. We describe three granite intrusions and associated dykes from Kainuu, Finland, that belong to this bimodal magmatic event. All these three granites show clear A2-type chemical affinities with high Y/Nb, HREE, Fe/Mg, Ga and Nb. Two of the intrusions, Rasinkylä and Pussisvaara, were dated at 2425±3 and 2427±3 Ma, respectively, u...

Hannu Huhma; Asko Kontinen; Perttu Mikkola; Yann Lahaye

2010-01-01

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Intrusive rocks from Polumir and Željin (Serbia: two contrasting granit?id types  

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Full Text Available This paper outlines correlation of the most distinctive features of intrusive rocks from Polumir (granite from Polumir, Polumir granite and from Željin (Željin granitoid. Although these two intrusions are notable similar in space (10-12 km and time (beginning of Miocene, they are very different, even contrasting concerning their petrography, genesis and geotectonic. Mineralogy, petrology and chemistry of Polumir granite (P?2.5 km2, and of Željin quartz diorite and tonalite, as well as of granodiorite and granite (P?56 km2, i.e. properties that directly reflect on their genesis and geotectonic setting, are presented in this paper. Chemistry of biotite, the only mineral observed in both plutons, as the direct evidence of different physical-chemical conditions during consolidation and proof for their genetic contrast, is contributed.

Milenko

2014-11-01

10

Uranium-bearing siliceous veins in younger granites, Eastern Desert, Egypt  

International Nuclear Information System (INIS)

The post-tectonic younger granites of Egypt represent the magmatic activity marking the end of the cratonization process of the Pan-African Orogeny. Several of these plutons are hosts of rare metal mineralization in the Eastern Desert of Egypt. Two of them, namely El-Erediya and El-Missikat plutons, are hosts of siliceous vein-type uranium mineralization. In both occurrences, the mineralization is structurally controlled by faults and their feather joints which are associated with NE to ENE shear zones. Widespread silicification, and to a lesser extent kaolinization and sericitization, as well as other alterations accompany the uranium mineralization. Uranium is concentrated in the centre of the mineralized faults and fractures together with jasper (in El-Erediya) or black silica and to a lesser extent jasper (in El-Missikat). Pitchblende is the primary mineral which suffered intensive oxidation and probably leaching relics protected by silica. This resulted in a spotty distribution of uranium and radioactivity in the oxidation zone. Present data suggest an origin by hydrothermal fluids derived, most probably, from the younger granite magma. Uranium was derived from the magma itself, or from another deep source. Contributions from the granitic plutons by leaching through circulation of meteoric waters cannot be ruled out at the present state of knowledge. (author)

11

Oxygen isotope geochemistry of the Granite Harbour Intrusives, Wilson Terrane, Northern Victoria Land, Antarctica  

International Nuclear Information System (INIS)

The oxygen and strontium isotope compositions of the Cambro-Ordovician granitoids cropping out in the Wilson Terrane (Granite Harbour Intrusives-GHI) constrain the petrological evolution of the magmatism in Antarctica, related to the Ross Orogeny. The measured ?18OWR values of three intrusives define three different compositional groups: the metaluminous rocks (MAG), with ?18OWR ranging from 6.9 (olivine gabbro) to 11.4 %o (monzogranite); the unaltered peraluminous granites (PAG), having ?18OWR values ranging from 10.6 to 13.2 %o, and the foliated peraluminous leucogranites (SKG), characterized by ?18OWR values above 14 %o. The analysis of equilibrium mineral assemblages indicates that the high ?18OWR values are magmatic and unaffected by low-temperature processes. A few peraluminous granites sampled in the vicinity of Cenozoic intrusions show anomalously low ?18OWR, due to meteoric-hydrothermal alteration. The isotopic data indicate that the coeval and spatially related metaluminous mafic and felsic intrusives forming the GHI were not comagmatic: the mafic and intermediate rocks were likely derived from lower crustal contamination of a pristine basaltic magma; their ?18OWR values were also increased during emplacement, due to the interaction with the adjacent 18O-rich hydrous felsic magmas (mixing). Oxygen isotope data indicate that the crustal sources producing the granite harbor intrusives were not homogeneous: the felsic metaluminous intrusives were produced by partial melting of fertile rock with possible igneous origin, whereas partial melting of a metapelitic source rock is claimed for the genesis of the peraluminous granites. (author)

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Three Paleoproterozoic A-type granite intrusions and associated dykes from Kainuu, East Finland  

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Full Text Available Mafic and felsic intrusive rocks aged 2.5–2.4 Ga have been observed over a large area in eastern and northern Finland, as well as in adjacent northwestern Russia. We describe three granite intrusions and associated dykes from Kainuu, Finland, that belong to this bimodal magmatic event. All these three granites show clear A2-type chemical affinities with high Y/Nb, HREE, Fe/Mg, Ga and Nb. Two of the intrusions, Rasinkylä and Pussisvaara, were dated at 2425±3 and 2427±3 Ma, respectively, using thermal ionisation mass spectrometry utilizing the chemical abrasion method (CA-TIMS. CA-TIMS ages are supported by single-grain age determinations obtained by using Laser Ablation Multicollector Inductively Coupled Plasma Mass Spectrometer (LA-MC-ICPMS. New data on the previously described Rasimäki granite from southern Kainuu is presented, including an age of 2389±5 Ma obtained with LA-MC-ICPMS. The variable magnetite content of the granites is proposed to reflect the differences in the oxidation state of the source, which in our interpretation is the local Archean lower crust. Partial melting and the emplacement of the granites occurred in an extensional environment. Heat for the partial melting was provided by mafic magmas under and intraplating the extended crust.

Hannu Huhma

2010-12-01

13

Genesis of Uranium in the younger granites of gabal abu hawis area, central eastern desert of Egypt  

International Nuclear Information System (INIS)

The younger granites cropping out in gabal abu hawis area are considered as uraniferous (fertile) granites (the fertile is mainly is mainly attributed to presence of radioactive zircon). Abu hawis granitic pluton is dissected by joints faults of different trends forming two mineralized shear zones in the northern peripheries and southern border. The younger granites hosting uranium mineralizations along the two mineralized shear zones. The uranium minerals include uranophane and carnotite. The altered granites have much lower Th/U ratios (0.03-0.10) than those of the fresh granites (1.69-2.05), indicating strong mobilization of uranium in this pluton by super-heated solutions that resulted from supergence meteoric water as well as U-addition by hypogene fluids. These solutions could pass through the structural network of fractures, joints and fault planes and have leached some of labile uranium from the surrounding rocks and/or the younger granites themselves. Then, changing in the physicochemical conditions of these solutions caused uranium precipitation as uranium minerals filling the cracks in the rock and/or adsorbed on the surface of clay minerals and iron oxides in the two shear zones

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The Rio Dourado Intrusive Suite - 1.88 Ga A-type Granite - Southeastern Amazonian Craton - Mato Grosso - Brazil  

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Full Text Available The Rio Dourado Intrusive Suite (RDIS is composed of granitic rocks which are exposed in the southeastern AmazonCraton, Central Amazon Province. These granites intruded into the Paleoproterozoic granites of the Vila Rica IntrusiveSuite. The predominantly pyroclastic felsic volcanic rocks of the Iriri Group are coeval and spatially associated with theintrusive granites. Petrographic studies allow us to divide the Rio Dourado granites into: biotite granites, amphibole-bearingbiotite granites and granophyric granites. Modal compositions range from monzo to syenogranites. The oxidized A-typegranite is characterized by FeO/FeO+MgO ranging from 0.8 - 0.95, high contents of FeOT and low contents of CaO, as wellas peraluminous composition. In the tectonic discrimination diagrams, samples of these granites plot in the post-collisionalfield. REE patterns show enrichment in the LREE relative to HREE and negative Eu anomalies. Negative anomalies ofTa and Nb, as well as depletion in the HREE, features which are typical of A-type granites of post-collisional settings, are observed in multi-element diagrams,. Ce, Yb, Nb and Ga contents are transitional between those of A2 and A1-type granites. U-Pbzircon dating by TIMS yielded an age of 1876 ± 39, whereas negative values of ?Nd (-3 to -10 and model ages (TDM between 2.6 and2.8 Ga indicate it was formed by re-melting of older (possibly Archean crust.

Márcia Aparecida de Sant’Ana Barros

2011-04-01

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Granite intrusion in a metamorphic core complex: the example of the Mykonos laccolith (Cyclades, Greece)  

Science.gov (United States)

Numerical and analogical modelling underlined the importance of a pre-existing anomaly of viscosity-density such as a granite or migmatitic body below the brittle-ductile transition as a primary cause of metamorphic core complex (MCC) developpement. While field studies of MCC show a spatial and temporal link between MCC formation and plutonic activity, thermochronological studies show that there is no link between the intrusion of granites and the velocity of slip on the detachement plane. The Aegean domain is a good natural laboratory for studying the formation of MCC and syn-tectonic granites. In the northern Cyclades, the Mykonos-Delos-Rhenia MCC is characterised by the intrusion of a plurikilometric Late Miocene pluton of I-type granite within a migmatitic gneiss dome. AMS (Anisotropy of magnetic susceptibility) and microstructural studies in the Mykonos granites combined with recent cooling rate data allow us to use the granites as strain marker. The Mykonos granitoïds form a plurikilometric laccolith slightly deeping to the east and presenting an elliptical shape with a N170°E long axis. The laccolith is strongly asymmetrical with an outlying root zone in the SW cropping out on Delos and Rhenia islands and a major body mainly developed to the NE and cropping out on Mykonos Island. The laccolith consists of various petrographic facies presenting straight contacts that demonstrate emplacement by successive pulses of more or less differentiated magmas. The laccolith was developed at the interface between the Cycladic Basement and the Blueschists Unit and within the Blueschist Unit. Two events of deformation have been recorded in the granites. The first event is characterized by submagmatic and high to middle temperature protomylonite microstructures developped during or just after the intrusion. The second event of deformation characterized by low temperature mylonites and cataclasites close to the major detachment fault corresponds to the localization of deformation at the top of the laccolith after cooling due to heat exchange with country rocks and exhumation of the Mykonos MCC. The study of fabric evolution in the laccolith suggests that the laccolith structuration results from the interaction between regional deformation and lateral extension of magmas. Fabrics are indeed strongly planar close to the detachment, show an evolution toward plano-linear close to the bottom of the laccolith and are strongly linear in the root zone. Structural data suggest an evolution of the Mykonos MCC in three stages as follows: (i) a first stage characterized by the formation of a migmatitic "a-type dome" with a major axis parallel to the lineation such as Naxos dome by competition between regional N20 extension and EW shortening; (ii) a second stage marked by the emplacement of the Mykonos laccolith at 13 Ma at the top of the migmatitic paragneiss in the Blueschist Unit (iii) a progressive localisation of the deformation occured at the top of the laccolith in semi-ductile conditions on a thickness at about 500 m and thus in brittle conditions in the major detachment plane. Our study shows that intensity of submagmatic to high temperature deformation observed in the laccolith remains low compared to the deformation observed in country-rocks. This suggests that intrusion of a laccolith in the roof of a MCC in partially molten rocks does not localize the deformation. By contrast the geometry of the intrusion shows that the magmas are sucked into the direction of regional extension and that the intrusion of magmas will inevitably cause a local acceleration of the MCC development. Finally, during its cooling the laccolith will localize the brittle ductile transition in its roof and caused the formation of a strong deformation zone first ductile and then brittle.

Denèle, Yoann; Lecomte, Emmanuel; Jolivet, Laurent; Huet, Benjamin; Labrousse, Loïc.; Le Pourhiet, Laetitia; Lacombe, Olivier

2010-05-01

16

Age of Pedra Branca granite (Goias) and possible geotectonic implications  

International Nuclear Information System (INIS)

Rb-Sr geochronologic dating of granites from the Pedra Branca Granite Massif (Nova Roma, Goias) shown an age of 1405 ± 21My. and a questionable initial Sr87/Sr86 ratio of 0,7004 ± 0,006. Rhyolite from the base of the Arai Group is probably of the same age as the granitic intrusion. The 475 ± 19 My. age for the granitic intrusion is evidence of the Brasiliano Cycle imprint in Pedra Branca region. The age attributed to the Pedra Branca Granite is lower than known ages of the Goias tin granites giving rise to new geotectonic interpretations. It is possible that the Pedra Branca Granite represents a low-level intrusion emplaced at the beginning of structuration and deposition of the Arai basin. It may be correlated with granitic intrusions related to a rift stage above mantle hot spots, like the Nigerian tin younger granites. (author)

17

Contribution to uranium geochemistry in intrusive granites; Contribution a la geochimie de l'uranium dans les granites intrusifs  

Energy Technology Data Exchange (ETDEWEB)

This work aims to define the position of a certain number of French granitic deposits within the field of the geochemistry of granites in general, and of the geochemistry of uranium in particular. The regions concerned are: - 3 French Hercynian ranges, in the Vendee, in Brittany and in the Morvan, - 1 African range, probably precambrian, of the Hoggar. For each range, the petrochemical framework is first of all determined and then the degree of chemical homogeneity of the rocks is evaluated. In the petrochemical groups thus obtained the geochemical behaviour of the uranium is studied. From a point of view of the geochemistry of the granites under investigation, a comparison of the laws of distribution of the major elements in the 4 ranges shows up a convergence of average composition which was not anticipated by geological and petrographic considerations alone. The statistical and geochemical distribution laws of the total uranium as a function of the petrochemical variations are established. A study of the chemical forms of uranium in the rocks has drawn an attention to the qualitative and quantitative importance of the fraction of this uranium soluble in dilute acids. We have therefore reconsidered on the one hand, the laws of distribution of the insoluble uranium, which represents essentially the uranium fixed in crystalline structures (zircon, allanite...), and we have justified on the other hand the interest presented by the soluble uranium: this, although more complex in character, presents a geochemical unity in post magmatic phenomena which makes possible to find a genetic connection between the uraniferous deposits and the intrusive massifs. Finally we have given a plan of the geochemical cycle of uranium, in which we hope to have provided some more accurate data on the igneous phase. (author) [French] Le but du travail presente est de situer sur le plan de la geochimie des granites en general, sur le plan de la geochimie de l'uranium en particulier, un certain nombre de massifs granitiques francais: - 3 massifs hercyniens francais, en Vendee, en Bretagne et dans le Morvan, - 1 massif africain, probablement precambrien, du Hoggar. Dans chaque massif, nous determinons en premier lieu le cadre petrochimique et evaluons le degre d'homogeneite chimique des roches. Dans les familles petrochimiques ainsi determinees, nous etudions le comportement geochimique de l'uranium. Du point de vue de la geochimie des granites etudies, le comparaison des lois de repartition des elements majeurs fait apparaitre dans les 4 massifs une convergence de composition moyenne que ne laissaient pas prevoir la geologie et la petrographie. Nous etablissons les lois de repartition statistiques et geographiques de l'uranium total en fonction des variations petrochimiques. L'etude des formes de l'uranium a l'interieur des roches a attire notre attention sur l'importance qualitative et quantitative de la fraction de cet uranium soluble dans les acides dilues. Nous reprenons donc, d'un cote les lois de repartition de l'uranium insoluble qui represente pratiquement l'uranium inclus dans les structures cristallines (zircon, allanite...) et justifions d'un autre cote l'interet presente par l'uranium soluble qui, malgre un caractere plus complexe, permet par son unite geochimique dans les phenomenes postmagmatiques, de trouver une liaison genetique entre les gisements uraniferes et les massifs intrusifs. Nous presentons enfin, un schema du cycle geochimique de l'uranium dans lequel nous esperons avoir pu apporter quelques precisions sur la phase ignee. (auteur)

Coulomb, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1959-01-15

18

Natural radioactivity of basement younger granite rocks from the Eastern Desert  

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The present work deals with a study of natural radioactivity of various samples of granite rocks from the Umm Gidri area located in North Eastern Desert. In this area, about 300 km apart from El-Minia, some geological investigations were carried out. Several samples of the basement rocks (of the Precambrian Age) 5 m subsurface were obtained from different locations. Suitable samples were prepared for natural gamma ray measurements using a 5 x 5 in. NaI(Tl) scintillation spectrometer. Qualitative analysis of natural gamma radiations from the present samples have revealed the presence of the radioisotopes: {sup 40}K, {sup 214}Bi, {sup 208}Tl and {sup 228}Ac in meaningful concentrations. These results are thought to correlate with the findings of a recent trace element geological assay done at the same area, and it would be of help in monitoring and assessing the national background radiation levels. (Author).

Hady, E.E.A.; El-Sayed, A.M.A.; Ahmed, A.A. [El-Minia Univ. (Egypt). Dept. of Physics; Hussein, A.Z. [Atomic Energy Authority, Cairo (Egypt). National Centre for Nuclear Safety and Radiation Control

1994-07-01

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Numerical Simulations of the Incremental Intrusion of Granitic Magma into Continental Crust  

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We have employed the visco-elasto-plastic Finite-Element & Marker-in-cell code, MILAMIN_VEP, to carry out a 2D modeling study of the incremental intrusion of granitic magma into continental crust. Algorithms of multiple pulses of magma and pseudo-diking are implemented into the code. New magma of an initial circular shape is regularly replenished at "magma source" regions at sub-crustal depths. Pseudo-dikes of rectangular shapes are added at location where the maximum differential stress along the melt-solid interface is greater than an assigned tensile strength of the surrounding solid host rock. Preliminary results show that when diking and multiple pulses of magma are included, later pulses of magma rise higher and faster and even reach the Earth's surface in some cases by taking advantage of the pre-heated low-viscosity pathways created by earlier dikes and pulses of magma. Host rocks display bedding rotation, and downward flow at two sides of a growing magma chamber but show discordantly truncation when magma ascend through the weak channels made by dikes. The effect of the thermal structure of the crust was tested as well. In a cold crust, "diking" is critical in breaking the high-viscosity crust, guiding the direction of magma rising, and facilitating later magma pulses to form chambers. In a warmer crust, magma rises in the form of diapirs, after which dikes take over in transporting later pulses of magma to the surface. The simulations also suggest that a magma chamber incrementally constructed by multiple magma bathes is a very dynamic environment featuring intra-chamber convection and recycling previous batches of magma. In simulations without diking and multiple pulses, magma is unable to reach the shallow crust. Instead, it is stuck in the middle crust, as the viscosity of the upper crust is too large to permit rapid motion, and at the same time magma-induced stresses are insufficient to deform the upper crust in a plastic manner. Intra-crustal convection in the middle and lower crust occurs regardless of the flow flaws and geothermal gradients employed. Simulations with only one of the algorithms also fail to bring magma to the shallow crust. The simulations suggest that multiple pulses and diking might be two important factors aiding the rise of granitic magma to the uppermost crust. These results have implications for the magmatic evolution of arcs such as the Mesozoic Sierra Nevada arc. They may help us to understand the processes such as the ascent of magma, incremental growth of a large magma chamber, and host rock deformation accompanying with magma ascent and emplacement.

Cao, W.; Kaus, B. J.; Paterson, S. R.

2012-12-01

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Interactions between extensional shear zones and syn-tectonic granitic intrusions: the example of Ikaria Island (Cyclades, Greece)  

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The Aegean domain is an ideal place to investigate the development of Metamorphic Core Complex (MCC) and to study the role of syn-tectonic granites on their development. MCCs of the Aegean domain are dynamically associated with a few major detachments, especially the North Cycladic Detachment System (NCDS) and the West Cycladic Detachment System (WCDS), which have accommodated a large part of the crustal thinning during the Oligocene and Miocene. The NCDS extends toward the East within the Simav Detachment that has exhumed the northern high-temperature part of the Menderes massif. The transition between the NCDS and the Simav Detachments is located above a major tear in the Aegean slab whose effects on lithospheric deformation are far from understood. The Aegean granitoids were emplaced during the Middle Miocene within a zone of high-temperature during the episode of slab tearing and recorded increments of extensional tectonics within this complex zone. Ikaria Island (Cyclades, Greece) is a metamorphic dome intruded by three Miocene granitoid plutons (one I-type intrusion, two S-type ones) including the largest pluton of the Aegean domain. However, geometry, structures and kinematics are still debated with several recent yet conflicting studies. We have reconsidered the geology of Ikaria to settle the geological and structural context of these plutons. The intrusion depth of the Raches granite has been estimated at 10-15 km by the Al-in-hornblende barometer. Our field study has led to the identification of two major structures: the Gialiskari and Kalamos detachments, which we interpret as belonging to the NCDS. A study of deformation in the granites has highlighted a continuum during cooling that can be described in three stages: i) magmatic deformation, ii) high-temperature ductile deformation from late magmatic stage until complete crystallization of the granite, iii) low-temperature brittle deformation. Throughout this evolution, the same top-to-the-NE shearing deformation was active below the Gialiskari and Kalamos detachments with a progressive localization of strain. A scenario of this deformation continuum below the Gialiskari-Kalamos detachments through the ductile-brittle transition is proposed. The granites were emplaced while the exhumation of the Ikaria high-temperature metamorphic dome was already underway. We conclude that the crustal-scale detachment has controlled the localization of the intrusion and not the opposite.

Laurent, Valentin; Beaudoin, Alexandre; Jolivet, Laurent; Arbaret, Laurent; Augier, Romain; Rabillard, Aurelien

2014-05-01

 
 
 
 
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The timing of partial melting, Barrovian metamorphism and granite intrusion in the Naxos metamorphic core complex, Cyclades, Aegean Sea, Greece  

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The relationship between partial melting and granite intrusion in a classic Barrovian metamorphic terrane has been assessed. Thirteen samples were dated by SHRIMP U-Pb zircon geochronology from the island of Naxos, Greece, one of the Aegean metamorphic core complexes. The effect of partial melting during peak Barrovian metamorphism on Naxos is recorded by fine (rims with distinctly different concordant ages, ranging from 20.7 to 16.8 Ma, both from different samples and from within the one handspecimen, suggests that zircon precipitation, associated with the partial melting process, was episodic over this age range on both local (cm) and regional (km) scales. Zircons from four granite intrusives were also dated and range in age from 15.4 to 11.3 Ma, with the main period of magmatic activity at ca. 12 Ma, clearly post-dating metamorphism. The sequence of partial melting, Barrovian metamorphism and magmatism in the Naxos metamorphic core complex can be related to a change from overall crustal shortening to extensional tectonism in the Aegean region, caused by post-collisional roll-back of the subducting African slab along the Hellenic trench system.

Keay, Sue; Lister, Gordon; Buick, Ian

2001-12-01

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Gravimetric modeling of the Parguaza granitic intrusion, Guyana Precambrian Shield, southwestern Venezuela using geochronological constraints  

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Full Text Available A combined gravimetric and geochronological interpretation of the Parguaza intrusion in the Guayana shield, southwestern Venezuela, indicates that there is a pattern of inverse cooling within this pluton. Based on a positive correlation between Rb/Sr whole rock apparent ages and residual Bouguer anomaly, density contrasts over the Parguaza intrusion are linked to temperature and crystallization of mineral phases. This hypothesis is supported by density measurements on hand samples and by independent geochemical evidence. A simple 2D gravity model is constrained by surface geology, Rb/Sr apparent ages (whole rock and residual Bouguer anomalies. Gravimetric modeling implies a model of horsts and grabens that accounts for inverse zoning of the intrusion as a result of geological and age contrasts across the faults.

Oscar Mirón-Valdespino

2004-12-01

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Contact metamorphism, partial melting and fluid flow in the granitic footwall of the South Kawishiwi Intrusion, Duluth Complex, USA  

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The footwall of the South Kawishiwi Intrusion (SKI) a part of the Mesoproterozoic (1.1 Ga) Duluth Complex consists of Archean granite-gneiss, diorite, granodiorite (Giant Range Batholith), thin condensed sequences of Paleoproterozoic shale (Virginia Fm.), as well as banded iron formation (Biwabik Iron Fm). Detailed (re)logging and petrographic analysis of granitic footwall rocks in the NM-57 drillhole from the Dunka Pit area has been performed to understand metamorphic processes, partial melting, deformation and geochemical characteristics of de-volatilization or influx of fluids. In the studied drillhole the footwall consists of foliated metagranite that is intersected by mafic (dioritic) dykes of older age than the SKI. In the proximal contact zones, in the mafic dykes, the orthopyroxene+clinopyroxene+plagioclase+quartz+Fe-Ti-oxide+hornblende±biotite porphyroblasts embedded in a plagioclase+K-feldspar+orthopyroxene+apatite matrix indicate pyroxene-hornfels facies conditions. Migmatitization is revealed by the euhedral crystal faces of plagioclase and pyroxene against anhedral quartz crystals in the in-situ leucosome and by the presence of abundant in-source plagioclase±biotite leucosome veinlets. Amphibole in the melanosome of mafic dykes was formed with breakdown of biotite and implies addition of H2O to the system during partial melting. Towards the deeper zones, the partially melted metatexite-granite can be characterized by K-feldspar+plagioclase+quartz+ortho/clinopyroxene+biotite+Fe-Ti-oxide+apatite mineral assemblage. The felsic veins with either pegmatitic or aplititic textures display sharp contact both to the granite and the mafic veins. They are characterized by K-feldspar+quartz±plagioclase±muscovite mineral assemblage. Sporadic occurrence of muscovite suggest local fluid saturated conditions. Emplacement of gabbroic rocks of the SKI generated intense shear in some zones of the granitic footwall resulting in formation of biotite-rich mylonites with lepidoblastic texture. High modal content of syn-tectonic biotite in these shear zones indicate involvement of large amount of fluids during deformation. Apatite is an omnipresent accessory mineral in all rock types, with up to 1-3% modal proportion. Crystal habit is columnar or rarely needle-like. XCl/XF and XOH/XF ratios of apatite were compared with depth in the drillhole and in relation to the host rock type. Apatite in the metagranite and in the mafic dyke is fluorine-rich (XFgranite?1,27-1,63; XFmafic dyke?1,51-1,83) and their XCl/XFgranite?0,083 to 0,051 and XCl/XFmafic dyke?0,051 to 0,044 ratios decrease towards the distal parts of the contact. Apatite in biotite-rich mylonite, as well as in the porphyroblasts of mafic dykes, is extremely depleted in chlorine- and hydroxyl-anions (XCl/XFmylonite?0,02 and XOH/XFmylonite?0,14), whereas apatite in felsic dykes and in the in-source leucosome are enriched in hydroxyl and chlorine relative to fluorine (XCl/XFfelsic vein?0,21 and XOH/XFfelsic vein?0,37). These variations suggest release of chlorine enriched fluids from the partially melted contact zones and movement and enrichments of these fluids in migration channels of partial melts. It has been for a long time accepted that fluids emerging from the metamorphosed Virginia Formation played an essential role in the formation of the Cu-Ni sulphide and PGE mineralization at the bottom of the gabbroic intrusions in the northwestern marginal zones of the Duluth Complex. Our study proves that the granitic footwall was also an important source of fluids and melts. We acknowledge the Austrian Science Found (FWF P23157-N21) to A. Mogessie for the financial support.

Benko, Z.; Mogessie, A.; Molnar, F.; Severson, M.; Hauck, S.; Lechler, P.; Arehart, G.

2012-04-01

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The Eburnean granitic Djebel Drissa ring complex (Eglab shield, Algeria): post-collisional intrusions in a transtentional tectonic setting  

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The Eburnean A-type granitic Djebel Drissa ring complex is part of the 2.08 Ga Aftout magmatic suites that intruded the 2.22-2.09 Ga-old Paleoproterozoic granitoids in the Eglab shield. This post-collisional pluton is composed of unfoliated granitoids disposed in near-concentric zones. The zoning feature is interpreted as intrusions of continuous magmatic pulses, leading to its in situ growing. New field observations and new geophysical data are presented in order to determine the structural context of Djebel Drissa complex emplacement. The magma internal structures were obtained by mapping the magnetic structures (foliation and lineation) from an Anisotropy of Magnetic Susceptibility (AMS) study. Modeling from together gravimetric and aeromagnetic data yielded its geometry in depth. The combined use of data of these different approaches provides a new and enriched image of the Drissa complex and of its evolution. Indeed, these data point out that the regional deformation controlled the emplacement of this complex. The sub-circular shape of the granitic body and AMS strain pattern are consistent with a transtensional tectonic setting along the NW-SE major Chenachane shear-zone and with an emplacement also controlled by an associated WNW- ESE extension fault. From all these data, a reliable model was inferred for the evolution of this ring complex, which emplacement marked the end of the main Proterozoic history of the Eglab shield.

Merabet, Nacer-Eddine; Mahdjoub, Yamina; Abtout, Abdeslam; Henry, Bernard; Kahoui, Mohamed; Maouche, Said; Lamali, Atmane; Ayache, Mohamed

2013-04-01

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The Blackwater Intrusion of the Grampian Orogeny: Implications for the Younger Basics and the Tectonic-Metamorphic Zonation of the Grampian Terrane, NE Scotland  

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The Dalradian Supergroup of NE Scotland hosts the classic Buchan low-pressure high-temperature metamorphic domain, as well as a suite of substantial ~470Myr syn-orogenic mafic intrusions (the 'Younger Basics') and a set of major, steeply-inclined shear zones which deform both the Dalradian country rocks and the Younger Basics. The Blackwater mafic intrusion is situated within one such shear zone, the Portsoy-Duchray Hill Lineament (PDHL), which runs SW inland from the coast at Portsoy and corresponds with the westernmost limit of Buchan metamorphism. Occupying a position between the Appin and Argyll Groups, the Blackwater Intrusion is emplaced at a deeper structural level than other more extensively studied Younger Basics to the East towards Aberdeen (such as the Insch Intrusion) and North along the PDHL (such as the Portsoy Gabbro). Uniquely for a Younger Basic mass, it is also in contact with older Dalradian meta-basic rocks, the somewhat enigmatic Blackwater Formation. A well as examining the Blackwater Intrusion, this study presents new evidence pertaining to the history of the Younger Basics and the PDHL, and their place within the Grampian Orogeny. The Blackwater Intrusion has an elongate shape roughly parallel to the strike of the surrounding Dalradian rocks, covers ~9km2 and mainly comprises blue-grey gabbro with scattered serpentinised ultramafic zones. Both the gabbro and serpentinite generally have massive texture, although some evidence of cm-scale modal layering (interpreted as cumulate texture) is present the north of the intrusion. It is in contact to the east with psammites, schists and meta-basic extrusives of the Argyll Group Blackwater Formation, and to the west with the Appin Group Glenfiddich Pelite Formation. Evidence for shearing is widespread, with sheared microstructures in pelites and meta-basites, mylonitised meta-sediments adjacent and parallel to the NW contact of the gabbro and vertical/sub-vertical NE-SW trending shear zones within the gabbro and serpentinite. Also, several apparently sheared m-scale pegmatite dykes cross-cut the gabbro, also with a NE-SW orientation. There is no evidence for significant hornfelsing adjacent to the intrusion. Collectively, this evidence suggests that the mass is largely tectonically emplaced, and that the PDHL was active both during and after emplacement of the Blackwater Gabbro. Meta-basic rocks of the Blackwater Formation have been interpreted as pillow basalts erupted from a submarine rift associated with the breakup of Rodinia. Vesicles are abundant in some outcrops, consistent with an extrusive origin. Determination of ?34S values in sulphide minerals and REE element profiles of the meta-basalts should further test the origin of these undated units. I will also present fluid inclusion data from mylonites adjacent to the intrusion and Cr-spinel-specific elemental data bearing on the nature of the original ultramafic melt composition, the mantle peridotite source, and tectonic setting of the Younger Basic bodies.

Webb, Gareth; Raub, Timothy

2014-05-01

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Structural record of mechanisms of granite intrusion in the Achaean gneisses  

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A model of diapiric formation of granite domes within green-stone areas is based on gravitational re-distribution mechanisms of rocks in the Precambrian continental crust (e.g. McGregor, 1951; Ramberg, 1951; Perchuk, 1989, 1993; Perchuk et al., 1992). In addition, the gravitational re-distribution is the leading mechanism to form Precambrian granulite facies terrains among green-stone belts. It has been proven by data on general geology, tectonics, petrology, geochemistry, isotopic geology, geophysics, and numerical modeling (Perchuk et al., 2001; Gerya et al., 2000, 2002). However the behavior of granite melt within gneisses of similar bulk composition is questionable. If the above mechanisms works well in the case of "granitic gneiss - granite melt", the ascending rocks must have structural features that indicate upward movement, while the adjacent wall rocks must demonstrate structural features of the opposite movement. In metamorphic rocks these features are represented by lineation, drag folds, orientation of fold hinges etc. Apart from "straight gneisses" (Davidson, 1984; Smit & van Reenen, 1997) no direct evidence for the internal dynamics of the formation of high-grade terrains has ever been considered. In this paper we formulate a rule allowing discrimination between cylindrical metamorphogenic and magmatogenic structures and demonstrate a model of their formation. Two types of ring structures are considered as indicators of ascending granulites toward the surface, i.e. cylindrical folds (sheath fold) and granite stocks. Systematic studies of such structures at diverse erosion sections allowing the conclusion on their formation. During exhumation (decompression) of granulite facies terrains the formation of sheath folds are resulted from generation of the granite magma within the same granitogneissic material and subsequent uprising due to difference in densities of contacting materials because all sheath folds con. This is recorded in the contrasting orientation of strong liniation and small folds axes in granulite facies complexes (see a micro model in Fig. 1a). Despite the fact that these structures are located more than hundred kilometers apart, they are characterized by similar orientation of foliation and lineations that are the evidence for their simultaneous formation. This conclusion is well supported by isotopic geochronological data (Boshoff et al., 2006; van Reenen et al., 2007). Numerical modeling (Fig. 1b-d) of this movement strongly supports this mechanism and suggests that the formation of sheath folds as the result of granite magma generation from gneisses of similar bulk composition reminds boiling of viscose liquids. This study was financially supported by NRF SA and the Russian Foundation for Basic Research, project nos. 06-05-64098 and 08-05-00354, and Russian President's Program for the support of leading scientific schools, grant NSh-1949.2008.5. References. Boshoff, R., Van Reenen, D.D., Smit, C.A. ?t al., 2006. J. Geology, 114, 699. Davidson, A. Journal of Geodynamics. 1984, 1, 433-444. Gerya, T.V., Perchuk, L.L., Van Reenen, D.D. et al. 2000. J. Geodynamics, 30, 17. Gerya T.V., Perchuk L.L., Maresch W.V et al., 2002. Europ. J Mineral., 14, 687-699. Macgregor A.M. Transactions of Geological Society of South Africa. 1951. V. 54. P. 27-71. Perchuk L.L., 1989. In Evolution of Metamorphic Belts. Geol. Soc. Lond. Spec. Pub. 42, P. 275. Perchuk, L.L., Podladchikov, Yu.Yu., Polyakov, A.N., 1992. J. Metam. Geol., 10, 311. Perchuk L.L., van Reenen D.D., Smit C.A., Boshoff, G. A. Belyanin, Yapaskurt V.O. Petrology, 2008, V. 16, No. 7, ?. 652-678. Ramberg H. Gravity, deformation and the Earth's crust. Academic Press. London-New-York-Toronto-San Francisco. 1981. 296 p. Smit, C.A. & Van Reenen, D.D., 1997. Journal of Geology, 105, 37-57. Van Reenen, D.D., Boshoff, R., Smit, C.A. et al., 2007, Gondwana Research (in press). To observe this Figure please contact the first author llp@geol.msu.ru Figure 1. Fragments of natural (?) and modified numerical (b - d

Perchuk, L. L.; van Reenen, D. D.

2009-04-01

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Depth Estimation of Digitized Aeromagnetic Data of the Western Part of the Younger Granite Rocks of North Central Nigeria, West Africa  

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Full Text Available The present study is aimed at estimating the depths extents of aeromagnetic anomalies over the younger granite rocks and their associates in the western part of North Central Nigeria. The Younger Granites rocks of North Central Nigeria are characterized by total magnetic intensity values ranging from 32670 to 33070 nanoTesla (nT. Most of the anomalous features trend in the northeast-southwest direction. Medium to higher magnetic intensity values occupy more than three quarter of the area. Third order polynomial trend surface fitting performed by least squares produced positive regional field without preferred direction. Higher regional field values are observed along the southern region and lower ones around the northeast. The surface residual anomaly has values between 32660 and 33061 nT. E-W, NE-SW and NNW-SSE are the main structural directions of the residual anomalies. Individual anomalies suggest discontinuity of the rock units. Residual anomalies of the total magnetic intensity fields fitted with third degree polynomial regional curves along four profiles produced both negative and positive values. Segments of the profiles with little variations are considered magnetic ‘quiet’ environments and those showing considerable variation are ‘noisy’ and indicate magnetic sources in the subsurface. Two and a half dimensional models of the subsurface structures suggest deep seated fault along the profiles that attained maximum depths of 12.0 km each along sections Mag1 and Mag2; 13.0 km along Mag3 and 26.6 km along Mag4. The steepness of the magnetic sources suggest possible relative displacement of the blocks of the rock bodies of these magnitudes. The fault correlate with Romanche fracture zone which, if extrapolated into Nigerian landmass will pass through the area diagonally in a NE-SW striking direction.

S.C. Alkali

2012-08-01

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Determination of concentrations and isotopic ratio of uranium in groundwaters drawn from two deep wells drilled in granitic rocks belonging to Itu intrusive suite  

International Nuclear Information System (INIS)

This paper presents the first results obtained in the determination of dissolved uranium concentrations and (234U/238U) activity ratios of groundwaters drawn from two deep wells drilled in granitic rocks belonging to Itu Intrusive Suite, which is located at eastern Sao Paulo State. One of the wells, whose groundwaters have been analyzed, is located in Salto Town, while the other one is located in Itu Town. The groundwater sampling is monthly and begun on September, 2004, in order to investigate possible sazonal variations. The alpha spectrometry technique, associated with isotopic dilution method, has been used for these determinations. The data obtained up to now show that the groundwaters from Salto present uranium concentrations significantly lower ((0.098 ± 0.007) - (0.17 ± 0.01) ng/g) than those from Itu ((0.22 ± 0.02) - (0.31 ± 0.02) ng/g). The 234U and 238U isotopes of the investigated groundwaters from both wells are in radioactive disequilibrium, with (234U/238U) activity ratios systematically higher than unity. Although the groundwaters from Salto well are characterized by low 234U and 238U specific activities they present higher (234U/238U) activity ratios than those from Itu. The observed differences on the behavior of uranium concentrations and (234U/238U) activity ratios in the groundwaters from the two wells are very prdwaters from the two wells are very probably due to the large variety of granitic rocks from Itu Intrusive Suite, which are characterized by distinct uranium abundances. (author)

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Cryogenian transpression and granite intrusion along the western margin of Rodinia (Mt. Abu region): Magnetic fabric and geochemical inferences on Neoproterozoic geodynamics of the NW Indian block  

Science.gov (United States)

The Mt. Abu batholith in NW India comprises variably deformed porphyritic, granophyric to medium-grained granites and granite gneisses. They are intruded by rhyolitic and mafic dykes; the latter also mark the terminal magmatic phase in this batholith. Granitoids and rhyolitic dykes form a coherent group; petrographic and geochemical characteristics indicate high level intrusion of felsic magma generated from high temperature melting of a lower crustal source. Geochemical similarity, spatial contiguity and coeval emplacement (766 to 763 Ma) of Mt. Abu granitoids with the Neoproterozoic (770 to 750 Ma) Malani Igneous Suite (MIS) underline that both are related to the same thermal event with Mt. Abu batholith as southeastern continuity of the MIS. Anisotropy of magnetic susceptibility data shows parallel fabric orientation in all granitoid types (NE trend, steep SW dip) as well as in a prominent shear zone (Delwara Shear Zone) along the western margin of the batholith with continued deformation during and after the emplacement of granitic magma as inferred from deformation of late-stage mafic dykes. Including coeval shear zones and associated melting in the region NE of Mt. Abu shear-controlled magma generation and ascent along a > 50 km NE trending corridor (Mt. Abu-Sirohi fault zone) is inferred. Structural elements and microstructural criteria (steep foliations, vertical lineations, dextral displacement) indicate a transpressional setting for this Cryogenian event. In regional geodynamic context the Mt. Abu-MIS can be regarded as northeastern continuation of the Neoproterozoic (800-700 Ma) magmatic belt extending from northern Madagascar, the Seychelles into NW India. This magmatic belt, located along the western margin of supercontinent Rodinia, was formed during eastward subduction of the Mozambique Ocean. Transpressional forces responsible for shaping the structural architecture in the Mt. Abu-Sirohi region were most likely induced during closure of the Mozambique Ocean and related translation of the Marwar craton.

de Wall, Helga; Pandit, Manoj K.; Dotzler, Ramona; Just, Jana

2012-07-01

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Extreme U-Th disequilibrium in rift-related basalts, rhyolites and granophyric granite and the timescale of rhyolite generation, intrusion and crystallization at Alid volcanic center, Eritrea  

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Rhyolite pumices and co-erupted granophyric (granite) xenoliths yield evidence for rapid magma generation and crystallization prior to their eruption at 15.2 ?? 2.9 ka at the Alid volcanic center in the Danikil Depression, Eritrea. Whole-rock U and Th isotopic analyses show 230 Th excesses up to 50% in basalts <10 000 years old from the surrounding Oss lava fields. The 15 ka rhyolites also have 30-40% 230Th excesses. Similarity in U-Th disequilibrium, and in Sr, Nd, and Pb isotopic values, implies that the rhyolites are mostly differentiated from the local basaltic magma. Given the (230 Th/232Th) ratio of the young basalts, and presumably the underlying mantle, the (230Th/232Th) ratio of the rhyolites upon eruption could be generated by in situ decay in about 50 000 years. Limited (???5%) assimilation of old crust would hasten the lowering of (230Th/232Th) and allow the process to take place in as little as 30 000 years. Final crystallization of the Alid granophyre occurred rapidly and at shallow depths at ???20-25 ka, as confirmed by analyses of mineral separates and ion microprobe data on individual zircons. Evidently, 30 000-50 000 years were required for extraction of basalt from its mantle source region, subsequent crystallization and melt extraction to form silicic magmas, and final crystallization of the shallow intrusion. The granophyre was then ejected during eruption of the comagmatic rhyolites. ?? 2006 Oxford University Press.

Lowenstern, J. B.; Charlier, B. L. A.; Clynne, M. A.; Wooden, J. L.

2006-01-01

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The Veikkola granite area in southern Finland: emplacement of a 1.83-1.82 Ga plutonic sequence in an extensional regime  

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Full Text Available Four granite intrusions and coeval small enderbite intrusions, belonging to the lateorogenic (1850–1820 Ma magmatism of the Svecofennian orogeny, are described in the Veikkola area of southern Finland. The granites are leucocratic, heterogeneous and characterizedby abundant garnet. The oldest granite is layered whereas the younger ones are more homogeneous. Geochemically the granites are peraluminous and have high contents of SiO2 (71–76 wt.%. Their major and minor element composition varies significantly but the REE patterns are fairly similar. Garnet mainly crystallized from melt but some garnet in the granites may be restitic. Garnet composition is relatively constant implying slow equilibration with the melt. In addition to garnet-bearing felsic layers in the oldest granite, the granites are crosscut by garnet-bearing dikes and veins. The layers, dikes and veins are higher in REE and Fe/Mg than the host granites and are considered partial melts from the granites. The abundant garnet in the felsic layers, dikes and veins crystallized from melt. Thermobarometry calculations indicate 3.5 – 5 kbar and ~650–700 °C estimates for crystallization of the felsic layers in the oldest granite whereas the host granite yields ~1.5 kbar higher pressure. The granites were probably derived by dehydration melting of layered, metagreywacke-dominated rocks. Melting was fluid-absent both during generation of the granites and during formation of the felsic layers, dikes and veins. The oldest granite (1850 Ma was emplaced at mid-crustal depth before extensional deformation. Layering in the oldest granite is regarded as the result of deformation-induced remelting of the host granite at a higher crustal level, during protracted extension and progressive regional metamorphism. The otherthree granites and the enderbite were emplaced at a late stage of extension, at or close to the peak of metamorphism (1.83 – 1.82 Ga.

Matti Kurhila

2008-01-01

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Structure and timing of Neoarchean gold mineralization in the Southern Cross district (Yilgarn Craton, Western Australia) suggest leading role of late Low-Ca I-type granite intrusions  

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The formation of structurally controlled lode-gold deposits is a controversial subject with both magmatic and metamorphic fluids considered a feasible source for gold. Here we present a study from the Southern Cross district (Yilgarn Craton, Western Australia), where structurally controlled Neoarchean gold deposits are hosted in amphibolite facies greenstones. We combine geochronological data with structural analysis to constrain the timing and structural control of ore deposition. We show that gold mineralization took place between c. 2638 and 2630 Ma, contemporaneous with the onset of voluminous intrusions of Low-Ca, I-type granites, which are ubiquitous in Southern Cross and elsewhere in the Yilgarn Craton. We argue that the timing of the intrusions, their spatial association with gold deposits, their chemical composition, and isotopic signature are consistent with Low-Ca granites being a major fluid source for mineralization. We propose that the fluid release by cooling plutons was facilitated by transport along active amphibolite facies shear zones. As gold mineralization was synchronous with Low-Ca magmatism across large areas of the Yilgarn Craton, our model may be applicable to orogenic gold deposits in other parts of the Yilgarn Craton as well as other Archean granite-greenstone terrains with a ‘late granite bloom’.

Doublier, Michael P.; Thébaud, Nicolas; Wingate, Michael T. D.; Romano, Sandra S.; Kirkland, Christopher L.; Gessner, Klaus; Mole, David R.; Evans, Noreen

2014-10-01

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Timing, petrogenesis and tectonic setting of the Late Paleozoic gabbro-granodiorite-granite intrusions in the Shalazhashan of northern Alxa: Constraints on the southernmost boundary of the Central Asian Orogenic Belt  

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The Late Paleozoic tectonic setting and location of the southernmost boundary of the Central Asian Orogenic Belt (CAOB) with respect to the Alxa Block or Alxa-North China Craton (ANCC) are debated. This paper presents new geochronological, petrological, geochemical and zircon Hf isotopic data of the Late Paleozoic intrusions from the Shalazhashan in northern Alxa and discusses the tectonic setting and boundary between the CAOB and ANCC. Using zircon U-Pb dating, intrusions can be broadly grouped as Late Carboniferous granodiorites (~ 301 Ma), Middle Permian gabbros (~ 264 Ma) and granites (~ 266 Ma) and Late Permian granodiorites, monzogranites and quartz monzodiorites (254-250 Ma). The Late Carboniferous granodiorites are slightly peraluminous and calcic. The remarkably high zircon Hf isotopes (?Hf(t) = + 6-+ 10) and characteristics of high silica adakites suggest that these granodiorites were mainly derived from “hot” basaltic slab-melts of the subducted oceanic crust. The Middle Permian gabbros exhibited typical cumulate textures and were derived from the partial melting of depleted mantle. The Middle Permian granites are slightly peraluminous with high-K calc-alkaline and low ?Hf(t) values from - 0.9 to + 2.9. These granites were most likely derived from juvenile materials mixed with old crustal materials. The Late Permian granodiorites, monzogranites and quartz monzodiorites are characterized as metaluminous to slightly peraluminous, with variable Peacock alkali-lime index values from calc-alkalic to alkali-calcic. These rocks were mainly derived from juvenile crustal materials, as evidenced by their high ?Hf(t) values (+ 3.3 to + 8.9). The juvenile sources of the above intrusions in the Shalazhashan are similar to those of the granitoids from the CAOB but distinct from the granitoids within the Alxa Block. These findings suggest that the Shalazhashan Zone belongs to the CAOB rather than the Alxa Block and that its boundary with the Alxa block can be regarded as the southernmost boundary of the CAOB. The recognition of Late Carboniferous typical adakite magmatism in the region provides evidence for the subduction of the oceanic crust of the CAOB. The Middle-Late Permian magmatisms (266-250 Ma) display a bimodal association with high-K calc-alkaline features and are interpreted as forming in a post-collision setting. These studies, by interaction of regional geology, provide new constraints on the tectonic evolution of the southern CAOB during the Late Paleozoic and the location of the southernmost margin of the CAOB.

Shi, Xingjun; Wang, Tao; Zhang, Lei; Castro, Antonio; Xiao, XuChang; Tong, Ying; Zhang, Jianjun; Guo, Lei; Yang, Qidi

2014-11-01

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Quartz And Zircon as markers of the magmatic-hydrothermal evolution of the Antônio Vicente Granite, Velho Guilherme Intrusive Suite, Carajás Province  

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Full Text Available the Antônio Vicente Granite, Carajás Province, by scanning electron microscope-cathodoluminescence (SEM-CL images. In the lessevolved rocks, containing amphibole and biotite, well developed anhedral to subhedral, luminescent and intensely fractured crystalsdominate, named Qz1. Hydrothermal fluids that percolated the granite modified the magmatic quartz (Qz1 into Qz2 and Qz3 throughprocesses of alteration, dissolution and recrystallization, with these changes much more evident in the intensely altered syenograniterocks. Qz4 constitute medium-to-coarse grained crystals, usually luminescent and comparatively little fractured. Its occurrence is restrictedto strongly hydrotermalized syenogranite rocks and bodies of greisens, suggesting the beginning of the greisenization process.In the greisens, medium-to-coarse grained euhedral, concentrically zoned quartz crystals dominate, with typical features of hydrothermalorigin (Qz5. Fine crystals of zoned cassiterite (? 100 ?m are common and fill cavities in the types Qz4 and Qz5. Zircon crystalsdominantly anhedral, corroded, with the highest contents of Hf and the lower Zr/Hf ratios belong to more evolved and hydrothermallyaltered rocks and to associated greisens, both carriers of Sn mineralization. This fact suggests that the geochemical signature of zircon,especially Zr/Hf ratio, can be used for the preliminary assessment of metallogenic potential of tin granites.

Claudio Nery Lamarão

2013-06-01

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Interacción termal entre magmas graníticos laramídicos y rocas encajonantes mesoproterozoicas: Historia de enfriamiento de intrusivos de la Sierrita Blanca, NW Sonora / Thermal interaction between Laramide granitic magmas and Mesoproterozoic country rocks: thermochronology of intrusives of Sierrita Blanca, NW Sonora  

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Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Un estudio termocronológico semi-cuantitativo, combinando técnicas geocronológicas de U-Pb y 40Ar/39Ar, permitió evaluar el fenómeno de cristalización y posterior enfriamiento del cuerpo intrusivo laramídico Sierrita Blanca, así como el efecto termal del mismo en las rocas encajonantes mesoproterozo [...] icas (~1.1 Ga) denominadas granito Murrieta. La disparidad en edades U-Pb en zircones para dos muestras del granito Sierrita Blanca (72.6 ± 1.2 Ma y 69.7 ± 1.0 Ma) pudiera estar asociada al enfriamiento más rápido del magma en la zona de contacto con el encajonante mesoproterozoico; pero no se puede descartar que esta unidad granítica esté compuesta por múltiples intrusiones de composición similar y relativamente espaciadas en el tiempo. Las edades de 40Ar/39Ar (biotita y feldespato potásico) de la muestra de granito más cercana al encajonante son también más antiguas que las de la roca recolectada en la zona más interna del intrusivo. El enfriamiento inicial del granito es relativamente rápido desde la temperatura de cierre del zircón hasta la de la biotita (~36-32°C/Ma), para que posteriormente se pase a enfriamientos relativamente lentos desde la biotita hasta el feldespato potásico (~10-9°C/Ma). Estos enfriamientos del granito Sierrita Blanca son comparables, aunque quizá un poco más lentos, a los estimados para otros granitoides laramídicos del NW de México. Tres muestras del granito mesoproterozoico Murrieta, recolectadas a diferentes distancias del intrusivo laramídico, fueron fechadas por U-Pb en zircones (~1.1 Ga), reiterándose la resistencia de esta sistemática a los efectos termales. Sin embargo, se aprecia la presencia de zircones con pérdida evidente de Pb, que se asocian a la exposición de estas rocas al calor y/o fuidos relacionados a la intrusión laramídica, siendo este efecto más pronunciado en la roca recolectada cerca del contacto con el granito. Este efecto de reajuste isotópico es mucho más marcado para la sistemática de 40Ar/39Ar en biotita y feldespato potásico, al encontrarse estos minerales totalmente reajustados a edades laramídicas. Las estimaciones de enfriamiento post-reajuste isotópico entre biotita y feldespato potásico (~18-15°C/Ma) de las rocas encajonantes son, en cierto modo, armónicas con los enfriamientos estimados para estos mismos minerales en el granito laramídico. Esto sugiere que el enfriamiento general del área de la Sierrita Blanca, después de la intrusión granítica lara-mídica, fue coherente, fnalizando este en las zonas más internas del intrusivo. Por último, destacar que el pulso magmático miocénico presente en la Sierrita Blanca no ha causado ningún efecto termal apreciable en las rocas graníticas cretácicas o mesoproterozoicas. Abstract in english A semi-quantitative thermochronological study, combining U-Pb and 40Ar/39Ar geochronology, has allowed assessment of the crystallization and cooling history of the Laramide Sierrita Blanca granite as well as the thermal effects resulting from the intrusion into the Mesoproterozoic host rocks (~1.1 G [...] a Murrieta granite). The U-Pb zircon age discrepancy between two samples of the Sierrita Blanca granite (72.6 ± 1.2 Ma and 69.7 ± 1.0 Ma) could be explained by a process of faster magma cooling in the contact zone with the host Murrieta granite. However, that the Sierrita Blanca granitic unit was made up of multiple intrusions of similar compositions emplaced relatively close in time cannot be discarded. The 40Ar/39Ar ages of both biotite and K-feldspar for the granite collected close to the contact are also signifcantly older than the ages for the sample collected in a more internal zone of the intrusion. The initial cooling of the Sierrita Blanca granite was fairly fast and monotonous from the closure temperature of zircon to that of biotite (~36-32°C/Ma). Subsequently, the cooling of these Laramide rocks became relatively slow (~10-9°C/Ma) between the closure temperature of biotite and K-f

Mónica A., Enríquez-Castillo; Alexander, Iriondo; Gabriel, Chávez-Cabello; Michael J., Kunk.

36

Interacción termal entre magmas graníticos laramídicos y rocas encajonantes mesoproterozoicas: Historia de enfriamiento de intrusivos de la Sierrita Blanca, NW Sonora / Thermal interaction between Laramide granitic magmas and Mesoproterozoic country rocks: thermochronology of intrusives of Sierrita Blanca, NW Sonora  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Un estudio termocronológico semi-cuantitativo, combinando técnicas geocronológicas de U-Pb y 40Ar/39Ar, permitió evaluar el fenómeno de cristalización y posterior enfriamiento del cuerpo intrusivo laramídico Sierrita Blanca, así como el efecto termal del mismo en las rocas encajonantes mesoproterozo [...] icas (~1.1 Ga) denominadas granito Murrieta. La disparidad en edades U-Pb en zircones para dos muestras del granito Sierrita Blanca (72.6 ± 1.2 Ma y 69.7 ± 1.0 Ma) pudiera estar asociada al enfriamiento más rápido del magma en la zona de contacto con el encajonante mesoproterozoico; pero no se puede descartar que esta unidad granítica esté compuesta por múltiples intrusiones de composición similar y relativamente espaciadas en el tiempo. Las edades de 40Ar/39Ar (biotita y feldespato potásico) de la muestra de granito más cercana al encajonante son también más antiguas que las de la roca recolectada en la zona más interna del intrusivo. El enfriamiento inicial del granito es relativamente rápido desde la temperatura de cierre del zircón hasta la de la biotita (~36-32°C/Ma), para que posteriormente se pase a enfriamientos relativamente lentos desde la biotita hasta el feldespato potásico (~10-9°C/Ma). Estos enfriamientos del granito Sierrita Blanca son comparables, aunque quizá un poco más lentos, a los estimados para otros granitoides laramídicos del NW de México. Tres muestras del granito mesoproterozoico Murrieta, recolectadas a diferentes distancias del intrusivo laramídico, fueron fechadas por U-Pb en zircones (~1.1 Ga), reiterándose la resistencia de esta sistemática a los efectos termales. Sin embargo, se aprecia la presencia de zircones con pérdida evidente de Pb, que se asocian a la exposición de estas rocas al calor y/o fuidos relacionados a la intrusión laramídica, siendo este efecto más pronunciado en la roca recolectada cerca del contacto con el granito. Este efecto de reajuste isotópico es mucho más marcado para la sistemática de 40Ar/39Ar en biotita y feldespato potásico, al encontrarse estos minerales totalmente reajustados a edades laramídicas. Las estimaciones de enfriamiento post-reajuste isotópico entre biotita y feldespato potásico (~18-15°C/Ma) de las rocas encajonantes son, en cierto modo, armónicas con los enfriamientos estimados para estos mismos minerales en el granito laramídico. Esto sugiere que el enfriamiento general del área de la Sierrita Blanca, después de la intrusión granítica lara-mídica, fue coherente, fnalizando este en las zonas más internas del intrusivo. Por último, destacar que el pulso magmático miocénico presente en la Sierrita Blanca no ha causado ningún efecto termal apreciable en las rocas graníticas cretácicas o mesoproterozoicas. Abstract in english A semi-quantitative thermochronological study, combining U-Pb and 40Ar/39Ar geochronology, has allowed assessment of the crystallization and cooling history of the Laramide Sierrita Blanca granite as well as the thermal effects resulting from the intrusion into the Mesoproterozoic host rocks (~1.1 G [...] a Murrieta granite). The U-Pb zircon age discrepancy between two samples of the Sierrita Blanca granite (72.6 ± 1.2 Ma and 69.7 ± 1.0 Ma) could be explained by a process of faster magma cooling in the contact zone with the host Murrieta granite. However, that the Sierrita Blanca granitic unit was made up of multiple intrusions of similar compositions emplaced relatively close in time cannot be discarded. The 40Ar/39Ar ages of both biotite and K-feldspar for the granite collected close to the contact are also signifcantly older than the ages for the sample collected in a more internal zone of the intrusion. The initial cooling of the Sierrita Blanca granite was fairly fast and monotonous from the closure temperature of zircon to that of biotite (~36-32°C/Ma). Subsequently, the cooling of these Laramide rocks became relatively slow (~10-9°C/Ma) between the closure temperature of biotite and K-f

Mónica A., Enríquez-Castillo; Alexander, Iriondo; Gabriel, Chávez-Cabello; Michael J., Kunk.

2009-12-01

37

Geochemistry of granitic rocks in Indian cratons, a prelude for uranium exploration  

International Nuclear Information System (INIS)

Peninsular India constitutes Archaean continental nuclei, supercrustals episodic granitic intrusive and effusives, mobile belts and all are welded together by rifts and sutures. The episodic nature of granitic magmatism is well represented with peak ages recorded around 470, 1100, 1800, 2200, 2500, 3100, 3300, 3500 Ma (1) and played a vital role in crustal growth of Peninsular Indian shield similar to the world wide crustal evolution during the Proterozoic times. These cratonic blocks are stabilized and formed basement for Proterozoic basins. This granite related magmatic events include juvenile granites and reactivated gneisses in several parts of the shield areas. These accretions brought metals from mantle and also helped in their remobilization from early formed crustal blocks. Large Ion Lithoplile elements including U, Th and K thus added to the crust, later formed the potential source for QPC, unconformity related uranium deposits. In this paper, geochemical and petrogenetic evolution of granites of Dharwar, Basta, Sighbhum and Bundelkhand cratons of various ages are presented with an emphasis to narrow down the target areas for uranium exploration. The late phase granites of crustal derived with A and S type characters occurring as younger variants in the craton are favourable horizons for uranium exploration. (author)

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A geochemical and Pb, Sr isotopic study of the evolution of granite-gneisses from the Bastar craton, Central India  

International Nuclear Information System (INIS)

Preliminary Pb-Pb and Rb-Sr geochronology of granitic and gneissic rocks from the Sukma area of the Bastar craton, Central India, provides important constraints on crustal evolution. Much of the craton is made up of felsic orthogneisses and younger granitic intrusives, compositionally ranging from tonalite to granite. Pb-Pb isotopic data suggest the presence of ca. 3.0 Ga old gneisses. Younger granitic intrusives have been dated at ca. 2.6 Ga which represents a widespread resetting and/or emplacement event. Comparison of the Pb-Pb and Rb-Sr whole rock ages suggests that the latter were more perturbed after the gneiss-forming or emplacement events. All rock suites show significant geological scatter of isotopic data probably because of sampling on a regional scale, and reflect multi-stage isotopic evolution in a complex terrain. The present isotopic data indicate the presence of Archaean rock in the Bastar craton and suggest temporal similarity with the oldest crustal rocks in the Singhbhum and Dharwar cratons. (author). 18 refs., 4 tabs., 8 figs

39

Granites of the Southern Mongolia Carboniferous Arc: New geochronological and geochemical constraints  

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The crust in southern Mongolia is part of the Central Asian Orogenic Belt, a vast accretionary orogen that records the opening and closure of the Palaeo-asian Ocean in the late Proterozoic to Palaeozoic. The crustal evolution of the region is revealed in basement inliers that also contain intrusion-related porphyry ore bodies that are important mineral exploration targets. The Saykhandulaan inlier in Southeast Mongolia is a Devonian-Carboniferous segment of island-arc crust, which is dominantly composed of extrusive and sedimentary lithologies, but which also contains the Oyut Ulaan I-type quartz-monzonite intrusion. A U-Pb zircon age for the Oyut Ulaan monzonite indicates emplacement at 330.0 ± 0.5 Ma. To the east of the Saykhandulaan inlier, intrusive complexes dominate the neighbouring Mandakh inlier. New ages are presented for four of these plutons; the Bronze Fox granodiorite (333.6 ± 0.6 Ma); the Narin Hudag monzonite (333.2 ± 0.6 Ma); the Shuteen quartz monzonite (325.5 ± 1.0 Ma); and the North Mandakh granite (292.3 ± 0.5). The intrusive bodies of the Saykhandulaan and Mandakh inliers have two distinct geochronological and geochemical associations: 1) mid-Carboniferous I-type monzonites that constitute the most easterly intrusive expression of the Southern Mongolia Carboniferous Arc and, 2) Early Permian A-type and peralkaline granites that represent a post-orogenic phase of voluminous granite emplacement. Both groups are significantly younger than the nearby Oyu Tolgoi and Tsagaan Suvarga Cu-porphyry ore bodies, which have previously been dated as early- and late-Devonian respectively. The new data presented here provide constraints on the timing of the transition from island-arc magmatism to post-collisional extension-related magmatism in the region and possible controls on fertile and infertile granitoid intrusions with respect to Cu-Au mineralisation.

Blight, James H. S.; Crowley, Quentin G.; Petterson, Michael G.; Cunningham, Dickson

2010-04-01

40

Geochronology of the Schurwedraai Alkali Granite and associated nepheline syenite and implications for the origin of the Vredefort structure  

International Nuclear Information System (INIS)

New Rb-Sr and Pb-Pb whole-rock and mineral age determinations indicate ages close to 2,2 Ga for the Schurwedraai Alkali Granite and associated nepheline syenite from the northwestern part of the collar around the Vredefort dome. The 2,2 Ga age is consistent with existing age data from another intrusion in the rim of the Vredefort structure and represents a significant upward revision of the age previously accepted for the Schurwedraai Granite. As such it removes the important constraint imposed by the synchronicity of the alkali magmatism and the Vredefort event on meteorite impact theories for the origin of the Vredefort structure. The younger overprint at approximately 2050 Ma can be interpreted to reflect either the age of the Vredefort event and associated deformation/alteration of the alkali intrusives or a thermal overprint related to the emplacement of the Bushveld Complex at this time. 48 refs., 9 figs., 2 tabs

 
 
 
 
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El Granito Calasuya: un intrusivo alcalifeldespático postcolisional en el batolito de Sierra Norte-Ambargasta, Córdoba / The Calasuya Granite: a postcollisional alkalifeldspar intrusive in the Sierra Norte-Ambargasta batholith, Córdoba province  

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Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish La zona central del extenso batolito Sierra Norte-Ambargasta, en el bloque más oriental de las Sierras Pampeanas orientales, está representada por granitoides de arco magmático tipo I (granodioritas, monzogranitos, pórfidos dacíticos y riolíticos denominados serie La Isla - Cerro de los Burros), int [...] ruidos por cuerpos menores félsicos postcolisionales, químicamente más evolucionados (denominados unidades Puesto de Los Caminos y Cerro Baritina), todos pertenecientes al Neoproterozoico- Cámbrico inferior. Nueva información geológica y geoquímica de la región centro-oriental del mismo batolito permitió identificar un plutón de composición alcalifeldespática, denominado Granito Calasuya, el primero de esta naturaleza en el batolito. Su mineralogía distintiva la constituyen la composición albítica de la plagioclasa magmática (An Abstract in english The central-western portion of the extended Sierra Norte-Ambargasta batholith, in the easternmost block of the eastern Sierras Pampeanas, is largely characterized by pre-collisional I-type magmatic arc granitoids (granodiorites, monzogranites, dacite and rhyolite porphyries named La Isla - Cerro de [...] los Burros series), and by smaller sized postcollisional felsic intrusives of higher evolved chemistry (named Puesto de los Caminos and Cerro Baritina units), all of which crystallized along the Late Proterozoic -Lower Cambrian time span. New geological and geochemical data from the central and oriental areas of the batholith allowed to identify an intrusive body of alkalifeldspar composition (the Calasuya granite), the first of its type in the batholith. Its distinctive mineralogy is highlighted by the albitic composition of magmatic plagioclase (molar An

Javier, Elortegui Palacios; Raúl, Lira; Fernanda, Poklepovic; Michael J., Dorais.

2008-09-01

42

Hepburn intrusive suite: Peraluminous plutonism within a closing back-arc basin, Wopmay orogen, Canada  

Science.gov (United States)

Within the Hepburn metamorphic-plutonic internal zone of the Wopmay orogen (Northwest Territories, Canada) there are two chronologically and petrologically distinct plutonic associations. The more voluminous of the two, the older 1.885 Ga Hepburn intrusive suite, includes rocks ranging in composition from gabbro to granite, peraluminous granite dominating. The younger 1.855 Ga neighboring Bishop intrusive suite (also gabbro to granite) represents the waning stages of a well-documented calc-alkaline arc, the Great Bear magmatic zone. The petrological distinctions between the two suites are all late-acquired features imposed primarily by contrasting environments of emplacement. Hepburn magmas were intruded within a closing, dominantly sedimentary, back-arc basin. Magma emplacement was synchronous with crustal imbrication, regional metamorphism, and translation of the basin-fill units onto Archean crust. Significant assimilation of sedimentary host rocks by the rising Hepburn magmas occurred, whereas the postregional metamorphism emplacement of the Bishop magmas precluded similar assimilation. The gabbroic contribution observed in the Hepburn intrusive suite is interpreted to reflect a mantle-derived precursor inherited from the back-arc rifting event that immediately preceded emplacement of the suite.

Lalonde, André E.

1989-03-01

43

Petrophysical and geochemical characteristics of late Variscan granites in the Karlovy Vary Massif (Czech Republic - implications for gravity and magnetic interpretation in shallow depths  

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Full Text Available The Karlovy Vary Massif (KVM in northern Bohemia is a composite granite body built up of Late Variscan biotite, two mica and lithium mica granites. We summarize the available whole-rock geochemical and petrological data and correlate them with similar information from three boreholes in the northern and southwestern parts of the Massif. The aim of the study was to determine whether various types of granites differ in their physical and chemical properties, and whether any differences in physical characteristics affect the accuracy of geophysical interpretation. In accord with the earlier studies, we distinguish two geochemically and petrophysically contrasting granite suites - the Older Intrusive Complex (OIC and Younger Intrusive Complex (YIC. The geochemical data show that the OIC and YIC granites differ significantly in the content of most major-element oxides (like SiO2, TiO2, FeO, Fe2O3tot, MgO and CaO. As to physical parameters, the granites differ markedly in magnetic susceptibilities and in the contents of radioactive elements (U and Th. From gravity and magnetic data we compiled a 22 km long geophysical profile, which crosses two of the three studied boreholes. For the construction of geological model along this profile, we used the data on the petrophysical properties measured on samples from the boreholes. Densities of the individual granite types are very similar to each other and thus the distinction of the OIC and YIC granites based on gravity data is not possible. Magnetic susceptibility differs markedly for the OIC and YIC granites in the drill logs, but absolute values of magnetic susceptibilities are very low. Modelling showed that neither gravimetry nor magnetometry are suitable methods for distinguishing between the different types of granites. On the other hand, it proved that the spatial distribution of individual granite intrusions does not affect the overall interpretation of the shape, size and depth of the whole granite body.

Blecha V

2012-07-01

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From explosive breccia to unidirectional solidification textures: magmatic evolution of a phosphorus- and fluorine-rich granite system (Podlesí, Krušné hory Mts., Czech Republic  

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Full Text Available The Podlesí granite stock in western Krušné hory Mts. represents the most highly fractionated part of the late Variscan Nejdek-Eibenstock pluton. Internal fabric of the stock has been studied in several boreholes up to 350 m deep. The stock is composed of two tongue-like bodies of albite-protolithionite-topaz granite (stock granite coalesced at depth, which were emplaced into Ordovician phyllite and biotite granite of younger intrusive complex (YIC of the Nejdek pluton. The uppermost part of the intrusion is bordered by a layer of marginal pegmatite (stockscheider up to 50 cm thick. Explosive breccia was found as an isolated block at the southwest contact of the stock. It is comprised of fragments of phyllite several millimetres to 5 cm in size cemented with fine-grained granitic matrix similar to the stock granite, but very fine-grained.
Within the uppermost 100 m, the stock granite is intercalated with several mostly flat-lying dykes of albite-zinnwaldite-topaz granite (dyke granite. Upper and lower contacts of the dykes are sharp, flat, but in detail slightly uneven. The thickest dyke (about 7 m outcrops in an old quarry. A prominent example of layering with unidirectional solidification textures (UST was found in the upper part of this major dyke. Individual Q-Afs laminae are separated by comb quartz layers and/or by layers of oriented fan-like zinnwaldite aggregates. A pegmatite-like layer with oriented megacrysts of Kfs up to 6 cm long was encountered in the uppermost part of the dyke. One thin layer of fine-grained quartz with oriented Kfs-megacrysts was found within the stock granite.
Post-magmatic processes, particularly greisenisation, developed only to a limited degree. The uppermost flat dyke of the dyke granite was partly greisenised into white quartz-rich (+topaz, Li-mica, wolframite greisen. Scarce thin, steep stringers of biotite greisen were encountered over the entire outcrop and in drilled parts of the stock granite and surrounding biotite granite.

Breiter K

2002-06-01

45

The search for the youngest granites in the southern part of the Natal Metamorphic Province  

International Nuclear Information System (INIS)

It is clear that the Belmont Pluton and the dykes are geochemically, isotopically and therefore, genetically distinct. The Belmont pluton is probably related to the garnet leucogranite phase of the Margate Complex. It is suggested that the dykes (? 965 Ma) are younger than the Belmont pluton (?1055 Ma). The relatively low initial 87Sr/86Sr are typical of the granites intruded at ?1000 Ma. The age of the dykes is comparable with the 951 ± 16 Ma (Ro=.70320 ± 13) given for the Sezela pluton. The high Ro (?0.715) of the dykes is similar to other, minor granite sheets from southern Natal, and is compatible with an origin by late-stage melting of pre-existing radiogenic material. Both the dykes and the Sezela pluton are unequivocally younger than the D3 deformation, whereas the young dates from the Oribi Gorge Suite are controversial. Thus, although it is possible that some of the minor, intrusive granitic sheets could yet be shown to be of Pan-African age, it is evident that no significant Pan-African magmatism or thermal overprinting has affected the Natal sector of the Namaqua-Natal-Maudheim belt. 1 fig., 7 refs

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The petrogenesis of a wolframite-bearing greisen in the Vykmanov granite stock, Western Krušné hory pluton (Czech Republic  

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Full Text Available A wolframite-bearing greisen at Vykmanov, near Ostrov (Czech Republic occurs at the contact of a small granite stock belonging to the Late Variscan Younger Intrusive Complex (YIC of the Western Krušné hory/Erzgebirge pluton. The stock emerges as an outcrop of 0.8 × 0.3 km size from a hidden granite body in the eastern continuation of the Nejdek-Eibenstock granite massif. The lens-like greisen body consists mainly of quartz, topaz, protolithionite, and muscovite; it also contains wolframite (ferberite and native bismuth mineralization. It was formed by replacement of a medium-grained, equigranular, slightly porphyritic Li-F granite of the Karlovy Vary pluton characterized by weak postmagmatic albitization and pervasive muscovitization. The greisen is geologically and compositionally transitional between the Li-rich greisens in albite granites (e.g. with zinnwaldite such as at Krásno and the Li-poor greisens (e.g. phengite greisens at Gottesberg and P?ebuz associated with weakly albitized granites of the Younger Intrusive Complex. The Vykmanov greisen formed in a subsolidus stage of granite evolution by progressive alkali loss and fluorine metasomatism, leading to the formation of Li-mica quartz greisen subsequently replaced by topaz-quartz greisen at the granite/crystalline contact. These greisens were affected by late-stage muscovitization and argillitization (sericitization, the formation of clay minerals. The Li-Fe mica composition of the greisens corresponds to protolithionite (lithian siderophyllite and is similar to the composition of micas in the enclosing granite. The tungsten-bearing greisenization represents a postmagmatic episode in the development of the Krušné hory/Erzgebirge batholith, and is located at the eastern contact of highly evolved YIC granites of the Western Krušné hory pluton. The greisen formed from CO2 -poor hydrothermal solutions, at about 400 °C, which evolved from highly saline brines as evidenced by fluid inclusion studies. The geological situation suggests that the mineralizing fluids were mostly magmatic and were responsible for the tungsten-bismuth specialization of the greisens, whereas meteoric waters participated in mineralization during later stages.

Štemprok M

2005-09-01

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Ad Duwayhi, Saudi Arabia: Geology and geochronology of a neoproterozoic intrusion-related gold system in the Arabian shield  

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The Ad Duwayhi gold deposit, located in the east-central part of the Arabian shield, is the newest gold discovery in Saudi Arabia. Exploration to date has identified a gold resource of greater than 1 million ounces (oz) with significant potential for expansion. Gold mineralization was closely associated, in time and space, with emplacement of a late- to postorogenic, intracrustal, northwest-oriented granite body (659 ?? 7 Ma) and comagmatic square quartz porphyry (646 ?? 11 Ma), a hypabyssal and perhaps younger phase of the granite. Mineralization was largely confined to northeast-striking, southeast-dipping fault zones. Hydrothermal alteration consisted of early biotitic alteration overprinted by sericitic alteration. Sericitic alteration was coincident with gold mineralization and produced a quartz-sericite-carbonate-pyrite-rutile mineral assemblage, found both as vein fill and wall-rock alteration products. Mineralization styles, in the following general paragenetic sequence, include (1) quartz-molybdenite veins in and near the granite stock, (2) low-grade gold-bearing quartz vein breccia in and along the margins of the granite stock, (3) gold-bearing stockwork and sheeted quartz veins, and (4) massive to banded gold-rich tabular quartz veins. The gold-bearing stockwork, sheeted, and tabular veins are generally spatially associated with square quartz porphyry dikes and more distal to the granite stock. Mineralized zones at Ad Duwayhi are characterized by low sulfide and base metal content and gold/silver ratios of approximately 6/1. Gold shows no significant correlation with other metals, except lead, and moderate correlation with silver. Re-Os dating of molybdenite from a quartz-molybdenite vein and a tabular quartz vein with cogenetic gold produced robust ages of 655.6 ?? 2.7 and 649.9 ?? 2.3 Ma, respectively, documenting that gold mineralization and crystallization of granite and square quartz porphyry were, within uncertainty, coeval events. This age correlation combined with granite textural features, the presence of unidirectional solidification textures in granite and square quartz porphyry, and the nature and time-space distribution of mineralization styles, all indicate that mineralization evolved in and near the interface between a crystallizing magma and the surrounding rocks and, thus, is consistent with an intrusion-related genesis. In light of our findings at Ad Duwayhi, a reassessment of similar intrusion-hosted deposits in the Arabian shield is warranted, and areas of late- to postorogenic plutonism, particularly in the Afif composite terrane, should be considered prospective for intrusion-related gold systems. ??2004 by Economic Geology.

Doebrich, J. L.; Zahony, S. G.; Leavitt, J. D.; Portacio, Jr. , J. S.; Siddiqui, A. A.; Wooden, J. L.; Fleck, R. J.; Stein, H. J.

2004-01-01

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The petrogenesis of late Neoproterozoic mafic dyke-like intrusion in south Sinai, Egypt  

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New field, petrographical and geochemical studies are presented here for the late Neoproterozoic Rimm intrusion (˜15 km long) exposed in the southern Sinai Peninsula, Egypt in the northernmost Arabian-Nubian Shield (ANS). Field relations indicate that the Rimm intrusion is younger than the surrounding metamorphic rocks and calc-alkaline syn-tectonic granodiorite and it was not affected by regional metamorphism. The anorogenic peralkaline granite of Gebel Serbal crosscuts the Rimm intrusion. The Rimm intrusion is made up of several consanguineous rock types with gradational contacts. It is composed chiefly of pyroxene-hornblende gabbro, hornblende gabbro and minor quartz diorite. The chemical composition of the mafic minerals indicated that the studied rocks derived from calc-alkaline mafic magma. Geochemically, the studied rocks are characterized by enrichment in LILE relative to HFSE and LREE relative to HREE [(Ce/Yb)N = 4.50-6.36]. Quartz diorite display slightly concave HREE pattern and slightly negative Eu-anomaly [(Eu/Eu*)n = 0.91] which may be the result of fractionation of amphibole and plagioclase from the source melt, respectively. The Rimm intrusion evolved from mafic mantle magma into different type rocks by fractional crystallization with minor crustal contamination. The initial magma corresponds to pyroxene-hornblende gabbro and the crystallization of hornblende was caused by slight H2O increase in magma after crystallization of near-liquidus clinopyroxene and Ca-rich plagioclase. Amphiboles geobarometer indicate that the gabbroic rocks of the Rimm intrusion crystallized at pressures between 4.8 and 6.4 Kb, while quartz diorite crystallized at 1.3-2.1 Kb. Crystallization temperatures range between 800 and 926 °C for the gabbros and between 667 and 784 °C for the quartz diorite. The Rimm intrusion represents a post-orogenic phase formed during the crustal thinning and extension of the Arabian-Nubian Shield.

Azer, M. K.; Abu El-Ela, F. F.; Ren, M.

2012-08-01

49

The Structure and Emplacement of the Western Granite, Isle of Rum, NW Scotland  

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The early Tertiary British Igneous Province has been a key site for the study of magma transport and emplacement processes for well over a century and has been noted for its diverse assemblage of magma types, including mixed mafic and felsic compositions. The origin and emplacement of felsic magma bodies has been of great interest, if not controversy. The Western Granite on Rum is the largest of several granitic bodies around the margin of the Rum Central Igneous Complex, all of which are interpreted as part of early felsic updoming and caldera collapse (Stage 1) that preceded intrusion of the Rum mafic to ultrabasic Layered Suite (Stage 2). We report anisotropy of magnetic susceptibility (AMS) and paleomagnetic data that bear on the emplacement and deformation of the Western Granite. The collection includes samples from 27 sites throughout the Western Granite, five sites in harrisitic peridotite, and two sites in intermediate to mafic hybrid rocks. On the basis of magnetic fabric magnitude and susceptibility parameters, two principal groupings characterize the Western Granite AMS dataset. Group 1 data, defined by rocks from the east and south, have comparatively high bulk susceptibilities (Kmean), relatively strong anisotropies (Pj), and oblate susceptibility ellipsoids. Group 2 data, from rocks in the west, have lower values of Kmean and Pj, and triaxial susceptibility ellipsoids. We argue that magma ascent occurred along the Long Loch Fault, or similarly oriented splay, and served as a conduit for emplacement of the Western Granite. The steep oblate fabrics in the east reflect near vertical magma ascent near the feeder conduit and subhorizontal, triaxial fabrics in the west reveal near horizontal flow away from the conduit as a tabular sheet. Paleomagnetic data from 21/27 sites in the granite provide an in-situ group mean D = 207.2°, I = -71.0°, a95 = 5.6° that is discordant to an early Paleocene expected field 183.7°, - 65.6°, A95= 4.3°. The discrepancy is eliminated by removing an inferred 12° of northwest-side-down tilting about a best fit horizontal tilt axis trending 044°. Data from the peridotite and hybrid rocks provide an in-situ group mean 182.6°, -64.8°, 4.0°, which is statistically indistinguishable from an early Paleocene expected field, and implies no post emplacement tilting of these rocks since remanence acquisition. The inferred tilt recorded in the Western Granite, which did not affect the younger ultrabasic rocks, suggests that emplacement of the ultrabasic rocks at a shallow level caused significant distortion and local remobilization of the country rocks; roof uplift and associated tilt of the Western Granite probably occurred to make space for mafic magma ascent.

Petronis, M. S.; O'Driscoll, B.; Troll, V. R.; Geissman, J. W.; Emeleus, C.

2006-12-01

50

Gravimetric, radiometric, and magnetic susceptibility study of the Paleoproterozoic Redenção and Bannach plutons, eastern Amazonian Craton, Brazil: Implications for architecture and zoning of A-type granites  

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The 1.88 Ga, anorogenic, A-type Redenção and Bannach granites, representative of the Jamon suite and associated dikes, are intrusive in Archean granitoids of the Rio Maria Granite-Greenstone Terrane in the eastern Amazonian Craton in northern Brazil. Petrographic and geochemical aspects associated with magnetic susceptibility and gamma-ray spectrometry data show that the Redenção and the northern part of Bannach plutons are normally zoned. They were formed by two magmatic pulses: (1) a first magma pulse was fractionated in situ after emplacement at shallow crustal level, generating a series of coarse, even-grained monzogranites with variable modal proportions of biotite and hornblende; and (2) a second, slightly younger magma pulse, located to the center of the plutons, was composed of a more evolved liquid from which even-grained leucogranites derived. Gravity modeling indicates that the Redenção and Bannach plutons are sheeted-like composite intrusions, approximately 6 and 2 km thick, respectively. These plutons follow the general power law for laccolith dimension and are similar in this respect to classical rapakivi granite plutons. Gravity data suggest that the growth of the northern part of the Bannach pluton resulted from the amalgamation of smaller sheeted-like plutons that intruded in sequence from northwest to southeast. The Jamon suite plutons were emplaced in an extensional tectonic setting, and the stress was oriented approximately NNE-SSW to ENE-WSW, as indicated by the occurrence of diabase and granite porphyry dyke swarms, orientated WNW-ESE to NNW-SSE and coeval with the Jamon suite. The 1.88 Ga A-type granite plutons and stocks of Carajás are disposed along a belt that follows the general trend defined by the dikes. The inferred tabular geometry of the studied plutons and the high contrast of viscosity between the granites and their Archean country rocks can be explained by magma transport via dikes.

de Oliveira, Davis Carvalho; Dall'Agnol, Roberto; Corrêa da Silva, João Batista; Costa de Almeida, José Arimatéia

2008-02-01

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Zircon geochronology and Hf-O isotope geochemistry from granites in the Iapetus Suture Zone in Ireland and the Isle of Man  

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Late Caledonian syn- to post-orogenic granites located in the Iapetus Suture Zone (ISZ) in Ireland and Britain have been related to A-type subduction and possible slab breakoff [1] following the Laurentia-Avalonian collision. Lack of reliable age data (especially in Ireland) has inhibited petrogenetic investigations of these rocks. Hence, ion microprobe U-Pb and oxygen isotope analyses as well as LA-MC-ICPMS Lu-Hf isotopic measurements on zircons from Irish and Isle of Man granites have been undertaken to provide better constraints on this enigmatic episode of the Caledonian Orogeny. Four stages of Late Caledonian granitic magmatism (c. 435, 417, 410 and 394 Ma) are indicated by U-Pb dating of oscillatory-zoned magmatic zircons. The Crossdoney, Kentstown, Drogheda and Ballynamuddagh granites together with a rhyolite from Glenamaddy have yielded U-Pb concordia ages, interpreted as intrusion-ages, between 419.9 ± 4.3 Ma (Glenamaddy) and 415.8 ± 2.0 Ma (Crossdoney) with a weighted average of 417.5 ± 0.9 Ma (MSWD = 1.3). The Glenamaddy Granite - which intruded the Glenamaddy Rhyolite - yielded an age of 410 ± 2.1 Ma. In addition, the Rockabill Granite yielded a younger age of 393.9 ± 1.9 Ma, whereas the Carnsore Granite yielded an older age of 434.6 ± 1.9 Ma. Inherited zircons (487 to 453 Ma) occur in several of the granites, and are interpreted to have been derived from Ordovician arc magmatic rocks accreted within the ISZ. A younger group of c. 440 Ma inherited zircons occurs in the c. 417 Ma Crossdoney and Ballynamuddagh granites. These grains could be related to continued or renewed Silurian arc magmatism. Hf-O isotopic measurements on the dated zircon grains range between -2 and +7 ?Hfi units and 5.5 to 8.5 o ?18O. These are interpreted to indicate the contribution of juvenile mantle melts - possibly derived from the Ordovician arc - to some of the granites. Significant heterogeneities in zircon oxygen isotopes in at least four of the granites further suggest the involvement of isotopically distinct protoliths. The Dhoon and Foxdale granites in the Isle of Man were previously regarded to be of Late Caledonian age. Surprisingly, zircons from these granites yielded concordant U-Pb ages of 455.6 ± 2.1 Ma (Dhoon) and 455.9 ± 2.1 Ma (Foxdale), respectively. Inherited cores are of Meso- and Palaeoproterozoic age. Hafnium isotopic analyses of the dated magmatic zircon rims from both intrusions are slightly more radiogenic than those from the Late Caledonian granites. Their ?18O values range between 5.5 to 7.5 o. The Isle of Man granites are now suggested to be the plutonic equivalents of a Late Ordovician (Caradocian) volcanic arc generated in the Iapetus Ocean. [1] Atherton & Ghani (2002), Lithos 62, 65-85.

Fritschle, Tobias; Daly, J. Stephen; Whitehouse, Martin J.; McConnell, Brian; Buhre, Stephan

2014-05-01

52

Petrographic and mineralogical features of the uraniferous pink granites in the north eastern desert of egypt  

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The present work is concerned with the petrological, mineralogical and geochemical studies of some uranium bearing younger granites in the north eastern desert of egypt particularly Gebel Gattar area. The area around Gebel Gattar comprises the following rock units (starting from the oldest): meta volcanic, diorite-grano-diorite complex- Dokhan volcanics- Hammamat sediments, younger granites and dykes. The most significant structural features are represented by NNE-ENE dominantly trending faults and joints. Petrographicaly, the pink granites are divided into normal and mineralized (uraniferous) granites. Normal granites are classified into three types; a) leucocratic perthitic granite, b) hornblende- biotite perthitic granite and c) two feldspars perthitic granite. Mineralized granites are sheared, deformed, pinkish brown in colour and strongly altered. A remarkable secondary uranium mineralization has been recorded along fault and fracture zones

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Pórfiro granítico Mojotoro (Salta: ¿Una cúpula intrusiva o un dique en el ciclo pampeano? The Mojotoro granitic porphyry (Salta: An intrusive roaf or a dike in the Pampean Cycle?  

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Full Text Available El pórfiro granítico Mojotoro, constituye la cúpula de un plutón epizonal, emplazado en un área geológica bien conocida, de la Formación Puncoviscana, en las inmediaciones de la ciudad de Salta (24º47´44,9"S - 65º21´35,9"W, 1.304 m s.n.m.. Sin bien se carece de determinaciones geocronológicas, los caracteres geológicos regionales y situación estratigráfica de no alcanzar los niveles del Grupo Mesón, sugieren edades pampeanas, correspondientes a la orogenia tilcárica. Los caracteres petrográficos corresponden a pórfiros graníticos, con fenocristales de feldespato potásico, acompañados por cuarzo, plagioclasa y biotita. Las rocas han sufrido intensa sericitización, caolinización y limonitización. Asimismo muestra esferulitas recristalizadas, inclusiones fluidas y fragmentos de granófiro, que indican emplazamiento somero, con rápido intercrecimiento conjunto de cuarzo en una masa de feldespato alcalino hipersolvus. La susceptibilidad magnética es baja con valores de 0,11 x 10-3 SI, típicos para granitos corticales formados a partir de protolitos metasedimentarios.The Mojotoro porphyritic granite is located close to the city of Salta (24°47´44,9"S - 65°21´35,9"W, 1304 m.a.s.l., at Cerro Mojotoro in the Eastern Cordillera. The pluton is emplaced in the Puncoviscana Formation (Late Precambrian-Early Cambrian, a lithological unit composed mainly of greenish pelites. The Puncoviscana Formation is covered unconformably by Cambrian quartzites of the Meson Group. Stratigraphic relationships of the granite indicate a Pampean age and emplacement during the Tilcaric orogenic phase. Petrographically it is a porphyritic granite with K-feldspar phenocrysts accompanied by quartz, plagioclase and biotite. The rock is strongly altered by sericitization, kaolinization, and limonitization. Likewise, the granite exhibits recrystalized spherules, fluid inclusions and granophyric fragments, indicative of shallow emplacement, with fast intergrowth of quartz in a mass of K-feldspar hypersolvus. Low magnetic susceptibility, with values of 0.11x10-3 SI, is typical of cortical granite that was formed from a metasedimentary protolith.

A.J. Toselli

2005-06-01

54

Magmatic constraints on localization of natural stone deposits in the Vehmaa rapakivi granite batholith, southwestern Finland  

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Full Text Available The 1580–1570 Ma old Vehmaa rapakivi granite batholith was studied with the aim to define the geological constraints for localization of natural stone deposits in the batholith. The batholith comprises four roughly concentric granite intrusions from the margin inwards: pyterlite, coarse-grained porphyritic rapakivi granite and two types of medium-grained porphyritic rapakivi granite. Also porphyry aplite and even-grained rapakivi granite occur. The batholith has intruded as a succession of pulses of subhorizontal sheet-like intrusions conceivably through repeated cauldron subsidence. Natural stone quarries are confined only to certain intrusions within the batholith. We show that the medium-grained porphyritic granite body in the centre of the batholith comprises two almost identical but different intrusions, with only slightly different appearances: the inner (IG and the outer (OG granite. The quarries are confined to the outer intrusion which has an appearance more attractive to the market than that of the inner intrusion. The localization of the natural stone deposits in the Vehmaa batholith is a result of the magmatic history of the batholith, producing intrusions of different appearances with different commercial potential.

Olavi Selonen

2011-08-01

55

The uranium, thorium and molybdenum distribution in selected leucogranites of the Cape-granite-suite  

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Younger intrusions and hydrothermally altered rocks like alkali granite, alaskite, syenite and episyenite resembling uranium ore deposits in France and the Roessing ore body in SWA/Namibia are found within the Saldanha and Darling batholiths of the south-western Cape Province. Two areas were geologically mapped in detail and surveyed with a portable gamma spectrometer in order to establish the regional variation in U and Th concentration. A quantitative study of alpha particle tracks on autoradiographs of selected thin sections led to the determination of the contributions by various minerals to the U and Th content of each individual rock type. The rocks were also investigated petrologically and geochemically with special attention to secondary alteration processes that could have played a part in causing the distribution pattern of U and Th. Radioelement analyses of 45 mineral separates and 51 whole rock analyses were utilised

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Rb-Sr and Pb-Pb geochronological studies on the granite gneiss of Kuilapal, Purulia-Bankura Midnapore district, West Bengal  

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The number of younger granite plutons intruding the Singhbhum Mobile Belt (SMB) surrounding the Singhbhum-Orissa Craton, viz. Kuilapal granite on the East, Mayurbhanj granite, Soda granite, Arkasoni granite, Chakradharpur granite gneiss and Tamper kola granite on the west. Of these Kuilapal granite body is the largest. Besides small granite bodies intruding the low-grade meta sediments and meta volcanics which occur north of the Dalma volcanic belt. Petrographic and geochemical characters of the minor granite bodies south of Dalma volcanics are similar to those of Kuilapal granite, which is inferred to have been produced by shallow-level fractional crystallisation of a crustally derived granodiorite melt. Dominance of xenoliths in the Kuilapal granite suggest large-scale assimilation of crustal rocks. The radiometric ages vis-a-vis isotope geochemistry of the various granitoid plutons occurring within the mobile belt were used to constrain the evolutionary history of the SMB supracrustals. The Singhbhum Shear Zone which marks the boundary of the SMB with Singhbhum-Orissa Craton, shows multiple reactivation, the oldest being at ? 3.09Ga. Further phases of granite plutonism and/or shearing and mineralisation have been reported along this shear zone occurred in Palaeo-to Mesoproterozoic periods at ? 2.2, 1.8, 1.6-1.5, 1.4 and 1.0 Ga respectively. The present work pertains to the Rb-Sr and Pb-Pb whole rock geochronological studies on Kuilapal granite, which are intrus on Kuilapal granite, which are intrusive into the metasediments of Singhbhum group in the tectonic setup of north Singhbhum Mobile Belt. Fourteen samples were collected, finely powdered form the homgenised representative which were processed further. The dissolution of the rock carried out in a class-100 clean chemical laboratory, followed by the elemental separation using exchange chromatography. The separated pure fractions of the elements were analysed on VG354 Thermal Ionisation Mass spectrometer for their isotopic ratios. The Rb-Sr data on ten samples define an isochron age of 1792±98 Ma, with an initial 87Sr/86Sr of 0.7064±0.0069 (MSWD = 13). The Pb isotopic data on these samples define a Pb-Pb isochron age of 1863 ± 80Ma (MlSWD =11.3) with a model ?1 value of 8.53±0.27. Both the Rb-Sr and the Pb-Pb ages are in agreement within the limits of experimental errors. Since the 87Sr/86Sr initial ratio and model ?1 value are higher than the contemporary mantle sources, the data indicate involvement of enriched crustal sources. This age obtained on Kuilapal granite can be taken as the age of one of those periods of reactivation which occurred during Palaeo-to Mesoproterozoic periods. (author)

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Pórfiro granítico Mojotoro (Salta): ¿Una cúpula intrusiva o un dique en el ciclo pampeano? / The Mojotoro granitic porphyry (Salta): An intrusive roaf or a dike in the Pampean Cycle?  

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Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish El pórfiro granítico Mojotoro, constituye la cúpula de un plutón epizonal, emplazado en un área geológica bien conocida, de la Formación Puncoviscana, en las inmediaciones de la ciudad de Salta (24º47´44,9"S - 65º21´35,9"W, 1.304 m s.n.m.). Sin bien se carece de determinaciones geocronológicas, los [...] caracteres geológicos regionales y situación estratigráfica de no alcanzar los niveles del Grupo Mesón, sugieren edades pampeanas, correspondientes a la orogenia tilcárica. Los caracteres petrográficos corresponden a pórfiros graníticos, con fenocristales de feldespato potásico, acompañados por cuarzo, plagioclasa y biotita. Las rocas han sufrido intensa sericitización, caolinización y limonitización. Asimismo muestra esferulitas recristalizadas, inclusiones fluidas y fragmentos de granófiro, que indican emplazamiento somero, con rápido intercrecimiento conjunto de cuarzo en una masa de feldespato alcalino hipersolvus. La susceptibilidad magnética es baja con valores de 0,11 x 10-3 SI, típicos para granitos corticales formados a partir de protolitos metasedimentarios. Abstract in english The Mojotoro porphyritic granite is located close to the city of Salta (24°47´44,9"S - 65°21´35,9"W, 1304 m.a.s.l.), at Cerro Mojotoro in the Eastern Cordillera. The pluton is emplaced in the Puncoviscana Formation (Late Precambrian-Early Cambrian), a lithological unit composed mainly of greenish pe [...] lites. The Puncoviscana Formation is covered unconformably by Cambrian quartzites of the Meson Group. Stratigraphic relationships of the granite indicate a Pampean age and emplacement during the Tilcaric orogenic phase. Petrographically it is a porphyritic granite with K-feldspar phenocrysts accompanied by quartz, plagioclase and biotite. The rock is strongly altered by sericitization, kaolinization, and limonitization. Likewise, the granite exhibits recrystalized spherules, fluid inclusions and granophyric fragments, indicative of shallow emplacement, with fast intergrowth of quartz in a mass of K-feldspar hypersolvus. Low magnetic susceptibility, with values of 0.11x10-3 SI, is typical of cortical granite that was formed from a metasedimentary protolith.

A.J., Toselli; R.N., Alonso.

2005-06-01

58

Gamma-spectrometric surveys in differentiated granites. II: the Joaquim Murtinho Granite in the Cunhaporanga Granitic Complex, Parana, SE Brazil  

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Detailed mapping at the NW corner of the large Neo proterozoic Cunhaporanga Granitic Complex (CGC), Parana state, SE Brazil, redefined the Joaquim Murtinho Granite (JMG), a late intrusion in CGC with an exposed area of about 10 km2, made up mainly by evolved 'alaskites' (alkali-feldspar leuco granites). This unit is in tectonic contact with the Neoproterozoic-Eocambrian volcano-sedimentary Castro Group, to the W, and is intrusive into other less evolved granitic units of the CGC to the E. Petrographically, JMG shows mainly mesoperthite and quartz, with subordinate amounts of altered micas and some accessory phases, mainly zircon. The equi to inequigranular granites are usually deformed with cataclastic textures, are often brecciated, and may have miarolitic structures. Formation of late albite, sericite, carbonate and hematite was caused by deuteric and hydrothermal alteration. A gamma-ray spectrometric survey at 231 stations which measured total counts (TC), Ueq K%, eU ppm and eTh ppm was used to construct several direct and derived maps. Compared to neighboring units the JMG has significant anomalies, especially in the TC, %K, eTh and eU maps, although the differences are less obvious in some derived maps. These evolved granites are enriched in these three elements. Geochemical behavior of K, Th and U is used to analyse the results observed in maps. Enhanced weathering under a subtropical climate with moderate to high average temperatures and heavy rainfall affects mainly feldspars and biotite, and may also destabilize most U and Th-bearing accessory phases. Th is most likely retained in restite minerals in soils, being relatively immobile, while part of U may migrate as uranyl ion in oxidizing media. K is especially affected by feldspar alteration to K-free clays (mainly kaolinite), and may be completely leached. Gamma-ray spectrometric methods are valid tools to study facies in granitic rocks, especially in those that are enriched in K, Th and U. (author)

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Special features of the accessory mineralization of the ore-bearing light-granite formation of the Southern Pamir  

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In the article was examined the distribution of the accessory minerals in six intrusive complexes, which relate to one light-granite formation type. According to the elementary sign, all accessory minerals of the light-granite formation of the Southern Pamir are classified to nine groups. It is compared the accessory minerals of the Southern Pamir with the accessory minerals of the light-granites of other regions. The connection between the accessory minerals of intrusive complexes and the mineralization are shown

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Tectono-magmatic evolution of the younger Gardar southern rift, South Greenland  

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Full Text Available The 1300–1140 Ma Gardar period in South Greenland involved continental rifting, sedimentation and alkaline magmatism. The latest magmatism was located along two parallel rift zones, Isortoq–Nunarsuit in the north and the Tuttutooq–Ilimmaasaq–Narsarsuaq zone in the south addressed here. The intrusive rocks crystallised at a depth of <4 km and are essentially undisturbed by later events. Magmatism in the southern zone began with the emplacement of two giant, ?800 m wide dykes and involved intrusion of transitional olivine basaltic, high Al/Ca magmas crystallising to troctolitic gabbros. These relatively reduced magmas evolved through marked iron enrichment to alkaline salic differentiates. In the Older giant dyke complex, undersaturated augite syenites grade into sodalite foyaite. The larger, c. 1163 Ma Younger giant dyke complex (YGDC mainly consists of structureless troctolite with localised developments of layered cumulates. A layered pluton (Klokkenis considered to be coeval and presumably comagmatic with the YGDC. At the unconformitybetween the Ketilidian basement and Gardar rift deposits, the YGDC expanded into a gabbroic lopolith. Its magma may represent a sample from a great, underplated mafic magma reservoir, parental to all the salic alkaline rocks in the southern rift. The bulk of these are silica undersaturated; oversaturated differentiates are probably products of combined fractional crystallisation and crustalassimilation.A major dyke swarm 1–15 km broad was intruded during declining crustal extension, with decreasing dyke widths and increasing differentiation over time. Intersection of the dyke swarm and E–W-trending sinistral faults controlled the emplacement of at least three central complexes (Narssaq, South Qôroq and early Igdlerfigssalik. Three post-extensional complexes (Tugtutôq,Ilímaussaq and late Igdlerfigssalik along the former rift mark the end of magmatism at c. 1140 Ma. The latter two complexes have oblate plans reflecting ductile, fault-related strain. The Tugtutôqcomplex comprises quartz syenites and alkali granites. The Ilímaussaq complex mainly consists of nepheline syenite crystallised from highly reduced, Fe-rich phonolitic peralkaline (agpaitic magma,and resulted in rocks with very high incompatible element concentrations.Abundant anorthositic xenoliths in the mafic and intermediate intrusions point to a large anorthosite protolith at depth which is considered of critical importance in the petrogenesis of the salicrocks. Small intrusions of aillikite and carbonatite may represent remobilised mantle metasomites. The petrological similarity between Older and Younger Gardar suites implies strong lithospheric control of their petrogenesis. The parental magmas are inferred to have been derived from restitic Ketilidian lithospheric mantle, metasomatised by melts from subducting Ketilidian oceanic crust and by small-scale melt fractions associated with Gardar rifting.There are numerous analogies between the southern Gardar rift and the Palaeogene East Africanrift.

Brian G.J. Upton

2013-11-01

 
 
 
 
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Review of engineering, hydrogeological and vadose zone hydrological aspects of the Lanseria Gneiss, Goudplaats-Hout River Gneiss and Nelspruit Suite Granite (South Africa)  

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Three major basement granites of South Africa, viz. the Lanseria Gneiss of the Johannesburg Dome Granite, the Goudplaats-Hout River Gneiss and the Nelspruit Suite, are compared in terms of existing and new geotechnical and hydrogeological data. Typical weathering profiles based on landform and climate are deduced, denoting typical engineering and hydrogeological behaviour. Finally, the vadose zone behaviour of the basement granites are described with the aim on better understanding of the behaviour of these systems under variable saturation. Ephemeral hillslope wetlands, seepage lines and catenas are specifically addressed as associated hydrological influences, as well as the associated processes of translocation forming duplex soils and pedogenesis forming ferricrete. The final summarised findings depict low plasticity and expansiveness of granites with the most notable geotechnical influences being collapsibility, dispersive behaviour, seepage and difficult excavation. Hydrologically, secondary porosity prevails and younger structures or intrusions govern groundwater occurrence. The vadose zone comprises thick fractured rock to be included in modelling with the soil zone having saturated conductivity typically in the order of 1 × 10-4 to 1 × 10-5 m/d.

Dippenaar, Matthys A.; van Rooy, J. Louis

2014-03-01

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Geochemistry and geochronology of Paleozoic intrusions in the Nalati (Narati) area in western Tianshan, Xinjiang, China: Implications for Paleozoic tectonic evolution  

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The Nalati (Narati) area in the Chinese western Tianshan is characterized by abundant Paleozoic intrusions, including granites, diorites and gabbros. They are not only indicators of the interaction between crust and mantle, but also useful clues for tracing the tectonic history of the Tianshan Orogen. Most Early Paleozoic granitoids (biotite monzonitic granites and muscovite granites) of this study are from the Yili Block. The biotite monzonitic granites (mixed-source-derived I-type granites) have a zircon U-Pb age of 497.0 ± 5.9 Ma, indicating the time of the subduction of the Terskey Oceanic crust in the Late Cambrian. The 427.2 ± 5.7 Ma Zircon U-Pb age of the S-type muscovite granites let us interpret that these granites may have been formed during the crust thickening process after the collision between the Yili Block and the Nalati Block. In western Tianshan the Late Paleozoic biotite granites, muscovite granites, quartz diorites, biotite monzonitic granites, granodiorites and alkali granites have respectively a LA-ICPMS zircon U-Pb age of 371.8 ± 6 Ma, 357.2 ± 7.5 Ma, 313.9 ± 2.5 Ma and 296.9 ± 2.4 Ma. The biotite granites display I-type geochemical features and are considered to have been derived from a lower continental crust source. The muscovite granites have a pronounced S-type affinity and are considered to have been formed by the partial melting of thickened continental crust after the collision between the Central Tianshan Belt and the South Tianshan Belt. The quartz-diorites are adakite-like and have an I-type affinity, which are considered to have been formed by partial melting of a delaminated lower crust in a post-orogenic extension setting. The granodiorites also show some typical geochemical features of adakite. Their formation is considered to be related to the lower crustal delamination and the ascending of asthenosphere after the collision event. The alkali granites show an A-type granite affinity. They may have been formed in a within-plate tectonic setting and possibly related to rifting as a consequence of extension. The gabbros can be divided into two groups based on their geochemical characteristics and ages. The older gabbros (415-429 Ma) with lower TiO2 contents are formed in an arc-related setting. The younger ones (340-318 Ma) with higher TiO2 content are formed in an intracontinental setting and influenced by crustal contamination. Magmatic activities recorded by Paleozoic intrusions can constrain the tectonic history of the Tianshan region from subduction of oceanic crust to intraplate extensional collapse and to rifting, and can also corroborate that the final closure of the South Tianshan Ocean occurred in the Late Devonian-Early Carboniferous time.

Xu, Xue-Yi; Wang, Hong-Liang; Li, Ping; Chen, Jun-Lu; Ma, Zhong-Ping; Zhu, Tao; Wang, Ning; Dong, Yun-Peng

2013-08-01

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Petrography and geochemistry of the topaz-bearing granite stocks in Artjärvi and Sääskjärvi, western margin of the Wiborg rapakivi granite batholith  

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Full Text Available The Artjärvi and Sääskjärvi granite stocks at the western margin of the Wiborg rapakivi batholith are multiphase rapakivi granite intrusions in which the most evolved phase is topaz-bearing granite. The Artjärvi stock is composed of porphyritic and even-grained biotite granite and even-grained topaz granite, and the Sääskjärvi stock comprises even-grained biotite granite and porphyritic topazgranite. The granites are metaluminous to peraluminous A-type granites, showing within-plate (WPG geochemical characteristics. The topaz granites from the Artjärvi and Sääskjärvi stocks are petrographically and geochemically similar to other topaz-bearing rapakivi granites in Finland. The anomalous geochemistry of the topaz granite is essentially magmatic; postmagmatic reactions have only slightly modified its composition. Greisen veins, some of which are mineralized, are widely found associated with the Artjärvi and Sääskjärvi stocks.The most characteristic feature of the Artjärvi granite stock is a stockscheider at the roof contact of the topaz granite. The stockscheider is composed of schlieren layering and pegmatite layers parallel to the contact. The most probable mechanism for the formation of the schlieren layering is velocity-gradient sorting parallel to the flow, which led to accumulation of mafic minerals along the upper contact of the topaz granite. Cooling and contraction of the topaz granite formed fractures parallel to the roof contact and the residual pegmatite magmas were injected along the fractures forming pegmatite layers. Textures like graphic intergrowths, aplitic groundmass and fan-shaped alkali feldspar crystals associated with the Artjärvi porphyritic biotite granite and pegmatite indicatecrystallization from undercooled magma. Miarolitic cavities found in the porphyritic biotite granite and topaz granite indicate at least local volatile saturation.

Sari Lukkari

2002-01-01

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EXPLOITATION OF GRANITE BOULDER  

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Full Text Available The processes of forming, petrography, features, properties and exploitation of granite boulders are described. The directional drilling and black powder blasting is the succesful method in exploitation of granite boulders (boulder technology.

Ivan Cotman

1994-12-01

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Rb-Sr, K-Ar and fission track ages for granites from Penang Island, West Malaysia: an interpretation model for Rb-Sr whole-rock and for actual and experimental mica data  

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Penang Island represents the northwestern extension of the western magmatic belt of Peninsular Malaysia. Thirty-one samples of highly evolved biotite-and biotite-muscovite granites were used in an integrated study to unravel the complex magmatic, tectonic and cooling histories of these rocks. Highly distorted Rb-Sr whole-rock age patterns are evident. These are attributed to the partial post-magmatic Sr homogenization within the granite batholith which led to the rotation of isochrons towards younger ages and higher (87/86)Sr intercepts. The recognition of this mechanism allowed the establishment of a new Rb-Sr interpretation model. The intrusion ages of the granites can be extrapolated based on the evolutionary trend of the initial (87/86)Sr. Including the data of Bignell and Snelling, three episodes of granite emplacement at 307±8 Ma, 251±7 Ma and 211±2 Ma are suggested for Penang and the NW Main Range. The late-Triassic intrusive induced a hydrothermal conductive convection system which affected all the granites. It is considered to be responsible for the Rb-Sr whole-rock age distortion, the Rb-Sr and K-Ar biotite age resetting and the textural and mineralogical changes in the granites. The duration of the hydrothermal convections, deduced from the Rb-Sr whole rock ages, is about 6 Ma and 20 Ma in the northern and southern parts of Penang respectively. Fast regional cooling to 350±50°C within a time span of 1 3 Ma is recognized for the late-Triassic Feringgi intrusive from the mica ages, followed by a generally slow cooling rate of about 1°C/Ma. Fission track ages, in addition, indicate blockwise uplift along the N-S and NW-SE tending faults, thus resulting in the exposure of deeper crustal levels in southern and eastern Penang. A change in the tensional regime since Oligocene/Miocene, accompanied by a southwest tilting of the island, is indicated by the fission track apatite ages. Variable sometimes younger K-Ar, respectively Rb-Sr biotite ages mainly depend on the degree of hydrothermal overprint at different crustal levels. An increase of the reaction surface by grain size reduction influences Rb-Sr and K-Ar mica ages in similar ways, as has been demonstrated by experimental data.

Kwan, T. S.; Krähenbühl, R.; Jager, E.

1992-09-01

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Gamma-spectrometric Surveys in Differentiated Granites. II: the Joaquim Murtinho Granite in the Cunhaporanga Granitic Complex, Paraná, SE Brazil  

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Full Text Available Detailed mapping at the NW corner of the large Neoproterozoic Cunhaporanga Granitic Complex (CGC, Paraná state, SE Brazil, redefined the Joaquim Murtinho Granite (JMG, a late intrusion in CGC with an exposed area of about 10 km2, made up mainly by evolved“alaskites” (alkali-feldspar leucogranites. This unit is in tectonic contact with the Neoproterozoic- Eocambrian volcano-sedimentaryCastro Group, to the W, and is intrusive into other less evolved granitic units of the CGC to the E. Petrographically, JMG shows mainlymesoperthite and quartz, with subordinate amounts of altered micas and some accessory phases, mainly zircon. The equi to inequigranulargranites are usually deformed with cataclastic textures, are often brecciated, and may have miarolitic structures. Formation of latealbite, sericite, carbonate and hematite was caused by deuteric and hydrothermal alteration. A gamma-ray spectrometric survey at 231stations which measured total counts (TC, Ueq K%, eU ppm and eTh ppm was used to construct several direct and derived maps. Comparedto neighboring units the JMG has signifi cant anomalies, especially in the TC, %K, eTh and eU maps, although the differences areless obvious in some derived maps. These evolved granites are enriched in these three elements. Geochemical behavior of K, Th and Uis used to analyse the results observed in maps. Enhanced weathering under a subtropical climate with moderate to high average temperaturesand heavy rainfall affects mainly feldspars and biotite, and may also destabilize most U and Th-bearing accessory phases. Th is most likely retained in restite minerals in soils, being relatively immobile, while part of U may migrate as uranyl ion in oxidizing media. K is especially affected by feldspar alteration to K-free clays (mainly kaolinite, and may be completely leached. Gamma-ray spectrometricmethods are valid tools to study facies in granitic rocks, especially in those that are enriched in K, Th and U.

Victor Miguel Oliveira Martin

2009-01-01

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The Younger Dryas Event  

Science.gov (United States)

This topic in depth deals with the Younger Dryas event, a short period of extremely cold temperatures interrupting the current interglacial period. It is currently debated whether the Younger Dryas event occurred solely in parts of the North hemisphere or throughout the world.The first website, (1), created by World History, provides a short, concise summary of the Younger Dryas period. Users can find a brief statement about the prevailing theory of the cause of this event. Lund University offers an amazing image of a stratigraphic record illustrating the Late Glacial sequence at the second website (2). Users can view the impressive Younger Dryas sedimentation layer and also see an image of the flower, _Dryas octopetala_, which the event is named after. Next, the Department of Natural Resources for the Province of Nova Scotia supplies images of the geologic landscape of Nova Scotia (3). Students can find descriptions of the Younger Dryas event and other glacial features. The forth website (4 ), produced by Klaus Keller as part of his lecture materials for classes at Penn State, is an online document illustrating the abrupt changes experienced on earth during the Younger Dryas. This website discusses the theorized relationship between the North Atlantic thermohaline circulation (THC) and the event. Next, the University of Arizona discusses its research on the environmental changes in mid-North America over the last several millennia (5). Users can learn how the researchers are attempting to create the first high-resolution chronology of the transition from the Late Glacial to the Early Holocene. In the sixth website (6 ), the University of Chicago offers an online article addressing the unknowns in our current understanding of climate change. Users can learn how the abrupt climate changes in the past such as the Younger Dryas are still difficult to model. Next, David J. Graham from the University of Wales addresses the importance of examining the moraine morphology and sedimentology in order to gather more knowledge about the climatic and glacio-dynamic conditions that occurred during the Younger Dryas period (7 ). This online poster provides images, figures, and descriptions of the interpretations of the landform-sediment associations present in the upper Ennerdale. Konrad Hughen from the Woods Hole Oceanographic Institution summarizes his group's research which illustrates the effects the northern tropical regions of the Southern Hemisphere experienced during the Younger Dryas event (8). In this downloadable document, users can learn about his group's creation of high-resolution records of tropical vegetation change that demonstrate the synchronization between the climate changes in the high latitude North Atlantic region and in the tropical South America during the event. Lastly, the U.S. Global Change Research Program discusses the classification of an abrupt climate change, the rapidity of past climate change according to the paleoclimatic records, the causes of climate change, and its consequences (9). Visitors can learn about the swiftness of the Younger Dryas event and how another occurrence like this may affect our society and the natural world.

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Multivariate analyses of Erzgebirge granite and rhyolite composition: Implications for classification of granites and their genetic relations  

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High-precision major, minor and trace element analyses for 44 elements have been made of 329 Late Variscan granitic and rhyolitic rocks from the Erzgebirge metallogenic province of Germany. The intrusive histories of some of these granites are not completely understood and exposures of rock are not adequate to resolve relationships between what apparently are different plutons. Therefore, it is necessary to turn to chemical analyses to decipher the evolution of the plutons and their relationships. A new classification of Erzgebirge plutons into five major groups of granites, based on petrologic interpretations of geochemical and mineralogical relationships (low-F biotite granites; low-F two-mica granites; high-F, high-P2O5 Li-mica granites; high-F, low-P2O5 Li-mica granites; high-F, low-P2O5 biotite granites) was tested by multivariate techniques. Canonical analyses of major elements, minor elements, trace elements and ratio variables all distinguish the groups with differing amounts of success. Univariate ANOVA's, in combination with forward-stepwise and backward-elimination canonical analyses, were used to select ten variables which were most effective in distinguishing groups. In a biplot, groups form distinct clusters roughly arranged along a quadratic path. Within groups, individual plutons tend to be arranged in patterns possibly reflecting granitic evolution. Canonical functions were used to classify samples of rhyolites of unknown association into the five groups. Another canonical analysis was based on ten elements traditionally used in petrology and which were important in the new classification of granites. Their biplot pattern is similar to that from statistically chosen variables but less effective at distinguishing the five groups of granites. This study shows that multivariate statistical techniques can provide significant insight into problems of granitic petrogenesis and may be superior to conventional procedures for petrological interpretation.

Forster, H. -J.; Davis, J. C.; Tischendorf, G.; Seltmann, R.

1999-01-01

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Proterozoic granitic magmatism in the Fennoscandian Shield  

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The main tectonic units of the Fennoscandian Shield are 1) the Archean 3.1--2.6 Ga granite gneiss (GGT) -- greenstone belt domain in the east, 2) the broad orogenic Svecofennian domain (1.9--1.8 Ga), and 3) the Southwest Scandinavian domain that consists of granitic gneisses, Gothian arc-type volcanic -- sedimentary and plutonic rocks (1.7--1.55 Ga), and has a Sveconorwegian (Grenvillian) overprint. The Svecofennian domain was formed by sequential accretion of volcanic arcs to the Archean craton (Lahtinen, 1994; Nironen, 1997). Rifting of the Archean craton at 2.50--2.44 Ga led to emplacement of a bimodal suite of layered mafic intrusions and minor A-type quartz syenites -- granites into the Archean crust in nortern Finland and adjacent Russia. Nd isotopes suggest Archean crustal source for some of the silicic plutons (Lauri and Mänttäri, 2003). The earliest Svecofennian granitoid rocks are ˜1.92 Ga gneissic calc-alkalic tonalities and granodiorites in central and northernmost Finland close to the Archean craton. I-type 1.89--1.87 Ga calc-alkalic granitoids of tonalite-granodiorite-granite association are common in the Svecofennian belts. In the Central Finland Granitoid Complex two suites can be separated: the 1.89--1.88 Ga calc-alkalic deformed granodiorites and granites, and the massive 1.88--1.87 Ga alkali-calcic or alkalic quartz monzonites and monzogranites (Nironen et al., 2000; Rämö et al., 2001). Southern Finland is characterized by 1.84--1.80 Ga migmatite-forming peraluminous S-type granites that were formed by anatectic melting of mainly sedimentary -- volcanic rocks of the thick Svecofennian crust. The Svecofennian plutonism was finished by intrusion of extension-related postorogenic (post-collisional) 1.80--1.77 Ga granite stocks that have a shoshonitic affinity and were possibly derived from enriched lithospheric mantle. Nd isotopes of the 1.81--1.77 Ga granites of northern Finland and the 1.88--1.86 Ga granites of eastern Finland near the Archean border indicate a major Archean source component (Huhma, 1986). The western margin of the Svecofennian domain is marked by the Transcandinavian Igneous Belt consisting of various 1.8--1.5 Ga granites. A-type rapakivi granites and associated diabase dikes of southern Finland, Russian Karelia, Baltic countries, and central Sweden can be divided into four age groups, from east to west: 1.56--1.53 Ga, 1.67--1.62 Ga, 1.59--1.54 Ga, 1.53--1.47 Ga. Bimodal magmatism, extensional setting and thinning of the lower crust below rapakivi granites can be explained by the mafic underplate model (Haapala and Rämö, 1992).

Haapala, I.; Lahtinen, R.; Rämö, O. T.

2003-04-01

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Thorite in an Apollo 12 granite fragment and age determination using the electron microprobe  

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We present the first quantitative compositional analysis of thorite in a lunar sample. The sample, a granitic assemblage, also contains monazite and yttrobetafite grains, all with concentrations of U, Th, and Pb sufficiently high to determine reliably with the electron microprobe. The assemblage represents the first documented occurrence of these three minerals together and only the second reported occurrence of thorite in a lunar rock. Sample 12023,147-10 is a small, monomict rock fragment recovered from an Apollo 12 regolith sample. It comprises graphic intergrowths of K-feldspar and quartz, and plagioclase and quartz, along with minor or accessory hedenbergite, fayalite, ilmenite, zircon, yttrobetafite, thorite, monazite, and Fe metal. Thorite, ideally ThSiO4, occurs in the assemblage adjacent to quartz and plagioclase, and includes a 12% xenotime ([Y,HREE]PO4) component. From quantitative electron-probe microanalysis (EPMA) of Th, U, and Pb in thorite, assuming that all of the measured Pb is radiogenic, we calculate an age of 3.87 ± 0.03 Ga. Yttrobetafite and monazite, which contain lesser concentrations of U, Th, and Pb than the thorite, yield ages of 3.78 ± 0.06 Ga and 3.9 ± 0.3 Ga, respectively. These dates are consistent with formation of the granitic material around 3.8-3.9 Ga, possibly associated with, or after, the formation of the Imbrium basin. This age falls within a group of younger ages for granitic samples, measured mainly by ion microprobe analysis of zircon, compared to a suite of older ages, ca. 4.20-4.32 Ga, also from zircons (Meyer et al., 1996). A 3.8-3.9 Ga age may reflect an origin following the Imbrium event whereby granitic melt formed as a result of heating and melting, and was mobilized and emplaced along an Imbrium-related ring-fracture system. Silicic volcanic or exposed intrusive materials occur in several circum-Imbrium locations such as the Mairan and Gruithuisen Domes and in ejecta excavated by Aristarchus crater. Perhaps sample 12023,147-10 and some of the other granitic materials sampled at the Apollo 12 site represent rocks similar to the rocks that make up these large silicic rock occurrences.

Seddio, Stephen M.; Jolliff, Bradley L.; Korotev, Randy L.; Carpenter, Paul K.

2014-06-01

71

Uranium rich granite and uranium productive granite in south China  

International Nuclear Information System (INIS)

The paper briefly introduces the differences between uranium rich granite and uranium productive granite in the 5 provinces of South China, and discusses their main characteristics in 4 aspects, the uranium productive granite is highly developed in fracture, very strong in alteration, often occurred as two-mica granite and regularly developed with intermediate-basic and acid dikes. The above characteristics distinguish the uranium productive granite from the uranium rich granite. (authors)

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Tectonic imprints within a granite exposed near Srinagar, Rajasthan, India  

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Partial melting in the middle to lower crustal level produces melts of granitic composition during orogeny. Thrusts play a vital role in their exhumation after consolidation of these granitic melts. In this paper we focus on one such granite along the eastern margin of the Delhi Fold Belt (DFB) rocks near Srinagar, Rajasthan, India. This is the first report of granite within the area and holds a key stratigraphic position in the entire rock package. The said granite is found to be intrusive to the DFB metasediments as well as their basement popularly known as the Banded Gneissic Complex (BGC). We disentangle the deformation fabrics seen within the granite and associated DFB metasediments, suggesting that subsequent to emplacement and consolidation, the granite has co-folded along with the country rocks. Three deformational events could be identified within the DFB metasediments namely, D1D, D2D and D3D. The peak metamorphism was achieved in the D1D event. The granite magma is generated and emplaced late syn-kinematic to D1D and thereafter is deformed by D2D and D3D producing D1G and D2G structural fabrics. These compressive deformations resulted in the collapse of the basin; the combined package of DFB rocks and the granite was thrusted eastwards over the basement rocks. The tectonic transport direction during thrusting is suggested eastwards from our structural analysis. Transverse faults developed perpendicular to the length of the granite have led to partitioning of the strain thereby showing a heterogeneity in the development of fabric within it.

Ruj, Trishit; Dasgupta, Nilanjan

2014-08-01

73

Granite ages in the Pine Creek Geosyncline  

International Nuclear Information System (INIS)

Rb-Sr data on high-level, late orogenic granitoid intrusions in the Pine Creek Geosyncline indicate that their emplacement was essentially synchronous. Low initial 87Sr/86Sr ratios strongly suggest that they did not originate by anatexis of crustal material of high Rb/Sr ratio but from a source of primitive strontium with low enrichments of 87Sr. The Allia Creek granite may be an exception. The geographic distribution of sampling sites demonstrates that this intrusive event was widespread throughout the Geosyncline in the early Proterozoic. The age of 1780+-20 m.y. is therefore interpreted as representing a minimum age for the regional metamorphism of the Pine Creek Geosyncline and a maximum age for the development of high grade, vein type, uranium mineralization. (author)

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The Neoproterozoic layered mafic-ultramafic intrusion of Gabal Imleih, south Sinai, Egypt: Implications of post-collisional magmatism in the north Arabian-Nubian Shield  

Science.gov (United States)

The Imleih layered mafic-ultramafic body is a Neoproterozoic intrusion covering about 45 km 2 in southern Sinai. The field relations as well as the fine grained chilled margins indicate that the layered intrusion is younger than the surrounding calc-alkaline syn-tectonic granodiorite and Iqna Shar ,a volcanics and older than the post-tectonic Iqna granite. There is a general consensus that there are no ophiolitic rocks younger than the syn-tectonic granitoids in the Arabian-Nubian Shield (ANS), which supports the non-ophiolitic origin of the Imleih layered intrusion. The studied layered intrusion is tilted to the north, with lower layers (peridotite and pyroxenite) exposed to the south and upper layers (cumulus gabbro and anorthosite) exposed to the north. Imleih rocks are cumulates, dominated by cumulus gabbro with subsequent amounts of peridotite, pyroxenite and anorthosite. Pegmatitic gabbro is locally observed. These rocks are unmetamorphosed. In the peridotite, the Fo content of olivine ranges from 0.81 to 0.83. Clinopyroxenes of the studied rocks range in composition from diopside to augite and have subalkaline affinities. Plagioclase in the cumulus gabbro is mostly bytownite (An 73-82). Two types of spinel are observed, chromite and pleonaste. Chromite has Cr# (Cr/(Cr + Al) of 0.60-0.81 whereas pleonaste have Cr# lower than 0.02. The present study revealed that the mafic-ultramafic complex of Gabal Imleih fractionated from a single batch of high Al-basaltic magma and evolved by fractional crystallization at the base of a Neoproterozoic magma chamber. Olivine and chromite were the first crystallized phases followed by pyroxene and plagioclase. Amphibole appears at nearly the same time as plagioclase. The Imleih mafic-ultramafic body was emplaced post-tectonically in a transitional phase between the calc-alkaline and alkaline magmatism.

Azer, M. K.; El-Gharbawy, R. I.

2011-06-01

75

Geology and Rb-Sr geochronology of mineralised and radioactive granites and alaskites, Namibia  

International Nuclear Information System (INIS)

The geology and Rb-Sr geochronology of four mineralised and radiometrically anomalous granites and alaskites have been studied in an attempt to establish their characteristic isotopic features. A four-fold classification of the Damaran intrusives from the central belt of the orogen into syn- to post-tectonic Salem-type granites and red granites, and late to post-tectonic leucogranites and alaskites is proposed. Whole-rock Rb-Sr ages are presented for the mineralised Ida Dome alaskite, a mineralised red granite on the farm Otjua 37, and the radioactive Salem granite and leucogranite on Stinkbank 62. The most important isotopic feature which appears to characterise the mineralised granites and alaskites is a high initial Sr-isotope ratio, and this ratio seems to increase with both time and uranium content

76

Petrology and geochemistry of the Los Cuartos granite, Tafi del Valle, Tucuman, northwest of Argentina: its integration to the regional magmatic layout  

International Nuclear Information System (INIS)

Los Cuartos Granite crops out on the western flank of the Cumbres Calchaquies, east of Tafi del Valle, Tucuman Province, Argentina. It has a granitic to granodioritic composition, of two micas, being biotite dominant. The granite is medium grained and inequigranular, with rare K-feldspar megacrysts. It contains host-rock xenoliths with different degrees of assimilation. The granite intrusion produced contact metamorphism in the surrounding basement, with development of andalucite porphyroblasts and poikiloblastic biotite. The granite is calk-alkaline and peraluminous, and is K- and P-rich and Ca- and Napoor compared to other granitoids of the region. The pluton shows late-tectonic features with regard to the regional deformation. The granite possibly intruded during the Ordovician (Famatinian Cycle) and its emplacement was structurally controlled by the Tafi Megafracture. Los Cuartos Granite and other intrusive bodies of the region share similar petrographical, geochemical, structural and geochronological characteristics. (Author).

77

Intrusion Detection Systems  

CERN Document Server

In our world of ever-increasing Internet connectivity, there is an on-going threat of intrusion, denial of service attacks, or countless other abuses of computer and network resources. In particular, these threats continue to persist due to the flaws of current commercial intrusion detection systems (IDSs). Intrusion Detection Systems is an edited volume by world class leaders in this field. This edited volume sheds new light on defense alert systems against computer and network intrusions. It also covers integrating intrusion alerts within security policy framework for intrusion response, rel

Pietro, Roberto Di

2008-01-01

78

The missing link between granites and granitic pegmatites  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this contribution we provide evidence for the extraction of volatile and incompatible element enriched melts from common granites. This provides a mechanism showing that at least a large proportion of granitic pegmatites could be genetically directly connected to a main granite body. In granites there are often two principal types of melt inclusions: (i) those that represent the bulk chemistry of the granite and (ii) those with very different compositions. In the Variscan Erzgebirge gr...

Thomas R; Davidson P

2013-01-01

79

Peralkaline and peraluminous granites and related mineral deposits of the Arabian Shield, Kingdom of Saudi Arabia  

Science.gov (United States)

In the Precambrian Arabian Shield, granitoid plutonic rocks are widespread and range in age from 800 to 550 Ma old; but the mineral-resource potential associated with these plutonic rocks is restricted mainly to the younger, postorogenic granites. Two granite types of current economic interest are zirconium- niobium-enriched per alkaline granites and tin-tungsten-enriched peraluminous granites. Both types are highly evolved, are enriched in lithium, rubidium, and fluorine, and have distinctive mineralogy, textures, and chemistry. The zirconium-niobium-enriched granites are related to medium- to large-sized plutons and complexes of peralkaline granite, and the tin-tungsten-enriched granites are related to medium-sized plutons of biotite or biotite-muscovite granite. Existing geochemical and geologic data for many parts of the Arabian Shield were compiled as a basis for evaluating the resource potential of the granites of the Shield. Commodities associated with granites that have potential for economic mineral deposits include tin, tungsten, molybdenum, beryllium, niobium, tantalum, zirconium, uranium, thorium, rare-earth elements, and fluorite. Prospecting methods useful in discriminating those granites having significant economic potential include reconnaissance geologic mapping, petrographic and mineralogic studies, geochemical sampling of rock and wadi sediment, and radiometric surveying.

Elliott, James E.

1983-01-01

80

SHRIMP zircon U-Pb dating of the mafic and felsic intrusive rocks of the Saza area in the Lupa goldfields, southwestern Tanzania: Implication for gold mineralization  

Directory of Open Access Journals (Sweden)

Full Text Available The Lupa Goldfield (LGF is one of the eight structural terranes in the NW – SE striking Ubendian Belt of SW Tanzania. The LGF is comprised of granitic gneisses with bands of amphibolites which are intruded by mafic intrusions including gabbros, granodiorites, diorites; and various granites as well as metavol-canics. These rocks are cross-cut by narrow mafic dykes and aplites. SHRIMP zircon U-Pb data are presented for the granodiorite and a mafic dyke that cross-cut the granodiorites in the Saza area of the LGF, with the aim of constraining the mafic and felsic magmatism and their implication to gold mineralization. The zircon U-Pb data shows that the Saza granodiorites were emplaced at 1924 ± 13 Ma (MSWD = 2.6 whereas the cross-cutting mafic dyke yielded a zircon U-Pb age of 1758 ± 33 Ma (MSWD = 0.88. The dated granodiorite sample was in sheared contact with an altered mafic intrusive rock, most likely a diorite, along which an auriferous quartz vein occurs. The 1924 ± 13 Ma age of granodiorites is within error of the reported molybdenite Re-Os age of 1937 Ma determined for the gold mineralization event in Lupa Goldfields. Although auriferous quartz veins are younger than the granodiorites, the more or less similar ages between the emplacement of granodiorites and the mineralizing event indicate that the granodiorites might be the heat source (or driver of hydrothermal fluids responsible for gold mineralization in the Lupa goldfields. This would further suggest that gold mineralization in the LGF is intrusion-related type. The mafic dykes represent the youngest rocks to have been emplaced in the area and hence the 1758 ± 33 Ma age of the mafic dykes conclude the magmatic evolution in the Lupa goldfields during the Palaeoproterozoic.

Shukrani Manya

2012-09-01

 
 
 
 
81

Chemical characteristics of zircon from A-type granites and comparison to zircon of S-type granites  

Science.gov (United States)

The trace element content in zircons from A-type granites and rhyolites was investigated by using back-scattered electron images and electron microprobe analyses. The studied Proterozoic (Wiborg batholith, Finland and Pará, Amazonas and Goiás states, Brazil) and Variscan (Krušné Hory/Erzgebirge, Czech Republic and Germany) plutons cover a wide range of rocks, from large rapakivi-textured geochemically primitive plutons to small intrusions of F-, Li-, Sn-, Nb-, Ta-, and U-enriched rare-metal granites. While zircon is one of the first crystallized minerals in less fractionated metaluminous and peraluminous granites, it is a late-crystallized phase in peralkaline granites and in evolved granites that may crystallize during the whole process of magma solidification. The early crystals are included in mica, quartz, and feldspar; the late grains are included in fluorite or cryolite or are interstitial. The zircon in hornblende-biotite and biotite granites from the non-mineralized plutons is poor in minor and trace elements; the zircon in moderately fractionated granite varieties is slightly enriched in Hf, Th, U, Y, and HREEs; whereas the zircon in highly fractionated ore-bearing granites may be strongly enriched in Hf (up to 10 wt.% HfO2), Th (up to 10 wt.% ThO2), U (up to 10 wt.% UO2), Y (up to 12 wt.% Y2O3), Sc (up to 3 wt.% Sc2O3), Nb (up to 5 wt.% Nb2O5), Ta (up to 1 wt.% Ta2O5), W (up to 3 wt.% WO3), F (up to 2.5 wt.% F), P (up to 11 wt.% P2O5), and As (up to 1 wt.% As2O5). Metamictized zircons may also be enriched in Bi, Ca, Fe, and Al. The increase in the Hf content coupled with the decrease in the Zr/Hf value in zircon is one of the most reliable indicators of granitic magma evolution. In the zircon of A-type granites, the Zr/Hf value decreases from 41-67 (porphyritic granite) to 16-19 (equigranular granite) in the Kymi stock, Finland, and from 49-52 (biotite granite) to 18-36 (leucogranite) in the Pedra Branca pluton, Brazil. In the in situ strongly fractionated Cínovec cupola (Erzgebirge), the Zr/Hf value decreases from 33-51 in the protolithionite granite at a depth of 1255 m to 7.5-25 in the zinnwaldite granite at a depth of 40 m. At the scale of individual crystals, the Zr/Hf value decreases from 86 to 68 from the cores to the rims of the zircons from the Teplice rhyolite and from 64 to 33 in the zircons from the biotite granite at Krupka, Erzgebirge. The contents of Hf and U in zircon are dependent mainly on the degree of granite fractionation and the nature and volume of the volatile phases and are independent of the A- or S-character of the parental melt. The zircon Zr/Hf ratios 55 and 25 are proposed to approximately distinguish common, moderately evolved and highly evolved granites. Zircons from the moderately and highly evolved granites of A- and S-type can be discriminated on the basis of their HREE content and the U/Th ratios. Nb, Ta, and W are present in zircon from the highly evolved granites from all studied areas, while high As, Bi, and Sc contents are typical only for the Erzgebirge.

Breiter, Karel; Lamarão, Claudio Nery; Borges, Régis Munhoz Krás; Dall'Agnol, Roberto

2014-04-01

82

Determination of the relative age for an intrusive body by gamma-ray spectrometry  

International Nuclear Information System (INIS)

Different types of intrusive bodies have different contents of U, Th and K, that is, the later the intrusive age, the higher the contents of U, Th and K. Gamma-ray spectrometry method can survey all these parameters in time on the spot. So that the gamma-ray spectrometry method can determine the age of an intrusive body. The author discusses the principle to divide the relative age of an intrusive body by the gamma-ray spectrometry method. The division of the relative ages of granite and diorite from the study area are given

83

On the origin of granites: a contribution to earth crust research from an isotopic point of view  

International Nuclear Information System (INIS)

Using isotope and element geochemical knowledge the limits of igneous formation are discussed. We offer two explanations which account for extremely different kinds of gineous granite formation: by anatexis of continental crust or by anatexis of subducted (or subfluenced) oceanic crust in the region of the upper mantle. Most of the granites might be mixed forms. Isotope and elemental studies concerning the younger granites of the Erzgebirge (G.D.R.) show a tendency to favour subcrustal formation of their magma source. (author)

84

Heater test 1, Climax Stock granite, Nevada  

International Nuclear Information System (INIS)

We conducted a series of in-situ tests in the Climax Stock, an intrusive granite formation at the Nevada Test Site, to validate the concept of housing a nuclear waste repository in granitic crystalline rock. The thermal properties of the granite were measured with resistance heaters and thermocouple frames that had been emplaced in drilled holes in the floor of a drift 420 m below the surface. Data analysis was performed primarily by comparing the measured and calculated temperature histories, varying conductivity and diffusivity in the calculations until reasonable agreement was achieved. The best-fit value for in-situ conductivity was approximately 3.1 W/m x K, and the deduced value for in-situ diffusivity was approximately 1.2 mm2/s. Anisotropic effects in the thermal field were less than 10%. Permeability was determined by sealing off portions of the drilled holes, using inflatable rubber packers and an air-pressurization system. We then compared the resulting decay in pressure with analytic solutions of the pressure loss from a cylindrical source in an infinite isotropic medium, obtaining a permeability of approximately 1 nanodarcy (nD) at about 300C. As the temperature increased, the permeability decreased to about 0.2 nD at about 500C and became too small to measure (<0.02 nD) at higher temperatures. These tests provided new data on the in-situ properties of a granite typical of the Basin and Range province and significantly advanced our understanding of and ability to perform in-situ thermal and permeability measurements. This knowledge will be of considerable value for future spent-fuel tests

85

Zircon fission-track dating of granites from the Vepor-Gemer Belt (Western Carpathians: constraints for the Early Alpine exhumation history  

Directory of Open Access Journals (Sweden)

Full Text Available We present new zircon fission-track (ZFT data from Variscan granitoid bodies in the Veporic (footwall unit and Gemeric (hangingwall unit thick-skinned nappe sheets of the Central Western Carpathians. All samples show Late Cretaceous to earliest Paleogene cooling ZFT ages, which contribute to constraining the low-temperature exhumation history of the Vepor-Gemer Belt. Four granite samples from the western part of the Gemericum near the contact with the underlying Veporicum provided central ZFT ages between 70.4 ± 5.4 and 74.7 ± 5.6 Ma. One sample from this area shows an older age of 87.7 ± 5.9 Ma, possibly owing to its higher structural position. One remoter sample from the SE part of the Gemeric Unit has 61.7 ± 3.4 Ma central ZFT age, which probably reflects exhumation associated with a younger compressional tectonic event in that area. One sample from the centre of the Veporic metamorphic core complex yielded a cooling age 64.9 ± 4.8 Ma. However, most of these samples exhibit an internal age scatter pointing to complex cooling and exhumation history influenced by a slow passage through the zircon partial annealing zone and/or reheating brought about by the Cretaceous Rochovce granite intrusion. In spite of this, the acquired ages generally match the exhumation trend of the Veporic metamorphic core complex.

Plasienka D

2007-07-01

86

Interior intrusion detection systems  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this NUREG is to present technical information that should be useful to NRC licensees in designing interior intrusion detection systems. Interior intrusion sensors are discussed according to their primary application: boundary-penetration detection, volumetric detection, and point protection. Information necessary for implementation of an effective interior intrusion detection system is presented, including principles of operation, performance characteristics and guidelines for design, procurement, installation, testing, and maintenance. A glossary of sensor data terms is included. 36 figs., 6 tabs.

Rodriguez, J.R.; Matter, J.C. (Sandia National Labs., Albuquerque, NM (United States)); Dry, B. (BE, Inc., Barnwell, SC (United States))

1991-10-01

87

Interior intrusion detection systems  

International Nuclear Information System (INIS)

The purpose of this NUREG is to present technical information that should be useful to NRC licensees in designing interior intrusion detection systems. Interior intrusion sensors are discussed according to their primary application: boundary-penetration detection, volumetric detection, and point protection. Information necessary for implementation of an effective interior intrusion detection system is presented, including principles of operation, performance characteristics and guidelines for design, procurement, installation, testing, and maintenance. A glossary of sensor data terms is included. 36 figs., 6 tabs

88

Intrusion detection sensors  

Energy Technology Data Exchange (ETDEWEB)

Intrusion detection sensors are an integral part of most physical security systems. Under the sponsorship of the U.S. Department of Energy, Office of Safeguards and Security, Sandia Laboratories has conducted a survey of available intrusion detection sensors and has tested a number of different sensors. An overview of these sensors is provided. This overview includes (1) the operating principles of each type of sensor, (2) unique sensor characteristics, (3) desired sensor improvements which must be considered in planning an intrusion detection system, and (4) the site characteristics which affect the performance of both exterior and interior sensors. Techniques which have been developed to evaluate various intrusion detection sensors are also discussed.

Williams, J.D.

1978-07-01

89

Intrusion detection sensors  

International Nuclear Information System (INIS)

Intrusion detection sensors are an integral part of most physical security systems. Under the sponsorship of the U.S. Department of Energy, Office of Safeguards and Security, Sandia Laboratories has conducted a survey of available intrusion detection sensors and has tested a number of different sensors. An overview of these sensors is provided. This overview includes (1) the operating principles of each type of sensor, (2) unique sensor characteristics, (3) desired sensor improvements which must be considered in planning an intrusion detection system, and (4) the site characteristics which affect the performance of both exterior and interior sensors. Techniques which have been developed to evaluate various intrusion detection sensors are also discussed

90

Network Intrusion Detection System  

Directory of Open Access Journals (Sweden)

Full Text Available Attacks on computers and data networks have become a regular and sophisticated issue. Intrusion detection has shifted its attention from hosts and operating systems to networks and has become a way to provide a sense of security to these networks. The aim of intrusion detection is to detect misuse and unauthorized use of the computer systems by internal and external elements. Typically, Intrusion Detection Systems allow statistical anomaly and rule-based misuse models to detect intrusions as the behavior of the intruding element is considered to be different from the authorized user behavior.

Gopalkrishna N. Prabhu,

2014-04-01

91

PETROGRAFÍA, GEOQUÍMICA Y GEOCRONOLOGÍA DEL GRANITO DE PARGUAZA EN COLOMBIA / PETROGRAPHY, GEOCHEMISTRY AND GEOCHRONOLOGY OF PARGUAZA GRANITE IN COLOMBIA  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish El Granito de Parguaza aflora en el departamento de Vichada-(Colombia), hacia la margen del río Orinoco y es parte del gran batolito descrito en Venezuela como Granito del Parguaza. Este cuerpo en Colombia aflora como cerros aislados tipo inselberg y serranías de poca extensión con pendientes abrupt [...] as que sobresalen entre las extensas llanuras terciarias. Representa uno de los granitos anorogénicos aflorantes más grandes del mundo y puede ser distinguido como una de las unidades colombianas más antiguas (Mesoproterozoico) que no han sufrido deformación. Se caracteriza por presentar textura rapakivi tipo wiborgita y piterlita, su composición es granítica a granítica de feldespato alcalino. Además de las variaciones composicionales y texturales, se encuentran zonas de grano fino, diques pegmatíticos, aplíticos y venas de cuarzo. Geoquímicamente se clasifica como un granito tipo A, metaluminoso a peralcalino, formado en ambiente post-colisional a anorogénico. Nuevas mediciones de U/Pb con LA-ICP-MS en circones indican nuevas edades concordantes de 1.392 ± 5 Ma y 1.402 ± 2 Ma para las partes más distales, respectivamente, mucho más jóvenes que edades propuestas anteriormente en territorio venezolano 1.545 Ma, lo cual puede ser interpretado como un intrusivo más complejo o como procesos de cristalización muy lentos de núcleo a borde. Por otro lado, estas edades son correlacionadas con granitos anorogénicos similares en el W del Cratón Amazónico en Brasil y con otros afloramientos rapakivi estudiados en el departamento de Guainía al SE de Colombia. Abstract in english The Parguaza Granite outcrops in the Vichada department of Colombia, towards the Orinoco River margin, where it conforms a portion of the large batholith described in Venezuela as Granito de El Parguaza. This intrusion outcrops in Colombia as isolated inselberg hills and moderately extended mountain [...] chains with abrupt slopes that protrude through Tertiary plains. It represents one of largest anorogenic granites worldwide and is one of the oldest colombian units (Mesoproterozoic) without tectonic deformation. The granite exhibits both typical Wiborgite and Pyterlite rapakivi texture, with a monzogranitic to alkali feldspar granitic composition. Among the compositional and textural variations, we find fine-grain zones, pegmatitic and aplitic dikes as well as quartz veins. Geochemically, it conforms a metaluminous to peralkaline A-type granite, intruded under post-collisional to rifting anorogenic conditions. New U/Pb measurements with LA-ICP-MS in zircons show hither to unknown concordant ages of 1392 ± 5 My to 1402 ± 2 My, respectively in the more distal zones; much younger than 1545 My ages reported in Venezuela, which may be explained or by a more complex intrusion and crystallization history or by a very slow crystallization process from the core to the edge; on the other hand, these ages are in concordance to similar anorogenic granites from the W Amazonian Craton in Brazil and with other rapakivi outcrops studied in the Guainía Department in the south-east of Colombia.

Amed, Bonilla-Pérez; José Carlos, Frantz; Juliana, Charão-Marques; Thomas, Cramer; José A., Franco-Victoria; Elise, Mulocher; Zeze, Amaya-Perea.

92

PETROGRAFÍA, GEOQUÍMICA Y GEOCRONOLOGÍA DEL GRANITO DE PARGUAZA EN COLOMBIA / PETROGRAPHY, GEOCHEMISTRY AND GEOCHRONOLOGY OF PARGUAZA GRANITE IN COLOMBIA  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish El Granito de Parguaza aflora en el departamento de Vichada-(Colombia), hacia la margen del río Orinoco y es parte del gran batolito descrito en Venezuela como Granito del Parguaza. Este cuerpo en Colombia aflora como cerros aislados tipo inselberg y serranías de poca extensión con pendientes abrupt [...] as que sobresalen entre las extensas llanuras terciarias. Representa uno de los granitos anorogénicos aflorantes más grandes del mundo y puede ser distinguido como una de las unidades colombianas más antiguas (Mesoproterozoico) que no han sufrido deformación. Se caracteriza por presentar textura rapakivi tipo wiborgita y piterlita, su composición es granítica a granítica de feldespato alcalino. Además de las variaciones composicionales y texturales, se encuentran zonas de grano fino, diques pegmatíticos, aplíticos y venas de cuarzo. Geoquímicamente se clasifica como un granito tipo A, metaluminoso a peralcalino, formado en ambiente post-colisional a anorogénico. Nuevas mediciones de U/Pb con LA-ICP-MS en circones indican nuevas edades concordantes de 1.392 ± 5 Ma y 1.402 ± 2 Ma para las partes más distales, respectivamente, mucho más jóvenes que edades propuestas anteriormente en territorio venezolano 1.545 Ma, lo cual puede ser interpretado como un intrusivo más complejo o como procesos de cristalización muy lentos de núcleo a borde. Por otro lado, estas edades son correlacionadas con granitos anorogénicos similares en el W del Cratón Amazónico en Brasil y con otros afloramientos rapakivi estudiados en el departamento de Guainía al SE de Colombia. Abstract in english The Parguaza Granite outcrops in the Vichada department of Colombia, towards the Orinoco River margin, where it conforms a portion of the large batholith described in Venezuela as Granito de El Parguaza. This intrusion outcrops in Colombia as isolated inselberg hills and moderately extended mountain [...] chains with abrupt slopes that protrude through Tertiary plains. It represents one of largest anorogenic granites worldwide and is one of the oldest colombian units (Mesoproterozoic) without tectonic deformation. The granite exhibits both typical Wiborgite and Pyterlite rapakivi texture, with a monzogranitic to alkali feldspar granitic composition. Among the compositional and textural variations, we find fine-grain zones, pegmatitic and aplitic dikes as well as quartz veins. Geochemically, it conforms a metaluminous to peralkaline A-type granite, intruded under post-collisional to rifting anorogenic conditions. New U/Pb measurements with LA-ICP-MS in zircons show hither to unknown concordant ages of 1392 ± 5 My to 1402 ± 2 My, respectively in the more distal zones; much younger than 1545 My ages reported in Venezuela, which may be explained or by a more complex intrusion and crystallization history or by a very slow crystallization process from the core to the edge; on the other hand, these ages are in concordance to similar anorogenic granites from the W Amazonian Craton in Brazil and with other rapakivi outcrops studied in the Guainía Department in the south-east of Colombia.

Amed, Bonilla-Pérez; José Carlos, Frantz; Juliana, Charão-Marques; Thomas, Cramer; José A., Franco-Victoria; Elise, Mulocher; Zeze, Amaya-Perea.

2013-12-01

93

Pre-Elsonian mafic magmatism in the Nain Igneous Complex, Labrador: the bridges layered intrusion  

Science.gov (United States)

Decades of work on the pristine, unmetamorphosed, and well exposed anorthositic, mafic and granitic rocks of the Nain igneous complex, Labrador, have led to the conclusion that all plutonic rocks in that area were emplaced in a short time intercal at about 1300 ?? 10 Ma). We report here new isotopic data for mafic intrusive rocks that appear to have crystallized several hundred Ma earlier than the bulk of the plutonic activity in the Nain complex. The Bridges layered intrusion (BLI) is a small (15-20 km2) lens of layered mafic rocks about 1.5 km thick, surrounded and intruded by anorthositic, leuconoritic and leucotroctolitic plutons in the middle of the coastal section of the Nain igneous complex. BLI shows very well developed magmatic structures, including channel scours, slump structures, and ubiquitous modally graded layering. Most rocks, however, show granular textures indicative of recrystallization, presumably caused by emplacement of younger anorthositic rocks. BLI contains cumulate rocks with slightly more primitive mineral compositions (An60-83, Fo66-71) than those of other mafic intrusions in the Nain igneous complex, including Kiglapait. SmNd isotopic data for 7 BLI whole-rocks ranging in composition between olivine melagabbro and olivine leucogabbro yield an age of 1667 ?? 75 Ma, which we interpret as the time of primary crystallization. The internal isotopic systematics of the BLI have been reset, probably by intrusion of adjacent anorthositic plutons. A SmNd mineral isochron (plag, whole-rock, mafics) for a BLI olivine melagabbro gives an age of 1283 ?? 22 Ma, equivalent within error of a mineral array (plag, whole-rock, opx, cpx) for an adjacent, igneous-textured, leuconorite vein (1266 ?? 152 Ma). The initial Nd ratio for BLI corresponds to ??{lunate}Nd = -3.18 ?? 0.44. Other whole-rock samples, however, some with vein-like alteration (Chlorite, serpentine, amphiboles), show ??{lunate}Nd values as low as -9.1, suggesting variable contamination by direct assimilation of early Archean crustal rocks and/or by fluids that have interacted with such crust. Adjacent anorthositic rocks also show variable ??{lunate}Nd some as low as -14.7, implying larger degrees if crustal assimilation, perhaps by parental magmas during lower crustal ponding prior to emplacement. These contamination effects preclude straightforward determination of the isotopic character of mantle sources for both BLI and the anorthositic rocks. ?? 1992.

Ashwal, L. D.; Wiebe, R. A.; Wooden, J. L.; Whitehouse, M. J.; Snyder, D.

1992-01-01

94

The assessment of human intrusion into underground repositories for radioactive waste Volume 2: Appendices  

International Nuclear Information System (INIS)

This report has been prepared with the primary objective of establishing a methodology for the assessment of human intrusion into deep underground repositories for radioactive wastes. The disposal concepts considered are those studied in the performance assessment studies Pagis and Pacoma, coordinated by the CEC. These comprise four types of host rock, namely: clay, granite, salt and the sub-seabed. Following a review of previous assessments of human intrusion, a list of relevant human activities is derived. This forms the basis for detailed characterization of groundwater abstraction and of exploitation of mineral and other resources. Approaches to assessment of intrusion are reviewed and consideration is given to the estimation of probabilities for specific types of intrusion events. Calculational schemes are derived for specific intrusion events and dosimetric factors are presented. A review is also presented of the capacity for reduction of the risks associated with intrusions. Finally, conclusions from the study are presented

95

The assessment of human intrusion into underground repositories for radioactive waste Volume 1: Main report  

International Nuclear Information System (INIS)

This report has been prepared with the primary objective of establishing a methodology for the assessment of human intrusion into deep underground repositories for radioactive wastes. The disposal concepts considered are those studied in the performance assessment studies Pagis and Pacoma, coordinated by the CEC. These comprise four types of host rock, namely: clay, granite, salt and the sub-seabed. Following a review of previous assessments of human intrusion, a list of relevant human activities is derived. This forms the basis for detailed characterization of groundwater abstraction and of exploitation of mineral and other resources. Approaches to assessment of intrusion are reviewed and consideration is given to the estimation of probabilities for specific types of intrusion events. Calculational schemes are derived for specific intrusion events and dosimetric factors are presented. A review is also presented of the capacity for reduction of the risks associated with intrusions. Finally, conclusions from the study are presented

96

Caracterización geoquímica del granito El Durazno, extremo norte de la sierra de Velasco, La Rioja / Geochemical characterization of El Durazno granite, Northern Sierrra de Velasco, La Rioja  

Scientific Electronic Library Online (English)

Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish El área de estudio se ubica en el norte de la sierra de Velasco, en la provincia de La Rioja. Está compuesta principalmente por rocas graníticas que cristalizaron durante dos eventos magmáticos principales en el Ordovícico y el Carbonífero. Los granitos más antiguos presentan diferentes grados de de [...] formación y los más jóvenes no están deformados. Los granitos datados como carboníferos hasta el presente en este sector son Asha y San Blas. Este último presenta una zona central más evolucionada químicamente, asociado a mineralizaciones de Sn. El granito El Durazno aflora al sureste del granito San Blas, no está deformado e intruye al ortogneis Antinaco, compuesto por rocas deformadas del Ordovícico. Es un granito postorogénico, peraluminoso y fuertemente diferenciado, con contenidos de Na2O>K2O. Presenta altos contenidos en Rb, Li, W, Cs, Nb y Ta y bajos en Ba, Sr, Y, Zr y Ce. El índice de caracterización geoquímica (GCI) para granitos asociados a mineralizaciones de W da valores positivos mayores que 4. Las tierras raras presentan contenidos totales bajos, entre 5,3 y 15,3 ppm, anomalía negativa de Eu y efecto tetrada convexo. En el borde norte del granito El Durazno existen vetas de cuarzo con wolframita y hematita distribuidas irregularmente que intruyen al ortogneis Antinaco. Tienen rumbo aproximado N-S y una corrida irregular. La ausencia de deformación, relaciones de campo y características geoquímicas indican que el granito El Durazno es un intrusivo muy diferenciado asociado a mineralización de W y de posible edad carbonífera. Abstract in english The studied area is located in the north of the sierra de Velasco, La Rioja province. It is mainly composed of granitic rocks that crystallized during two main magmatic events in the Ordovician and Carboniferous. The older granites have different types of deformation whereas the younger granites are [...] not deformed. Two Carboniferous granites have been dated in this area: Asha and San Blas. The latter has a chemically evolved central zone related to Sn mineralization. The El Durazno undeformed granite outcrops southeast of the San Blas granite, and intrudes into the deformed Ordovician Antinaco orthogneiss. It is a postorogenic, peraluminous and strongly differentiated granite, with contents of Na2O>K2O. It has high values of Rb, Li, W, Cs, Nb and Ta, and low values of Ba, Sr, Y, Zr and Ce. The geochemical characterization index (GCI) for W-bearing differentiated granites is positive with values greater than 4. The REE show low total contents, between 5,3 and 15,3 ppm, negative Eu anomalies and a convex tetrad effect. At the northern border of the El Durazno granite, quartz veins with irregularly distributed wolframite and hematite cross-cut the Antinaco orthogneiss. The veins have irregular north-south strike. The absence of deformation, field relations and geochemical characteristics indicate that the El Durazno granite is a highly differentiated intrusive associated with W mineralization and of possible Carboniferous age.

Miguel A, Báez; Ana S, Fogliata; Steffen, Hagemann; Fernando G, Sardi.

97

Ion Probe U-Pb dating of the Central Sakarya basement: a peri-Gondwana terrane cut by late Lower Carboniferous subduction/collision related granitic magmatism  

Science.gov (United States)

Our aim here is to better understand the age and tectonic history of crystalline basement units in the Sakarya Zone of N Turkey, north of the Neotethyan ?zmir-Ankara-Erzincan Suture Zone, utilising field, petrographic and ion probe dating, the latter carried out at the University of Edinburgh. One of the largest basement units, Central Sakarya, is dominated by paragneisses and schists that are best exposed between Bilecik and Sar?cakaya, forming a belt ~15 km wide x 100 km long. Smaller outcrops of this basement are exposed further north, for instance in the Geyve area. High-grade metamorphic basement is unconformably overlain by Lower Jurassic-Upper Cretaceous cover sediments of the Sakarya Zone and is in tectonic contact with the Late Palaeozoic-Early Mesozoic Karakaya Complex to the south. Ion-probe U-Pb dating of 89 detrital zircons, separated from one garnet micaschist sample, range from 551 Ma (Ediacaran) to 2738 Ma (Neoarchean). 85% of the ages are > 90 % concordant. Zircon populations cluster at ~550-750 Ma (28 grains), ~950-1050 Ma (27 grains) and ~2000 Ma (5 grains), with smaller groupings at ~800 Ma and ~1850 Ma. The first, prominent population (Neoproterozoic) reflects derivation from a source area related to a Cadomian-Avalonian magmatic arc, likely to be associated with a Cadomian/NE African terrane rather than Baltica (Baltica is known to be magmatically inactive during this period), or Avalonia/Amazonia (in view of the absence of Mesoproterozoic ages in Avalonian-Amazonian terranes). The early Neoproterozoic ages (0.9-1 Ga) deviate significantly from the known age spectra of Cadomian terranes (i.e. Armorican Terrane Assemblage) and instead suggest derivation from an original part of NE Africa. The detrital zircon age spectrum of Cambrian-Ordovician sandstones deposited at the northern periphery of the Arabian-Nubian Shield (i.e. the Elat sandstone) is notably similar to that of the Sakarya basement. The Central Sakarya terrane may have rifted in the Early Palaeozoic, relatively early compared to other E Mediterranean inferred Minoan terranes (e.g. Menderes, Crete, Bitlis), and then accreted to the Eurasian margin, possibly in during Late Palaeozoic time. The Central Sakarya metamorphic basement is cut by a number of granitic intrusions (collectively termed the Sö?üt Granite or Sar?cakaya Granite), three of which were dated in this study. Pink, alkali feldspar-rich granite (Küplü granite) yielded an age of 324.3 ±1.5 Ma. Grey, blastomylonitic biotite granite (Çalt? granite) is dated at 327.2 ± 1.9 Ma. Another granitic body with biotite and amphibole (Borçak granite) yielded a significantly younger age of 319.5 ± 1.1 Ma. Thus, late Early Carboniferous granitic magmatism in the Central Sakarya terrane could have persisted for ? 8 Ma, possibly related to subduction or collision of a Central Sakarya terrane with the Eurasian margin. This work was supported by Y?ld?z Technical University Research Fund (Project No: 29.13.02.01) and a Royal Society Travel Grant.

Ayda Ustaömer, P.; Ustaömer, Timur; Robertson, Alastair. H. F.

2010-05-01

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Caracterización geoquímica del granito El Durazno, extremo norte de la sierra de Velasco, La Rioja / Geochemical characterization of El Durazno granite, Northern Sierrra de Velasco, La Rioja  

Scientific Electronic Library Online (English)

Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish El área de estudio se ubica en el norte de la sierra de Velasco, en la provincia de La Rioja. Está compuesta principalmente por rocas graníticas que cristalizaron durante dos eventos magmáticos principales en el Ordovícico y el Carbonífero. Los granitos más antiguos presentan diferentes grados de de [...] formación y los más jóvenes no están deformados. Los granitos datados como carboníferos hasta el presente en este sector son Asha y San Blas. Este último presenta una zona central más evolucionada químicamente, asociado a mineralizaciones de Sn. El granito El Durazno aflora al sureste del granito San Blas, no está deformado e intruye al ortogneis Antinaco, compuesto por rocas deformadas del Ordovícico. Es un granito postorogénico, peraluminoso y fuertemente diferenciado, con contenidos de Na2O>K2O. Presenta altos contenidos en Rb, Li, W, Cs, Nb y Ta y bajos en Ba, Sr, Y, Zr y Ce. El índice de caracterización geoquímica (GCI) para granitos asociados a mineralizaciones de W da valores positivos mayores que 4. Las tierras raras presentan contenidos totales bajos, entre 5,3 y 15,3 ppm, anomalía negativa de Eu y efecto tetrada convexo. En el borde norte del granito El Durazno existen vetas de cuarzo con wolframita y hematita distribuidas irregularmente que intruyen al ortogneis Antinaco. Tienen rumbo aproximado N-S y una corrida irregular. La ausencia de deformación, relaciones de campo y características geoquímicas indican que el granito El Durazno es un intrusivo muy diferenciado asociado a mineralización de W y de posible edad carbonífera. Abstract in english The studied area is located in the north of the sierra de Velasco, La Rioja province. It is mainly composed of granitic rocks that crystallized during two main magmatic events in the Ordovician and Carboniferous. The older granites have different types of deformation whereas the younger granites are [...] not deformed. Two Carboniferous granites have been dated in this area: Asha and San Blas. The latter has a chemically evolved central zone related to Sn mineralization. The El Durazno undeformed granite outcrops southeast of the San Blas granite, and intrudes into the deformed Ordovician Antinaco orthogneiss. It is a postorogenic, peraluminous and strongly differentiated granite, with contents of Na2O>K2O. It has high values of Rb, Li, W, Cs, Nb and Ta, and low values of Ba, Sr, Y, Zr and Ce. The geochemical characterization index (GCI) for W-bearing differentiated granites is positive with values greater than 4. The REE show low total contents, between 5,3 and 15,3 ppm, negative Eu anomalies and a convex tetrad effect. At the northern border of the El Durazno granite, quartz veins with irregularly distributed wolframite and hematite cross-cut the Antinaco orthogneiss. The veins have irregular north-south strike. The absence of deformation, field relations and geochemical characteristics indicate that the El Durazno granite is a highly differentiated intrusive associated with W mineralization and of possible Carboniferous age.

Miguel A, Báez; Ana S, Fogliata; Steffen, Hagemann; Fernando G, Sardi.

2012-12-01

99

Application of Sr Isotopic Data to Tuolumne Intrusive Series, Sierra Nevada, CA  

Science.gov (United States)

In this problem set students are given Rb/Sr and 87Sr/86Sr data for whole rock and mineral samples from three granitic intrusions in the Sierra Nevada. They use these data (in EXCEL) to calculate isochron ages and initial ages for the intrusions and then interpret their results. This problem is intended to teach some spreadsheet skills (linear regressions, graphing) as well as having them think about the use of radiogenic isotopes.

Tepper, Jeff

100

Sr-Nd isotope geology and tectonomagmatic setting of the Dehsalm intrusives (Lut Block, Eastern Iran)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Dehsalm porphyritic shallow intrusives belong to the Lut Block volcanic-plutonic belt (central eastern Iran). Previous research on alteration, mineralization and hydrothermal fluids indicates that a Cu-Mo porphyry type mineralization system is related with these intrusives (Arjmandzadeh et al., 2012). The rocks studied in this work range in composition from gabbro-diorite to granite, with dominance of monzonites and quartz monzonites, and have geochemical features of high-K calc alkaline ...

Arjmandzadeh, R.; Santos, J. F.; Ribeiro, S.

2013-01-01

 
 
 
 
101

Geochronology of the Xihuashan composite granitic body and tungsten mineralization, Jiangxi province, south China.  

Science.gov (United States)

One of the goals of this visit was to collect samples of different granitic rocks in the pluton for radiometric dating to establish the geochronology of intrusion, alteration, and mineralization. This report summarises geochronologic studies during a visit by Chinese and US scientists to the Xihuashan mine.-after Authors

McKee, E. H.; Rytuba, J. J.; Xu, Keqin

1987-01-01

102

The regional geological and structural setting of the uraniferous granitic provinces of Southern Africa  

International Nuclear Information System (INIS)

Uranium-bearing granites, comprising both potentially economic deposits and source rocks for uranium deposits is duricrustal and sedimentary sequences, are confined chiefly to the mobile belts of Southern Africa and to the Cape granites emplaced during late Precambrian times. The direct uranium potential of the mobile belts, i.e. the Damara, Namaqua-Natal and Limpopo belts, decreases with an increase in the age of associated ensialic diastrophism. This review paper is thus mainly confined to the Damara Belt, although a brief discussion of the potential of the Namaqua Belt is presented. Aspects of the Damara Belt that are discussed in detail, with particular reference to the occurrence of uraniferous granite, include regional tectonic setting, stratigraphy, structure, metamorphism and the patterns and origin of the uranium mineralization. Initial concentrations of uranium in basement and Nosib rocks have led, through ultrametamorphism and fractionation, to uraniferous granites of both economic and sub-economic grade. These granites, in turn, have acted as source of secondary mineralization in overlying superficial calcareous and gypsiferous deposits. The Damara Belt thus provides a good example of multicyclic processes of ore formation. With regard to the uraniferous granites of Namaqualand it is concluded that the porphyroblastic gneisses and late-intrusive Concordia granites, although not of direct economic interest, represent major sources of uranium for secondary superficial deposits. Smaller bodies of late-phase differentiates associated with the Concordia granitic gneiss may themselves, however, represent potentially economically viable deposits

103

The missing link between granites and granitic pegmatites  

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Full Text Available In this contribution we provide evidence for the extraction of volatile and incompatible element enriched melts from common granites. This provides a mechanism showing that at least a large proportion of granitic pegmatites could be genetically directly connected to a main granite body. In granites there are often two principal types of melt inclusions: (i those that represent the bulk chemistry of the granite and (ii those with very different compositions. In the Variscan Erzgebirge granites, the second type is characterized by the abundance of fluorine. However, in other geodynamic settings inclusions in granites can contain high concentrations of other elements which may take over the function of fluorine. From textural relationships the second inclusion type represents intergranular melts enriched in all elements incompatible with the ideal haplogranite system. Due to the high volatile content of such melts, the viscosity can be several orders of magnitude lower than the quasi-solid bulk system and can therefore move rapidly through the partially or totally crystallized host, and flow together into a separate system forming pegmatite bodies inside or outside the granite body. Another important effect of the high volatile content is the phase separation resulting from the speciation changes OH- ? H2O or CO32- ? CO2 due to temperature and/or pressure changes at different locations within the granite-intergranular melt system. Since melt inclusions provide a means of conserving original un-degassed compositions, they provide important evidence for closing the gap between granites and granitic pegmatites.The paper is dedicated to two Czech colleagues - Petr ?erný and Milan Novák - who have devoted their lives to the study of granitic pegmatites.

Thomas R

2013-07-01

104

The rapakivi granite plutons of Bodom and Obbnäs, southern Finland: petrography and geochemistry  

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Full Text Available The Obbnäs and Bodom granite plutons of southernmost Finland show the typical petrographic and geochemical features of the Proterozoic rapakivi granites in Finland and elsewhere: they cut sharply across the 1900 Ma Svecofennian metamorphic bedrock and have the geochemical characteristics of subalkaline A-type granites. The Bodom pluton is composed of porphyritic granites (hornblende-, hornblende-biotite-, and biotite-bearing varieties and an even-grained granite that probably represent two separate intrusive phases. This lithologic variation does not occur in the Obbnäs pluton, which is almost entirely composed of porphyritic hornblende-biotite granite that gradually becomes more mafic to the southwest. Three types of hybrid granitoids resulting from magma mingling and mixing occur on the southwestern tip of the Obbnäs peninsula. The Bodom granites are syenogranites, whereas the composition of the Obbnäs granite varies from syeno- to monzogranite. The main silicates of both the Bodom and Obbnäs granites are quartz, microcline, plagioclase (An1541, biotite (siderophyllite, and generally also amphibole (ferropargasite or hastingsite. Plagioclase-mantled alkali feldspar megacrysts are absent or rare. The accessory minerals are fluorite, allanite, zircon, apatite, and iron-titanium oxides; the Obbnäs granite also contains titanite. The Bodom and Obbnäs granites are metaluminous to weakly peraluminous, with average A/CNK of 1.00 and 1.05, respectively, have high Fe/Mg (average FeOtot/[FeOtot+MgO] is 0.94 for the Bodom and 0.87 for the Obbnäs granites, and high Ga/Al (3.78 to 5.22 in Bodom and 2.46 to 4.18 in Obbnäs. The REE contents are high with LREE-enriched chondrite-normalized patterns and moderate (Obbnäs to relatively strong (Bodom negative Eu-anomalies. The Obbnäs granite is enriched in CaO, TiO2, MgO, and FeO, and depleted in SiO2 and K2O compared to the Bodom granites. Also, there are differences in the Ba, Rb, and Sr contents of the two plutons (Ba and Sr higher, Rb lower in Obbnäs that cannot easily be traced to single parental granite magma. These features, together with the presence of titanite in the Obbnäs pluton, suggest different sources for the granites of the two plutons: a potassium feldspar-rich source for Bodom and potassium feldspar-poor for Obbnäs.

Kosunen, P.

1999-12-01

105

Study on Kalimantan uranium province: The assessment on uranium mineralization of metamorphic and granitic rocks at Schwaner mountains  

International Nuclear Information System (INIS)

Uranium exploration activities done by CEA-BATAN had discovered uranium occurrences as the radiometric and uranium content anomalies at metamorphic and granite rocks of Schwaner Mountains, Kalimantan. A part of the occurrences on metamorphic rocks at Kalan basin has been evaluated and be developed onto follow-up step of prospecting by construction of some drilling holes and an exploration adit. In order to increase the national uranium resources, it is necessarily to extent the exploration activity to out side or nearby of Kalan basin. The goal of this assessment is to understand the uranium accumulation mechanism at Pinoh metamorphic rocks of Kalan Kalimantan and to delineate areas that uranium may exist. The assessment was based on the aspect of geology, anomaly of radioactivity and uranium contents, tectonics and alterations. Pinoh metamorphic rocks which is influenced by Sukadana granite intrusion are the high potential rocks for the uranium accumulation, because the intrusion contains a relatively high of U, Th, Cu, Zn, Nb, Mn, and W. The potential rock distributions are in between G. Ransa granite intrusion at the east and Kotabaru granite intrusions at the west. The mineralizations are categorized as vein type deposits of granitic association

106

Magnetic fabric and emplacement mechanisms in a co-mingled mafic and felsic magma chamber: the Espinharas granite (Borborema Province, NE Brasil)  

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The Espinharas granite is a co-mingled mafic and felsic magmatic complex forming part of the widespread Brasiliano plutonism that affected the Borborema Province during the Neoproterozoic. Syenogranite is mixed and mingled with diorite generating a range of aluminous shoshonitic hybrid rocks containing mafic microgranular enclaves (MME) of various shapes and orientations. Geochemical modelling shows that the pluton originated by upper-mantle magma underplating and fault-assisted intrusion of diorite, which would supply heat for partial melting of the crust and formation of syenogranite. The Espinharas granite comprises syenogranites and diorites associated with quartz-monzonites, monzodiorites and syenites mainly deformed in the magmatic state. The pluton is emplaced within Paleoproterozoic augen gneisses from the basement and is bounded by high-temperature NE-trending mylonitic shear zones at its western and eastern borders. To the south, the pluton is in contact with the E-trending high-grade transpressional Patos shear zone. Magmatic foliations can be observed throughout the syenogranite and in the felsic rocks, being defined by a SPO of feldspars and quartz. However, they appear to be absent in the diorite. The microgranular enclaves display irregular contacts with the host syenogranite and may be often aligned in agreement with the magmatic foliation; they are also randomly dispersed and disrupted by monzo- to syenogranitic veins. The Anisotropy of Magnetic Susceptibility (AMS) technique was employed in order to investigate the mechanical relationships between mingled mafic and felsic magmas, as well as their emplacement mechanisms. Susceptibilities are usually high (k > 1.3 mSI), suggesting that Ti-magnetite is the main carrier of the magnetic signal. The magnetic lineation plunges shallowly to NE, parallel to the pluton main elongation axis. Zircons from diorite and syenogranite yield U-Pb (SHRIMP) ages of ~ 620 Ma, which are attributed to the crystallization of the granite and are younger than the main metamorphic event in the Seridó Belt (~ 575 Ma). These data suggest that the magnetic fabric of the Espinharas granite records the high-temperature deformation observed in the Seridó Belt. This deformation was active during a prolonged time range (~ 100 Ma) in a hybrid magmatic chamber emplaced in the middle- to shallow continental crust. These conditions indicate that the Patos shear zone controlled the development of the magmatic- to solid-state fabric of the Espinharas granite, highlighting the contribution of strain partitioning in the mechanical mingling of magmas in the continental crust.

Viegas, G.; Gouveia, F.; Archanjo, C.; Hollanda, M.

2013-12-01

107

Uranium distribution in the Um Samra-Um Bakra granitic plutons and associated pegmatites, Central Eastern Desert, Egypt  

International Nuclear Information System (INIS)

Um Samra -Um Bakra granitic plutons are located in the central Eastern Desert between latitudes 25 degree 15 and 25 degree 19 N and longitudes 34 degree 03 and 34 deg 11 E. The younger granites in the studied area are subdivided into two varieties, monzogranites and syenogranites. The syenogranites could be considered as uraniferous (fertile) granites, originated from highly fractionated, U-rich magma. They contain from 15.5 to 24.5 ppm uranium and from 20.5 to 25.0 ppm thorium. Both U and Th were essentially concentrated during the magmatic stage in accessory minerals as apatite, fluorite and zircon. The secondary processes as fracturing and alteration processes allowed the meteoric water and hydrothermal solutions to liberate labile uranium and redeposited their loads along micro fractures. Pegmatites show higher U-contents relative to both types of the studied younger granites. Pegmatites could be classified into two separate groups: 1) mineralized pegmatites which are located near the contact of Um Samra younger granites; they possess U-mineralization (kasolite) and 2) non-mineralized pegmatites which are distributed within Um Bakra younger granites themselves; they show lower U-contents relative to the first type. (author)

108

Petrogenesis and Zircon U-Pb radiometric dating in Herris granite (NW Shabestar) East Azarbaijan Province  

International Nuclear Information System (INIS)

Heris intrusive body has cut Kahar Formation and has been covered by Permian basal sediments, non-conformably. The composition of this body is granite- alkali granite with meta luminous to weak peraluminous nature. The strong negative anomaly of Eu in REE diagram indicates the presence of plagioclase in the source area or differentiation of it during evolution of the magma. Negative anomaly of Ba and enrichment of Rb and Th relative to Ta and Nb is an indicator of crustal origin. These granites are within-plate and A-type granites, which have been formed by partial melting of tonalitic- granodioritic source in extensional setting. Zircon U-Pb dating yields 306±34 Ma for crystallization of these rocks. This age is consistent with primary extensions of rifting in Arabian- Iranian platform.

109

Contribution to the uranium geochemistry on granites in Ecuador  

International Nuclear Information System (INIS)

This work aims to define the position of two of Ecuador granitic deposits within the field of the geochemistry of granites in general and of the geochemistry of uranium in particular. The regions concerned are: The Bonita and ABITAGUA. For each range the petrochemical framework is first of all determined and then the degree of chemical homogeneity of rocks is evaluated. In the petrochemical groups thus obtained the geochemical behaviour of the uranium is studied. From the viewpoint of the geochemistry of the granites under investigation, a comparison of the laws of distribution of the mayor elements in two ranges shows up a covergence of average composition which was not anticipated by geological and petrografic considerations alone. The statistical and geochemical distribution laws of the total uranium as a function of petrochemical variations are established. A study of chemical forms of uranium in the rocks has drawn an attention to the qualitative and quantitative importance of the faction of uranium soluble in delute acids. We have therefore reconsidered on the one hand, the laws of distribution of the insoluble and we have justified on the other hand the interest presented by the soluble post magmatic phenomena which makes possible to find a genetic connection between the uraniferous deposits and the intrusive massifs. Finally we have given tables of analytic composition total of the granites. (Author)

110

Radioactive elements behaviour in multiphase intrusive series and petrological significance of radiogeochemical data  

International Nuclear Information System (INIS)

The behaviour of radioactive elements (RE) during formation of multiphase intrusive series of various ages, types and alkalinity nature, placed in different structural formation zones of West Uzbekistan is discussed (on the basis of 230 quantitative determinations). It is established that maximum RE concentrations in the intrusive series considered are U=3-5, Th=11-17 g/t and correspond to granodiorites, adamellites, granites and granosienites. The typical behaviour for U and Th is the growth of their concentrations in the direction from gabbro- to granodiorites (granosienites) and granites, and then decrease to leucocrat granites (alkaline, biotite or bimica ones). The evolution of magmatic systems occurred not along the line of differentiation of melts, but along the line of their ''washing'' with fluid mainly at the level of magma generation and on their way to upper horizons of Earth crust. High concentrations (several times more than a clark) must occur in cases of additional RE introduction

111

Research on isotope geology. Assessment of heat production potential of granitic rocks and development of geothermal exploration techniques using radioactive/stable isotopes and fission track 2  

Energy Technology Data Exchange (ETDEWEB)

Radioelements and heat production rates of granitic rocks and stable isotopes of groundwaters were analyzed to investigate the geothermal potential of Wolchulsan granite complex in the southern Yeongam area. Wolchulsan granite complex is composed mainly by Cretaceous pink alkali-feldspar granite and partly Jurassic biotite granite. The main target for the geothermal exploration is the alkali-feldspar granite that is known in general to be favorable geothermal reservoir(e.g., Shap granite in UK). To develop exploration techniques for geothermal anomalies, all geochemical data were compared to those from the Jeonju granite complex. Heat production rates(HPR) of the alkali-feldspar granite is 1.8 - 10.6 {mu}Wm{sup -3}. High radio-thermal anomalies were revealed from the central western and northern parts of the granite body. These are relatively higher than the Caledonian hot dry granites in the UK. The integrated assessment of Wolchulsan granite complex suggests potential of the Cretaceous alkali-feldspar granite as a geothermal targets. Groundwater geochemistry of the Yeongam area reflects simple evaporation process and higher oxidation environment. Stable isotope data of groundwaters are plotted on or close to the Meteoric Water Line(MWL). These isotopic data indicate a significant meteoric water dominance and do not show oxygen isotope fractionation between groundwater and wall rocks. In despite of high HPR values of the Yeongam alkali-feldspar granite, groundwater samples do not show the same geochemical properties as a thermal water in the Jeonju area. This reason can be well explained by the comparison with geological settings of the Jeonju area. The Yeongam alkali-feldspar granite does not possess any adjacent heat source rocks despite its high radio-thermal HPR. While the Jeonju granite batholith has later heat source intrusive and suitable deep fracture system for water circulation with sedimentary cap rocks. (Abstract Truncated)

Shin, Seong Cheon; Chi, Se Jung [Korea Inst. of Geology Mining and Materials, Taejon (Korea, Republic of)

1995-12-01

112

Damaging of granites and argilites  

International Nuclear Information System (INIS)

This book is a special issue of the journal 'Revue francaise de genie civil' (vol.6, no 1/2002). It gathers several papers written in the framework of the CNRS-ANDRA 'Forpro' research program on the feasibility of radioactive waste disposal in deep geological formations. It treats of the researches carried out on the fracturing of granites and argilites: physical and mechanical characteristics of the Vienne granite and of the Argilite de l'Est formation; modeling of the anisotropic damaging by meso-cracking of the Vienne granite; modeling of the anisotropic damaging of the Vienne granite; microstructural modeling of the Vienne granite damaging; modeling of an argilite using the CLoE model; elasto-plastic modeling coupled with the induced anisotropic damaging for the argilites; comparison between model concepts and forecasts. (J.S.)

113

U-Pb ages and Nd isotope characteristics of the lateorogenic, migmatizing microcline granites in southwestern Finland  

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Full Text Available U-Pb ages and whole-rock Nd isotope data have been obtained from the Paleoproterozoic lateorogenic migmatizing microcline granites of southwestern Finland. Isotope dilution and ion microprobe U-Pb data on zircons and monazites show that the age spectrum of these granites is at least 1.85-1.82 Ga. Commonly, zircons and monazites record the same ages. The age variation in the Veikkola granite area is of the order of 25 Ma and indicates that this seemingly homogeneous granite consists of two separate intrusions. The zircons of the lateorogenic granites are pervasively altered and conventional U-Pb results are commonly discordant. The ion microprobe studies reveal that the granites contain very few inherited zircons with preserved original U-Pb isotope ratios, with the exception of the Oripää granite. Initial ?Nd values, mostly in the range of ?0.5 to ?1.0, imply a moderate input of older crustal material into most of the lateorogenic granites. A shift from more juvenile to less radiogenic Nd isotope composition is observed from north to south, and the variation pattern of ?Nd values of the lateorogenic granites is thus similar to that of the surrounding synorogenic granitoid rocks.

Matti Kurhila

2005-01-01

114

Radioelemental characterization of neoproterozoic south Khasi batholith and mylliem granite pluton by portable gamma-ray spectrometry: its implication on uranium exploration in parts of east and west Khasi hills, Meghalaya  

International Nuclear Information System (INIS)

Younger granite activity in the form of South Khasi Batholith (SKB), Kyrdem, Mylliem and Nongpoh plutons occur as intrusive into the basement gneissic complex and Paleo-Mesoproterozoic Shillong group of rocks. Ground portable gamma ray spectrometric survey carried out over the SKB, the Mylliem pluton and the basement gneissic complex. The eTh, eTh/eU and K contours clearly demarcate their lithocontacts. Radiometrically, these plutons are of hyperacidic to alkaline in nature. The magmatic evolution and the differentiated origin of granites are reflected by high concentration of eTh and K. The low Th/K values within the pluton indicate presence of diorite bodies and also suggest K enrichment along the margin of the Mylliem pluton. Higher concentration of radioelements along the margin of Mylliem pluton may be due to the role of hydrothermal phase to transport the radioelements. The high eTh/eU values and uranium favourability index of the SKB may imply possible loss of considerable amount of uranium to become provenance for the nearby uranium districts. (author)

115

Geochronology of Triassic-Jurassic granitoids in the southern frames of Mongol-Okhotsk fold belt and the principles of early mesozoic granitic formation in the Central and East Asia  

International Nuclear Information System (INIS)

Results of U-Pb and U-Pb-Th-isotope dating of zircon from biotite and leucocratic granites in the southern frames of the Mongol-Okhotsk fold belt are presented. The similar estimates of the above mentioned granite ages (208±9 and 190±3 mln. years), the granites being referred traditionally to different intrusive complexes, permit defining essentially the scale of the early mesozoic magmatism manifestations in the Central and East Asia

116

Artificial weathering of granite  

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Full Text Available This article summarizes a series of artificial weathering tests run on granite designed to: simulate the action of weathering agents on buildings and identify the underlying mechanisms, determine the salt resistance of different types of rock; evaluate consolidation and water-repellent treatment durability; and confirm hypotheses about the origin of salts such as gypsum that are often found in granite buildings. Salt crystallization tests were also conducted, using sodium chloride, sodium sulphate, calcium sulphate and seawater solutions. One of these tests was conducted in a chamber specifically designed to simulate salt spray weathering and another in an SO2 chamber to ascertain whether granite is subject to sulphation. The test results are analyzed and discussed, along with the shortcomings of each type of trial as a method for simulating the decay observed in monuments. The effect of factors such as wet-dry conditions, type of saline solution and the position of the planes of weakness on the type of decay is also addressed.En este trabajo se hace una síntesis de varios ensayos de alteración artificial realizados con rocas graníticas. Estos ensayos tenían distintos objetivos: reproducir las formas de alteración encontradas en los edificios para llegar a conocer los mecanismos que las generan, determinar la resistencia de las diferentes rocas a la acción de las sales, evaluar la durabilidad de tratamientos de consolidación e hidrofugación y constatar hipótesis acerca del origen de algunas sales, como el yeso, que aparecen frecuentemente en edificios graníticos. En los ensayos de cristalización de sales se utilizaron disoluciones de cloruro de sodio, sulfato de sodio, sulfato de calcio y agua de mar. Uno de estos ensayos se llevó a cabo en una cámara especialmente diseñada para reproducir la alteración por aerosol marino y otro se realizó en una cámara de SO2, con el objeto de comprobar si en rocas graníticas se puede producir sulfatación. Se analizan los resultados obtenidos en cada ensayo y se discuten las limitaciones de los mismos para reproducir las patologías desarrolladas en los monumentos así como la influencia que pueden tener en dichas patologías aspectos como las condiciones de humectación y secado, el tipo de disolución salina (mixta-simple y la influencia de los planos de debilidad de las rocas en el desarrollo de unas u otras formas de alteración.

Silva Hermo, B.

2008-06-01

117

Geochemistry of pegmatites associated with the Cape Coast granite complex of southern Ghana  

International Nuclear Information System (INIS)

The Cape Coast granite complex, which is associated with the metasedimentary basin rocks of Birimian in Ghana are, also referred to as the basin - type granitoids, and forms part of the two major types of Eburan granitoids in Ghana. The Cape Coast granite complex is characterized by various intrusions such as acid intrusion and pegmatites. The pegmatites associated with the Cape Coast granite complex are noted to be related to the margin of the granite batholiths. The mineralogical characteristics of the pegmatites have been documented, but there is little published information on the geochemical characteristics, source and tectonic settings and mode of emplacement of these pegmatites as compared to the Cape Coast granite complex. The objectives of this project were therefore to determine the compositions and geochemistry of the pegmatite and use the data to infer the possible source of these pegmatites. The geochemical data indicates that the pegmatites of the Egyaa, Saltpond and Akim Oda areas consist of a low to high-K, S-type characteristics, with three samples from Saltpond having metaluminous character. Lower values of molar CaO/ (MgO + FeOtot) coupled with higher values of molar Al2O3/ MgO + Fetot) suggest their derivation from partial melting from metabalistic source. The data suggests the rocks so have emplaced in a volcanic arc and ocean ridge geotectonic environment. (au)

118

The density of dry and hydrous granitic magmas  

Science.gov (United States)

Large volumes of granitic magmas form through partial melting of the lower crust and are subsequently emplaced in the higher crustal levels [1]. In addition, granite-like liquids may form through partial melting of subducted sediments [2] or as an end-product of magmatic differentiation [3]. Moreover, water rich magmas of granitic composition are a major source of explosive volcanism. The physical properties of granitic melts, and particularly their density, are key controls on the migration rate and emplacement depth of granitic intrusions. However, because of the high viscosity of granitic liquids, density and compressibility measurements with the sink/float method and sound velocity measurements are challenging. As a result, the density and compressibility of dry and volatile-bearing granitic liquids is poorly constrained, particularly for the pressure-temperature conditions relevant for their formation and emplacement. In this study, we present in situ experimental data on the density of dry and hydrous haplogranitic melts (5 and 10 wt% water) at pressure and temperature conditions relevant for the crust and the subducting slab (1.0-2.7 GPa, 1350-1720 K). The experiments were performed with a panoramic Paris-Edinburgh press installed at the ID27 beamline of ESRF. The samples were contained in a cylindrical diamond capsule, capped with a platinum disk on either side, surrounded by hexagonal boron nitride (hBN) and placed inside a graphite heater and boron epoxy gasket. Pressure and temperature were determined from the X-ray diffraction patterns of hBN and platinum using the double-isochore method [4]. The density of the melts was determined from the X-ray absorption contrast between the sample and the diamond capsule (Mo edge, 20 keV). The molten state of the sample at the condition of the density measurements was verified by X-ray diffraction. The run products were analyzed by electron microprobe and infrared spectroscopy to verify the chemical composition and volatile content of the samples. Our results, combined with literature data on granite melt density at atmospheric pressure, provides the first experimentally derived equation of state of dry and hydrous granitic liquids at crustal and upper mantle conditions. This equation of state enables the prediction of the partial molar volume of water and granite melt density for the pressures, temperatures and water contents relevant for partial melting in the lower crust, melt migration through the middle crust and the emplacement of intrusions in the upper crust. [1] N. Petford, A.R. Cruden, K.J.W. McCaffrey, J.-L. Vigneresse, 2000, Nature, 408, 669. [2] Y. Tatsumi, 2000, Geology, 29, 323. [3] N.L. Bowen, 1956, The evolution of igneous rocks. [4] W.A. Chrichton, M. Mezouar, 2002, High Temp.-High Press, 34, 235.

Malfait, W. J.; Sanchez-Valle, C.; Seifert, R.; Petitgirard, S.; Perrillat, J.

2011-12-01

119

Adaptive intrusion data system  

International Nuclear Information System (INIS)

An Adaptive Intrusion Data System (AIDS) was developed to collect data from intrusion alarm sensors as part of an evaluation system to improve sensor performance. AIDS is a unique digital data compression, storage, and formatting system. It also incorporates capability for video selection and recording for assessment of the sensors monitored by the system. The system is software reprogrammable to numerous configurations that may be utilized for the collection of environmental, bi-level, analog and video data. The output of the system is digital tapes formatted for direct data reduction on a CDC 6400 computer, and video tapes containing timed tagged information that can be correlated with the digital data

120

The Torres del Paine intrusion as a model for a shallow magma chamber  

Science.gov (United States)

The shallow magmatic Torres del Paine Intrusive Complex (TPIC) belongs to a series of sub-volcanic and plutonic igneous bodies in Southern Chile and Argentina. This trench-parallel belt is located in a transitional position between the Patagonia Batholith in the West, and the alkaline Cenozoic plateau lavas in the East. While volumetrically small amounts of magmatism started around 28 my ago in the Torres del Paine area, and a second period occurred between 17-16 Ma, it peaked with the TPIC 12.59-12.43 Ma ago. The spectacular cliffs of the Torres del Paine National park provide a unique opportunity to study the evolution of a very shallow magma chamber and the interaction with its host rocks. Intrusion depth can be estimated based on contact metamorphic assemblages and granite solidus thermobarometry to 750±250 bars, corresponding to an intrusion depth of ca. 3km, ca. 500m above the base of the intrusion. Hornblende thermobarometry in mafic rocks agrees well with these estimates (Leuthold et al., 2014). The TPIC is composed of a granitic laccolith emplaced over 90ka (Michel et al., 2008) in 3 major, several 100m thick sheets, forming an overall thickness of nearly 2 km. Contacts are sharp between sheets, with the oldest sheet on the top and the youngest on the bottom (Michel et al., 2008). The granitic laccolith is under-plated by a ca. 400m thick mafic laccolith, built up over ca. 50ka (Leuthold et al. 2012), constructed from the bottom up. Granitic and mafic sheets are themselves composed of multiple metric to decametric pulses, mostly with ductile contacts between them, resulting in outcrop patterns resembling braided stream sediments. The contact of the TPIC with the Cretaceous flysch sediments document intrusion mechanism. Pre-existing sub-horizontal fold axes are rotated in the roof of the TPIC, clearly demonstrating ballooning of the roof; no ballooning was observed in the footwall of the intrusion. Extension during ballooning of the roof is indicated by dykes emanating from the roof of the intrusion into the host rocks. The dykes are perpendicular to the contact, radially shooting into the country rocks. Since the oldest granite is found in the roof, it is also permeated by dykes of successive intrusions. Contact metamorphism can be used to constrain the granite intrusion temperature to ca. 1000°C. Intrusion occurred in multiple pulses along the granite-host rock contact, in rapid succession, before significant cooling occurred in the aureole. Hydration of the biotite and feldspar of the immature sediments in the outer aureole contributed significantly to the overall thermal signature of the host-rock-TPIC system. In contrast, stable isotopes do not document significant fluid circulation. Leuthold, J., Müntener, O., Baumgartner, L., Putlitz, B., Ovtcharova, M., Schaltegger, U. (2012) Time resolved construction of a granitic to mafic laccolith (Torres del Paine, Patagonia). Earth Plan Sci Lett. 325. 85-92 Leuthold J., Müntener O., Baumgartner L.P., Putlitz B., (2014) Recycling of mafic crystal mush, transport and emplacement in the Torres del Paine mafic complex (Patagonia). J. Petrology; accepted pending revision Michel, J., Baumgartner, L.P. Putlitz, B., Ovtcharova, M., Schaltegger, U. (2008) Incremental growth of a shallow crustal laccolith over 80 kyrs: the Torres del Paine Granite, Patagonia. Geology vol. 36, 459-462

Baumgartner, Lukas; Bodner, Robert; Leuthold, Julien; Muntener, Othmar; Putlitz, Benita; Vennemann, Torsten

2014-05-01

 
 
 
 
121

Geology of the Northern part of the Strath Ossian Granite, Scotland  

International Nuclear Information System (INIS)

The Strath Ossian Granite is made up of granodiorite, dark, variable 'granodiorites' interpreted as mobilised diorite or basic material, appinite and porphyritic granodiorite. Huge rafts of psammitic metasediments occur within the mass and three fracture-zones and numerous dykes, dominantly of porphyrite, cut across it in a north-easterly direction. Granite emplacement may have occurred in stages, early batches being xenolith-rich and later ones xenolith-poor. New batches were intruded centrally, which created strong radial stresses, sufficiently strong to make room for the intrusion by forcing the metasedimentary country rocks downwards and aside. (author)

122

New evidence of basement in the Svalbard Caledonides: Early Proterozoic zircon ages from Ny Friesland granites  

International Nuclear Information System (INIS)

In Ny Friesland, northeastern Spitsbergen, the younger sedimentary rocks of the Hecla Hoek Complex closely resemble strata of similar age (ca. 800 to 470 Ma) in East Greenland. The pass downwards, apparently concordantly, into metasedimentary rocks which increase in metamorphic grade with depth. In their lower parts the latter include a variety of granitic gneisses. Zircons from a granite and gneissic granite have been analysed by the U-Pb and 207Pb/206Pb single crystal methods and have yielded ages of appr. 1700 to 1800 Ma. One of these granites intrudes metasediments, indicating an Early Proterozoic age. These ages imply that significant segments of pre-Caledonian crystalline basement are incorporated in the base of the Caledonian pile in northeastern Spitsbergen. 63 refs., 5 figs., 3 tabs

123

Uranium enriched granites in Sweden  

International Nuclear Information System (INIS)

Granites with uranium contents higher than normal occur in a variety of geological settings in the Swedish Precambrian, and represent a variety of granite types and ages. They may have been generated by (1) the anatexis of continental crust (2) processes occurring at a much greater depth. They commonly show enrichement in F, Sn, W and/or Mo. Only in one case is an important uranium mineralization thought to be directly related to a uranium-enriched granite, while the majority of epigenetic uranium mineralizations with economic potential are related to hydrothermal processes in areas where the bedrock is regionally uranium-enhanced. (Authors)

124

Intrusion detection: systems and models  

Science.gov (United States)

This paper puts forward a review of state of the art and state of the applicability of intrusion detection systems, and models. The paper also presents a classfication of literature pertaining to intrusion detection.

Sherif, J. S.; Dearmond, T. G.

2002-01-01

125

Granites and granitoids of the southern region - Granite molybdenite system  

International Nuclear Information System (INIS)

Economic concentrations of molybdenum are genetically closely associated with acidic and moderately acid granitoids-granites, granodiorites, monzonites and diorites, and are located in two geotectonic settings: subduction-related and rift-related. The aim of this paper is twofold, first succinctly approach the geology, tectonic setting and chemical parameters of the 'granite molybdenite system' as defined by Mutschler and/or alcali granite porphyry bodies emplaced in the North American continent for occasion of a Mesozoic-Fanerozoic extensile event; second to relate the computer-assisted evaluation of 422 major element chemical analysis of granites and granitoids of southern region of Brazil, using chemical fingerprints (SiO2 ? 74. Owt%, Na2O ? 3.6wt%, K2O ? 4.5wt%), and K2O/Na2O ratio > 1.5 developed and testified from North American and Finnish occurrences, may locate molybdenite-bearing granite bodies with high exploration potential. These techniques suggest that some late Precambrian to early Paleozoic granite-rhyolite assemblages inserted at domains of the SG. 22/23 Curitiba/Iguape, SH. 21/22 Uruguaiana/Porto Alegre and SI.22 Lagoa Mirim Sheets, have exploration potential for molybdenum. (author)

126

Test in situ in granite  

International Nuclear Information System (INIS)

This paper describes research program on thermal pollution by radioactive wastes in granite. Field tests and bench-scale experiments have allowed to show that heat propagation in fractured medium is submitted to Fourier law. 3 figs

127

Radioelement geochemistry of Irish granites  

International Nuclear Information System (INIS)

Data for U, Th, and K, determined by neutron activation analysis, in 128 rock samples from 14 Irish Caledonian and Tertiary granite plutons are summarized. Irish Newer Caledonian granites (ninety-four samples) have values of radioelements (average 3.6 ppm U, 12.1 ppm Th, and 3.4% K) consistent with derivation from a source of broadly uniform composition. U mineralization occurs in the voluminous and forcefully emplaced Main Donegal and Leinster plutons whereas smaller passively emplaced granites (Galway, Barnesmore, Rosses) lack mineralization. Irish Tertiary granites (thirty-four samples), which represent small batches of highly fractionated acid magmas, show moderate or high radioelement contents (11.5 ppm U, 39.9 ppm Th, 4.5% K) but are not mineralized. It is concluded that the use of elevated radioelement contents as a criterion of granite 'fertility' may be misleading in the British Isles Caledonian Province. The radioelement chemistry of granites may reflect their source composition more closely than expected for differentiated and/or contaminated acid melts. (author)

128

A new interpretation of the structure of the Sept Iles Intrusive suite, Canada  

Science.gov (United States)

The layered mafic intrusion at Sept Iles, Canada, is one of the largest intrusions in the world. A new interpretation of its structure is proposed, based on a review of its geology and a comparison with the Skaergaard intrusion, Greenland. Several different magmatic components are recognized; hence the name Sept Iles Intrusive suite (SIIS) is proposed. Emplacement of the suite may have been preceded by eruption of flood basalts. The first magmas of the suite rose in the crust to accumulate beneath the density filter afforded by the basalts. The largest component is the Sept Iles Mafic intrusion (SIMI). The Lower series of the SIMI is dominated by leucotroctolites and leucogabbros. Above it lie the Layered series, which is largely comprised of gabbro and troctolite. Both these units are unchanged from earlier interpretations. The anorthosites (s.l.), gabbros and monzogabbros, formerly called the Transitional series, are now considered to be the Upper Border series, developed by floatation of plagioclase. Common autoliths in the Layered series are parts of the hydrothermally altered Upper Border series from towards the interior of the intrusion, which have foundered and settled through the magma. The contamination of the magma that accompanied this event oxidised iron in the magma and led to the precipitation of magnetite around the periphery of the intrusion. The subsequent depletion of Fe 3+ and/or increase in SiO 2, CaO and P 2O 5 may have induced apatite saturation and accumulation to form two layers rich in apatite, near the base and at top of the Layered series. Granitic magma was developed by fractional crystallisation and was emplaced along the roof of the chamber, where it acquired large quantities of xenoliths. These were probably derived from the flood basalts, their evolved members and fragments of mafic dykes chilled by the granitic magma. Accumulations of monzonite pillows in this unit testify to another magmatic event and a floor to the granitic magma chamber, indicating lateral transport of magma. Chemically distinct syenites in the upper part of the intrusion are part of the Point du Criade intrusion, a large, late composite sill. Diabase and leucogabbro components show a close link with the SIMI and all the acidic magmas may have originally formed by differentiation of the main magma in cupolas towards the centre of the intrusion. A series of late gabbro intrusions that cut the SIMI may represent a rejuvenation of magmatism. The Border zone is a mass of fine-grained rocks that occurs along the border of the SIMI: it may be another magmatic component, or just the lateral border series of the SIMI.

Higgins, Michael D.

2005-08-01

129

Geochemistry and petrography of U-Th-Y mineralisation in alkali feldspar granite (alaskite) dykes around Dhanota, Mahendragarh district, Haryana, India  

International Nuclear Information System (INIS)

Radioactive alkali feldspar granite (alaskite) occurs as dykes within the Proterozoic granite gneiss around Dhanota. Samples have assayed 0.011 to 0.16% U3O8 and 0.005 to 0.16% ThO2. Yttrium values range from 250 to 800 ppm. Uranothorite occurs in association with zircon, xenotime, magnetite, hematite, sphene and goethite. The U-Th-Y mineralization in alaskites of Dhanota is disseminated syn-magmatic intrusive type. (author)

130

Interior intrusion alarm systems  

International Nuclear Information System (INIS)

In meeting the requirements for the safeguarding of special nuclear material and the physical protection of licensed facilities, the licensee is required to design a physical security system that will meet minimum performance requirements. An integral part of any physical security system is the interior intrusion alarm system. The purpose of this report is to provide the potential user of an interior intrusion alarm system with information on the various types, components, and performance capabilities available so that he can design and install the optimum alarm system for his particular environment. In addition, maintenance and testing procedures are discussed and recommended which, if followed, will help the user obtain the optimum results from his system

131

Palaeomagnetism of the Loch Doon Granite Complex, Southern Uplands of Scotland: The Late Caledonian palaeomagnetic record and an Early Devonian episode of True Polar Wander  

Science.gov (United States)

The Southern Uplands terrane is an Ordovician-Silurian back-arc/foreland basin emplaced at the northern margin of the Iapetus Ocean and intruded by granite complexes including Loch Doon (408.3 ± 1.5 Ma) during Early Devonian times. Protracted cooling of this 130 km 3 intrusion recorded magnetic remanence comprising a predominant ('A') magnetisation linked to initial cooling with dual polarity and mean direction D / I = 237 / 64° ( ?95 = 4°, palaeopole at 316°E, 21°N). Subsidiary magnetisations include Mesozoic remanence correlating with extensional tectonism in the adjoining Irish Sea Basin ('B', D / I = 234/- 59°) and minority populations ('C', D / I = 106/- 2° and 'D', D / I = 199/1°) recording emplacement of younger (˜ 395 Ma) granites in adjoining terranes and the Variscan orogenic event. The 'A' directions have an arcuate distribution identifying anticlockwise rotation during cooling. A comparable rotation is identified in the Orthotectonic Caledonides to the north and the Paratectonic Caledonides to the south following closure of Iapetus. Continental motion from midsoutherly latitudes (˜ 40°S) at 408 Ma to equatorial palaeolatitudes by ˜ 395 Ma is identified and implies minimum rates of continental movement between 430 and 390 Ma of 30-70 cm/year, more than double maximum rates induced by plate forces and interpreted as a signature of true polar wander. Silurian-Devonian palaeomagnetic data from the British-Scandinavian Caledonides define a 430-385 Ma closed loop comparable to the distributed contemporaneous palaeomagnetic poles from Gondwana. They reconcile pre-430 Ma and post-380 Ma APW from this supercontinent and show that Laurentia-Baltica-Avalonia lay to the west of South America with a relict Rheic Ocean opening to the north which closed to produce Variscan orogeny by a combination of pivotal closure and right lateral transpression.

Piper, J. D. A.

2007-03-01

132

Modelling of deformation around magmatic intrusions with application to gold-related structures in the Yilgarn Craton, Western Australia  

Science.gov (United States)

This study simulates rock deformation around high temperature granite intrusions and explores how gold bearing shear zones near intrusions were developed in the Yilgarn, using a new continuum damage mechanics algorithm that considers the temperature and time dependent elastic-visco-plastic constitutive behaviour of crustal materials. The results demonstrate that strain rates have the most significant effects on structural patterns for both extensional and compressional cases. Smaller strain rates promote the formation of narrow high-strain shear zones and strong strain localisation along the flank or shoulder areas of the intrusion and cold granite dome. Wider diffuse shear zones are developed under higher strain rates due to strain hardening. The cooling of the intrusion to background temperatures occurred over a much shorter time interval when compared to the duration of deformation and shear zones development. Strong strain localisation near the intrusion and shear zone development in the crust occurred under both extensional and compressional conditions. There is always clear strain localisation around the shoulders of the intrusion and the flanks of the "cold" granitic dome in early deformation stages. In the models containing a pre-existing fault, strain localisation near the intrusion became asymmetric with much stronger localisation and the development of a damage zone at the shoulder adjacent to the reactivated fault. At higher deformation stages, the models produced a range of structural patterns including graben and half graben basin (extension), "pop-up" wedge structures (compression), tilted fault blocks and switch of shear movement from reverse to normal on shear zones. The model explains in part why a number of gold deposits (e.g. Wallaby and Paddington deposits) in the Yilgarn were formed near the flank of granite-cored domes and deep "tapping" faults, and shows that the new modelling approach is capable of realistically simulating high strain localisation and shear zone development.

Zhang, Y.; Karrech, A.; Schaubs, P. M.; Regenauer-Lieb, K.; Poulet, T.; Cleverley, J. S.

2012-03-01

133

Uraniferous granite in central Texas  

International Nuclear Information System (INIS)

The Precambrian Oatman Creek granite exposed in Gillespie County, central Texas, contains 5 to 10 times more uranium than that of an average granite. Samples of this granite, collected from outcrops and quarry openings, were studied by petrographic, delayed neutron counting, fission track, and gamma-ray spectrometry methods. Experiments of leaching uranium from disaggregated samples were also made. The granite is medium grained with an average composition of 36% quartz, 25% K-feldspar, 38% plagioclase, and 1% biotite and others. In an 80-acre (32 ha.) outcrop area 32 samples, most of which have some uranium removed from weathering, show an average uranium content of 25 ppM; relatively unweathered samples have 50 to 100 ppM uranium. Most uranium occurs between grain boundaries which is called integranular uranium; some occurs in microfractures developed during late, hydrothermal stages. A portion of the uranium also occurs in discrete minerals, particularly oxides of iron or iron-titanium, and accessory minerals such as zircon, sphene, garnet, and others. This distribution indicates that much of the uranium mineralization was a result of deuteric or hydrothermal activities. Selected acids of various concentrations were used in experimental leaching of uranium from Oatman Creek granite. Other variables in the experiments were degree of disaggregation and duration of leaching. The results indicate that more than two thirds of the uranium can be leached in a few hours tim uranium can be leached in a few hours time from the granite without excessive grinding, when a 5N acid is used. This study shows that the Oatman Creek granite may be a long-term source of uranium in the future

134

Intrusion detection system elements  

International Nuclear Information System (INIS)

This report highlights elements required for an intrusion detection system and discusses problems which can be encountered in attempting to make the elements effective. Topics discussed include: sensors, both for exterior detection and interior detection; alarm assessment systems, with the discussion focused on video assessment; and alarm reporting systems, including alarm communication systems and dislay/console considerations. Guidance on careful planning and design of a new or to-be-improved system is presented

135

Perimeter intrusion sensors  

International Nuclear Information System (INIS)

To obtain an effective perimeter intrusion detection system requires careful sensor selection, procurement, and installation. The selection process involves a thorough understanding of the unique site features and how these features affect the performance of each type of sensor. It is necessary to develop procurement specifications to establish acceptable sensor performance limits. Careful explanation and inspection of critical installation dimensions is required during on-site construction. The implementation of these activities at a particular site is discussed

136

Perimeter intrusion alarm systems  

International Nuclear Information System (INIS)

Paragraph 73.50(b)(4) of 10 CFR Part 73 requires at fuel reprocessing plants and other plants processing enriched U, 233U, or Pu that the isolation zone be monitored to detect intruders so that response by the security forces can be initiated. This guide describes six types of perimeter intrusion alarm systems and presents criteria for their performance and use as a means acceptable to NRC for meeting the regulations

137

Radiometric age and origin of Abu Garadi Granite-central eastern desert Egypt  

International Nuclear Information System (INIS)

Rb-Sr whole rock isochron age of 620 m.y. was obtained for Abu Garadi granite. One of the late orogenic plutonites of the Central Eastern Desert, Egypt. Evaluation of this age as well as correlation with previously reported ages on granites of the same orogenic stage in the Central Eastern Desert are presented. The value 0.7183 obtained for the initial Sr Sr87/Sr86 ratio is significantly higher than other ratios obtained on similar granitic intrusions in the Eastern Desert of this age. This high value may be attributed to either partial fusion of the older metamorphic rocks in the area followed by emplacement or to assimilation of a large portion of pre-existing meta-sedimentary by a primary with subsequent homogenization of Sr isotopes throughout the rocks. The second model is preferred

138

Uranium and other microelement ditribution in granites and host rocks of Kumyshtag mass (Northern Tien Shan)  

International Nuclear Information System (INIS)

Behaviour of uranium and other micro-elements for stating the dependence of their distribution in granites and enclosing rocks on the conditions of magma crystallization is considered. Distribution of the mentioned elements is characterized with account of geological and petrological factors and carbon isotope composition in inclusions of the volatile phase in granite minerals. Uranium weakly migrated in the volatile phase during the intrusive formation; uranium migration increases by the end of granite crystallization when melt acidity and its saturation with uranium grow to the utmost. Matter mass transfer in time covered magmatic-autometasomatic stages and proceeded on the background of sharp increase of the melt acidity. The main tendency in substance migration is evacuation of strong bases and accumulation of amphoteric elements including uranium

139

Petrochemistry and geochronology of pink granite from Songsak, East Garo Hills, Meghalaya  

International Nuclear Information System (INIS)

The pink granite of Songsak area, East Garo Hills district, Meghalaya, intrusive into Precambrian gneisses is inferred to be S-type, peraluminous, low calcium, post-kinematic granite. It is characterised by initial 87Sr/86Sr ratio of 0.728±.002, high K2O, high differentiation index and presence of normative corundum. The major mineral constituents are perthitic microcline, fresh interstitial microline, orthoclase with different degree of triclinisation, two generations of quartz and biotite. Sericitization of feldspars, presence of muscovite, rare chiastolite, fluorite and uraninite are other characteristics of the pink granites. Whole rock Rb-Sr dating assign an age of 500± 40 m.y. (author). 12 refs., 5 figs

140

Intrusive rocks northeast of Steamboat Springs, Park Range, Colorado, with a section on geochronology  

Science.gov (United States)

Major Precambrian and minor Tertiary intrusive rocks northeast of Steamboat Springs in the Park Range between 40?30' and 40?45' N. lat. are described and compared with related rocks elsewhere in Colorado and Wyoming. The Precambrian intrusives were emplaced in a sequence of high-grade interlayered felsic gneisses, amphibolites, and pelitic schists of sedimentary and volcanic origin. These rocks are cut by a major northeast-trending Precambrian shear zone where mainly left lateral movement of 1/ 2 to 1 mile is certain. Cumulative movement of many miles is possible. The Precambrian intrusives consist of a batholith, the Mount Ethel pluton, a smaller Buffalo Pass pluton, and small dikes or lenses of fine-grained porphyry, pegmatites, and ultramafics. The Mount Ethel pluton is an oval shaped body 7 miles wide by about 40 miles long (shown by geophysical data to extend beneath younger sediments in North Park). Outer batholithic contacts are sharp and dip steeply outward at about 85?. Five mappable internal variants consist, in order of decreasing age, of granodiorite, quartz monzonite porphyry of Rocky Peak, quartz monzonite of Roxy Ann Lake, granite and quartz monzonite, and. leucogranite. Internal contacts between these plutonic variants are sharp, and evidence of liquid-solid relationships abounds; despite this, all rocks except the granodiorite contribute to an Rb-Sr whole-rock isochron indicating emplacement about 1.4 b.y. (billion years) ago. The most important variants volumetrically are: the quartz monzonite porphyry of Rocky Peak, which forms an irregular 2-mile-thick carapace or mapped band around the west edge of the pluton and is lithologically similar to nearby Sherman Granite, and the quartz monzonite of Roxy Ann Lake, which forms most of the rest of the pluton and is lithologically similar to Silver Plume Granite. An apparent Sherman -Silver Plume dichotomy with similar rock types and similar relative ages is noted throughout Colorado plutons of that age. The Buffalo Pass pluton consists of the quartz monzonite and gra- nodiorite augen gneiss of Buffalo Mountain and equigranular quartz monzonite gneiss. Internal contacts are not exposed. These rocks contribute to an Rb-Sr whole-rock isochron indicating syntectonic emplacement 1.7-1.8 b.y. ago, essentially the same as the metamorphism of the felsic gneiss wallrocks in the area of this report, and of rocks of Boulder Creek age elsewhere in Colorado. The fine-grained porphyry dikes cut the Buffalo Pass pluton, the ultramafics, and some pegmatites. The dikes are within the age range of the Mount Ethel pluton and are older than the mylonite and shear zones. They occur in both an older northwest-trending and a somewhat younger northeast-trending set but do not appear to change compositionally from one set to the other. Regional considerations indicate that they were emplaced between about 1.1 and 1.5 b.y. ago, a time when intermediate to mafic dikes were commonly emplaced throughout Colorado, Wyoming, and southwestern Montana. The pegmatite and ultramafic bodies are not dated directly, but clustering of many pegmatites outside the contacts of the Mount Ethel pluton may indicate a genetic relation of the pegmatites to the Mount Ethel rocks. Fluorite is a common accessory mineral in the rocks of the Mount Ethel pluton; it has not been observed in this area in the petrographically similar rocks of the Buffalo Pass pluton. Fluorite was precipitated most abundantly from the Precambrian magma that formed the quartz monzonite of Roxy Ann Lake. In 70 percent of these rocks fluorite is observed in amounts as great as 2 percent and is successively less abundant in both older and younger plutonic phases. Textural evidence indicates that, although most fluorite is intergrown with and contemporaneous with other magmatic minerals, some fluorite is associated with alteration minerals in a manner demonstrating its mobility since its initial deposition. Five areas of ec

Snyder, George L.; Hedge, Carl E.

1978-01-01

 
 
 
 
141

Cretaceous evolution of the Adria-Europe plate boundary: succession of events recorded in granites and enclaves of the Moslava?ka Gora (Croatia)  

Science.gov (United States)

Complex Cretaceous S-type granitoid pluton, geotectonically related to an active continental margin, makes a central part of the Moslava?ka Gora (MG) crystalline and hosts two groups of enclaves. Cognate enclaves, genetically related to the granitoid host rocks, comprise different types of microgranular enclaves, tourmaline nodules, K-feldspar megacrysts and other inhomogenities found inside the two-mica granitoids. All of these enclaves provide evidence of the petrogenetic processes that took place inside the MG Cretaceous magmatic system. On the other hand, foreign enclaves, mostly xenoliths of metapelitic and metabasic rocks, hold information about the metamorphic events that preceded or were contemporaneous with the intrusion and solidification of the igneous body. Based on the age data gathered by earlier researchers of the MG crystalline and P-T data extracted from the study of Cretacoeus granitoids and their enclaves, it was possible to characterize multiple episodes of Cretaceous igneous and metamorphic evolution of the MG. Intrusion of the mantle-related mafic magma at pressures ~8 kbar and temperatures ~920 °C has been regarded as the oldest Cretaceous magmatic pulse (~110-90 Ma) recorded in the MG crystalline complex, leaving behind local occurrences of gabbroic rocks. Its relation to the medium-pressure metamorphic event recorded in amphibole-bearing xenoliths reaching ~8 kbar and max. ~800 °C has not been elucidated so far. It was followed by a younger LP-HT event (100-90 Ma), recorded in a sequence of partial melting reactions in the metapelitic rocks reaching granulite facies conditions (2-5 kbar, ~720-790 °C). Such melt-producing reactions documented in the km-sized metapelitic xenoliths point to the nature and extent of processes in the metapelitic source rocks that contributed to the overall production of the granitic magma in this setting. All of the aforementioned events preceded the Late Cretaceous intrusion of the central granitoid body and oscillations of igneous activity recored in the products of mixing and hybridization between granitoids and more mafic magmas (MME enclaves) and the onset of immiscibility (tourmaline nodules) nad the intrusion of leucogranites. According to our data, all of these pulses occurred in a low-pressure crustal setting (opens new perspectives for future research of the processes that took place in the mobile zone on the southeastern margins of Mesozoic Europe.

Petrinec, Zorica; Balen, Dražen

2014-05-01

142

Petrochemical characteristics of Serra do Meio alkaline granite (Campo Alegre de Lourdes - Bahia State)  

International Nuclear Information System (INIS)

The Serra do Meio granite outcrops near the town of Campo Alegre de Lourdes, north-northeast of Bahia State. The granite is intrusive into micachists, which are correlatives of the Salgueiro-Cachoeirinha Group (Early Proterozoic), during early to the syn-tectonic shear phase. The geological setting also comprises a phosphatic rock-bearing carbonatitic complex and gabbroid complexes with one of the main world resources of Fe-Ti-V. The granite mineralogical composition grades from Aegerine-augite alkali-feldspar granite/syenites to Leuco alcali-feldspar granite. The geochemical analysis shows SiO2-enrichment (67 to 76%), in alkalis (Na2+K2O, 7,5 to 12,5%), Nb (up to 680ppm), Zr (up to 2,390ppm), Y (up to 250ppm) e REE (up to 796ppm). The geochemical behaviour is peculiar to alkaline series, denoting a silica-oversaturated, potassium-rich, magma. The chondrite-normalized REE patterns display a first group with smooth slopes from the La to Lu, and a second one with negative slopes. Negative Eu anomalies are displayed in all the patterns. The first group is HREE-enriched, with low fractionation ratios. Samples with milonytic fabrics and higher fractionation ratios are related to the second group, suggesting the interaction of metassomatic fluids and the alkaline magma. Discriminant diagrams for Nb, Y and Rb, coupled with geophysical data, point to an intrusive granite in an extensional within a plate tectonic setting of attenuated continental crust. (author)

143

Geochemical, petrological, geo dynamic and radiometric age dating investigation of Aqdarreh intrusion massive (north of Takab) northwest of Iran  

International Nuclear Information System (INIS)

Aqdarreh intrusi body with an area of 30 km 2 is located in 34 km north of Takab, northwest of Iran. This batholith is situated in Central Iran, cutting Paleozoic rocks. Radiometric age of Aqdarreh batholith by K-Ar method is 48.38 m. a.,corresponding to Eocene magmatism. Aqdarreh intrusive body consists of tonalite, granodiorite, alkali feldspar granite and monzogranite in which the main mafic mineral is biotite. Further more, there is not any enclave in these rocks. Study of the investigated samples shows that Aqdarreh intrusive rocks have two different generations. Part of the collected samples belongs to I-type granite (calc-alkaline) and others represent the A-type granite (alkaline). It seems that this process is created by the contamination of alkaline magma by crustal materials. Geochemistry of the rare earth elements shows that the tectonic setting of the body is compatible with Post Orogenic Granitoids

144

Status of LLNL granite projects  

International Nuclear Information System (INIS)

The status of LLNL Projects dealing with nuclear waste disposal in granitic rocks is reviewed. This review covers work done subsequent to the June 1979 Workshop on Thermomechanical Modeling for a Hardrock Waste Repository and is prepared for the July 1980 Workshop on Thermomechanical-Hydrochemical Modeling for a Hardrock Waste Repository. Topics reviewed include laboratory determination of thermal, mechanical, and transport properties of rocks at conditions simulating a deep geologic repository, and field testing at the Climax granitic stock at the USDOE Nevada Test Site

145

Groundwater evolution of the granite area, Korea  

International Nuclear Information System (INIS)

The geochemistry and environmental isotopes of groundwater in the Cretaceous granite of the Yeongcheon area has been investigated. The hydrochemistry of groundwater belongs to the Ca-HCO3 type. The oxygen-18 and deuterium data are clustered along the meteoric water line, indicating that the groundwater is of meteoric water origin. Tritium data show that the groundwaters were mostly recharged before pre-thermonuclear period and have been mixed with younger surface water flowing rapidly along fractured zones. Based on the mass balance and reaction simulation approaches using both the hydrochemistry of groundwater and the secondary mineralogy of fracture-filling materials, the low-temperature hydrogeochemical evolution of groundwater in the area has been modeled. The results of geochemical simulation show that the concentrations of Ca, Na and HCO3 and pH of waters increase progressively owing to the dissolution of reactive minerals in flow paths. The concentrations of Mg and K first increase with the dissolution of reactant minerals, but later decrease when montmorillonite and illitic material are precipitated respectively. The continuous adding of reactive minerals, i. e. the progressively larger degrees of water/rock interaction, causes the formation of secondary minerals with the following sequence: hematite > gibbsite > kaolinite > montmorillonite > illitic material > microcline. The results of reaction simulation agree well with the observed water chemistry and secondary mineralogy, indicating the successful applicability of this simulation technique to delineate the complex hydrogeochemistry of bedrock groundwaters. (author)

146

Acoustic emission intrusion detector  

Science.gov (United States)

An intrusion detector is provided for detecting a forcible entry into a secured structure while minimizing false alarms. The detector uses a piezoelectric crystal transducer to sense acoustic emissions. The transducer output is amplified by a selectable gain amplifier to control the sensitivity. The rectified output of the amplifier is applied to a Schmitt trigger circuit having a preselected threshold level to provide amplitude discrimination. Timing circuitry is provided which is activated by successive pulses from the Schmitt trigger which lie within a selected time frame for frequency discrimination. Detected signals having proper amplitude and frequency trigger an alarm within the first complete cycle time of a detected acoustical disturbance signal.

Carver, Donald W. (Knoxville, TN); Whittaker, Jerry W. (Knoxville, TN)

1980-01-01

147

Distributed Intrusion Detection System  

Science.gov (United States)

Internet worms and other malicious code often scan firewalls to determine which ports are unprotected. While firewall users have access to their port scanning data in the form of log files, most do not make use of it. The Distributed Intrusion Detection System remotely monitors trends in worldwide port scanning, and the data it has collected is available at this site. The data can be used by Internet professionals for early detection of worms or for implementing improved security measures. Firewall users can contribute to this project by downloading the free DShield Client, which automatically sends log reports for inclusion in worldwide data or by submitting logs online via a Web interface.

148

Patherns in the rare earth elements of the Serra do Carambei granite (Parana) and the others associated ignous rocks  

International Nuclear Information System (INIS)

The rare earth elements (REE) distribution patters in igneous rocks of the Serra do Carambei Granite area (Parana) were a very important tool to elucidate the genetic processes and the cogenetic relationships between these rocks. The porphyroid facies of the Cunhaporanga Granitoid Complex has a REE distribution pattern characterized by decreasing concentrations in direction to the heavy rare earth elements (HREE) and the smooth Eu negative anomalie, compatible with amphibole fractionation during the magma ascent and the incipient plagioclase fractionation. The REE pattern of the Serra do Carambei Granite is characterized by the strong Eu negative anomalie, by the light rare earth element (LREE) depletion and by the HREE increase. This shape of the REE patterns is frequently observed in Sn-W granites, according to French authors. However in the igneous rocks of the Serra do Carambei Granite area this is not true. ''Rhyolite'' dytes intrusives in the Serra do Carambei Granite exhibit REE pattern similar to the wall rock, indicating then the same genetic processes. The Castro Group rhyolites have REE patterns with decreasing concentrations in direction to the HREE and smooth Eu negative anomalie. The REE distribution patterns is against the consanguinity between the ''rhyolites'' intruded in the Serra do Carambei Granite and the rhyolites of the Castro Group and also between these rhyolites and the above mentioned Granite. (autho

149

Spatial and temporal relationships between granites and porphyry copper deposits in northern Chile  

Science.gov (United States)

Chile is the leading copper producing country in the world, hosting ~30% of known worldwide copper reserves. Subduction-related magmatism in Chile has been ongoing since at least Mesozoic time, with progressive inland migration of the magmatic arc from the Jurassic coast eastward to the active western cordillera in the high Andes. Porphyry copper deposits (PCDs) in Chile are spatially and temporally related to emplacement of shallow, felsic to intermediate composition plutons that sourced the ore-forming magmas and mineralising fluids. However, not every such intrusion in Chile is associated with a mineralised deposit, suggesting that there are other controls on whether or not an intrusion hosts a PCD. Models for porphyry copper formation typically assume emplacement of these felsic to intermediate intrusions at shallow crustal levels (5-15 km depth) [1], but absolute constraints on emplacement depths for both mineralised and barren systems are lacking. In order to explore the relationship between granite emplacement depths and occurrences of PCDs in northern Chile, we have created a geospatial database that compares the age, geochemistry, and depth of mapped felsic to intermediate plutons (e.g. granites, tonalities, and diorites) with the locations of known PCDs, as well as major fault zones and volcanic centres. Emplacement depths have been calculated from published geochemical analyses using existing calibrations of the Al-in-hornblende barometer, which is widely used for calc-alkaline granitic rocks [2]. We are also developing a new experimental calibration of the barometer using a combination of piston cylinder experiments (5, 7, and 10 kbar), externally heated pressure vessel experiments (0.5-2 kbar), and electron microprobe analyses on a granitic sample of the Lluta batholith, collected in northern Chile. This improved Al-in-hornblende barometer, calibrated for shallow intrusions, will provide a viable alternative to estimating depths of PCD formation from fluid inclusions, which is often hampered by alternations between lithostatic and hydrostatic pressure. Furthermore, the results of this study will be broadly applicable to investigating the potential links between intrusion depth, PCD formation, and parameters such as regional tectonic patterns and fluid/melt interactions. References: [1] Sillitoe, 2010, Porphyry Copper Systems, Ec. Geol., 105, 3-41. [2] Anderson et al., 2008, Thermometers and Thermobarometers in Granitic Systems, Rev. Min. Geochem., 69, 121-142.

Jiskoot, Courtney; Mutch, Euan; Cooper, Frances; Tattitch, Brian; Matjuschkin, Vladimir; Blundy, Jon

2014-05-01

150

Gamma-spectrometric surveys in differentiated granites. II: the Joaquim Murtinho Granite in the Cunhaporanga Granitic Complex, Parana, SE Brazil; Levantamentos gamaespectrometricos em granitos diferenciados. II: O exemplo do Granito Joaquim Murtinho, Complexo Granitico Cunhaporanga, Parana  

Energy Technology Data Exchange (ETDEWEB)

Detailed mapping at the NW corner of the large Neo proterozoic Cunhaporanga Granitic Complex (CGC), Parana state, SE Brazil, redefined the Joaquim Murtinho Granite (JMG), a late intrusion in CGC with an exposed area of about 10 km{sup 2}, made up mainly by evolved 'alaskites' (alkali-feldspar leuco granites). This unit is in tectonic contact with the Neoproterozoic-Eocambrian volcano-sedimentary Castro Group, to the W, and is intrusive into other less evolved granitic units of the CGC to the E. Petrographically, JMG shows mainly mesoperthite and quartz, with subordinate amounts of altered micas and some accessory phases, mainly zircon. The equi to inequigranular granites are usually deformed with cataclastic textures, are often brecciated, and may have miarolitic structures. Formation of late albite, sericite, carbonate and hematite was caused by deuteric and hydrothermal alteration. A gamma-ray spectrometric survey at 231 stations which measured total counts (TC), Ueq K%, eU ppm and eTh ppm was used to construct several direct and derived maps. Compared to neighboring units the JMG has significant anomalies, especially in the TC, %K, eTh and eU maps, although the differences are less obvious in some derived maps. These evolved granites are enriched in these three elements. Geochemical behavior of K, Th and U is used to analyse the results observed in maps. Enhanced weathering under a subtropical climate with moderate to high average temperatures and heavy rainfall affects mainly feldspars and biotite, and may also destabilize most U and Th-bearing accessory phases. Th is most likely retained in restite minerals in soils, being relatively immobile, while part of U may migrate as uranyl ion in oxidizing media. K is especially affected by feldspar alteration to K-free clays (mainly kaolinite), and may be completely leached. Gamma-ray spectrometric methods are valid tools to study facies in granitic rocks, especially in those that are enriched in K, Th and U. (author)

Ferreira, Francisco Jose Fonseca [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Geologia. Lab. de Pesquisas em Geofisica Aplicada; Fruchting, Allan [Votorantim Metais, Sao Paulo, SP (Brazil)], e-mail: allan.fruchting@vmetais.com.br; Guimaraes, Gilson Burigo [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil). Dept. de Geociencias], e-mail: gburigo@ig.com.br; Alves, Luizemara Soares [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)], e-mail: luizemara@petrobras.com.br; Martin, Victor Miguel Oliveira; Ulbrich, Horstpeter Herberto Gustavo Jose [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias. Dept. de Mineralogia e Geotectonica], e-mail: vicmartin6@ig.com.br, e-mail: hulbrich@usp.br

2009-07-01

151

MORPHOMETRY OF ZIRCON FROM BETLIAR GRANITE  

Directory of Open Access Journals (Sweden)

Full Text Available Morphometrical analyse has been provided, using the method of [10] , on zircon from granite porphyry at Betliar. The result of this investigation indicate a comagmatic origin of Betliar and other granite bodies in the Gemericum. The source materila for at the granite magma formation originated by hybridization of crust-mantle rocks.

Jakabská Katarína

1997-10-01

152

Metamorphic charnockite in contact aureoles around intrusive enderbite from Natal, South Africa  

Science.gov (United States)

In the Port Edward area of southern Kwa-Zulu Natal, South Africa, charnockitic aureoles up to 10m in width in the normally garnetiferous Nicholson's Point Granite, are developed adjacent to intrusive contacts with the Port Edward Enderbite and anhydrous pegmatitic veins. Mineralogical differences between the country rock and charnockitic aureole suggest that the dehydration reaction Bt+Qtz-->Opx+Kfs+H2O and the reaction of Grt+Qtz-->Opx+Pl were responsible for the charnockitization. The compositions of fluid inclusions show systematic variation with: (1) the Port Edward Enderbite being dominated by CO2 and N2 fluid inclusions; (2) the non-charnockitized granite by saline aqueous inclusions with 18-23 EqWt% NaCl; (3) the charnockitic aureoles by low-salinity and pure water inclusions (<7 EqWt% NaCl); (4) the pegmatites by aqueous inclusions of various salinity with minor CO2. As a result of the thermal event the homogenization temperatures of the inclusions in charnockite show a much larger range (up to 390°C) compared to the fluid inclusions in granite (mostly <250°C). Contrary to fluid-controlled charnockitization (brines, CO2) which may have taken place along shear zones away from the intrusive body, the present ``proximal'' charnockitized granite formed directly at the contact with enderbite. The inclusions indicate contact metamorphism induced by the intrusion of ``dry'' enderbitic magma into ``wet'' granite resulting in local dehydration. This was confirmed by cathodoluminescence microscopy showing textures indicative for the local reduction of structural water in the charnockite quartz. Two-pyroxene thermometry on the Port Edward Enderbite suggests intrusion at temperatures of 1000-1050°C into country rock with temperature of <700°C. The temperature of aureole formation must have been between 700°C (breakdown of pyrite to form pyrrhotite) and 1000°C. Charnockitization was probably controlled largely by heat related to anhydrous intrusions causing dehydration reactions and resulting in the release and subsequent trapping of dehydration fluids. The salinity of the metamorphic fluid in the contact zones is supposed to have been higher at an early stage of contact metamorphism, but it has lost its salt content by K-metasomatic reactions and/or the preferential migration of the saline fluids out of the contact zones towards the enderbite. The low water activity inhibited the localized melting of the granite. Mineral thermobarometry suggests that after charnockite aureole genesis, an isobaric cooling path was followed during which reequilibration of most of the aqueous inclusions occurred.

van den Kerkhof, Alfons M.; Grantham, Geoffrey H.

153

Network Intrusion Forensic Analysis Using Intrusion Detection System  

Directory of Open Access Journals (Sweden)

Full Text Available The need for computer intrusion forensics arises from the alarming increase in the number of computer crimes that are committed annually. After a computer system has been breached and an intrusion has been detected, there is a need for a computer forensics investigation to follow. Computer forensics is used to bring to justice, those responsible for conducting attacks on computer systems throughout the world. Because of this the law must be follow precisely when conducting a forensics investigation. It is not enough to simple know an attacker is responsible for the crime, the forensics investigation must be carried out in a precise manner that will produce evidence that is amicable in a court room. For computer intrusion forensics many methodologies have been designed to be used when conducting an investigation. With the birth of the Internet and networks, the computer intrusion has never been as significant as it is now. There are different preventive measures available, such as access control and authentication, to attempt to prevent intruders. Intrusion detection systems (IDS are developed to detect an intrusion as it occurs, and to execute countermeasures when detected. Intrusion detection (ID takes over where preventive security fails. In order to choose the best IDS for a given system, one should be aware of the advantages and disadvantages of the each IDS. This paper views a forensic application within the framework of Intrusion Detection and details the advantages and disadvantages of IDS.

Manish Kumar

2011-05-01

154

Vertical zonality of fractionated granite plutons reflected in zircon chemistry: the Cínovec A-type versus the Beauvoir S-type suite  

Science.gov (United States)

We studied vertical changes in the chemical composition of zircon from two contrasting Variscan granite systems. The Beauvoir system (Massif Central, France) composed of three successive intrusions (B1, B2, B3) represents typical peraluminous S-type granite extremely enriched in P, F, Li, Rb, Cs, Be, Sn, Nb, Ta, and poor in Zr, Th, REE and Y. The Cínovec system (Krušné hory Mts/Erzgebirge, Czech Republic/Germany) composed of two successive intrusions (protolithionite granite, zinnwaldite granite) is only slightly peraluminous, P-poor, F, Li, Rb, Cs, U, Th, REE, Y, Sc, Sn, W, Nb, Ta-rich granite, which may be classified as A-type. In both localities, the most fractionated intrusions are located on the top of the system. Samples from borehole GPF-1 (Beauvoir) represent an 800 m long vertical section through the entire granite stock, while CS-1 borehole (Cínovec) reached a depth of 1600 m. Chemical compositions of zircons from both granite systems show distinct vertical zonality, but their shape and elemental speciation is highly contrasting. At Beauvoir, zircon shows a remarkable increase in Hf-content from 2-4 wt. % HfO2 (~0.03 apfu Hf) in the deepest B3-unit to 15-19 wt. % HfO2 (up to 0.18 apfu Hf) in the uppermost B1-unit. The highest contents of F, P, and U were detected in the intermediate unit B2 at a depth of 400-600 m. At Cínovec, Hf shows only moderate enrichment from ca. 2 wt. % HfO2 in the deeper protolithionite granite to 5-10 wt. % HfO2 in the uppermost part of the zinnwaldite granite. High contents of Th (3-8 wt. % ThO2) are entirely bound in the uppermost section of the granite copula to a depth of 200 m, but below this level the contents only sporadically exceed 1 wt. % ThO2. Concentrations of U, Y, HREE, Sc and Bi also reach their highest values in the uppermost parts of the zinnwaldite granite, but their decrease downward is much gentler. Extreme enrichment of outer zones of zircon crystals from some granites with Hf or high contents of Th, U, REE, Y, Nb and of some other elements in zircons from other localities is not considered to be a specific phenomenon characterizing melts of A- or S-type granite, but reflects a high degree of fractionation of systems rich in Na and F.

Breiter, Karel; Škoda, Radek

2012-11-01

155

The intrusive complexof the Island of Giglio: geomagnetic characteristics of plutonic facies with low susceptibility contrast  

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Two main plutonic facies characterize the intrusive complex of the Island of Giglio, and the trend of their contact at depth has been modelled using a 2D½ analysis based on a detailed geomagnetic survey in order to verify the geological hypothesis of the subsurface geometry of this contact. The magnetic anomaly connected with the discontinuity is quite low, due to the small difference between the magnetic susceptibilities of the two granitic facies. Development of this model of inversion of ...

Cavallini, R.; Carmisciano, C.; Beverini, N.; Innocenti, F.; Westerman, D.; Faggioni, O.; Dini, A.

1998-01-01

156

Rb-Sr geochronology of the radioactive granites of Nanded area, Maharashtra, India  

International Nuclear Information System (INIS)

Rubidium and strontium age data are reported here for the first time from radioactive granites forming part of the peninsular gneiss exposed in the Nanded area of Maharashtra. The whole rock data define an Rb-Sr isochron age of 2385±40 Ma, with an initial 87Sr/86Sr ratio of 0.7009±0.0005. This age with such a low initial ratio is perhaps indicating the younger phase of generation of granitic melts from the source rocks of appropriate composition, possibly from upper mantle zone, during the evolution of Dharwar craton. The Rb-Sr age of the granitic rocks is correctable with the existing data on similar type of rocks exposed in northern Andhra Pradesh and Mysore areas. (author). 17 refs., 1 tab., 2 figs

157

Expansion of the granitic post-orogenic magmatism in the formation of Serrinha (Northeastern Bahia, B R), Sao Francisco craton  

International Nuclear Information System (INIS)

The Pedra Vermelha Granitic Massif, located at the North area of Serrinha Nucleus, presents a circular shape, being intrusive at the Archaean geoscience-magmatic basement rocks and the Paleoproterozoic volcano sedimentary sequences. The single zircon U-Pb dating yield a crystallization age of 2080 ± 8 Ma. The geological, petrographic al and litogeochemical characteristics of the studied rocks are similar to those of the Morro do Lopes granitic magmatism (2076 ± 6 a 2071 ± 6 Ma), which is located at the South area of this nucleus. These allow us to infer that those post-orogenic alkaline bodies are widespread throughout the Serrinha Nucleus and constitute its last Paleoproterozoic magmatic expression. (author)

158

Intrusion detection sensor testing tools  

Energy Technology Data Exchange (ETDEWEB)

Intrusion detection sensors must be frequently tested to verify that they are operational, and they must be periodically tested to verify that they are functioning at required performance levels. Concerns involving this testing can include: The significant amount of manpower required, inconsistent results due to variability in methods and personnel, exposure of personnel to hazardous environments, and difficulty in obtaining access to the areas containing some of the intrusion sensors. To address these concerns, the Department of Energy directed Sandia National Labs. to develop intrusion detection sensor testing tools. Over the past two years Sandia has developed several sensor testing tool prototypes. This paper describes the evolution of an exterior intrusion detection sensor tester and automatic data logger, and also describes various interior intrusion detection sensor test fixtures that can be remotely activated to simulate an intruder.

Hayward, D.R.

1994-08-01

159

Fission track age of apatite from the Jurassic and cretaceous granites in South Korea and its tectonic implications  

International Nuclear Information System (INIS)

Twenty-six apatite separates obtained from 35 Daebo and Bulgugsa granites in South Korea were dated and studied by fission tracks. Apparent ages for the two groups are generally similar and range from about 40 to 80 Myr, which are younger than the emplacement ages and indicate the times at which the granites cooled below about 1000C. Track length distributions suggest that the Daebo granites were emplaced in the katazone and/or mesozone and initially cooled slowly while the Bulgugsa granites were emplaced in the epizone and cooled more rapidly. The relationship between the apatite ages and topographic elevation of the samples in the northeast suggests that uplift was very slow before the Early Tertiary but has probably increased subsequently to a rate of at least 70 m/Myr in this area. (author)

160

Passive intrusion detection system  

Science.gov (United States)

An intrusion detection system is described in which crystal oscillators are used to provide a frequency which varies as a function of fluctuations of a particular environmental property of the atmosphere, e.g., humidity, in the protected volume. The system is based on the discovery that the frequency of an oscillator whose crystal is humidity sensitive, varies at a frequency or rate which is within a known frequency band, due to the entry of an intruder into the protected volume. The variable frequency is converted into a voltage which is then filtered by a filtering arrangement which permits only voltage variations at frequencies within the known frequency band to activate an alarm, while inhibiting the alarm activation when the voltage frequency is below or above the known frequency band.

Laue, E. G. (inventor)

1980-01-01

 
 
 
 
161

Nystagmus and saccadic intrusions.  

Science.gov (United States)

We review current concepts of nystagmus and saccadic oscillations, applying a pathophysiological approach. We begin by discussing how nystagmus may arise when the mechanisms that normally hold gaze steady are impaired. We then describe the clinical and laboratory evaluation of patients with ocular oscillations. Next, we systematically review the features of nystagmus arising from peripheral and central vestibular disorders, nystagmus due to an abnormal gaze-holding mechanism (neural integrator), and nystagmus occurring when vision is compromised. We then discuss forms of nystagmus for which the pathogenesis is not well understood, including acquired pendular nystagmus and congenital forms of nystagmus. We then summarize the spectrum of saccadic disorders that disrupt steady gaze, from intrusions to flutter and opsoclonus. Finally, we review current treatment options for nystagmus and saccadic oscillations, including drugs, surgery, and optical methods. Examples of each type of nystagmus are provided in the form of figures. PMID:21601073

Thurtell, Matthew J; Leigh, R John

2011-01-01

162

Geochemical investigations on some of the Infra Cambrian Acid intrusive and volcanic rocks in Iran  

International Nuclear Information System (INIS)

Geochemical investigations on some of the acid intrusive and volcanic rocks of Iran, which are attributed to the Infra cambrian, have been carried out to reveal their possible genetic relationships. These igneous rocks include: Do ran, Shah-Bolaghi, Sarve-Jahan, NE Ardakan - Yazd (Darbastegoon), south Mahabad, Bornavard (Tak nar), Zarigan, Narigan, Chardormaloo granites, Rizo and De zoo micro granites and volcanic rocks, Ga chin rhyolites (Bandar-Abass), and Ghareh-Dash (east of Sae en-De j). These intrusive s, except south Mahabad granodiorite, belong to the class of the alkali feldspathic granite to granitic rocks. Most of these rocks are hololeucocratic and devoid of ferro magnesian minerals. The volcanic rocks are mainly felsic (Rhyolite and Quartz porphyra) associated with vacillation's rocks. These suites of rocks plot on the chemical diagrams in sub alkaline field. Regarding to variations of Na2O, K2O and Ca O contents, they can further be subdivided into sodi c, potas sic, sodi-potas sic and sodi-calci c subgroups. The normalized values (MORB and chondritic) of their trace elements on the spider diagrams overlap each other indicates that some genetic relations ships exist among samples of white Doran Granite, Shahbolaghi, Sarve-Jahan and some Darbastegoon, in one hand, and Taknar, Narigan Granites, Gachin, Rizoo and Dezoo Rhyolites, on the other hand. The overlap also shows that the mentioned igneous bodies have been originated from contious bodies have been originated from continental crust and the samples of each groups, at least belong to a distinct tectonic al regime

163

Miniscrews for upper incisor intrusion.  

Science.gov (United States)

The aim of this study was to investigate if true incisor intrusion can be achieved using miniscrews. Eleven patients (three males and eight females; mean age: 19.8 +/- 4.8 years) with normal vertical dimension showing a pre-treatment deep bite of 5.9 +/- 0.9 mm and a 'gummy' smile were enrolled in the study. After levelling of the maxillary central and lateral incisors with a segmental arch, an intrusive force of 80 g using closed coil springs was applied from two miniscrews placed between the roots of the lateral and canine teeth. The amount of incisor intrusion was evaluated on lateral cephalometric headfilms taken at the end of levelling (T1) and at the end of intrusion (T2). Statistical analysis of the data was performed using a paired t and Wilcoxon signed rank tests. A significance level of P intrusion was 1.92 mm and the mean overbite decrease 2.25 +/- 1.73 mm in 4.55 months. Upper incisor angulation resulted in a 1.81 +/- 3.84 degree change in U1-PP angle and a 1.22 +/- 3.64 degree change in U1-NA angle. However, these were not statistically significant (P > 0.05). True intrusion can be achieved by application of intrusive forces close to the centre of resistance using miniscrews. However, studies with a larger number of subjects and long-term follow-up are necessary. PMID:19289539

Polat-Ozsoy, Omur; Arman-Ozcirpici, Ayca; Veziroglu, Firdevs

2009-08-01

164

The Cordilheira Intrusive Suite: Late Proterozoic peraluminous granitoids from southern Brazil  

Science.gov (United States)

The Cordilheira Intrusive Suite is made up of peraluminous two-mica leucogranites related to the Brasiliano Cycle. Located in the east region of the Sul-rio-grandense Shield, in southernmost Brazil, the granitic bodies were emplaced mainly inside mylonitic zones belonging to a transcurrent system with NE orientation. The structural relationship of this intrusion with shear zones indicates a syn- to late-kinematic emplacement. The Cordilheira Intrusive Suite rocks are mainly syenogranites and monzogranites, with inequigranular texture, sometimes modified by mylonitic deformational effects. Mineralogically they are composed of alkali feldspar, plagioclase, quartz, muscovite and biotite, with minor amounts of gamet, tourmaline, apatite, zircon, sphene and fluorite. The analyzed samples show a SiO 2 range of 71.55 to 77.68%, and a reduction in the K 2O/Na 2O ratio with increasing differentiation. Trace-element contents, including REE, are similar to that of granites produced by partial melting of quartz-feldspathic rocks. Field relationships and geochemical data are suggestive of partial crustal melting along transcurrent shear zones developed during the late orogenic stages of the Brasiliano Cycle. The evidence considered in this paper shows the remarkable similarity of the Cordilheira Intrusive Suite to Hercynian granitoids of Portugal and France.

Nardi, L. V. S.; Frantz, J. C.

1995-01-01

165

Jakob Granit | Staff at SEI  

... Options for cooperative action in the Euphrates and Tigris Region. Paper 20, Stockholm: SIWI. Granit, J., ... Identifying Business Models for Transboundary River Basin Organisations. In Earle, A., Jägerskog, A. & Öjendal, ... Publications Charting a Sustainable Path for Renewable Energy Development (Report - 2014) Unpacking the Water-Energy-Food Nexus: Tools for Assessment and Cooperation Along ...Continuum (Book chapter - 2013) A scalable approach towards realizing tangible benefits in transboundary river basins and regions (Book chapter - 2012) Complete list ...

166

Geology and geochemistry of the Redrock Granite and anorthosite xenoliths (Proterozoic in the northern Burro Mountains, Grant County, New Mexico, USA  

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Full Text Available Mineral ages from the A-type granites and anorthosite xenoliths in the Redrock area in the northwestern Burro Mountains in southwestern New Mexico cluster around ~1220–1225 Ma and provide yet another example of bimodal igneous activity during this time period in the southwestern United States. The metaluminous to peraluminous, marginally alkaline to subalkaline Redrock Granite exhibits the textural, mineralogical, and geochemical features of A-type granitethat was emplaced at a relatively high crustal level. Field relationships, whole rock and mineral geochemical and isotopic trends suggest that the four phases of the Redrock Granite are genetically related, with the miarolitic biotite/alkali feldspar granite being the youngest phase. Spatial relationships and geochemical data suggest that the anorthosite xenoliths were coeval with the RedrockGranite, which is consistent with the anorthosite being derived from the upper mantle, possibly due to deep mantle upwellings, and the Redrock Granite from the lower crust. The process involved melting in the upper mantle, emplacement of anorthosite in the crust resulting in partial crustal melting and thinning, and, finally, intrusion of shallow silicic plutons, the Redrock Granite. The Redrock Granite and anorthosite were presumably derived from sources characterized by subtle, long-term LREE depletion, with ?Nd (at 1220 Ma values on theorder of +1 to +2.

Virginia T. McLemore

2002-01-01

167

Pan-African granite emplacement mechanisms in the Eastern Desert, Egypt  

Science.gov (United States)

The late Pan-African Fawakhir, Um Had and Um Effein Granite Plutons in the Egyptian Central Eastern Desert are small, elongate to circular bodies of pink monzogranite and syenogranite, and grey monzodiorite. Structural investigation of the intrusive contacts of these plutons reveals marginal sub-horizontal intrusive sheets as magma injection along pre-existing flat-lying structures including mineral foliations and thrust faults. Space for emplacement of granitic plutons was accommodated by uplift of the country rocks along steep marginal faults with rotation of the wall rocks whose outer contacts are in the style of laccoliths. Overall, the Um Had Granite Pluton has a phacolithic shape controlled by a south-plunging domed mylonitic shear zone, which separates gneissic rocks (preserved as a pluton core) from low grade overthrust units. The structural features of these plutons are consistent with upper crustal level emplacement at depths where ? 3 is vertical. Emplacement is likely to have occurred after northeast-southwest transpression, rather than in an extensional tectonic environment.

Fowler, T. J.

2001-01-01

168

Localisation of deformation in the thermal contrast at a granite batholith margin, New Zealand  

Science.gov (United States)

The Wainui Shear Zone is a ˜ 1.2 km wide steeply dipping ductile shear zone that is intimately associated with the western margin of a very extensive granite batholith in central New Zealand. Shear sense indicators and lineation orientations within the central high-strain portion of shear zone consistently show a reverse dip-slip east-side-up sense of motion. Shallower foliation in the margins of the shear zone is interpreted to pre-date the central high-strain zone. However, U-Pb and Ar-Ar data reveal that all ductile deformation occurred between ˜114 and 109 Ma (and probably between 114 and 111 Ma) requiring: (1) that deformation kinematics within the shear zone changed over a short time period, and (2) the shear fabrics formed immediately after emplacement of the voluminous granite batholith. The temporal and spatial link between the deformation and plutonism is hypothesised to be a result of thermal weakening of the cooler Paleozoic crust by Cretaceous granite intrusion, which promoted localisation of deformation onto the intrusive contact. Deformation was initially distributed over a wide zone but became focused into a central mylonite zone. Continental-scale shortening is recorded as a network of ductile shear zones that formed on thermal contrasts within the upper, middle and lower crust along the New Zealand Gondwana margin.

Scott, J. M.; Borcovsky, D. A.; Palin, J. M.; Toy, V. G.

2014-07-01

169

Origin of a late Neoproterozoic (605 ± 13 Ma) intrusive carbonate-albitite complex in Southern Sinai, Egypt  

Science.gov (United States)

New geochemical, isotopic, and geochronological data and interpretations are presented for late Neoproterozoic intrusive carbonates and related rocks of southern Sinai, Egypt (northernmost Arabian-Nubian Shield). The Tarr carbonates are coarsely crystalline and related to explosive emplacement of hypabyssal and volcanic albitite at 605 ± 13 Ma. The carbonates associated with the albitites are divisible into two types: primary dolomitite and secondary breunneritite (Fe-rich magnesite). The dolomitite was clearly intrusive but differs from classic igneous carbonatites, containing much lower abundances of incompatible elements, such as REE, U, Th, Rb, Nb, Y, P, Sr, Zr, Ba, and total alkalies. The breunneritite is a secondary replacement of dolomitite, probably marking the roots of a vigorous hydrothermal system. Albitites show pristine abundances of major and trace elements and were not subjected to a major metamorphic overprint. They are relatively more fractionated, alkaline and related to within-plate A-type magmas, were emplaced in an extensional or non-compressive tectonic regime in the cupola of high-level A-type granite. Tarr albitites may represent residual magma remaining after near-total crystallization of an A-type granite pluton at depth, forcibly emplaced into the roof above the cooling pluton. The intrusive dolomitite exsolved from highly differentiated albitite melt, in the apical regions of a still-buried alkaline “A-type” granite pluton that was rich in CO2; these volatiles migrated upwards and towards the cooler margins of the magma body. Late NNE-SSW extension allowed a shallow-level cupola to form, into which albitite melts and carbonate fluids migrated, culminating in explosive emplacement of albitite breccia and intrusive carbonate. Isotopic compositions of Tarr dolomitite and albitite indicate these are consanguineous and ultimately of mantle origin. Magmatic volatiles fenitized the wall rock, while submarine hydrothermal activity transformed some of the dolomitite into breunneritite. Recognition of Tarr-type should encourage similar hypabyssal complex intrusions to be sought for in association with A-type granitic plutons elsewhere.

Azer, Mokhles Kamal; Stern, Robert J.; Kimura, Jun-Ichi

2010-03-01

170

Human intrusion in geologic disposal  

International Nuclear Information System (INIS)

This report discusses the possibility of human intrusion into the WIPP facility, an undergound disposal facility for alpha-bearing wastes. The probability of exploratory drilling occurring at the site is described

171

groundwater saline intrusion classification method  

...Are threshold values exceeded: (electrical conductivity 800 µS/cm, chloride 25...intrusion into groundwater bodies electrical conductivity 800 µS/cm 800 µS...has collected field observed electrical conductivity and tested samples for chloride...

172

Natural radionuclide distribution in Brazilian commercial granites  

Energy Technology Data Exchange (ETDEWEB)

The dimension stones sector in Brazil produces several varieties of granites, marbles, slates and basalts. More than half of this production corresponds to around 200 different commercial types of granites with specific names, geographical and geological origins and mineral compositions. The well-known natural radioactivity present in rocks, where high radiation levels are associated with igneous rocks such as granite, can be used to determine their general petrologic features. This subject is important in environmental radiological protection, since granites are widely used as building and ornamental stones. In this paper, it is applied to correlate the petrographic characteristics of commercial granites with their corresponding dose rates for natural radioactivity. Amounts of thorium, uranium and potassium concentrations have been reported in several Brazilian commercial granite samples.

Anjos, R.M. [Instituto de Fisica da Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (BR)]. E-mail: meigikos@if.uff.br; Veiga, R. [Instituto de Fisica da Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (BR); Soares, T. [Instituto de Fisica da Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (BR); Santos, A.M.A. [Fundacao Jorge Duprat Figueiredo de Seguranca e Medicina do Trabalho-Fundacentro, C.P. 11484, 05499-970 Sao Paulo, SP (BR); Aguiar, J.G. [Fundacao Jorge Duprat Figueiredo de Seguranca e Medicina do Trabalho-Fundacentro, C.P. 11484, 05499-970 Sao Paulo, SP (BR); Frasca, M.H.B.O. [Instituto de Pesquisas Tecnologicas do Estado de Sao Paulo-IPT, Av. Prof. Almeida Prado 532, Cidade Universitaria, 05508-901 Sao Paulo, SP (BR); Brage, J.A.P. [Instituto de Fisica da Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (BR); Uzeda, D. [Instituto de Fisica da Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (BR); Mangia, L. [Instituto de Fisica da Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (BR); Facure, A. [Instituto de Fisica da Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (BR); Mosquera, B. [Instituto de Fisica da Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (BR); Carvalho, C. [Instituto de Fisica da Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (BR); Gomes, P.R.S. [Instituto de Fisica da Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (BR)

2005-06-01

173

Intrusion Detection A Machine Learning Approach  

CERN Document Server

This important book introduces the concept of intrusion detection, discusses various approaches for intrusion detection systems (IDS), and presents the architecture and implementation of IDS. It emphasizes on the prediction and learning algorithms for intrusion detection and highlights techniques for intrusion detection of wired computer networks and wireless sensor networks. The performance comparison of various IDS via simulation will also be included.

Tsai, Jeffrey JP

2011-01-01

174

A hybrid composite dike suite from the northern Arabian Nubian Shield, southwest Jordan: Implications for magma mixing and partial melting of granite by mafic magma  

Science.gov (United States)

The Arabian Nubian Shield is an exemplary juvenile continental crust of Neoproterozoic age (1000-542 Ma). The post-collisional rift-related stage (~ 610 to 542 Ma) of its formation is characterized among others by the intrusion of several generations of simple and composite dikes. This study documents a suite of hybrid composite dikes and a natural example of partial melting of granite by a mafic magma from the northernmost extremity of Arabian Nubian Shield in southwest Jordan. The petrogenesis of this suite is discussed on the basis of field, petrographic, geochemical, and Rb/Sr isotopic data. These dikes give spectacular examples of the interaction between basaltic magma and the granitic basement. This interaction ranges from brecciation, partial melting of the host alkali feldspar granite to complete assimilation of the granitic material. Field structures range from intrusive breccia (angular partially melted granitic fragments in a mafic groundmass) to the formation of hybrid composite dikes that are up to 14 m in thickness. The rims of these dikes are trachyandesite (latite) with alkali feldspar ovoids (up to 1 cm in diameter); while the central cores are trachydacite to dacite and again with alkali feldspar ovoids and xenoliths from the dike rims. The granitic xenoliths in the intrusive breccia have been subjected to at least 33% partial melting. A seven-point Rb/Sr isochron from one of these composite dikes yields an age of 561 ± 33 Ma and an initial 87Sr/86Sr ratio of 0.70326 ± 0.0003 (2?) and MSWD of 0.62. Geochemical modeling using major, trace, rare earth elements and isotopes suggests the generation of the hybrid composite dike suite through the assimilation of 30% to 60% granitic crustal material by a basaltic magma, while the latter was undergoing fractional crystallization at different levels in the continental crust.

Jarrar, Ghaleb H.; Yaseen, Najel; Theye, Thomas

2013-03-01

175

Age of granites of Wrangel Island metamorphic complex  

Science.gov (United States)

Within huge arctic shelf of Eastern-Siberian and Chukchi seas the metamorphic basement (Wrangel complex, Berri Formation) is exposed only on the Wrangel Island. There are different points of views on the age of metamorphic rocks of Wrangel complex (Berri Formation): (1) Neoproterozoic (Kameneva, 1970; Ageev, 1979; Kos'ko et al., 1993, 2003), (2) Devonian (Til'man et al., 1964, 1970; Ganelin, 1989). Metamorphic basement is represented by stratified complex, composed of dislocated metavolcanic, metavolcaniclastic and metasedimentary rocks (schists, metasandstones, metaconglomerated) with single lenses and layers of carbonate rocks (Wrangel Island…, 2003). Among basement rocks in the central part of Wrangel Island there are felsic intrusive bodies. They form small tabular bodies from tens centimeters to 70-80 meters in thickness, rarely dikes and small stocks (up to 20 x 30 m) and are composed of granite-porphyres, rarely muscovite porphyr-like granites and granosyenites (Wrangel Island…, 2003). The age of intrusions allow to determine the age of basement formation. Earlier the age of intrusions was determined by different methods and correlated to the boundary between Neoproterozoic and Paleozoic: K-Ar 570-603 Ma, Pb-Pb 590±50 Ma (S.M. Pavlov, Institute of Precambrian Geology and Geochronology, USSR Academy of Sciences), Rb-Sr 475±31 Ma (I.M.Vasil'eva, Institute of Precambrian Geology and Geochronology, USSR Academy of Sciences), U-Pb 609, 633, 677 Ma (Geological Survey of Canada) (Wrangel Island…, 2003; Kos'ko et al., 1993; Cecile et al., 1991). In the lower part of metamorphic rocks of Wrangel complex there are conformable tabular bodies of gneissosed and foliated granitoides. The latter are meramorphosed and transformed in biotite-muscovite-feldspar-quartz-sericite and muscovite-feldspar-quartz-sericite gneisses and schists, where relics of primary minerals (quartz, plagioclase, potassium feldspar, rarely biotite and muscovite) and equigranular granitic texture are preserved. Accessory minerals of granitoides are zircon, sphene, apatite. During field work of 2006 year the probes for U-Pb SHRIMP zircon datings were collected (upper reaches of Khishchnikov River). Dating was carried out on SHRIMP-II in the Center of Isotopic Studies of Federal State Unitary Enterprize "A.P.Karpinsky Russian Geological Research Institute". Wheited mean ages of zircons from three probes are: 702±3 Ma (N=19), 701±7 Ma (N=3), 707±4 Ma (N=25). They indicate Neoproterozoic age of granitoides. Furthermore, some zircons contain inherited cores, for which following datings were obtained: 1.1; 1,21; 1.107; 1.2-1,4; 1.58; 1.8; 2.6 Ga. These data allow supposing the presence of ancient (Neoproterozoic-Mesoproterozoic) rocks in the basement of Wrangel Island and their participation in the melting process during granite magmas formation. The work was supported by Russian Fund of Basic Researhes projects 13-05-00249, 14-05-00031, Scientific school NSh-2981.2014.5.

Luchitskaya, Marina; Sergeev, Sergey; Sokolov, Sergey; Tuchkova, Marianna

2014-05-01

176

Thermal History and Crystallinity of Sheet Intrusions  

Science.gov (United States)

Magma emplaced in a sheet intrusion has two potential fates: to crystallize, or quench to glass. Rapidly chilled sheet margins are typically glassy or microcrystalline, while interiors are coarser-grained. The actual textures result from a combination of thermal history and crystallization kinetics, which are related by various feedback mechanisms. The thermal history of cooling sheet intrusions is often approximated using the analytical solution for a semi-infinite half-space, which uses constant thermal properties such as heat capacity (CP), thermal diffusivity (D) and thermal conductivity (k = D?CP), where ? is density. In reality, both CP and D are strongly T-dependent for glasses and crystals, and melts have higher CP and lower D than crystals or glasses. Another first-order feature ignored in the analytical solution is latent heat of crystallization (?Hxt), which can be implemented numerically as extra heat capacity over the crystallization interval. For rhyolite melts, D is ~0.5 mm2s-1 and k is ~1.5 Wm-1K-1, which are similar to those of major crustal rock types and granitic protoliths at magmatic temperatures, suggesting that changes in thermal properties accompanying partial melting of the crust should be relatively minor. Numerical models of hot (~920°C liquidus for 0.5 wt.% H2O) shallow rhyolite intrusions indicate that the key difference in thermal history between bodies that quench to obsidian, and those that crystallize, results from the release of latent heat of crystallization, which enables bodies that crystallize to remain at high temperatures for much longer times. The time to solidification is similar in both cases, however, because solidification requires cooling through the glass transition (Tg ~620°C) in the first case, and cooling only to the solidus (~770°C) in the second. For basaltic melts, D is ~0.3 mm2s-1 and k is ~1.0 Wm-1K-1, compared to ~0.6 mm2s-1 and 2.5 Wm-1K-1 for crystalline basalt or peridotite at magmatic temperatures, suggesting that changes in thermal properties accompanying partial melting of the mantle or crystallization of basalt may be important. Numerical models of basaltic sheet intrusions indicate that they will almost always crystallize, even at sheet margins, because their emplacement temperature (~1220°C) is sufficiently high that the country rock adjacent to the sheet will be raised above the Tg of the melt (~650°C). The long period of time spent above Tg, combined with the rapid crystallization kinetics of basaltic melts, ensures that crystallization is near-complete, even if the crystal size is small, except where unusually rapid chilling occurs due to efficient convective or radiative losses (for example subaerial, subaqeous or subglacial lava flows).

Whittington, A. G.; Nabelek, P. I.; Hofmeister, A.

2011-12-01

177

Status of the GRANIT facility  

CERN Document Server

The GRANIT facility is a follow-up project, which is motivated by the recent discovery of gravitational quantum states of ultracold neutrons. The goal of the project is to approach the ultimate accuracy in measuring parameters of such quantum states and also to apply this phenomenon and related experimental techniques to a broad range of applications in particle physics as well as in surface and nanoscience studies. We overview the current status of this facility, the recent test measurements and the nearest prospects.

Roulier, Damien; Baessler, Stefan; Clément, Benoît; Morton, Daniel; Nesvizhevsky, Valery; Pignol, Guillaume; Rebreyend, Dominique

2014-01-01

178

Thermomechanical properties of Stripa granite  

International Nuclear Information System (INIS)

The Stripa material properties testing program was initiated to study, by laboratory testing, the thermomechanical behavior of the Stripa rock mass and to provide material properties for input into numerical programs for simulation of the in situ heater experiments at Stripa. The portion of the program dealing with measurement of elastic moduli and coefficients of thermal expansion of dry, intact samples of Stripa granite was completed in fiscal year 1980. A summary of the most significant findings resulting from tests on six samples are presented in this report

179

Radioactive waste disposal in granite  

International Nuclear Information System (INIS)

The principal geotechnical problems in selecting a repository site for radioactive waste disposal in granite are to evaluate the suitability of the rock mass in terms of: (1) fracture characteristics, (2) thermomechanical effects, and (3) fracture hydrology. Underground experiments in a mine in Sweden have provided an opportunity to study these problems. The research has demonstrated the importance of hydrogeology and the need to improve predictions of the thermomechanical behavior of fractured rocks. To characterize a site, measurements made from the surface must be supplemented by extensive subsurface experiments. Much effort is needed to generate the technology required for the development of waste repositories

180

Contrasting Structures and Deformational History of Syntectonic Granites of Campina Grande and Serra Redonda, Borborema Province, NE Brazil  

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Full Text Available The Campina Grande and Serra Redonda Granites are intrusive along the contact of the Paleoproterozoic basement(Alto Moxotó Domain with the Tonian gneisses (Alto Pajeú Domain of the Borborema Province (northeast Brazil. TheCampina Grande Granite (U-Pb age = 581± 2 Ma shows a concentric oval-shaped structure whereas the Serra RedondaGranite (U-Pb age = 576 ± 3 Ma has a tabular shape, elongated in the NE-SW direction. The plutons are separated bythe left-lateral Galante transcurrent shear zone. In this study, the anisotropy of magnetic susceptibility (AMS was appliedto 64 outcrops of granites to determine the internal structures of these plutons and to explore the relationship betweenmagmatism and deformation in an orogenic setting. The magnetic fabrics are concordant with the metamorphic structure ofthe host rocks. Strike-slip shear zones controlled the emplacement of the Serra Redonda Granite, as indicated by sigmoidalfoliation, defining shear bands associated with the Galante shear zone. In contrast, the magmatic/magnetic fabric of theCampina Grande granite seems to have been produced by body (ascensional forces. The pluton displays an inward dipping, concentric planar fabric parallel to the wall rock contact and lineations highly oblique to the foliation trend. The fabric of the Campina Grande pluton is consistent with a magma moving over a ramp dipping to southwest, with the lineation at high angle to the NE-trending flow direction. The contrasting structures of the plutons reflect the episodic nature of orogenic deformation, which was punctuated by the alternation of weak and strong strains, affecting the fabric development of the syntectonic intrusions.

Sérgio Wilians de Oliveira Rodrigues

2011-04-01

 
 
 
 
181

Discussion on zircon LA-ICP-MS ages of Lianshanguan-Gaojiagou granites and its significance  

International Nuclear Information System (INIS)

Through method of LA-ICP-MS to single zircon,the authors obtained an accurate 2198±31.5 Ma and 2162±31 Ma ages of Lianshanguan-Gaojiagou granite which located in the eastern of Liaoning province, China. These two isotopic ages suggest a comprehensive crustal melting-tectonic event occurred in Eastern Liaoning and Southern Jilin area, which can be proved by other single zircon U-Pb ages and regional geology evidence. Furthermore, these ages indicate the precise and reliable time of such re-melt event which benefit to uranium pre-enrichment and strengthened by local evidence from petrology geochemistry and contact relation of field outcrop rocks. Lianshanguan-Gaojiagou complex is a re-melt and multi-intrusion granite occurred under crust extension in paleo-proterozoic era. (authors)

182

INTRUSION DETECTION ON CLOUD APPLICATIONS  

Directory of Open Access Journals (Sweden)

Full Text Available Cloud computing has grown from being a promising business concept to one of the fastestgrowing segments of the IT industry. So, cloud environment always remains vulnerable to attacks. Theframework serves as an excellent platform for making cloud services intrusion tolerant. The feasibility of theframework has been tested by making cloud’s Infrastructure as a Service (IaaS and Data Storage Serviceintrusion tolerant. The proposed framework has been validated by integratingIntrusion Tolerance via Threshold Cryptography (ITTC mechanism in the simulated cloud’s IaaS. For this,the data centre authentication key is distributed among the hosts using Shamir Secret Sharing algorithm.Performance of the new simulated service model is measured using various performance metrics such astotal execution time, intrusion detection time, recovery time, number of cloudlets etc. It involves, usingproposed Cloud Intrusion Tolerance framework for securing cloud Data Storage. The correctness of user’sdata is ensured by using erasure-correcting code in the file distribution preparation to provide redundancyparity vectors. Performance analysis using erasure-correcting code for securing data storage is also done. Weare also implementing the different networks such as SHIM (System Health and Intrusion Monitoring isused as an exemplary host-based IDS to validate our approach, DRCP (Dynamic Registration andConfiguration Protocol is an auto configuration protocol in mobile AdHoc networks, OLSR (Optimized LinkState Routing protocol is a proactive, table-driven routing protocol in MANETs.

A. Venkat Reddy

2013-09-01

183

Incorporation of granite waste in red ceramics  

International Nuclear Information System (INIS)

This work has as its objective to evaluate the effect of granite powder waste incorporation in a red ceramic body. The granite waste came from an industry of stone sawing operations located in the municipal area of Santo Antonio de Padua, State of Rio de Janeiro, Brazil. Initially the granite sawing waste was characterized in terms of chemical composition, particles size distribution and X-ray diffraction. After that, clay mixtures with 0, 10, 20, 30 and 40 wt.% of granite waste were prepared. Red ceramic specimens were fabricated by extrusion and then fired in an industrial furnace at 970 deg. C. The specimens were also tested to determine the water absorption, linear shrinkage and three points bending flexural strength. Microstructural evaluation was carried out by scanning electron microscopy, X-ray diffraction and mercury porosimetry. The results indicate that granite waste presents favorable characteristics for addition into red ceramics due to facilities on the drying stages and decrease in porosity

184

Integration of remote sensing data and ground data as an aid to exploration for granite related mineralization, Salamanca Province, W Spain  

International Nuclear Information System (INIS)

This paper reports that the major geological features associated with the Los Santos tungsten skarn are: vicinity of the intrusive granite contact: geochemical zoning within the granite; anomalous width of the contact aureole; presence of fault zones; development of limonitic soil; presence of limestone horizons. Digital image processing techniques are applied to recognize and enhance these features in satellite images and airborne geophysical datasets. In satellite images the granites are textually distinct from other terrains, due to a higher degree of variation between adjoining pixels and a higher density of lineaments. Supervised classification of TM-bands 3,4,5 and 7 allows discrimination of granite and regional metamorphic terrain, while contact-metamorphic and limonitic soils are classified better using bands 1,3,4 and 7. Airborne magnetometry discriminates well between granites and sediments. The magnetization of the sedimentary rocks in the contact aureole is reset due to thermal and chemical overprinting. This is visible in the magnetic image. Large faults are detected. Radiometric data allow distinction between granite and sediments and recognition of the geochemical zoning within the granite

185

DOE Intrusion Detection Systems Handbook  

International Nuclear Information System (INIS)

The article reviews the Intrusion Detection Systems Handbook that was prepared by Sandia Laboratories for the U.S. Department of Energy, Office of Safeguards and Security. The purpose of the handbook is to provide information pertinent to the selection, procurement, installation, testing, and maintenance of the elements of an intrusion detection system. These elements include interior and exterior sensors, alarm assessment equipment, and alarm reporting equipment. The handbook also contains a discussion of how these elements can be integrated into an operationally effective system

186

The atmosphere during the younger dryas.  

Science.gov (United States)

One of the most dramatic climate change events observed in marine and ice core records is the Younger Dryas, a return to near-glacial conditions that punctuated the last deglaciation. High-resolution, continuous glaciochemical records, newly retrieved from central Greenland, record the chemical composition of the arctic atmosphere at this time. This record shows that both the onset and the termination of the Younger Dryas occurred within 10 to 20 years and that massive, frequent, and short-term (decadal or less) changes in atmospheric composition occurred throughout this event. Changes in atmospheric composition are attributable to changes in the size of the polar atmospheric cell and resultant changes in source regions and to the growth and decay of continental biogenic source regions. PMID:17829276

Mayewski, P A; Meeker, L D; Whitlow, S; Twickler, M S; Morrison, M C; Alley, R B; Bloomfield, P; Taylor, K

1993-07-01

187

P-T path fluid evolution in the Gross Spitzkoppe granite stock, Namibia  

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Full Text Available The Gross Spitzkoppe granite stock (GSS is a zoned 30 km^2 epizonal intrusion that consists of three main granites: 1 medium-grained biotite granite (marginal, 2 a coarse-grained biotite granite, and 3 a central, porphyritic granite. The stock contains pegmatites as banded marginal stockscheiders and isolated pockets composed of large alkali feldspar and quartz, dark mica, interstitial fluorite, and euhedral topaz and beryl crystals. In the porphyritic granite there are local wolframite-bearing greisens and hydrothermal fluorite and topaz-rich veins.Fluid inclusion studies were conducted on: 1 topaz and quartz crystals from the marginal stockscheider; 2 quartz, topaz, fluorite and beryl crystals from isolated pegmatites; 3 topaz from a miarolitic pegmatite; 4 beryl and quartz veins from greisenized porphyritic granite; and 5 fluorite from a late fluorite vein inthe coarse-grained biotite granite. Preliminary data indicate the presence of three compositionally distinct primary and pseudosecondary inclusion types that are of late magmatic-hydrothermal origin.Type 1. Low salinity (0–10 eq. wt% NaCl H2O (± CO2 inclusions that homogenize to the liquid phase in the temperature range of 300 to 550?C. These inclusions are from quartz, topaz and beryl. Inclusions in fluorite from the fluorite vein homogenize at ~170?C and have a salinity of ca. 1–2 eq. wt% NaCl.Type 2. Saline (25–30 eq. wt% NaCl halite-bearing H2O (± CO2 inclusions that homogenize to the liquid phase in the temperature range of 300 to 400?C. These inclusions are from quartz.Type 3. Low salinity (0–3 eq. wt% NaCl H2O-CO2 inclusions that homogenize to vapor phase in the temperature range of 330 to 550?C. These inclusions are from quartz and topaz.Hydrothermal fluids from greisen minerals are represented by type 1 and type 2 H2O inclusions. They are predominantly of low salinity (~8 eq. wt% NaCl and homogenize to the liquid phase in the temperature range of 300 to 500?C. Isochores for contemporaneous type 2 and type 3 inclusions with homogenization temperature range of 330 to 400?C indicate a maximum trapping pressure of about 900 bar for the marginal stockscheider.

Stephen Frindt

2002-01-01

188

AMS studies in Portuguese variscan granites  

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A large volume of Variscan granitic rocks outcrop in Central Iberian Zone which are well documented concerning geological mapping, petrography and geochemistry but whose magnetic characteristics and fabric remain unknown. In this study we summarize the available AMS data from approximately 644 sampling stations (5152 samples) on different massifs of Variscan Portuguese granites. Despite their different geological, petrographic and geochemical characteristics, magnetic susceptibility (K) values obtained for the majority of the studied granites range from 15 to 300 × 10-6 SI. The dominant paramagnetic behaviour of the granite bodies reflects the presence of ilmenite as the main iron oxide. This feature indicates the reduced conditions involved in the granite melt formation during the Variscan orogeny. The two-mica granites show K values ranging between 15 to 70 × 10-6 SI which are lower than values displayed by the biotite-rich facies scattered within the interval of 70 and 300 × 10-6 SI. The magnetite-bearing granites are scarce but represented in Lavadores, Gerês and Manteigas. Even so, only the Lavadores body could be considered as a true magnetite-type granite (K >3.0 × 10-3 SI) in face of its K, comprised between 1550 and 19303 × 10-6 SI. Magnetic anisotropy can be used as a "marker" for the deformation experienced by granite mushes during their crustal emplacement and further cooling. Magnetic anisotropy can thus be correlated with the finite deformation of a rock, as record by mineral fabrics. Post-tectonic granites, such as those from Vila Pouca de Aguiar, Pedras Salgadas, Caria, Vila da Ponte, Chaves and Lamas de Olo, have a magnetic anisotropy bands of quartz surrounded by mica flakes). In the late to post-tectonic granite bodies, such as those from Castro Daire, Valpaços, Castelo Branco, Mangualde-Trancoso or Serra da Estrela, the magnetic anisotropy falls within the 2.5% and 5% range. The magnetic anisotropy of the Lavadores granite is always higher than 10%. This feature, however, reflects the presence of rough alignments of magnetite co-existent with magmatic to submagmatic microstructures. The shape parameter T is quite variable; however, the average values, for all the massifs, are always higher than zero, suggesting the presence of oblate AMS ellipsoids due to the magnetocrystalline anisotropy of biotite. The values of magnetic susceptibility and magnetic anisotropy allowed a petrophysical characterization of the paramagnetic Variscan granites as was proposed by Sant'Ovaia & Noronha (2005).

Sant'Ovaia, Helena; Martins, Helena; Noronha, Fernando

2014-05-01

189

Radioactive waste disposal in granite  

International Nuclear Information System (INIS)

Within the framework of completing its knowledge of various rock formations, the Federal Government also considers the suitability of granite for radioactive waste disposal. For this purpose, the Federal Minister of Research and Technology participated from 1983 to 1990 in relevant research and development activities in the NAGRA rock laboratory at Grimsel, Switzerland. After about 17 field tests, it can be stated that the understanding of basic connections and interactions between the mechanical behaviour of the rock, which is determined, for instance, by natural or artificially induced rock movements, and the hydrogeological or rock hydraulic relations could be clearly improved. So far, the German share in the project costs amounts to a total of approximately DM 20.7 million. Till the end of 1993, further activities are scheduled to be carried out which will require financial funds of about DM 6.3 million. (orig./HSCH)

190

Late-Archaean Potassic Granite from the Bundelkhand Craton, Central India  

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Late-Archaean granitoids, show wide range of compositional variation: (i) TTG like granitoids with strongly fractionated REE patterns, which can be both Na-rich and K-Mg-rich (Sanukitoids) (ii) K-rich, Mg-poor biotite granites with less fractionated REE patterns and showing negative Eu-anomalies (type area, the Closepet Granite, Eastern Dharwar Craton, India). Amongst them Late-Archaean Sanukitoid or K-rich Closepet-type granitoids are most widely reported from the Archaean Cratons world-wide: Superior Province, Canada, Pilbara Craton, Yilgarn Craton, Antarctica, Limpopo Belt, Dharwar Craton. Several models proposed so far for the origin of these granitoids mostly include partial melting of hydrated basalts, reaction of slab melts with mantle wedge peridotites, re-melting of an enriched mantle and then mixing of the resulting melt with the anatectic melt generated during the melting of continental crust in subduction zone settings. The Closepet-type potassic biotite-rich granites were mostly produced by re-melting of TTG-like continental basements most likely in a subduction zone setting. Most of the proposed models suggest such partial melting to have taken place in garnet-stability field and some in orthopyroxene-stability field. In this study we report late-Archaean (~2.61-2.5 Ga) potassic granite from the Bundelkhand Craton in central India. The Late-Archaean granitoids recorded from the craton are intrusive into the high-grade supracrustal rocks of the craton. They are classified as coarse grained grey, pink porphyritic granite, medium granied pink granite, granite porphyry and fine-grained pink granite. The supracrustal rocks of the craton have been metamorphosed at ~2.78 Ga under high-pressure conditions (~17-18 kbar)- medium temperature (600ºC) in a subduction zone setting. The intrusions of the granitoids at ~2.6-2.5 Ga mark the stability of the craton. The pink-porphyritic granite studied here preserves plagioclase-potash feldspar-orthopyroxene-muscovite-biotite-quartz. Plagioclase megacrysts mostly contain orthopyroxene inclusions and are rimmed by anti-perthite and potash feldspar. Biotite and muscovite mostly occur along the potash feldspar grain boundaries or along the grain fractures. The textural observations hence indicate that these granitic rocks are formed in two stages: (i) initial TTG-like melts formed by partial melting of pre-existing mafic supracrustal rocks in the orthopyroxene-stability field, as evidenced by orthopyroxene inclusions in the plagioclase megacrysts, followed by (ii) fractionation of plagioclase crystals, thus making the melt progressively enriched in potassium that led to rimming of the plagioclase megacrysts by anti-perthite or potash feldspar. Biotite and muscovite were formed during later retrogression due to fluid ingression. Whether such magma-forming processes were related to the ~2.78 Ga tectonics recorded from the craton or may be related to a short phase of collision tectonics post to that, needs further investigation.

Sarkar, Saheli; Saha, Lopamudra; Nasipuri, Pritam; Pati, Jayanta Kumar; Patole, Vishal

2014-05-01

191

Two-mica granites of northeastern Nevada.  

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The field settings are described and analytical data are presented for six two-mica granites from NE Nevada. High delta 18O and 87Sr/86Sr values indicate that all are S-type granite, derived from continental crust. The major element chemistry and accessory mineral contents of these rocks also are characteristic of S-type granites. Chemical, X ray, and other data are presented for the micas recovered from these granites. The muscovites are notably high in Fe2O3, FeO, and MgO. Except for one hydrobiotite, each of the biotites has an MgO content near 6.0 wt%. Two different types of two-mica granites are recognized in the area of this study. One type is distinguished by the presence of many biotite euhedra within muscovite phenocrysts and by an unusual suite of accessory minerals completely devoid of opaque oxides. This type probably resulted from anatexis of late Precambrian argillites under conditions of relatively low oxygen fugacity, along a line that roughly coincides with the westward disappearance of continental basement. In the other textural type of two-mica granite the micas are equigranular and there is a greater variety of accessory minerals. The magmatic evolution of this type also appears to reflect the influence of late Precambrian argillites; there may be age differences between the two types of two-mica granites.-Author

Lee, D.E.; Kistler, R.W.; Friedman, I.; Van Loenen, R. E.

1981-01-01

192

Contrasting zircon morphology and UPb systematics in peralkaline and metaluminous post-orogenic granite complexes of the Arabian Shield, Kingdom of Saudi Arabia  

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Uzircon ages are reported for seven metaluminous-to-peralkaline post-orogenic granites from the Late Proterozoic Arabian Shield of Saudi Arabia. Zircons from the metaluminous rocks are prismatic, with length-to-width ratios of ??? 2-4: 1 and small pyramidal terminations. In contrast, zircons from three of the four peralkaline complexes either lack well-developed prismatic faces (are pseudo-octahedral) or are anhedral. Some zircons from the peralkaline granites contain inherited radiogenic Pb and have very high common Pb contents (206Pb/204Pb Arabian Shield but rather occurred as multiple intrusive episodes from the Late Proterozoic to the Middle Ordovician. ?? 1989.

Aleinikof, J. N.; Stoeser, D. B.

1989-01-01

193

Site selection methods for nuclear waste storage in sub-schistic granites  

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Intrusive granites in schists, where most of the roof is at a depth of several hundred metres can be regarded as favourable sites for storing radioactive waste since the schistic cover has extremely low permeability. This configuration exists in various parts of France. In this paper the authors describe methods which can be applied to the study of such structures, taking a region in the Armorican Massif as a reference example. The geological evidence here showed an extensive zone with a slight gravimetric anomaly around a few granite outcrops dispersed in the schists. This structure gave reason to believe that a shallow granite mass would be found under the schistic cover, and geological and gravimetric surface studies did indeed prove that this supposition was correct. Apart from the slight gravimetric anomaly, the extent of which has been confirmed and the outlines determined, the transformations (contact metamorphism and hydrothermalism) of the enclosing schists are particularly indicative of the presence of granite. The gravimetric model shows that the thickness of the granite is at least 2.3 km and provides an initial representation of the shape and depth of the roof. These results, together with those of the structural analysis, can be used to demarcate a favourable region for investigations at depth which will make it possible: to monitor the geological structures; to define the geotechnical characteristics of the formations; to analyse and model the hydrogeological behaviour, at present known only from surface studies which do not appear to indicate any circulation of water upwards towards the surface

194

Emotional and Behavioral Reaction to Intrusive Thoughts  

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A self-report measure of the emotional and behavioral reactions to intrusive thoughts was developed. The article presents data that confirm the stability, reliability, and validity of the new seven-item measure. Emotional and behavioral reactions to intrusions emerged as separate factors on the Emotional and Behavioral Reactions to Intrusions

Berry, Lisa-Marie; May, Jon; Andrade, Jackie; Kavanagh, David

2010-01-01

195

Grusification of granite (scheme based on the study of granites from Sudety Mts., SW Poland)  

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Gruses that are developed on the Karkonosze granite (three outcrops) and the Izera granite (one outcrop) were investigated using optical microscope, scanning electron microscope equipped with EDS and electron microprobe, X-ray diffraction, IR spectrometry, chemical analysis (ICP-AES and ICP-MS), hydrogen and oxygen isotopic ratio determination and K-Ar dating. Three groups of samples were distinguished according to the degree of grusification (group I - compact granite; group II - friable granite; group III - granitic grus). The results of the examination allowed to present the simplified scheme of the grusification: 1. Development of microcracks (caused by tectonic stress, mechanical upload or magma cooling processes) promote circulation of hydrothermal fluids in granites; 2. The presence of the microcracks in granite facilitate the circulation of low-temperature fluids (low-temperature hydrothermal or weathering fluids). Fluids cause hydration and expansion of primary biotite (vermiculitization), what leads to development of secondary cracks in a rock. Fluids can also induce advanced alteration of plagioclases into clay minerals (mainly smectite or vermiculite). Expansion of biotite during vermiculitization is the most important factor in grusification. Other processes of alteration also contribute to grusification. Hydrothermal fluids in granite contribute the increase of alteration degree of primary minerals (e.g. sericitization and albitization of feldspar, chloritization or muscovitization of biotite, decomposition of monazite-(Ce) and formation of secondary REE phosphates). If primary biotite is subjected to muscovitization or chloritization, complete grusification of granite does not occur because of lack of vermiculitation.

Kajdas, Bartlomiej; Michalik, Marek

2014-05-01

196

Petrology and textural evolution of granites associated with tin and rare-metals mineralization at the Pitinga mine, Amazonas, Brazil  

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The Água Boa and Madeira igneous complexes at the Pitinga mine were emplaced into acid volcanic rocks of the Paleoproterozoic Iricoumé Group, and host major tin, rare-metal (Zr, Nb, Ta, Y, REE) and cryolite mineralization. The igneous complexes are elongate NE-SW and each is composed of three major facies that, in order of emplacement, include porphyritic and equigranular rapakivi granite and biotite granite in both igneous complexes, followed by topaz granite in the Água Boa igneous complex (ABIC) and albite granite in the Madeira igneous complex (MIC). Rapakivi, porphyritic and granophyric textures observed in the granites are interpreted to reflect multiple stages of crystallization at different pressures (depths). Decompression during ascent shifted the magmas into the plagioclase stability field, causing partial resorption of quartz, with subsequent growth at lower pressure. Fluid saturation and separation probably occurred after final emplacement at shallow levels. Temperature and pressure estimates based on phase relations and zircon concentrations range from a maximum of 930 °C and 5 kbar for the rapakivi granites to below 650 °C and 1 kbar for the peralkaline albite granite. This suggests initial crystallization of early intrusive phases at around 15 km depth, with final emplacement of more volatile-rich crystal-mush at a depth of 0.5-1 km. Accessory minerals, including zircon, thorite, monazite, columbite-tantalite, cassiterite, bastnaesite and xenotime are present in almost all facies of the Água Boa and Madeira igneous complexes, attesting to the highly evolved character of the magmas. The presence of magnetite and/or primary cassiterite indicate crystallization under oxidizing conditions above the NNO buffer. The evolutionary sequence and Nd isotope characteristics ( TDM=2.2-2.4 Ga) of the Pitinga granites are similar to those of other Proterozoic rapakivi granites. However, petrographic, geochemical and Nd isotopic data ( ?Nd initial=-2.1 to +0.5) suggest that the different facies of the Pitinga granites were derived from different crustal sources with variable input of a mantle component.

Lenharo, Sara Lais Rahal; Pollard, Peter J.; Born, Helmut

2003-01-01

197

Crustal growth and reworking during Lapland-Kola orogeny in northern Fennoscandia: U-Pb and Lu-Hf data from the Nattanen and Litsa-Aragub-type granites  

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In this paper we present new zircon U-Pb, Lu-Hf and REE data for Palaeoproterozoic intrusions (Nattanen- and Litsa-Aragub-type granites) of the Fennoscandian shield, to obtain a more detailed understanding of their petrogenesis. The intrusions form a chemically homogenous group of SiO2-rich A-type, post-kinematic granites that were emplaced between 1.79 and 1.76 Ga. The Hf isotopes indicate that the source was dominated by an Archaean crustal component although a mantle contribution cannot be ruled out. The isotopic data further constrain the evolution of the Archaean and Palaeoproterozoic crust and the assembly of the Nuna (Columbia) supercontinent. The Nattanen- and Litsa-Aragub-type granites are part of a voluminous phase of granitoid magmatism in Fennoscandia at 1.8-1.75 Ga, reflecting large-scale processes at the margin of the Nuna supercontinent.

Heilimo, Esa; Elburg, Marlina A.; Andersen, Tom

2014-09-01

198

Origin of the Lyme Dome and implications for the timing of multiple Alleghanian deformational and intrusive events in southern Connecticut  

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Geologic mapping, structural analysis, and geochronology in the area of the Lyme dome, southern Connecticut provides constraints on the origin of the rocks in the core of the dome, the absolute timing of the principal deformational and thermal events attributed to Alleghanian orogenesis, and the processes that generated the dome. Detrital zircon geochronology in combination with ages on intrusive rocks brackets the deposition of quartzite in the core of the dome sometime between ca. 925 and 620 Ma. Granite and granodiorite intruded the Neoproteorozic metasedimentary rocks in the core of the dome at ca. 620 to 610 Ma. Four major early Permian events associated with the Alleghanian orogeny affected the rocks in the Lyme dome area. Syn-tectonic migmatization and widespread penetrative deformation (D1, ca. 300 - 290 Ma) included emplacement of alaskite at 290 ?? 4 Ma during regional foliation development and aluminosilicate-orthoclase metamorphic conditions. Rocks of the Avalon terrane may have wedged between Gander cover rocks and Gander basement in the core of the Lyme during D1. Limited structural evidence for diapiric uplift of the Lyme dome indicates that diapirism started late in D1 and was completed by D2 (ca. 290 - 280 Ma) when horizontal WNW contractional stresses dominated over vertical stresses. Second sillimanite metamorphism continued and syn-tectonic D2 granite pegmatite (288 ?? 4 Ma) and the Joshua Rock Granite Gniess (284 ?? 3 Ma) intruded at this time. North-northwest extension during D3 (ca. 280 - 275 Ma) led to granitic pegmatite intrusion along S3 cleavage planes and in extensional zones in boudin necks during hydraulic failure and decompression melting. Intrusion of a Westerly Granite dike at 275 ?? 4 Ma suggests that D3 extension was active, and perhaps concluding, by ca. 275 Ma. Late randomly oriented but gently dipping pegmatite dikes record a final stage of intrusion during D4 (ca. 275 - 260 Ma), and a switch from NNW extension to vertical unloading and exhumation. Monazite and metamorphic zircon rim ages record this event at ca. 259 Ma. The evolution of the Lyme dome involved D1 mylonitization, intrusion, and migmatization during north-directed contraction, limited late D1 diapirism, D2 migmatization during WNW contraction with associated flexural flow and fold interference, D3 NNW horizontal extension and decompression melting, and final D4 vertical extension and rapid exhumation. Late regional uplift, extension, and normal faulting at higher crustal levels may have been caused by diapiric rise of the lower crust, below the structural level of the Lyme dome. The rocks record no evidence of Acadian metamorphism or deformation, suggesting that the Gander zone here was not tectonically juxtaposed with Avalon until the Alleghanian orogeny.

Walsh, G.J.; Aleinikoff, J.N.; Wintsch, R.P.

2007-01-01

199

Head and neck malignancies in younger patients  

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We treated 23 (1.4% of all our primary cases) younger patients who are from 15 years old to 29 years old with head and neck malignancies at the Department of Head and Neck Surgery of the Miyagi Cancer Center Hospital for the past 12 years. There were 12 male and 11 female, and the sex ratio was approximately 1:1. There were 12 oral cancer patients, 6 epipharyngeal cancer patients and so on. There were 14 squamous cell carcinomas, 3 nasopharyngeal carcinomas and so on. 60% of all cases were squamous cell carcinomas. Clinically, advanced stage (stage III and IV) was diagnosed in 70% of patients at presentation. Although 19 patients had no past history, 2 patients had bronchial asthma, one had schizophrenia, and one had psychological disorder. Radical treatment was performed in 20 of 23 examples. The estimated Kaplan-Meier 5-year cause-specific survival rates for all patients were 76% and the 10-year cause-specific survival rates were 63%, respectively. It was thought that survival consequence was excellent in the whole. The problems of head and neck tumor treatment in a younger patient were thought about with late effect by radioactive rays and genital disorder by cancer chemotherapy. (author)

200

Meltwater routing and the Younger Dryas.  

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The Younger Dryas--the last major cold episode on Earth--is generally considered to have been triggered by a meltwater flood into the North Atlantic. The prevailing hypothesis, proposed by Broecker et al. [1989 Nature 341:318-321] more than two decades ago, suggests that an abrupt rerouting of Lake Agassiz overflow through the Great Lakes and St. Lawrence Valley inhibited deep water formation in the subpolar North Atlantic and weakened the strength of the Atlantic Meridional Overturning Circulation (AMOC). More recently, Tarasov and Peltier [2005 Nature 435:662-665] showed that meltwater could have discharged into the Arctic Ocean via the Mackenzie Valley ~4,000 km northwest of the St. Lawrence outlet. Here we use a sophisticated, high-resolution, ocean sea-ice model to study the delivery of meltwater from the two drainage outlets to the deep water formation regions in the North Atlantic. Unlike the hypothesis of Broecker et al., freshwater from the St. Lawrence Valley advects into the subtropical gyre ~3,000 km south of the North Atlantic deep water formation regions and weakens the AMOC by 30%. We conclude that meltwater discharge from the Arctic, rather than the St. Lawrence Valley, was more likely to have triggered the Younger Dryas cooling. PMID:23129657

Condron, Alan; Winsor, Peter

2012-12-01

 
 
 
 
201

Precambrian crustal evolution and Cretaceous–Palaeogene faulting in West Greenland: Pre-Nagssugtoqidian crustal evolution in West Greenland: geology, geochemistry and deformation of supracrustal and granitic rocks north-east of Kangaatsiaq  

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Full Text Available The area north-east of Kangaatsiaq features polyphase grey orthogneisses, supracrustal rocks and Kangaatsiaq granite exposed within a WSW–ENE-trending synform. The supracrustal rocks are comprised of garnet-bearing metapelites, layered amphibolites and layered, likewise grey biotite paragneisses. Their association and geochemical compositions are consistent with a metamorphosed volcano-sedimentary basin (containing both tholeiitic and calc-alkali lavas and is similar to other Archaean greenstone belts. The Kangaatsiaq granite forms a 15 × 3 km flat, subconcordant body of deformed,pink, porphyritic granite occupying the core of the supracrustal synform, and is demonstrably intrusive into the amphibolites. The granite displays a pronounced linear fabric (L or L > S. Thepost-granite deformation developed under lower amphibolite facies conditions (400 ± 50°C, and is characterised by a regular, NE–SW-trending subhorizontal lineation and an associated irregular foliation, whose poles define a great circle; together they are indicative of highly constrictional strain. The existence of a pre-granite event is attested by early isoclinal folds and a foliation within the amphibolites that is not present in the granite, and by the fact that the granite cuts earlier structures in the supracrustal rocks. This early event, preserved only in quartz-free lithologies, resulted in high-temperature fabrics being developed under upper amphibolite to granulite facies conditions.

Watt, Gordon R.

2006-12-01

202

Adaptive Intrusion Data System (AIDS)  

International Nuclear Information System (INIS)

The adaptive intrusion data system (AIDS) was developed to collect data from intrusion alarm sensors as part of an evaluation system to improve sensor performance. AIDS is a unique data system which uses computer controlled data systems, video cameras and recorders, analog-to-digital conversion, environmental sensors, and digital recorders to collect sensor data. The data can be viewed either manually or with a special computerized data-reduction system which adds new data to a data base stored on a magnetic disc recorder. This report provides a synoptic account of the AIDS as it presently exists. Modifications to the purchased subsystems are described, and references are made to publications which describe the Sandia-designed subsystems

203

The Maua granitic massif, Central Ribeira Belt, Sao Paulo, Brazil: petrography, geochemistry and U-Pb dating  

International Nuclear Information System (INIS)

The Maua granitic massif is an elongated body dominated by a porphyritic biotite monzogranite which grades, in its southwestern extremity, to lighter equi granular granite and greisenized (tourmaline)-biotite-muscovite leuco granite. Abundant enclaves can be divided in three types: grey micro granular enclaves, with rounded shapes and igneous textures, are compositionally similar to the enclosing porphyritic granites; dark, rounded, micaceous enclaves have high K/Na, and may correspond to highly assimilated meta sedimentary xenoliths; and angulous gneiss xenoliths seem to be fragments of an unexposed type of country rock. The primitive magmas that formed the massif were Zr, P and LREE-saturated, and became progressively enriched in U, Cs, Y, HREE, F and possibly Ta. Geochemical data show that most of the observed compositional variation can be a reflection of crystal fractionation at the level of emplacement. However, other processes such as magma mixing, contamination and post-magmatic alteration seem to respond for local chemical variations. U-Pb monazite dating point to a crystallization age of 588 ± 2 Ma which is ca. 20 myr. younger than those of nearby crust-derived syn-orogenic granites. (author)

204

Magmatic Evolution of the REE-rich, Strange Lake A-type Peralkaline Granite  

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Although A-type granitic peralkaline complexes are widely distributed in anorogenic tectonic settings and many of them contain elevated concentrations of the REE and other HFSE, their evolution, and particularly the processes controlling the concentration of the REE/HFSE, is still poorly understood. The 1240 Ma (Miller et al., 1997) Strange Lake peralkaline granitic pluton, northern Québec-Labrador, Canada is an extraordinary example of hyper-enrichment of the REE, Zr, and Nb in an A-type granite, and an ideal setting in which to study late stage granitic melt evolution. At least four intrusive phases are distinguishable in the six km diameter cylindrical pluton, based on grain-size, mineralogical composition, and crystallization sequence deduced from petrographic examination. The first and least evolved phase, a hypersolvus granite, is characterized by a high proportion of early crystallizing perthite and subordinate proportions of late crystallizing arfvedsonite and quartz. The subsequent subsolvus granite is distinguished from the hypersolvus granite by early crystallizing arfvedsonite and quartz, and the occurrence of discrete albite and microcline crystals rather than perthite. A third, porphyritic granite type occurs as a quenched zone between the hypersolvus and subsolvus granites, and it shows features of both granite types. Pegmatites, emplaced as sheets at the top of the pluton were the last igneous phase to form and are of special interest because they host the bulk of the mineralization. A model is proposed in which the first step was evolution of the hypersolvus granite by crystallization of alkali feldspar, as proposed previously by Boily and Williams-Jones (1994). This evolution is manifested by trends of decreasing whole-rock concentrations of K2O with Al2O3 and corresponding increases in REE, HFSE and F. The second step was marked by a change in the magma evolution due to the appearance of arfvedsonite as a liquidus mineral in place of perthite. This led to a decrease in Fe accompanied by a continued increase in HFSE, REE and F; the co-crystallization of quartz had the effect of increasing the concentrations of all elements except Si. Significantly, the arfvedsonite contains appreciable concentrations of REE (up to 1 wt. %) and F (up to 3.4 wt. %). Indeed local cumulates of arfvedsonite may contain whole-rock concentrations of up to 1.4 wt. % TREO and 0.5 wt. % ZrO2. However, the concentrations of HFSE and REE increased in the melt despite the fractional crystallization of arfvedsonite. This was due to the greater proportions of minerals free of REE and HFSE that were crystallizing (feldspar and quartz). The hyper-enrichment in REE and HFSE in the pegmatites is interpreted to have been due to the incompatible nature of these elements, the small proportion of the residual liquid forming the pegmatites, the extreme alkalinity of this liquid and the complexation of the REE and HFSE with fluorine. Miller, R.R., Heaman, L.M., and Birkett, T.C. (1997) Precambrian Research, 81, 67-72 Boily, M. and Williams-Jones, A.E. (1994) Contributions to Mineralogy and Petrology, 118(1), 33-47

Siegel, K.; Williams-Jones, A. E.

2013-12-01

205

Relationships Between Shearing and Granitic Magma Emplacement: the Remígio-Pocinhos Shear Zone in the São José do Campestre Massif, NE Brazil  

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Full Text Available Based on mineralogical, geochemical and textural characteristics, a variety of granite types was identified amongstthe intrusions emplaced during the tectonic activity along the Remígio-Pocinhos shear zone in NE Brazil during the lateststages of the Brasiliano orogeny. They include peraluminous granites with I-type mineralogical compositions as well astransitional-to-alkaline geochemical characteristics. These granites contain mafic to intermediate microgranular enclaves.Overall, they are very similar to many other Brasiliano-age plutons in the extreme NE of Brazil. Metaluminous alkalinegranites with aegirine-augite usually contain andradite as a minor phase, and titanite as an important accessory mineral.Several aspects of their trace element geochemistry repeat features of syn to late- tectonic alkaline granites in other parts ofNE Brazil and in the rest of the world. The shear zone has deep roots, and the heat flow during granite genesis was probablyhigh. A variety of lower crustal source rocks was probably involved in the genesis of these granites.

Rielva Solimairy Campelo do Nascimento

2010-10-01

206

Geochemical and Sr-isotopic signatures in the 2.6 B.Y. Lepakshi granite, Anantapur district, Andhra Pradesh: implications for its origin and evolution  

International Nuclear Information System (INIS)

The predominantly leucocratic 2.6 b.y. old Lepakshi granite (a suite of granite, granodiorite and quartz-monzonite), near Hindupur in the Anantapur district of Andhra Pradesh is intrusive into the Archaean schistose rocks and contains xenolithic patches of amphibolite. Compositionally, it is predominantly quartz-monzonitic with granodiorite and granite variants. The relatively low initial 87Sr/86Sr (Sri = 0.7026) of this Lepakshi granite implies its derivation from a juvenile crustal source with very limited crustal residence time, indicating the absence of involvement of any metasedimentary source. The source also appears to have fair amount of mafic component. A volcanic arc type tectonic setting, along with the collision processes and the associated tectonic activity operating in tandem, resulting in an increased P-T regime, granulite facies metamorphism and anatectic melting at mid- to lower crustal levels is suggested for the origin of this granite. The large ion lithophile (LIL) elements removed from the lower crust (due to granulite facies metamorphism and the associated fluid activity) were incorporated in the granites of the Lepakshi type. (author). 45 refs., 12 figs., 2 tabs

207

Mineralogy, chemistry, and age of granitic veins at Nicholson's Point, South Coast, Natal  

International Nuclear Information System (INIS)

Undeformed granitic veins exposed at Nicholson's Point, southern Natal, intrude nearly all the foliated rock types between Drakes Beach and Leisure Bay and therefore appear to post-date the major deformation episodes. The veins define an en echelon array and appear to have been emplaced syn-tectonically to post-tectonically. In addition to quartz and feldspar, the veins are characterized by variable ferro magnesian minerals, namely, tourmaline, magnetite, dumortierite, and biotite. A Rb/Sr isotope study yields a date of 960 ± 32 Ma which is within error of the date of the nearby deformed Glenmore Granite. These results imply that much of the deformation history recorded in the southern sector of Natal Structural and Metamorphic Province either occurred within a relatively short period or that the age of the Glenmore Granite is a reset age. The veins represent one of the youngest events recognized in the tectonic and intrusive history of the Natal Structural and Metamorphic Province. 18 refs., 7 figs., 5 tabs

208

Correlations between microstructures, K-feldspar triclinicity and trace element geochemistry in stanniferous and barren granites, northern Nigeria  

Science.gov (United States)

The biotite granites in the Nigerian Younger Granites are a major source of the economic metals Sn, Nb, Zn and W. The textural variations in these rocks are considered together with the composition and structural state of the K-feldspars. The curious disparity in the degree of mineralization of these rocks of similar mineral assemblage is considered to be related to the textural and structural variations. The stanniferous granites are characterized by medium- to fine-grained texture, miarolitic cavities, subsolidus crystallization of biotite and albite; turbidity, coarsening and incoherent perthitic texture of the K-feldspar. The barren granites are usually coarse-grained with few druses, silvery irridescent feldspar grains and coherent perthitic texture. K-feldspars in the stanniferous granites are mainly of maximum microcline structure while the barren ones are characterized by intermediate microcline structure. Compositionally, all the K-feldspars have less than 3% An; they have crystallized in the binary system at temperatures close to 700°C but have now re-equilibrated to various lower temperatures as a result of variable rock-fluid interaction. Positive correlations are observed between Nb, Sn, Rb, Li and F in granites and triclinicity of their K-feldspars. Enhancement of Rb-values is observed in both the stanniferous rocks and their K-feldspar constituents. The variable textures, degree of Al, Si order in the feldspars and enrichment in ore and trace elements are attributed to the presence and abundance of a fluid phase. It is suggested that in the course of magmatic evolution of these rocks an alkali-rich volatile phase developed, accumulated and was trapped in the roof zone of the stanniferous granites.

Badejoko, T. A.

209

Intrusive rocks and tectono-metamorphic evolution of the Mako Paleoproterozoic belt (Eastern Senegal, West Africa)  

Science.gov (United States)

The Kedougou Kenieba Inlier (KKI) (Paleoproterozoic of Eastern Senegal) is a portion of the West African Craton (WAC) containing a granite-greenstone terrain that experienced three distinct periods of magmatic activity, peaking at 2200, 2160-2130 and 2100-2070 Ma. In the Inlier, Paleoproterozoic granitoids and large-scale transcurrent shear zones are spatially associated, suggesting a genetic link between magma bodies and shear zones. Granitic intrusions are associated with all the volcanic episodes and phases of deformation, and have been used to constrain the age of many of these events. Our structural data and deformation sequence indicate that the Mako Greenstone Belt and the adjacent granitoid complexes have undergone a multi-phase evolutionary history that is spread over a prolonged period. The available geochronological data and field studies allowed classification of the granitoids of the KKI into four generations GI, GII, GIII and GIV. The current data suggest that the oldest rocks in the KKI, the Badon granites (2198 ± 2 Ma) and the tonalitic gneisses from Tonkouto (2200-2198 Ma) (GI), could be correlated with an early Birimian magmatic event. The gneisses, crystallized at depth, record the earliest deformation and in contrast to other tonalites, do not appear to have intruded volcanic rocks. The second manifestation of magmatism was intrusion of mafic diorite - the Gabbro Sandikounda Layered Igneous Complex type (GII) and development of the Laminia Kaourou Plutonic Complex (LKPC) (2160-2130 Ma). These bodies pre-date or are sometimes synchronous with a major deformational episode, and may, therefore, have formed very early in convergent Birimian orogenesis. The third major peak of magmatic activity occurred after the above major episode with the development of the oval shaped Diombalou and Bouroumbourou plutons (GIII). The orientation of these plutons parallel to the regional strike of the schistosity indicates structural control on granite emplacement. Eburnean magmatism was terminated in the Mako Belt following compressional Eburnean deformation, with the emplacement of the Tinkoto, Mamakono plutons (GIV) in the east of the complex and continued in the Dialé-Daléma supergroup with the syntectonic emplacement of the Saraya batholith. Garnitiferous granites of crustal derivation were emplaced in the final period of extensional activity around 2080 Ma. Field observations suggest the early plutons of the complex granitic (Kakadian) batholith intruded during convergent deformation whereas later igneous activity accompanied regional orogen-parallel extension, followed by exhumation. In the Mako Belt, thickening of the crust was proposed to have caused heating and the 'apparent diapiric rise' of the Diombalou and Bouroumbourou plutons.

Gueye, Mamadou; Ngom, Papa Malick; Diène, Mouhamadane; Thiam, Yaouba; Siegesmund, Siegfried; Wemmer, Klaus; Pawlig, Sabine

2008-02-01

210

Is stratospheric air getting younger with time?  

Science.gov (United States)

Most climate models have predicted that with the increase in greenhouse gases concentrations, the stratospheric circulation will intensify, showing younger age-of-air (AoA) values in this region (e.g. Butchart et al., 2010; WMO, 2011). However, balloon and satellite observations do not agree with the widespread modelled trend towards younger age-of-air (Engel et al., 2009; Stiller et al., 2012). To increase our confidence in climate-chemistry projections, the causes for the apparent age-of-air disagreement between observations and most models need to be identified. Here we have carried out stratospheric simulations with a chemistry transport model (CTM) to evaluate the stratospheric circulation with the ERA-Interim dataset produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). The ERA-Interim reanalysis provides age-of-air (AoA) distributions in very good agreement with observations in the lower stratosphere. Given this agreement, we have used our simulations to quantify interannual variability and trends in the stratospheric AoA for the whole ERA-Interim period (1979-present). Our model results with ERA-Interim fields disagree with the decreasing tendency in age-of-air widespread in most models, but are in good agreement with the recent age-of-air studies based on observations. To explore potential causes for the AoA trends in our model, Lagrangian calculations are also performed to assess mixing processes for the ERA-Interim period. Potential links between our modelled AoA trends and stratospheric ozone evolution are also shown. References: Butchart, et al., 2010. J. Climate, 23, 5349-5374, doi:10.1175/2010JCLI3404.1. Engel et al., 2009. Nat. Geosci. 2: 28-31, doi:10.1038/ngeo388. Stiller et al., 2012. Atmos. Chem. Phys. 12: 3311-3331, doi:10.5194/acp-12-3311-2012. WMO. 2011. Global Ozone Research and Monitoring Project -Report No. 52.

Monge-Sanz, Beatriz; Chipperfield, Martyn; Dee, Dick; Simmons, Adrian; Stiller, Gabriele

2014-05-01

211

Intrusion Detection Using Data Mining Technique  

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Full Text Available In reality it is not possible to prevent security breaches completely using the existing security technologies. The intrusion detection plays an important role in network security and information system. However, many current intrusion detection systems (IDSs are signature based systems. The signature based IDS also known as misuse detection looks for a specific signature to match, and identify an intrusion. When the signatures or patterns are provided, they can detect all known attack patterns, but there are some problems for unknown attacks. The rate of false positives is very low but these types of systems are poor at detecting new attacks, variation of known attacks or attacks that act as normal behavior. Statistical Based Intrusion detection System (SBIDS can overcome many of the aforementioned limitations of signature based intrusion detection systems. Statistical based intrusion detection systems performs better than signature based intrusion detection system for novelty detection i.e. detection of new attack is very important for intrusion detection system. Researchers have implemented various classification algorithms for intrusion detection. This dissertation evaluates a decision tree classifier over a benchmark dataset. It will help intrusion detection system in novelty detection i.e. detection of new attacks. KDD99 dataset is used as the training data set

Stuti Singh

2013-03-01

212

Rare metal granites and related rocks of the Ukrainian shield  

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Full Text Available Two rare metal leucocratic granites, Perga and Kamennaya complexes, can be distinquished on the Ukrainian shield. The Perga complex consists of medium- and coarse grained, mainly porphyric, biotite, riebeckite and aegirine granites, granite porphyries, microclinites and albitites with rare metal mineralization (genthelvite, phenacite, tantalite, cassiterite and wolframite etc.. Granites from several stocks (up to 30 km2 in the northwestern part of the shield, situated along the fracture zone, restricted the large Korosten pluton of rapakivi granites to the northwest. The age of these granites (Pb-Pb and U-Pb methods on zircon and monazite practically coincide with the age of rapakivi granites being 1750 Ma. Within the Korosten complex of rapakivi granites we consider that zinnwaldite granites, which are characterized by fluorite and topazine mineralization, represent the final phase of pluton. These granites differ from the Perga ones by their low content of rare metals. The Kamennaya Mogila complex lies in the southeastern part of the Ukrainian shield. It consists of biotite and muscovite-biotite, medium- and coarse-grained (also porphyric, and occasionally greisining granites with rare metal mineralization (cassiterite, columbite, molybdenite, wolframite and beryl. Granites form several stocks (5-30 km2 situated 10-30 km to the west-northwest of the South-Kalchik gabbro-syenite-granite pluton. Granitoids in both of these complexes have similar isotopic ages (1800 Ma. Leucocratic subalkaline granites (the Novoyanisol type are known within the pluton itself, occupying an intermediate position between the above mentioned in terms of mineral and geochemical composition. The gabbro-syenite-granite formation of the Nearazov region has a substantial similarity to the anorthosite-rapakivi-granite formation. In this respect the relation of each of them to rare metal granites is rather remarkable. This relation is, most probably, not only spatial, but also genetic. The typical rare metal granites are situated not in the parent plutons but at some distance from them.

Esipchuk, K.Ye.

1993-12-01

213

Sorption behaviour of granite for radionuclides in groundwater condition  

International Nuclear Information System (INIS)

The sorption behavior of granite for Cs and Nd in the underground water condition was investigated as the function of mineralogical alteration of granite and particle size. The physicochemical characterization of the granite samples was carried out in terms of mineral phase, pore structure and elements eluted by soft acid treatment as the function of alteration of the granite. The increase of porosity of granite, and phase change of biotite and plagioclase into chlorite and illite, respectively were observed with the increase of alteration degree. The sorption capacities of the series of granites slightly increased with the increase of alteration degree. (authors)

214

Wireless Intrusion Detection and Logging System  

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Full Text Available Intrusion detection is the security patrol, and become the eyes and ears of the network, alerting the potential vulnerabilities and intrusion attempts. Monitoring can help to spot problems in the network, as well as identify performance problems, but watching every second of traffic that passes through the network, manually searching for attacks, would be impossible. This is why there is need of specialized network intrusion detection software. This software inspects all network traffic, looking for potential attacks and intrusions. Wireless Intrusion Detection System (WIDS is wireless network sniffing tool. It is used for securing the WLAN. And it generates the alarms to the administrator as soon as something goes wrong in the WLAN.WIDS attempts to identify computers system, network intrusions and misuse by gathering and analyzing data.WIDS can monitor and analyze user and system activities. It generates the alerts based either on predefined signatures or on anomalies in the traffic.

SURAJ KENDHEY

2013-03-01

215

Magnetic fabric and modeled strain distribution in the head of a nested granite diapir, the Melechov pluton, Bohemian Massif  

Science.gov (United States)

The Melechov pluton, Bohemian Massif, is interpreted as a mid-crustal nested granitic diapir with an apical part exposed at the present-day erosion level. The diapir head exhibits a concentric structure defined by lithologic zoning and by the anisotropy of magnetic susceptibility (AMS). In concert with theoretical models, outward-dipping margin-parallel magnetic foliations are associated with oblate shapes of the susceptibility ellipsoids and higher degree of anisotropy, passing inward into weaker triaxial to prolate fabric. By contrast, magnetic fabric in an inner granite unit is in places oriented at a high angle to internal contacts and is interpreted as recording an internal diapir circulation. We use inverse modeling to calculate strain variations across the diapir from the AMS data. The magnetic fabric parameters and calculated strains are in agreement with strain distribution in heads of model Newtonian diapirs traveling a distance of two body radii and suggest granitic magma ascent as a crystal-poor suspension followed by crystallization of fabric markers and their response to strain near the final emplacement level. The intrusive fabric thus formed late but, though generally weak, was still capable of recording incremental strain gradient in the granite diapir.

Truba?, Jakub; Žák, Ji?í; Chlupá?ová, Marta; Janoušek, Vojt?ch

2014-09-01

216

Analysis of the Younger Dryas Impact Layer  

Energy Technology Data Exchange (ETDEWEB)

We have uncovered a thin layer of magnetic grains and microspherules, carbon spherules, and glass-like carbon at nine sites across North America, a site in Belgium, and throughout the rims of 16 Carolina Bays. It is consistent with the ejecta layer from an impact event and has been dated to 12.9 ka BP coinciding with the onset of Younger Dryas (YD) cooling and widespread megafaunal extinctions in North America. At many locations the impact layer is directly below a black mat marking the sudden disappearance of the megafauna and Clovis people. The distribution pattern of the Younger Dryas boundary (YDB) ejecta layer is consistent with an impact near the Great Lakes that deposited terrestrial-like ejecta near the impact site and unusual, titanium-rich projectile-like ejecta further away. High water content associated with the ejecta, up to 28 at. percent hydrogen (H), suggests the impact occurred over the Laurentide Ice Sheet. YDB microspherules and magnetic grains are highly enriched in TiO{sub 2}. Magnetic grains from several sites are enriched in iridium (Ir), up to 117 ppb. The TiO{sub 2}/FeO, K/Th, TiO{sub 2}/Zr, Al{sub 2}O{sub 3}/FeO+MgO, CaO/Al{sub 2}O{sub 3}, REE/ chondrite, FeO/MnO ratios and SiO{sub 2}, Na{sub 2}O, K{sub 2}O, Cr{sub 2}O{sub 3}, Ni, Co, U, Th and other trace element abundances are inconsistent with all terrestrial and extraterrestrial (ET) sources except for KREEP, a lunar igneous rock rich in potassium (K), rare-earth elements (REE), phosphorus (P), and other incompatible elements including U and Th. Normal Fe, Ti, and {sup 238}U/{sup 235}U isotopic abundances were found in the magnetic grains, but {sup 234}U was enriched over equilibrium values by 50 percent in Murray Springs and by 130 percent in Belgium. 40K abundance is enriched by up to 100 percent in YDB sediments and Clovis chert artifacts. Highly vesicular carbon spherules containing nanodiamonds, glass-like carbon, charcoal and soot found in large quantities in the YDB layer are consistent with an impact followed by intense burning. Four holes in the Great Lakes, some deeper than Death Valley, are proposed as possible craters produced by the airburst breakup of a loosely aggregated projectile.

Firestone, Richard B.; West, Allen; Revay, Zsolt; Hagstrum, Jonathon T,; Belgya, Thomas; Hee, Shane S. Que; Smith, Alan R.

2010-02-27

217

Archean and paleoproterozoic granitoids and crustal evolution of the Rio Maria granite-greenstone terrane, Eastern Amazonian craton Brazil  

International Nuclear Information System (INIS)

The Rio Maria Granite-Greenstone Terrane (RMGGT) is situated in the Caraj Province, which is the most important Archean domain of the Amazonian craton (Machado et al., 1991; Macambira and Lafon, 1995; Tassinari and Macambira, 1999; Santos et al., 2000; Dall'Agnol et al., 2000). Several Archean granitoid suites and supracrustal sequences have been described in the RMGGT (Dall'Agnol et al., 1997; Althoff et al., 2000; Souza et al., 2001). Geochemical and isotopic data are now available allowing a better evaluation of the crustal evolution of this terrane. Paleoproterozoic, A-type oxidized granites (Dall'Agnol et al., 1999a) are intrusive in the Archean rocks of the RMGGT and their evolution will also be discussed (au)

218

Survey paper on intrusion detection techniques  

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Full Text Available Network security has been one of the most important problems in Computer Network Management and Intrusion is the most publicized threats to security. In recent years, intrusion detection has emerged as an important field for network security. IDSs obtain better results when each class ofattacks is treated as a separate problem and handled by specialized algorithms. Now in days various model and method are available for intrusion detection. In this paper, we present a study of intrusion detection. Detection method to improve the detection rate & helping the users to develop secure information systems.

Rachna Kulhare

2013-05-01

219

Granite Sludge Reuse in Mortar and Concrete  

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Full Text Available The disposal of solid wastes produced in granite industry to the environment without any treatment cause not only economical but also serious environmental problems. In this study Granite Powder (GP which produced as solid waste from the cutting and polishing of granite rocks was reused as additive to mortar and concrete cement. Incorporation of GP in mortar and concrete in ratios of 10, 20, 30 wt.% improved mortar and concrete compressive strengths and the concrete workability. The experimental results show that GP can be used to replace cement or fine aggregate in concrete which provide not only solve an environmental problem by safe disposal of GP but also reduce the stress on the limited natural resources and the cost of concrete production.

Husam D. Al- Hamaiedeh

2013-01-01

220

Intrusive images and intrusive thoughts as different phenomena: two experimental studies.  

Science.gov (United States)

According to the dual representation theory of PTSD, intrusive trauma images and intrusive verbal thoughts are produced by separate memory systems. In a previous article it was shown that after watching an aversive film, participants in non-movement conditions reported more intrusive images than participants in a free-to-move control condition (Hagenaars, Van Minnen, Holmes, Brewin, & Hoogduin, 2008). The present study investigates whether the experimental conditions of the Hagenaars et al. study had a different effect on intrusive thoughts than on intrusive images. Experiment 2 further investigated the image-thoughts distinction by manipulating stimulus valence (trauma film versus neutral film) and assessing the subsequent development of intrusive images and thoughts. In addition, both experiments studied the impact of peri-traumatic emotions on subsequent intrusive images and thoughts frequency across conditions. Results showed that experimental manipulations (non-movement and trauma film) caused higher levels of intrusive images relative to control conditions (free movement and neutral film) but they did not affect intrusive thoughts. Peri-traumatic anxiety and horror were associated with subsequent higher levels of intrusive images, but not intrusive thoughts. Correlations were inconclusive for anger and sadness. The results suggest intrusive images and thoughts can be manipulated independently and as such can be considered different phenomena. PMID:20391178

Hagenaars, Muriel A; Brewin, Chris R; van Minnen, Agnes; Holmes, Emily A; Hoogduin, Kees A L

2010-01-01

 
 
 
 
221

Minimally intrusive operator control unit  

Science.gov (United States)

We have designed a minimally intrusive Operator Control Unit (OCU) intended to be used by a dismounted soldier. The OCU is operated using a combination of head aiming, plus a small wireless controller that is integrated in the grip of the soldier's rifle. This minimally intrusive OCU allows soldiers to navigate a software interface (for example, to call up a map), operate a remote camera system or other sensors on an unmanned vehicle, and/or tele-operate the vehicle itself, all while the soldiers have their heads up and their hands on their weapons. Central to the concept is the idea of a head-aimed software interface, where natural and intuitive head motion is used instead of traditional mouse movements to efficiently navigate, point or even select items in the display-operators simply move their heads in the direction that they want to "look" and the display is seamlessly updated with new information. When combined with the controller that is integrated in the weapon grip, this allows almost hands free operation, as opposed to operating a PDA or other standard controller system which generally occupies both hands and requires operators to look down at a screen.

Massey, Kent; Chatten, Martha Jane

2005-05-01

222

Fluid inclusion planes and paleofluid records in the Podlesí granite, Krušné hory Mts., Czech Republic  

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Full Text Available Three generations of fluid inclusion planes (FIP were distinguished in rocks of the PTP-3 borehole from the Podlesí granite stock (Krušné hory Mts.. The oldest generation of FIP is believed to have followed the propagation of proto-tectonic subhorizontal aplite dykes and steep veinlets of greisen mineralization, at temperatures of about 400 °C and pressures less than 100 MPa. The later FIP contain fluid inclusions with homogenization temperatures from 140 to 270 °C, and likely represent hydrothermal fluids associated with the repeated opening of fractures during the late stages of intrusive complex development.

Dobeš P

2005-06-01

223

Efficient Intrusion Detection Scheme based on SVM  

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Full Text Available The network intrusion detection problem is the focus of current academic research. In this paper, we propose to use Support Vector Machine (SVM model to identify and detect the network intrusion problem, and simultaneously introduce a new optimization search method, referred to as Improved Harmony Search (IHS algorithm, to determine the parameters of the SVM model for better classification accuracy. Taking the general mechanism network system of a growing city in China between 2006 and 2012 as the sample, this study divides the mechanism into normal network system and crisis network system according to the harm extent of network intrusion. We consider a crisis network system coupled with two to three normal network systems as paired samples. Experimental results show that SVMs based on IHS have a high prediction accuracy which can perform prediction and classification of network intrusion detection and assist in guarding against network intrusion.

Guangping ZHOU

2013-09-01

224

Self-adaptive web intrusion detection system  

CERN Document Server

The evolution of the web server contents and the emergence of new kinds of intrusions make necessary the adaptation of the intrusion detection systems (IDS). Nowadays, the adaptation of the IDS requires manual -- tedious and unreactive -- actions from system administrators. In this paper, we present a self-adaptive intrusion detection system which relies on a set of local model-based diagnosers. The redundancy of diagnoses is exploited, online, by a meta-diagnoser to check the consistency of computed partial diagnoses, and to trigger the adaptation of defective diagnoser models (or signatures) in case of inconsistency. This system is applied to the intrusion detection from a stream of HTTP requests. Our results show that our system 1) detects intrusion occurrences sensitively and precisely, 2) accurately self-adapts diagnoser model, thus improving its detection accuracy.

Guyet, Thomas; Wang, Wei; Cordier, Marie-Odile

2009-01-01

225

Intrusion Preventing System using Intrusion Detection System Decision Tree Data Mining  

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Full Text Available Problem statement: To distinguish the activities of the network traffic that the intrusion and normal is very difficult and to need much time consuming. An analyst must review all the data that large and wide to find the sequence of intrusion on the network connection. Therefore, it needs a way that can detect network intrusion to reflect the current network traffics. Approach: In this study, a novel method to find intrusion characteristic for IDS using decision tree machine learning of data mining technique was proposed. Method used to generate of rules is classification by ID3 algorithm of decision tree. Results: These rules can determine of intrusion characteristics then to implement in the firewall policy rules as prevention. Conclusion: Combination of IDS and firewall so-called the IPS, so that besides detecting the existence of intrusion also can execute by doing deny of intrusion as prevention.

Syurahbil

2009-01-01

226

Relation Between Tectonics and Intrusions in the Western Rhodope Mountains, SW Bulgaria  

Science.gov (United States)

We present an E-W profile through the Western Rhodopes (Bulgaria). It runs through basement rocks, granitic intrusions therein and Tertiary extension-related structures such as the Strouma and the Mesta Graben. Two major alpine units are exposed in the basement, the Pangaion-Pirin complex below and a mixed gneiss unit above. The Pangaion-Pirin unit consists mainly of marbles, variscan orthogneisses, and Tertiary ganitic intrusions and underwent only upper greenschist facies conditions during the alpine cycle. The mixed gneiss unit is made up of different continental and oceanic high-grade metamorphic rocks, including preserved HP and UHP relicts at several localities. U/Pb zircon geochronology was carried out on samples from three granitic intrusions, the Spanchevo, Teshovo and Dolno Dryanovo plutons using LA-ICP-MS at GEUS in Copenhagen. The Teshovo pluton is located in the Pangaion-Pirin complex. Apart from a weak magmatic foliation, it is undeformed and thus intruded posttectonically. Zircons within the assayed samples are single-phased and give well defined crystallization ages of around 32 Ma. The Spanchevo and Dolno Dryanovo plutons are partly deformed bodies within the mixed gneiss unit. Single-phase magmatic zircons and magmatic rims yield ages of around 56 Ma, whereas inherited cores display ages of around 146 Ma. We propose that (1) ductile deformation in the Pangaion-Pirin complex ceased before 32 Ma and (2) penetrative deformation lasted beyond 56 Ma in the mixed gneiss unit above. Due to the lack of inherited variscan cores in zircons from the Spanchevo and Dolno Dryanovo plutons, we infer that the upper complex was not yet placed upon the Pangaion-Pirin complex at 56 Ma. Hence, the southwestward thrusting of the upper complex over the Pangaion-Pirin complex took place between 56 and 32 Ma.

Jahn-Awe, S.; Froitzheim, N.; Nagel, T.; Frei, D.; Georgiev, N.

2008-12-01

227

Intraplate crustal remelting as the genesis of Jurassic high-K granites in the coastal region of the Guangdong Province, SE China  

Science.gov (United States)

The origin and tectonic significance of high-K granites (>3 wt% K2O at 70 wt% SiO2), calc-alkaline I-type granites in particular, remain controversial. This paper takes granitic plutons distributed in the coastal region of the Guangdong Province of southeastern China as examples to explore the genesis of such rocks. SIMS zircon U-Pb geochronological data show that the granites were emplaced at 166-159 Ma. These granites can be subdivided generally into two groups on the basis of integrated mineralogical, geochemical, whole-rock Sr-Nd isotopic and in situ zircon Hf-O isotopic studies. The group A granites (SiO2 = 64-72 wt%) are characterised by their common occurrence of amphibole (±titanite) and dominantly metaluminous feature (A/CNK = 0.85-1.03). They are high in K2O (3.5-7.0 wt%) and K2O/Na2O (>1), and have trace element concentrations (e.g., Nb, Y, Zr and Ga) similar to typical I-type granites in the Lachlan Fold Belt, southeastern Australia. Their whole-rock ISr (0.7057-0.7077) and ?Nd(t) (-6.46 to -3.13) are less evolved than many coeval granites in this region. As in situ zircon Hf-O isotopes show little evidence of magma mixing, these granites with low zircon ?18O (6.3-7.9‰) and high ?Hf(t) (-5.9 to -0.2) could have been generated from melting of oxidised high-K basaltic rocks. The group B granites, emplaced to the east of group A granites, are dominantly weakly peraluminous (A/CNK = 1.00-1.05). They have higher SiO2 (70-76 wt%), less common or absence of amphibole, higher zircon ?18O (6.6-9.0‰) and lower ?Hf(t) (-11.4 to -5.9) than the group A granites. Zircon Hf-O isotope data reveal that the group B granites contain higher percentage of supracrustal materials than those of the group A, but the variations of major and trace elements do not support an assimilation and fractional crystallization (AFC) model. Instead, the group B granites, with features transitional between typical I-type and S-type granites, were most likely formed in a region where there was physical juxtaposition between infracrustal metaluminous and supracrustal peraluminous source rocks. Thus, granites of both groups represent products of crustal reworking likely due to asthenosphere upwelling and/or underplating and intrusion of mafic magmas. The close association in time and space of these granites with OIB-like basaltic rocks and the secular compositional change of Jurassic basaltic rocks in the region suggest that these rocks probably formed in an intraplate extensional setting resulted from the delamination of a flat-subducted oceanic slab.

Huang, Hui-Qing; Li, Xian-Hua; Li, Zheng-Xiang; Li, Wu-Xian

2013-09-01

228

Geochemical evolution of magmatism in Archean granite-greenstone terrains  

Science.gov (United States)

Evolution of Archean magmatism is one of the key problems concerning the early formation stages of the Earth crust and biosphere, because that evolution exactly controlled variable concentrations of chemical elements in the World Ocean, which are important for metabolism. Geochemical evolution of magmatism between 3.5 and 2.7 Ga is considered based on database characterizing volcanic and intrusive rock complexes of granite-greenstone terrains (GGT) studied most comprehensively in the Karelian (2.9-2.7 Ga) and Kaapvaal (3.5-2.9 Ga) cratons and in the Pilbara block (3.5-2.9 Ga). Trends of magmatic geochemical evolution in the mentioned GGTs were similar in general. At the early stage of their development, tholeiitic magmas were considerably enriched in chalcophile and siderophile elements Fe2O3, MgO, Cr, Ni, Co, V, Cu, and Zn. At the next stage, calc-alkaline volcanics of greenstone belts and syntectonic TTG granitoids were enriched in lithophile elements Rb, Cs, Ba, Th, U, Pb, Nb, La, Sr, Be and others. Elevated concentrations of both the “crustal” and “mantle-derived” elements represented a distinctive feature of predominantly intrusive rocks of granitoid composition, which were characteristic of the terminal stage of continental crust formation in the GGTs, because older silicic rocks and lithospheric mantle were jointly involved into processes of magma generation. On the other hand, the GGTs different in age reveal specific trends in geochemical evolution of rock associations close in composition and geological position. First, the geochemical cycle of GGT evolution was of a longer duration in the Paleoarchean than in the Meso-and Neoarchean. Second, the Paleoarche an tholeiitic associations had higher concentrations of LREE and HFSE (Zr, Ti, Th, Nb, Ta, Hf) than their Meso-and Neoarchean counterparts. Third, the Y and Yb concentrations in Paleoarchean calc-alkaline rock associations are systematically higher than in Neoarchean rocks of the same type, while their La/Yb ratios are in contrast lower than in the latter. These distinctions are likely caused by evolution of mantle magmatic reservoirs and by changes in formation mechanisms of silicic volcanics and TTG granitoids. The first of these factors was likely responsible for appearance of sanukitoid magmatic rocks in the Late Mesoarchean. Representative database considered in the work includes ca. 500 precision analyses of Archean magmatic rocks.

Samsonov, A. V.; Larionova, Yu. O.

2006-05-01

229

Fractal patterns of fractures in granites  

Science.gov (United States)

Fractal measurements using the Cantor's dust method in a linear one-dimensional analysis mode were made on the fracture patterns revealed on two-dimensional, planar surfaces in four granites. This method allows one to conclude that: 1. (1)|The fracture systems seen on two-dimensional surfaces in granites are consistent with the part of fractal theory that predicts a repetition of patterns on different scales of observation, self similarity. Fractal analysis gives essentially the same values of D on the scale of kilometres, metres and centimetres (five orders of magnitude) using mapped, surface fracture patterns in a Sierra Nevada granite batholith (Mt. Abbot quadrangle, Calif.). 2. (2)|Fractures show the same fractal values at different depths in a given batholith. Mapped fractures (main stage ore veins) at three mining levels (over a 700 m depth interval) of the Boulder batholith, Butte, Mont. show the same fractal values although the fracture disposition appears to be different at different levels. 3. (3)|Different sets of fracture planes in a granite batholith, Central France, and in experimental deformation can have different fractal values. In these examples shear and tension modes have the same fractal values while compressional fractures follow a different fractal mode of failure. The composite fracture patterns are also fractal but with a different, median, fractal value compared to the individual values for the fracture plane sets. These observations indicate that the fractal method can possibly be used to distinguish fractures of different origins in a complex system. It is concluded that granites fracture in a fractal manner which can be followed at many scales. It appears that fracture planes of different origins can be characterized using linear fractal analysis. ?? 1991.

Velde, B.; Dubois, J.; Moore, D.; Touchard, G.

1991-01-01

230

Intrusion detection using secure signatures  

Energy Technology Data Exchange (ETDEWEB)

A method and device for intrusion detection using secure signatures comprising capturing network data. A search hash value, value employing at least one one-way function, is generated from the captured network data using a first hash function. The presence of a search hash value match in a secure signature table comprising search hash values and an encrypted rule is determined. After determining a search hash value match, a decryption key is generated from the captured network data using a second hash function, a hash function different form the first hash function. One or more of the encrypted rules of the secure signatures table having a hash value equal to the generated search hash value are then decrypted using the generated decryption key. The one or more decrypted secure signature rules are then processed for a match and one or more user notifications are deployed if a match is identified.

Nelson, Trent Darnel; Haile, Jedediah

2014-09-30

231

Leaky cable intrusion detection sensors  

International Nuclear Information System (INIS)

Buried Line Field Disturbance Sensors used for the purpose of outdoor perimeter intrusion detection are unique in the sense that they are covert and terrain following. Considerable effort has been spent in recent years to develop an effective Buried Line Sensor using leaky (or ported) cable technology. To date, a modular CW (Continuous Wave) approach to designing such a sensor has proven to be the most effective compromise in terms of cost, performance and installation. Proper design of a leaky cable sensor requires an in-depth knowledge of the coupling performance and attenuation characteristics of the sensor cable to be used. The ''Forward Wave'' (codirectional) method of detection is discussed. This paper contains theoretical and experimental expressions developed to demonstrate operation in terms of cost, performance and ease of installation

232

The distribution of radioelements in Archaean granites of the Kaapvaal Craton, with implications for the source of uranium in the Witwatersrand Basin  

International Nuclear Information System (INIS)

Approximately 500 samples from the Archaean granitic basement of the southern Kaapvaal Craton have been analysed for U and Th. When viewed in conjunction with geological relationships, the radioelement distribution patterns in the Archaean basement provide contraints regarding the origin of uranium in the Witwatersrand Basin. Granites in the Barberton region are sub-divided into three magmatic cycles, the earliest cycle comprising tonalite-trondjemite gneisses, the intermediate cycle comprising laterally extensive K-rich batholiths and the final stage consisting of discrete intrusive granitic plutons. Uranium and thorium contents vary as a function of age and rock type, and increase progressively from the first cycle through to the third cycle. Certain of the late granite plutons may be S-type in origin, have relatively low Th/U ratios, high U contents, and are characterized by accessory minerals dominated by monazite-like phases. The late granite plutons with the highest radioelement contents appear to have formed circa 2,8 Ga ago, an age which coincides with granulite facies metamorphism and uranium-thorium depletion in the lower crust, as recorded in the Vredefort crustal profile. Uranium has been leached from portions of the regolith profile, but also concentrated into leucoxene-rich zones derived from the breakdown of pre-existing titanium-bearing phases. The widespread development of an uraniferous leucoxene protore in weathered source rocks of the Witwatersrand Basin has relevance to the genesis of authigenic U-Ti phases (brannerite) in the reefs themselves. The study of radioelement distribution in Archaean granites adjacent to the Witwatersrand Basin provides a framework within which considerations regarding the origin of the uranium deposits in the basin can be viewed. The secular evolution of the Archaean granitic basement, hydrothermal processes, and palaeoweathering all played a role in the formation of the Witwatersrand deposits. 22 figs., 5 tabs., 51 refs

233

The distribution of radioelements in archaean granites of the Kaapvaal Craton, with implications for the source of uranium in the Witwatersrand Basin  

International Nuclear Information System (INIS)

Approximately 500 samples from the Archaean granitic basement of the southern Kaapvaal Craton have been analysed, for U and Th. When viewed in conjunction with geological relationships, the radioelement distribution patterns in the Archaean basement provide contraints regarding the origin of uranium in the Witwatersrand Basin. Granites in the Baberton region are sub-divided into three magnetic cycles, the earliest cycle comprising tonalite-trondhjemite gneisses, the intermediate cycle comprising literally extensive K-rich batholiths and the final stage consisting of discrete intrusive granitic plutons. Uranium and thorium contents vary as a function of age and rock type, an increase progressively from the first cycle through to the third cycle. Certain of the late granite plutons may have been S-type in origin, have relatively low Th/U ratios, high U contents, and are characterized by accessory minerals dominated by monazite-like phases. The late granite plutons with highest radioelement contents appear to have formed circa 2,8 Ga, an age which coincides with granulite facies metamorphism and uranium-thorium depletion in the lower crust, as recrorded in the Vredeford crustal profile. Uranium has been leached from portions of the regolith profile, but also concentrated into leucoxene-rich zones derived from the breakdown of pre-existing titanium-bearing phases. The widespread development of an uraniferous leucoxene protore in weathered source rocks of the Witwatersrand Basin has relevance to the genesis of authigenic U-Ti phases (brannerite) in the reefs themselves. The study of radioelement distribution in Archaean granites adjacent to the Witwatersrand Basin provides a framework within which considerations regarding the origin of the uranium deposits in the basin can be viewed. The secular evolution of the Archaean granitic basement, hydrothermal processes, and palaeoweathering all played a role in the formation of the Witwatersrand deposits

234

Zircon U-Pb geochronology and elemental and Sr-Nd-Hf isotopic geochemistry of the Daocheng granitic pluton from the Yidun Arc, SW China  

Science.gov (United States)

The Garze-Litang suture zone, located in the eastern part of the Tethyan tectonic domain, is notable for widespread Late Triassic granitic plutons, which are genetically associated with the evolution of the Paleo-Tethys Ocean. The Daocheng granitic pluton in the eastern Yidun Arc, SW China, is located in the middle of the Garze-Litang suture zone and has an outcrop area of ˜2800 km2. In the present study, we report zircon U-Pb ages and elemental and Sr-Nd-Hf isotopic data for the Daocheng granitic intrusion. Secondary ion mass spectrometry and laser ablation inductively coupled plasma mass spectrometry U-Pb analyses on zircons yield consistent ages of ca. 216 Ma for three samples from the pluton. All the Daocheng granitic rocks are enriched in Si (SiO2 = 68.1-76.4%) and large-ion lithophile elements but depleted in high-field-strength elements (e.g., Nb, Ta, and Ti). Mineralogical and geochemical features indicate that these are high-K and calc-alkaline and I-type granites. They are characterized by relatively variable initial 87Sr/86Sr ratios (0.7059-0.7102), negative ?Nd(t) values (-5.7 to -7.8), wide-ranging ?Hf(t) values (-9.8 to +3.4), and two-stage Hf model ages of 1.04 to 1.88 Ga. These isotopic signatures indicate that the source for the Daocheng granite was probably derived from partial melting of a Late Paleoproterozoic to Early Mesoproterozoic mafic-intermediate lower crust with a variably minor addition (ocean triggered the underplating of large-scale mantle-derived magma and provided heat for the anatexis of the lower crust. Hybrid melts including minor depleted mantle-derived magma and lower crustal magma were then generated; these thereafter were continuously injected into a shallow-level chamber and gave rise to the Daocheng granite.

He, De-Feng; Zhu, Wei-Guang; Zhong, Hong; Ren, Tao; Bai, Zhong-Jie; Fan, Hong-Peng

2013-05-01

235

Oxygen- and strontium-isotopic studies of the skye intrusive complex, northwest Scotland  

International Nuclear Information System (INIS)

This dissertation is comprised of three parts, each of which addresses some aspect of the meteoric-hydrothermal fluid/rock interaction which affected the rocks within and near the Skye intrusive complex. Part 1 was undertaken to determine the scale and magnitude of hydrothermal Sr contamination in the Coire Uaigneich Granophyre (CUG). Sr- and O-isotopic and electron microprobe results show that Sr was mobile in the low-18O meteoric-hydrothermal fluids, that Sr-exchange between these fluids and the CUG was limited to thin (less than or equal to 1 cm) zones of bleached and albitized granophyre adjacent to fractures, and that the scale of O-exchange was much larger. Part 2 focuses on the stable isotopic and mineralogical compositions of the Beinn an Dubhaich Granite and its Durness Limestone host rocks. Part 3 is an attempt to discriminate between magmatic and subsolidus 18O depletions in porphyritic felsitic dikes from two widely separated regions of the intrusive complex. Eastern Red Hills felsites, collected approximately 9 km from the exposed margin of the Cuillins intrusion, probably crystallized from O-isotopically normal magmas. Empirical and experimental data on the kinetics of volume diffusion of oxygen in feldspar minerals and quartz (in the presence of H2O) suggest that the 18O depletion in quartz and feldspar from the SPF may be attributed to very high-temperature (>6000C) subsolidus exchange with circulating low-18O fluids

236

The Late Archaean Qôrqut Granite Complex of southern west Greenland  

Science.gov (United States)

Granites and granite pegmatites composing the ˜ 2550-Ma Qôrqut granite complex occur in a SSW-NNE trending linear belt >150 km long extending through the Buksefjorden-Ameralik-Godthåbsfjord region of southern West Greenland. The main body of the complex crops out over a distance of 50 km from Ameralik to Kapisigdlit kangerdluat and reaches a maximum outcrop width of 18 km between Storø and Qôrqut. Around Qôrqut the complex comprises three main groups of granites: early leucocratic granites, various grey biotite granites, and late aplogranite-granite pegmatites. Within the 1500-m vertical section available in this area the complex has a tripartite structure comprising a lower zone dominantly of polyphase granite, an intermediate zone where country rock occurs as rafts in polyphase granite with a complex sheeted structure, and an upper zone dominantly of country rock sheeted by granite. Fifty-two specimens of granite have been analyzed for major, minor, and some trace elements. Geochemical variation within the complex is consistent with either fractional crystallization or partial melting, but in both cases, feldspar + biotite must have been involved either as fractionating phases or as residual phases during melting to account for the trace element chemistry. Two possible models for the generation of the complex are either anatexis of granulite facies rocks in the lower crust following an influx of volatiles and heat from the mantle or melting at intermediate depths of amphibolite facies rocks with volatiles supplied by breakdown of hydrous phases.

Brown, Michael; Friend, C. R. L.; McGregor, V. R.; Perkins, W. T.

1981-11-01

237

Dolichol levels in younger and older rat hearts heterotopically transplanted in younger recipients.  

Science.gov (United States)

Dolichol (D) levels increase dramatically in older tissue. An understanding of the exchangeability of D between tissues may be essential in order to understand the mechanism of the abnormal accumulation associated with aging. The question was investigated by the use of organ transplantation. D-poor hearts donated by 3-mon-old and D-rich by 22-mon-old male Lewis rats were transplanted heterotopically in 3-mon-old syngenic recipients, whose peripheral tissues and liver were poor in D. Native and transplanted hearts were taken 7 and 21 d after surgery. Native hearts of 3-mon- and 22-mon-old male Lewis rats served as control. D concentration and quantity were higher in older than in younger native hearts as expected. In the transplanted hearts, the quantity of D was unchanged, irrespective of the age of the donor and of the time of transplantation, whereas D concentration increased because of the remarkable disuse atrophy. No changes in D were observed in recipients' tissues. It is concluded that dolichol is not redistributed via circulation from the transplanted heart to the tissues and liver of the younger recipient. PMID:12458628

Cavallini, Gabriella; Parentini, Ilaeia; Di Stefano, Rossella; Maccheroni, Marco; Masini, Matilde; Pollera, Maria; Gori, Zina; Mosca, Franco; Bergamini, Ettore

2002-09-01

238

2005 dossier: granite. Tome: phenomenological evolution of the geologic disposal  

International Nuclear Information System (INIS)

This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the phenomenological aspects of the geologic disposal of high-level and long-lived radioactive wastes (HLLL) in granite formations. Content: 1 - introduction: ANDRA's research program on disposal in granitic formation; 2 - the granitic environment: geologic history, French granites; 3 - HLLL wastes and disposal design concepts; 4 - identification, characterization and modeling of a granitic site: approach, geologic modeling, hydrologic and hydro-geochemical modeling, geomechanical and thermal modeling, long-term geologic evolution of a site; 5 - phenomenological evolution of a disposal: main aspects of the evolution of a repository with time, disposal infrastructures, B-type wastes disposal area, C-type wastes disposal area; spent fuels disposal area, radionuclides transfer and retention in the granitic environment; 6 - conclusions: available knowledge, methods and tools for the understanding and modeling of the phenomenological evolution of a granitic disposal site. (J.S.)

239

Rb-Sr geochronology and petrogenesis of granitoids from the Chhotanagpur granite gneiss complex of Raikera-Kunkuri region, Central India  

International Nuclear Information System (INIS)

The Precambrian Chhotanagpur granite gneiss complex (CGGC) terrain covers more than 80,000 sq km area, and is dominated by granitoid gneisses and migmatites. Recent geochronological data indicate that the CGGC terrain has witnessed five tectonomagmatic thermal events at: (i) 2.5-2.4 Ga, (ii) 2.2-2.0 Ga (iii)1.6-1.4 Ga (iv) 1.2-1.0 Ga and (v) 0.9-0.8 Ga. Of these, the third and the fourth events are widespread. The whole-rock Rb-Sr isotopic analysis of twenty granite samples from the CGGC of Raikera-Kunkuri region, Jashpur district, Chhattisgarh, Central India yields two distinct isochrons. The eleven samples of grey granites define an isochron age of 1005±51 Ma with moderate initial 87Sr/86Sr ratio of 0.7047±0.0065, which corresponds to the fourth tectonomagmatic event. On the other hand, the nine samples of pink granites indicate younger isochron age of 815±47 Ma with a higher initial 87Sr/86Sr ratio of 0.7539±0.0066 that matches with the fifth phase of the thermal event. The data suggest emplacement of large bodies of grey granite at ?1005 Ma that evolved possibly from precursors of tonalitic-granodioritic composition. Furthermore, the younger age (? 815 Ma) suggests the age of metasomatism, involving isotopic resetting, that resulted in genesis of pink granite bodies of limited areal extent. By analogy, the age of metasomatism (?815 Ma) may also be taken to represent the age of Y-mineralisation in the Raikera-Kunkuri region of the CGGC terrain. (author)

240

Early Precambrian crustal evolution in Eastern India: The ages of the Singhbhum granite and included remnants of older gneiss  

Science.gov (United States)

Geochronology of samples from the Indian Shield was discussed. New Sm-Nd data was given for the Singhbhum granite, which give model ages (T sub DM of 3.36 to 3.40 Ga, essentially equivalent to ages of included gneissic remnants of the older metamorphic group (OMG) (T sub DM = 3.35 to 3.41 Ga). Lead-lead and Rb-Sr ages of the granite and OMG range between 3.28 to 3.38 Ga. These results are considerably younger than the 3775 + or - 89 Ma Sm-Nd isochron of Basu et al., which Taylor and colleagues interpret as an artifact caused by regressing two suites of unrelated rock samples.

Moorbath, Stephen; Taylor, Paul N.

 
 
 
 
241

The role of estrogen in intrusive memories.  

Science.gov (United States)

Intrusive memories are highly vivid, emotional and involuntary recollections which cause significant distress across psychological disorders including posttraumatic disorder (PTSD). Recent evidence has potentially extended our understanding of the development of intrusive memories by identifying biological factors which significantly impact on memories for emotionally arousing stimuli. This study investigated the role of stress on the development of intrusions for negative and neutral images, and indexed the potential contributions of sex (estrogen and progesterone) and stress (noradrenaline and cortisol) hormones. Whilst viewing the images, half the participants underwent a cold pressor stress (CPS) procedure to induce stress while the control participants immersed their hands in warm water. Saliva samples were collected to index estrogen, progesterone and noradrenergic and cortisol response. Participants (55 university students, 26 men, 29 women) viewed a series of negatively arousing and neutral images. Participants completed recall and intrusions measures 2 days later. Negative images resulted in greater recall and more intrusions than neutral images. In the cold water condition females recalled fewer neutral memories than males. Cortisol increase predicted decreased recall of negative memories in males, and estrogen predicted increased intrusions of negative images in women. These findings are consistent with evidence that circulating levels of ovarian hormones influence memory for emotionally arousing events, and provides the first evidence of the influence of sex hormones on intrusive memories. These results provide one possible explanation for the higher incidence of anxiety disorders in women. PMID:23891994

Cheung, Jessica; Chervonsky, Liza; Felmingham, Kim L; Bryant, Richard A

2013-11-01

242

Innovative Method for Saltwater Intrusion Control  

Directory of Open Access Journals (Sweden)

Full Text Available Salt water intrusion is the migration of saltwater into freshwater aquifers under the influence of groundwater development (Freeze and Cherry, 1979. The most detrimental effect that ground water depletion causes lowering of water table. Another problem due to saltwater intrusion is changing saltwater freshwater interface. Methods for controlling intrusion vary widely depending on the source of the saline water, the extent of intrusion, local geology, water use and economic factors. The proposed methodology to control saltwater intrusion is (ADR Abstraction, Desalination and Recharge. The proposed methodology interplays between the major parameters of the system to control saltwater intrusion. These parameters include the soil/aquifer properties, the well locations, the well depths, the rates and the relation between the abstraction and recharge rates which depends on the recovery rate and the salinity degree. It is capable of completely preventing saltwater intrusion because it increases the volume of fresh groundwater and decreases the volume of saltwater, while considering economical aspects, environmental impact and sustainable development of water resources.

Z. Payal

2014-02-01

243

The Younger Dryas impact hypothesis: A requiem  

Science.gov (United States)

The Younger Dryas (YD) impact hypothesis is a recent theory that suggests that a cometary or meteoritic body or bodies hit and/or exploded over North America 12,900 years ago, causing the YD climate episode, extinction of Pleistocene megafauna, demise of the Clovis archeological culture, and a range of other effects. Since gaining widespread attention in 2007, substantial research has focused on testing the 12 main signatures presented as evidence of a catastrophic extraterrestrial event 12,900 years ago. Here we present a review of the impact hypothesis, including its evolution and current variants, and of efforts to test and corroborate the hypothesis. The physical evidence interpreted as signatures of an impact event can be separated into two groups. The first group consists of evidence that has been largely rejected by the scientific community and is no longer in widespread discussion, including: particle tracks in archeological chert; magnetic nodules in Pleistocene bones; impact origin of the Carolina Bays; and elevated concentrations of radioactivity, iridium, and fullerenes enriched in 3He. The second group consists of evidence that has been active in recent research and discussions: carbon spheres and elongates, magnetic grains and magnetic spherules, byproducts of catastrophic wildfire, and nanodiamonds. Over time, however, these signatures have also seen contrary evidence rather than support. Recent studies have shown that carbon spheres and elongates do not represent extraterrestrial carbon nor impact-induced megafires, but are indistinguishable from fungal sclerotia and arthropod fecal material that are a small but common component of many terrestrial deposits. Magnetic grains and spherules are heterogeneously distributed in sediments, but reported measurements of unique peaks in concentrations at the YD onset have yet to be reproduced. The magnetic grains are certainly just iron-rich detrital grains, whereas reported YD magnetic spherules are consistent with the diffuse, non-catastrophic input of micrometeorite ablation fallout, probably augmented by anthropogenic and other terrestrial spherular grains. Results here also show considerable subjectivity in the reported sampling methods that may explain the purported YD spherule concentration peaks. Fire is a pervasive earth-surface process, and reanalyses of the original YD sites and of coeval records show episodic fire on the landscape through the latest Pleistocene, with no unique fire event at the onset of the YD. Lastly, with YD impact proponents increasingly retreating to nanodiamonds (cubic, hexagonal [lonsdaleite], and the proposed n-diamond) as evidence of impact, those data have been called into question. The presence of lonsdaleite was reported as proof of impact-related shock processes, but the evidence presented was inconsistent with lonsdaleite and consistent instead with polycrystalline aggregates of graphene and graphane mixtures that are ubiquitous in carbon forms isolated from sediments ranging from modern to pre-YD age. Important questions remain regarding the origins and distribution of other diamond forms (e.g., cubic nanodiamonds). In summary, none of the original YD impact signatures have been subsequently corroborated by independent tests. Of the 12 original lines of evidence, seven have so far proven to be non-reproducible. The remaining signatures instead seem to represent either (1) non-catastrophic mechanisms, and/or (2) terrestrial rather than extraterrestrial or impact-related sources. In all of these cases, sparse but ubiquitous materials seem to have been misreported and misinterpreted as singular peaks at the onset of the YD. Throughout the arc of this hypothesis, recognized and expected impact markers were not found, leading to proposed YD impactors and impact processes that were novel, self-contradictory, rapidly changing, and sometimes defying the laws of physics. The YD impact hypothesis provides a cautionary tale for researchers, the scientific community, the press, and the broader public.

Pinter, Nicholas; Scott, Andrew C.; Daulton, Tyrone L.; Podoll, Andrew; Koeberl, Christian; Anderson, R. Scott; Ishman, Scott E.

2011-06-01

244

The SHRIMP zircon U-Pb dating and its geological significance on the volcanic-intrusive rocks in broken crater of Xunwu, Jiangxi province  

International Nuclear Information System (INIS)

Xunwu broken crater located in the transition zone of Wuyi rise belt and Nanling tectonic belt, controlled by the NE direction Huichang-Xunwu fault belt and the EW direction Sannan-Xunwu fault belt,and developed a volcanic-intrusive rocks that made up of porphyroclastic lava and granite-porphyry. The zircon U-Pb dating with a higher accuracy yields the following results: the age of pyroclastic rocks in the volcanic-intrusive rocks in broken crater is (96.7±1.1) Ma and the age of granite-porphyry is (97.3±0.9) Ma. According to the geological chronology,the boundary between the Early Cretaceous and the Late Cretaceous is (99.6±0.9)Ma, the geological age of the volcanic-intrusive rocks of Xunwu broken crater is early Late Cretaceous. Age determinations of the volcanic-intrusive rocks provide the age evidence for Xunwu broken crater which belong to Yousheng formation. (authors)

245

Geochronological (Rb-Sr and Sm-Nd) studies on intrusive gabbro and dolerite dykes from parts of Northern and Central Indian cratons: implications for the age of onset of sedimentation in Bijawar and Chattisgarh basins and uranium mineralisation  

International Nuclear Information System (INIS)

The Dargawan gabbros intrusive into the Moli Subgroup of Bijawar Group, yielded Rb-Sr whole rock isochron age of 1967 ± 140 Ma. Based on the oldest age from overlying Lower Vindhyan (1.6 Ga) and the underlying youngest basement ages (2.2 Ga), the time range of Bijawar sedimentation may be assigned as 2.1-1.6 Ga (Paleoproterozoic). Sm-Nd Model ages (TDM), obtained, for Dargawan gabbros, is c. 2876-3145 Ma. High initial 87Sr/86Sr ratio of 0.70451 (higher than the contemporary mantle) and negative ?Ndi (at 1.9 Ga) value of -1.5 to - 4.5, indicate assimilation of Archaean lower crustal component by the enriched mantle source magma at the time of gabbroic intrusion. The dolerite, from Damdama area, which is intrusive into the basement and overlying sediments of Chandrapur Group in the central Indian craton, yielded Rb-Sr internal isochron age of 1641 ± 120 Ma. The high initial 87Sr/86Sr ratio of 0.7098 and ?Ndi value of -3.5 to -3.7 (at 1.6 Ga) is due to contamination of the mantle source magma with the overlying sediments. These dolerites have younger Sm-Nd Model ages (TDM) than Dargawan gabbros as c. 2462-2675 Ma, which is similar to the age of the Sambalpur granite, from which probably sediments to this part of Chattisgarh basin are derived. Hence mixing of sediments with the Damdama dyke during its emplacement, gives rise to high initial 87Sr/86Sr and low ip>87Sr/86Sr and low initial 143Nd/144 ratios for these dykes. The c. 1600 Ma age indicates minimum age of onset of the sedimentation in the Chandrapur Group of Chattisgarh basin. Both the above mafic intrusions might have taken place in an intracratonic rift related (anorogenic) tectonic setting. This study is the first reliable age report on the onset of sedimentation in the Chandrapur Group. The total minimum time span of Chandrapur and Raipur Group may be 1.6 Ga to 1.0 Ga (Mesoproterozoic). The unconformably underlying Shingora Group of rocks of Chattisgarh Supergroup thus indicates Paleoproterozoic age (older than 1.6 Ga). Most part of the recently classified Chattisgarh Supergroup and Bijawar-Vindhyan sequence are of Mesoproterozoic-Paleoproterozoic age and not of Neoproterozoic-Mesoproterozoic age as considered earlier. Petrographic study of basic dykes from Damdama area (eastern margin of Chattisgarh Supergroup) indicated presence of primary uranium mineral brannerite associated with goethite. This is the evidence of mafic intrusive providing geotherm and helping in scavenging the uranium from the surrounding and later alterations causing remobilisation and reconcentration of pre-existing uranium in host rocks as well as in mafic dyke itself otherwise mafic rocks are poor source of uranium and can not have primary uranium minerals initially. It can be concluded that mafic dykes have role in uranium mineralisation although indirectly. (author)

246

A Novel Approach for Intrusion Detection  

Directory of Open Access Journals (Sweden)

Full Text Available Research in the field of computer and network science demands for tools and methodology to test their security effectively. Intrusion Detection System is used to perform the same with a fact that an intruder's behavior will be noticeably different from that of a legitimate user and would exploit security vulnerabilities. Proposed here is a novel intrusion detection approach with the application of Generalized Regression Neural Network and the MIT's KDD Cup 99 dataset. The result clearly demonstrates an efficient way for intrusion feature selection and detection and promises a good scope for further research.

Vikram Chopra

2011-07-01

247

Signature Based Intrusion Detection System Using SNORT  

Directory of Open Access Journals (Sweden)

Full Text Available Now a day’s Intrusion Detection systems plays very important role in Network security. As the use of internet is growing rapidly the possibility of attack is also increasing in that ratio. People are using signature based IDS’s. Snort is mostly used signature based IDS because of it is open source software. World widely it is used in intrusion detection and prevention domain. Basic analysis and security engine (BASE is also used to see the alerts generated by Snort. In the paper we have implementation the signature based intrusion detection using Snort. Our work will help to novel user to understand the concept of Snort based IDS.

Vinod Kumar

2012-11-01

248

Diffusion interfaces of fractures in granitic rocks  

International Nuclear Information System (INIS)

The report presents a method to describe pore space around the major fractures in granitic rocks. The method is based on conventional technique, such as microscopy, porosity measurements and chemical analyses. The results are presented as profiles perpendicular to the fracture surface. Two types of open fracture and a partially filled carbonate fracture. In the examined cases, about 80 - 90 % of the range of variations in porosity and chemical contents were related to the first 4 - 5 mm from the fracture surface into the rock matrix. Porosity of the interface was decreased down to the reported average porosity of granites (5.2 - 0.4 % vol) within 10 - 20 mm from the fracture surface. Porosity profiles were not, however, completely stabilized within this distance. The marked trends in chemical profiles are caused by both deformation history of the rock and recent interaction between rock and water in pore space. Porosity and geochemical profiles are observed fracture specific

249

Performance assessment of geological isolation systems for radioactive waste. Disposal in granite formations  

International Nuclear Information System (INIS)

In the framework of the PAGIS project of the CEC Research Programme on radioactive wastes, a performance assessment of a repository of vitrified HLW in granite was carried out. Three disposal sites were considered: the reference site Auriat and two alternative sites, Barfleur and a site in the U.K. The report describes the methodology adopted (a deterministic and a stochastic approach) with the corresponding data base and the models used. A parametric study of sub-systems (near field, far field and biosphere) was carried out by CEA-ANDRA using AQUARIUS, DIMITRIO and BIOS. A global evaluation of the performances was carried out by CEA-IPSN using MELODIE code. The results of deterministic calculations showed for Auriat a maximum dose equivalent evaluated at 6.10-3m Sv/a arising 3 millions years after disposal. Results of human intrusion scenario analyses, uncertainty analyses and global sensitivity analyses are presented. This document is one of a set of 5 reports covering a relevant project of the European Community on a nuclear safety subject having very wide interest. The five volumes are: the summary (EUR 11775-EN), the clay (EUR 11776-EN), the granite (EUR 11777-FR), the salt (EUR 11778-EN) and the sub-seabed (EUR 11779-EN)

250

Geology and tin-greisen mineralization of the Akash granite, northern Arabian Shield  

Science.gov (United States)

The western margin of the postorogenic Akash granite, 30 km E of Ha'il in the northern Arabian Shield, is greisenized and contains anomalous concentrations of Sn. The pluton intrudes metamorphic and intrusive rocks, and crops out as a 10 by 15 km elliptical body with its long axis oriented N. It consists predominantly of metaluminous alkali-feldspar granite or syenogranite, with accessory biotite and muscovite, and traces of fluorite. Greisenization extends discontinuously in a zone at least 3 km long parallel to the western contact, and along E-trending hematitic quartz veins for more than 2 km from the contact. The veins occupy fractures that were probably conduits for ascending mineralizing fluids. Within about 20 m of the contact, they are enclosed in quartz-white mica greisen containing hematite, fluorite, and locally, topaz and cassiterite. Composite chip samples from the greisenized zone have an average Sn content of 710 ppm, and a maximum of 1600 ppm. Anomalous values for Zn, Fe, Mn, Mo, Bi and Cu also occur, but none of the samples contain detectable W. Three samples of hematitic quartz averaged 126 ppm Sn, and one contained 200 ppm W. ?? 1986.

Kellogg, K. S.; Smith, C. W.

1986-01-01

251

AIDE - Advanced Intrusion Detection Environment  

Energy Technology Data Exchange (ETDEWEB)

Would you like to know when someone has dropped an undesirable executable binary on our system? What about something less malicious such as a software installation by a user? What about the user who decides to install a newer version of mod_perl or PHP on your web server without letting you know beforehand? Or even something as simple as when an undocumented config file change is made by another member of the admin group? Do you even want to know about all the changes that happen on a daily basis on your server? The purpose of an intrusion detection system (IDS) is to detect unauthorized, possibly malicious activity. The purpose of a host-based IDS, or file integrity checker, is check for unauthorized changes to key system files, binaries, libraries, and directories on the system. AIDE is an Open Source file and directory integrity checker. AIDE will let you know when a file or directory has been added, deleted, modified. It is included with the Red Hat Enterprise 6. It is available for other Linux distros. This is a case study describing the process of configuring AIDE on an out of the box RHEL6 installation. Its goal is to illustrate the thinking and the process by which a useful AIDE configuration is built.

Smith, Cathy L.

2013-04-28

252

Alpha intrusion on ovenight polysomnogram  

Directory of Open Access Journals (Sweden)

Full Text Available No abstract available. Article truncated after 150 words. A 30 year-old Army veteran with a past medical history significant for chronic lumbar back pain stemming from a fall-from-height injury sustained in 2006 was referred to the sleep laboratory for evaluation of chronic fatigue and excessive daytime hypersomnolence. His Epworth sleepiness scale score was 16. He denied a history of snoring and witnessed apnea. Body Mass Index (BMI was 25.7 kg/m2. His main sleep related complaints were frequent nocturnal arousals, poor sleep quality, un-refreshing sleep, prolonged latency to sleep onset, and nightmares. An In-lab attended diagnostic polysomnogram was performed. Sleep efficiency was reduced (73% and overall arousal index was not significantly elevated (3.2 events/hour. The sleep study showed rapid eye movement (REM related sleep disordered breathing that did not meet diagnostic criteria for sleep apnea. There was no evidence for period limb movement disorder. However, the study was significant for alpha wave intrusion in stage N2 non-REM and stage ...

Nahapetian R

2014-06-01

253

Perimeter intrusion detection and assessment system  

Energy Technology Data Exchange (ETDEWEB)

The key elements of the system considered at a materials storage site are intrusion sensors, alarm assessment, and system control and display. Three papers discussing each of these topics are compiled. They are abstracted individually. (JSR)

Eaton, M.J.; Jacobs, J.; McGovern, D.E.

1977-01-01

254

Prevention and analysis of hacker's intrusion  

International Nuclear Information System (INIS)

The author analyzes the behavior characteristics and relevant technologies about the hacker's intrusion, and gives some corresponding solutions pertinently. To the recent events about hackers, the author gives detailed introduction and puts forward the relevant advice and valuable consideration

255

STATISTICAL TECHNIQUES IN ANOMALY INTRUSION DETECTION SYSTEM  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, we analyze an anomaly based intrusion detection system (IDS for outlier detection in hardware profile using statistical techniques: Chi-square distribution, Gaussian mixture distribution and Principal component analysis. Anomaly detection based methods can detect new intrusions but they suffer from false alarms. Host based Intrusion Detection Systems (HIDSs use anomaly detection to identify malicious attacks i.e. intrusion. The features are shown by large set of dimensions and the system becomes extremely slow during processing this huge amount of data (especially, host based. We show the comparative results using three different approaches: Principal Component Analysis (PCA, Chi-square distribution and cluster with Gaussian mixture distribution. We get good results using these techniques.

Hari Om

2012-11-01

256

Intrusion Detection Architecture Utilizing Graphics Processors  

Directory of Open Access Journals (Sweden)

Full Text Available With the thriving technology and the great increase in the usage of computer networks, the risk of having these network to be under attacks have been increased. Number of techniques have been created and designed to help in detecting and/or preventing such attacks. One common technique is the use of Intrusion Detection Systems (IDS. Today, number of open sources and commercial IDS are available to match enterprises requirements. However, the performance of these systems is still the main concern. This paper examines perceptions of intrusion detection architecture implementation, resulting from the use of graphics processor. It discusses recent research activities, developments and problems of operating systems security. Some exploratory evidence is presented that shows capabilities of using graphical processors and intrusion detection systems. The focus is on how knowledge experienced throughout the graphics processor inclusion has played out in the design of intrusion detection architecture that is seen as an opportunity to strengthen research expertise.

Branislav Madoš

2012-12-01

257

Autonomous Rule Creation for Intrusion Detection  

Energy Technology Data Exchange (ETDEWEB)

Many computational intelligence techniques for anomaly based network intrusion detection can be found in literature. Translating a newly discovered intrusion recognition criteria into a distributable rule can be a human intensive effort. This paper explores a multi-modal genetic algorithm solution for autonomous rule creation. This algorithm focuses on the process of creating rules once an intrusion has been identified, rather than the evolution of rules to provide a solution for intrusion detection. The algorithm was demonstrated on anomalous ICMP network packets (input) and Snort rules (output of the algorithm). Output rules were sorted according to a fitness value and any duplicates were removed. The experimental results on ten test cases demonstrated a 100 percent rule alert rate. Out of 33,804 test packets 3 produced false positives. Each test case produced a minimum of three rule variations that could be used as candidates for a production system.

Todd Vollmer; Jim Alves-Foss; Milos Manic

2011-04-01

258

Numerical investigation of transient hydrothermal processes around intrusions: Heat-transfer and fluid-circulation controlled mineralization patterns  

Science.gov (United States)

New insights on the circulation of fluids around magmatic intrusions have been obtained through coupled hydrothermal numerical modelling that takes into account i) a continuous variation of permeability with depth, ii) the period of intrusion emplacement, iii) the physical likelihood of ore deposition using a restricted rock alteration index, and iv) the so-far unexplored pluton floor, and then comparing the results against well-constrained natural cases showing different emplacement depths, high permeability zones (cracked thermal aureoles), faults and plutonic apexes. We show that emplacement depth is a key physical parameter controlling the extent and geometries of advective heat dissipation zones, and that shallow apexes strongly modify the fluid-flow pattern by acting as a focus for convective fluids and mineralization zones. We also show that the cooling phase is not the main convective phase for large plutons commonly associated with long-lived magma emplacement; major advective heat dissipation and mineral deposition zones may also develop before and during the hottest phase of the emplacement, i.e. before magma crystallization. The comparison with natural cases shows that we successfully reproduce, in space and time, the physical conditions required for mineral deposition. In particular, extensional detachment is able to restrain and modify classical fluid-flow patterns induced by coeval intrusion. Finally, even though lacking chemical arguments, we conclude that convection induced by granite emplacement plays a major role in the genesis of granite-related Au deposits. Moreover, the formation of this type of deposit is favoured and controlled by the presence of a fractured thermal aureole around the intrusion.

Eldursi, Khalifa; Branquet, Yannick; Guillou-Frottier, Laurent; Marcoux, Eric

2009-10-01

259

Using internal sensors for computer intrusion detection  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This dissertation introduces the concept of using internal sensors to perform intrusion detection in computer systems. It shows its practical feasibility and discusses its characteristics and related design and implementation issues. ^ We introduce a classification of data collection mechanisms for intrusion detection systems. At a conceptual level, these mechanisms are classified as direct and indirect monitoring. At a practical level, direct monitoring can be implemented using external or...

Zamboni, Diego

2001-01-01

260

Sr and Nd isotopic characteristics of 1.77-1.58 Ga rift-related granites and volcanics of the Goias tin province, Central Brazil  

International Nuclear Information System (INIS)

Supracrustal rocks of the Arai Group, together with coeval A-type granites represent a ca. 1.77-1.58 Ga old continental rift in Brazil. Two granite families are identified: the older (1.77 Ga) group forms small undeformed plutons, and the younger granites (ca. 1.58 Ga) constitute larger, deformed plutons. Sr-Nd isotopic data for these rocks indicate that the magmatism is mostly produced of re-melting of Paleoproterozoic sialic crust. Initial Sr ratios for both granite families are ca 0.276 and 0.720. Most TDM model ages are between 2.58 and 1.80 Ga. ?Nd (T) values are between +3.6 and -11.9. Arai volcanics are bimodal, with basalts and dacites/rhyolites interlayered with continental sediments. The felsic volcanics show Nd isotopic characteristics which are very similar to the granites, and are also interpreted as reworking of Paleoproterozoic crust. Detrital sediments of the Arai Group revealed TDM model ages between 2.4 and 2.16 Ga., indicating that they are the product of erosion of Paleoproterozoic crust. The data indicate that the Arai rift system was established on crust that had just become stable after the Paleoproterozoic orogeny. (author)

 
 
 
 
261

A fluid inclusion and stable isotope study of 200 Ma of fluid evolution in the Galway Granite, Connemara, Ireland  

Science.gov (United States)

Fluid inclusions in granite quartz and three generations of veins indicate that three fluids have affected the Caledonian Galway Granite. These fluids were examined by petrography, microthermometry, chlorite thermometry, fluid chemistry and stable isotope studies. The earliest fluid was a H2O-CO2-NaCl fluid of moderate salinity (4-10 wt% NaCl eq.) that deposited late-magmatic molybdenite mineralised quartz veins (V1) and formed the earliest secondary inclusions in granite quartz. This fluid is more abundant in the west of the batholith, corresponding to a decrease in emplacement depth. Within veins, and to the east, this fluid was trapped homogeneously, but in granite quartz in the west it unmixed at 305-390°C and 0.7-1.8 kbar. Homogeneous quartz ?18O across the batholith (9.5+/- 0.4‰n=12) suggests V1 precipitation at high temperatures (perhaps 600°C) and pressures (1-3 kbar) from magmatic fluids. Microthermometric data for V1 indicate lower temperatures, suggesting inclusion volumes re-equilibrated during cooling. The second fluid was a H2O-NaCl-KCl, low-moderate salinity (0-10 wt% NaCl eq.), moderate temperature (270-340°C), high ?D (-18+/-2‰), low ?18O (0.5-2.0‰) fluid of meteoric origin. This fluid penetrated the batholith via quartz veins (V2) which infill faults active during post-consolidation uplift of the batholith. It forms the most common inclusion type in granite quartz throughout the batholith and is responsible for widespread retrograde alteration involving chloritization of biotite and hornblende, sericitization and saussuritization of plagioclase, and reddening of K-feldspar. The salinity was generated by fluid-rock interactions within the granite. Within granite quartz this fluid was trapped at 0.5-2.3 kbar, having become overpressured. This fluid probably infiltrated the Granite in a meteoric-convection system during cooling after intrusion, but a later age cannot be ruled out. The final fluid to enter the Granite and its host rocks was a H2O-NaCl-CaCl2-KCl fluid with variable salinity (8-28 wt% NaCl eq.), temperature (125-205°C), ?D (-17 to -45‰), ?18O (-3 to+1.2‰), ?13CCO2 (-19 to 0‰) and ?34Ssulphate (13-23‰) that deposited veins containing quartz, fluorite, calcite, barite, galena, chalcopyrite sphalerite and pyrite (V3). Correlations of salinity, temperature, ?D and ?18O are interpreted as the result of mixing of two fluid end-members, one a high-?D (-17 to -8‰), moderate-?18O (1.2-2.5‰), high-?13CCO2 (> -4‰), low-?34Ssulphate (13‰), high-temperature (205-230°C), moderate-salinity (8-12 wt% NaCl eq.) fluid, the other a low-?D (-61 to -45‰), low-?18O (-5.4 to -3‰), low-?13C (V3 veins are late Triassic; the high-?D end-member is interpreted as a contemporaneous surface fluid, probably mixed meteoric water and evaporated seawater and/or dissolved evaporites, whereas the low-?D end-member is interpreted as a basinal brine derived from the adjacent Carboniferous sequence. This study demonstrates that the Galway Granite was a locus for repeated fluid events for a variety of reasons; from expulsion of magmatic fluids during the final stages of crystallisation, through a meteoric convection system, probably driven by waning magmatic heat, to much later mineralisation, concentrated in its vicinity due to thermal, tectonic and compositional properties of granite batholiths which encourage mineralisation long after magmatic heat has abated.

O'Reilly, C.; Jenkin, G. R. T.; Feely, M.; Alderton, D. H. M.; Fallick, A. E.

262

A system for distributed intrusion detection  

Energy Technology Data Exchange (ETDEWEB)

The study of providing security in computer networks is a rapidly growing area of interest because the network is the medium over which most attacks or intrusions on computer systems are launched. One approach to solving this problem is the intrusion-detection concept, whose basic premise is that not only abandoning the existing and huge infrastructure of possibly-insecure computer and network systems is impossible, but also replacing them by totally-secure systems may not be feasible or cost effective. Previous work on intrusion-detection systems were performed on stand-alone hosts and on a broadcast local area network (LAN) environment. The focus of our present research is to extend our network intrusion-detection concept from the LAN environment to arbitarily wider areas with the network topology being arbitrary as well. The generalized distributed environment is heterogeneous, i.e., the network nodes can be hosts or servers from different vendors, or some of them could be LAN managers, like our previous work, a network security monitor (NSM), as well. The proposed architecture for this distributed intrusion-detection system consists of the following components: a host manager in each host; a LAN manager for monitoring each LAN in the system; and a central manager which is placed at a single secure location and which receives reports from various host and LAN managers to process these reports, correlate them, and detect intrusions. 11 refs., 2 figs.

Snapp, S.R.; Brentano, J.; Dias, G.V.; Goan, T.L.; Heberlein, L.T.; Ho, Che-Lin; Levitt, K.N.; Mukherjee, B. (California Univ., Davis, CA (USA). Div. of Computer Science); Grance, T. (Air Force Cryptologic Support Center, San Antonio, TX (USA)); Mansur, D.L.; Pon, K.L. (Lawrence Livermore National Lab., CA (USA)); Smaha, S.E. (Haystack Labs., Inc., Austin, TX (USA))

1991-01-01

263

Network Intrusion Detection using Support Vector Regression  

Directory of Open Access Journals (Sweden)

Full Text Available Data Mining is the use of algorithms to extract the information and patterns derived by the knowledge discovery in databases process. Classification maps data into predefined groups or classes. It is often referred to as supervised learning because the classes are determined before examining the data. This paper addresses using ensemble approach of Support Vector Regression for intrusion detection. Due to increasing incidents of cyber attacks, building effective intrusion detection systems (IDS are essential for protecting information systems security, and yet it remains an elusive goal and a great challenge. The feasibility and the benefits of the proposed approach are demonstrated by means of data mining problem: Network Intrusion Detection. Intrusion detection systems help network administrators prepare for and deal with network security attacks. These systems collect information from a variety of systems and network sources, and analyze them for signs of intrusion and misuse.  We show that proposed ensemble of Support Vector Regression is superior to individual approach for intrusion detection in terms of classification rate.

Govindarajan Muthukumarasamy

2011-04-01

264

Mobile Agents in Intrusion Detection System: Review and Analysis  

Directory of Open Access Journals (Sweden)

Full Text Available Intrusion Detection System (IDS is used to detect intrusion and then alert the system administrator about the intrusion. This is what traditional IDS is all about. It is then up to the system administrator to deal with the intrusion. Human intervention is still needed when it comes to dealing with intrusion. This is because traditional IDS could only detect the intrusion but could not, on its own respond towards the intrusion. IDS is only able to alert the system administrator when it detects an intrusion. How and when the intrusion is dealt with is up to the system administrator. Human intervention when dealing with intrusion is not a problem if the person assigned to that task is always reliable. Therefore, this paper analyzes the evolution of IDS and how mobile agents such as SNORT could increase the integrity of traditional systems without human intervention.

Kamaruzaman Maskat

2011-11-01

265

Zircon U-Pb and Hf-Nd isotopic constraints on the genesis of granites from the vicinity of Bosumtwi crater  

Science.gov (United States)

The well preserved Bosumtwi crater (Ghana), 10.5 km in diameter and 1.07 Myr old (e.g., Koeberl and Reimold 2005), was excavated in rocks of the Early Proterozoic Birimian Supergroup. These rocks were deposited 2.1-2.15 Gyr ago in a volcanic arc environment and were metamorphosed to greenschist facies during the Eburnean tectono-thermal event (e.g., Jones et al. 1981, Feybesse et al. 2006). The Birimian Supergroup mainly consists of two contemporary units: volcanic belts and sedimentary basins aligned in multiple parallel features. Additionally, numerous granitoid intrusions were emplaced within the Birimian Supergroup (Wright et al. 1985). Two main types of granitoid intrusions are recognized in Ghana: belt granitoids and basin granitoids (Leube et al. 1990). Both types can be distinguished according to petrology, chemistry, and age. Whereas previous studies of target rocks from the Bosumtwi crater focused on metasedimentary rocks (e.g., Karikari et al. 2007), in this study we investigate felsic intrusive bodies. This work will also provide more data on the geological evolution of the Kumasi basin and Ashanti belt regions in Ghana. We analyzed thirteen samples for their major- and trace element compositions, as well as their U-Pb, Lu-Hf, and Sm-Nd systematics. Twelve samples come from three different felsic intrusive bodies. Two intrusions are located to the north of the crater, previously described as basin-type granitoids, whereas one intrusion was classified as belt-type granite (Koeberl and Reimold 2005). One sample represents a mafic (diabase) dyke. Analyses were performed using optical microscopy, XRF, and INAA at the University of Vienna, as well as by MC-ICPMS at the University of Bonn. Additional zircon U-Pb ages were obtained with VG Sector-54 multicollector TIMS at the Massachusetts Institute of Technology. Zircon ages for samples from four different intrusive bodies vary within a narrow range between 2091.96 ± 7 Ma and 2097.70 ± 7 Ma. A whole-rock 147Sm-143Nd regression line, defined by six samples coming from all sampled bodies, correlates to an age of 2048±63 Ma, in accordance with the U-Pb data for zircons. Notably, a sample from a mafic intrusion plots also on the regression line. Whole-rock 176Lu-176Hf data define a regression line yielding no meaningful geological age, possibly due to inherited old zircons from the source. Our first results suggest that, despite previous research (Koeberl and Reimold 2005), all studied intrusions genetically belong to the basin-type intrusions. All intrusions share common geochemical and petrologic properties, and were emplaced at approximately the same time.

Losiak, A.; Schulz, T.; Koeberl, C.

2012-04-01

266

Natural radioactivity of granites used as building materials  

Energy Technology Data Exchange (ETDEWEB)

Sixteen kinds of different granites, used as building materials, imported to Greece mainly from Spain and Brazil, were sampled and their natural radioactivity was measured by gamma-ray spectrometry. The activity concentrations of {sup 238}U, {sup 226}Ra, {sup 232}Th and {sup 4}K of granites are presented and compared to those of other building materials as well as other granite types used all over the world. In order to assess the radiological impact from the granites investigated, the absorbed and the effective doses were determined. Although the annual effective dose is higher than the limit of 1 mSv y{sup -1} for some studied granites, they could be used safely as building materials, considering that their contribution in most of the house constructions is very low. An attempt to correlate the relatively high level of natural radioactivity, shown by some of the granites, with their constituent radioactive minerals and their chemical composition, was also made.

Pavlidou, S. [Department of Mineralogy, Petrology and Economic Geology, School of Geology, Aristotle University of Thessaloniki, 541 24 Thessaloniki (Greece)]. E-mail: sophia_pavlidou@hotmail.com; Koroneos, A. [Department of Mineralogy, Petrology and Economic Geology, School of Geology, Aristotle University of Thessaloniki, 541 24 Thessaloniki (Greece)]. E-mail: koroneos@geo.auth.gr; Papastefanou, C. [Laboratory of Atomic and Nuclear Physics, Aristotle University of Thessaloniki, 541 24 Thessaloniki (Greece)]. E-mail: papastefanou@physics.auth.gr; Christofides, G. [Department of Mineralogy, Petrology and Economic Geology, School of Geology, Aristotle University of Thessaloniki, 541 24 Thessaloniki (Greece)]. E-mail: christof@geo.auth.gr; Stoulos, S. [Laboratory of Atomic and Nuclear Physics, Aristotle University of Thessaloniki, 541 24 Thessaloniki (Greece)]. E-mail: stoulos@auth.gr; Vavelides, M. [Department of Mineralogy, Petrology and Economic Geology, School of Geology, Aristotle University of Thessaloniki, 541 24 Thessaloniki (Greece)]. E-mail: vavelides@geo.auth.gr

2006-07-01

267

Natural radioactivity of granites used as building materials.  

Science.gov (United States)

Sixteen kinds of different granites, used as building materials, imported to Greece mainly from Spain and Brazil, were sampled and their natural radioactivity was measured by gamma-ray spectrometry. The activity concentrations of (238)U, (226)Ra, (232)Th and (40)K of granites are presented and compared to those of other building materials as well as other granite types used all over the world. In order to assess the radiological impact from the granites investigated, the absorbed and the effective doses were determined. Although the annual effective dose is higher than the limit of 1mSvy(-1) for some studied granites, they could be used safely as building materials, considering that their contribution in most of the house constructions is very low. An attempt to correlate the relatively high level of natural radioactivity, shown by some of the granites, with their constituent radioactive minerals and their chemical composition, was also made. PMID:16713662

Pavlidou, S; Koroneos, A; Papastefanou, C; Christofides, G; Stoulos, S; Vavelides, M

2006-01-01

268

Natural radioactivity of granites used as building materials  

International Nuclear Information System (INIS)

Sixteen kinds of different granites, used as building materials, imported to Greece mainly from Spain and Brazil, were sampled and their natural radioactivity was measured by gamma-ray spectrometry. The activity concentrations of 238U, 226Ra, 232Th and 4K of granites are presented and compared to those of other building materials as well as other granite types used all over the world. In order to assess the radiological impact from the granites investigated, the absorbed and the effective doses were determined. Although the annual effective dose is higher than the limit of 1 mSv y-1 for some studied granites, they could be used safely as building materials, considering that their contribution in most of the house constructions is very low. An attempt to correlate the relatively high level of natural radioactivity, shown by some of the granites, with their constituent radioactive minerals and their chemical composition, was also made

269

CDC Vital Signs: Preventing Pregnancies in Younger Teens  

Science.gov (United States)

... message, please visit this page: About CDC.gov . Vital Signs Share Compartir Preventing Pregnancies in Younger Teens April ... Behind the Issue MMWR Science Clips Related Pages Vital Signs Issue details: Births to Teens Aged 15–17 ...

270

Geochronological and geochemical study of the Pan African intrusive rocks along the Najd Fault system in El Wajh area, Saudi Arabia  

Science.gov (United States)

In the active tectonic regions, shear zones play an important role to re-configure the structure of the lithosphere. One of the largest shear zones on the Earth is the Najd Fault system of the Arabian-Nubian Shield. Literature data record the main active phase of this shear zone during the last stages of the Pan-African Orogeny (ca. 650-550 Ma). Compilation of new geochronological and geochemical data in addition to field relation is used to figure the tectonic history of the Najd Fault system. Different relationships between igneous intrusions and the Najd Fault System are observed. Some igneous bodies predate the activity of the shear zone, others intruded during the shearing process and a later phase intruded after the activity of the Najd Fault system ceased. The intrusive rocks in the study area show a geochemical and compositional diversity. Intrusives with dioritic composition were derived from a metaluminous tholeiitic magma around 700 Ma, and granodiorite-tonalite intrusions have calcalkaline characters and display a metaluminous to peraluminous character (ca. 740 and 660 Ma) then the magmatic activity terminated with peraluminous calcalkaline intrusives which formed granitic rocks with intrusion ages of 605-580 Ma. These magmatic events are identical for the Arabian-Nubian Shield but contamination from the crust or different rates of fractionation are recorded in our samples which are responsible for variations in the geochemical signature of the intrusive rocks. Based on field observations and contact relations, the intrusive rocks within the Ajjaj shear zone were studied in details in order to determine the age and the tectonic history of this shear zone that marks the termination of the Najd System against the eastern margin of the Red Sea. The provided zircon U-Pb dating by LA-ICP-MS and field relationships confine the activation age of the Ajjaj shear zone in limited period between 605 Ma and 580 Ma.

Hassan, Mahmoud; Abu-Alam, Tamer; Hauzenberger, Christoph; Stüwe, Kurt; Tiepolo, Massimo

2014-05-01

271

Subchondral insufficiency fracture of the femoral head in younger adults  

International Nuclear Information System (INIS)

We report two cases of subchondral insufficiency fracture of the femoral head observed in younger adults without any history of overexertion. In both cases, MRI revealed an irregular, discontinuous low-intensity band on the T1-weighted images. Both patients were treated operatively, and histological examination confirmed the diagnosis of subchondral fracture. A diagnosis of subchondral insufficiency fracture needs to be put in as one of the diagnoses in younger patients with a hip pain. (orig.)

272

Transition from oceanic to continental lithosphere subduction in southern Tibet: Evidence from the Late Cretaceous-Early Oligocene (~ 91-30 Ma) intrusive rocks in the Chanang-Zedong area, southern Gangdese  

Science.gov (United States)

Little is known about the detailed processes associated with the transition from oceanic to continental lithosphere subduction in the Gangdese Belt of southern Tibet (GBST). Here, we report zircon U-Pb age, major and trace element and Sr-Nd-Hf isotopic data for Late Cretaceous-Early Oligocene (~ 91-30 Ma) intermediate-acid intrusive rocks in the Chanang-Zedong area immediately north of the Yarlung-Tsangpo suture zone. These rocks represent five magmatic episodes at ~ 91, ~ 77, ~ 62, ~ 48, and ~ 30 Ma, respectively. The 91-48 Ma rocks have slightly lower initial 87Sr/86Sr (0.7037 to 0.7047), and higher ?Nd(t) (+ 1.8 to + 4.3) and ?Hf(t) (+ 3.5 to + 14.7) values in comparison with those (0.7057 to 0.7062, - 3.3 to - 2.5 and + 2.2 to + 6.6) of the ~ 30 Ma intrusive rocks. The ~ 91, ~ 62 and ~ 30 Ma rocks are geochemically similar to slab-derived adakites. The ~ 91 Ma Somka adakitic granodiorites were likely derived by partial melting of the subducting Neo-Tethyan oceanic crust with minor oceanic sediments, and the ~ 91 Ma Somka dioritic rocks with a geochemical affinity of adakitic magnesian andesites likely resulted from interactions between adakitic magmas and overlying mantle wedge peridotite. The ~ 77 Ma Luomu diorites were probably generated by partial melting of juvenile basaltic lower crust. The ~ 62 Ma Naika and Zedong adakitic diorites and granodiorites were likely generated mainly by partial melting of thickened juvenile mafic lower crust but the source region of the Zedong adakitic rocks also contained enriched components corresponding to Indian continental crust. The ~ 48 Ma Lamda granites were possibly generated by melting of a juvenile basaltic crust. The younger (~ 30 Ma) Chongmuda adakitic quartz monzonites and minor granodiorites were most probably derived by partial melting of Early Oligocene northward-subducted Indian lower crust beneath the southern Lhasa Block. Taking into account the regional tectonic and magmatic data, we suggest that the Gangdese Belt of southern Tibet (GBST) underwent a tectonodynamic transition from oceanic subduction to continental subduction between 100 and 30 Ma. It evolved through four stages: 100-65 Ma roll-back of subducted Neo-Tethyan oceanic lithosphere; 65-60 Ma initial collision between Indian and Asian continents; 60-40 Ma breakoff of subducted Neo-Tethyan oceanic lithosphere; and ~ 30 Ma northward subduction of the Indian continent.

Jiang, Zi-Qi; Wang, Qiang; Wyman, Derek A.; Li, Zheng-Xiang; Yang, Jin-Hui; Shi, Xiao-Bing; Ma, Lin; Tang, Gong-Jian; Gou, Guo-Ning; Jia, Xiao-Hui; Guo, Hai-Feng

2014-05-01

273

Portuguese granites associated with Sn-W and Au mineralizations  

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Full Text Available In northern and central Portugal, there are different tin-bearing granites. Most of them are of S-type, others have mixed characteristics of I-type and S-type granites and a few are of I-type. Tin-tungsten deposits are commonly associated with Hercynian tin-bearing S-type granites. Some quartz veins with wolframite are associated with an I-type granite, which has a low Sn content. In suites of tin-bearing S-type granitic rocks, Sn content increases as a function of the degree of fractional crystallization. Greisenizations of two-mica S-type granites associated with tin-tungsten mineralizations are accompanied by an increase in SiO2, H2O+, Sn, W, Nb, Ta, Rb, Zn, and Pb and decrease in MgO, Na2O, V, Sc,Zr, and Sr. The granite associated with the Jales gold deposit is of S-type and strongly differentiated like the tin-bearing S-type granites, but it has a very low Sn content. During fractional crystallization, Si, Rb, Sn, Pb, Au, As, Sb, and S increase. During increasing degree of hydrothermal alteration of this granite at the gold-quartz vein walls, there are progressive increases in K2O, H2O+, Sn, Cs, Cu, Pb, Au, Sb, As, and S.

Ana M.R. Neiva

2002-01-01

274

Novel Approach for Hybrid Intrusion Detection System  

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Full Text Available This Paper titled “Novel Approach for Intrusion Detection System” is an intrusion detection system (IDS proposed by analyzing the principle of the intrusion detection system based on host and network. Basically this paper is to develop host based cum network based intrusion detection system for Microsoft Windows XP environment. Proposed concept that had used in this was applying intrusion detection rule matching technique on the Security Log File and Event Log File in Microsoft Windows XP for the Host based IDS module. The intrusion had identified when there was finding of attacks that is creating with these two file in Microsoft Windows XP. In Network based IDS module DOS, U2R, Rejected (RST attacks are finding during packet capturing in network. Moreover, the security and performance of the proposed IDS is also estimated. The proposed IDS approve the effectiveness of the proposed method, and it shows advantages of host based as well as network based security. The proposed model of hybrid IDSs offers several advantages over alternative systems. First of all it provided higher security, it supported high availability and scalability, and most important thing it produced good results in terms of normal and abnormal behaviors of arrived packet. The proposed model includes integration of individual components to produced batter results. It supports to a system/network administrator the privileges for finding the intrusions which is reliable, secure and fast. The proposed model of hybrid IDS implemented in short time and at a low cost. It also provides a best user interface.

Ravi Kishore Sharma, Mr. Gajendra Singh Chandel

2012-11-01

275

Palaeomagnetism of the Puerto Vallarta intrusive complex and the accretion of the Guerrero terrain, Mexico  

Science.gov (United States)

The batholith exposed around Puerto Vallarta is part of the Guerrero tectonostratigraphic terrain, presumably accreted to Mexico during the Laramide orogenic phase. Fourteen sites on this batholith were studied palaeomagnetically and geochemically. Nine sites define a paleopole at 76.6°N, 181.8°E, with ?95 = 6.6°, coinciding with the reference pole for stable North America. It is proposed that no important movements of the region relative to North America have occurred since emplacement of the intrusive rocks ˜ 80 Ma ago. This would mean that the Guerrero terrain was accreted to the Mexican continental margin before that time. Geochemical data support this interpretation, characterizing the rocks as volcanic-arc granites intruded at an active continental margin.

Böhnel, H.; Negendank, J. F. W.

1988-11-01

276

Simulation of bentonite colloid migration through granite  

International Nuclear Information System (INIS)

colloids. In the model, each group of clusters is transported as one solution component and the kinetics of coagulation are implemented as reactions between the components: a shift of particles among groups of particles with similar migration properties, according to size of the clusters of colloids. The simulation of migration of bentonite colloid through granite using the coagulation model was calibrated according to experiment results. On the basis of the simulation, one can estimate the basic processes that occur during bentonite colloid migration. That could be useful for prediction of spent nuclear fuel repository safety with the help of model of bentonite colloid behavior during migration. (authors)

277

Characterization of mechanical damage in granite  

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Full Text Available This paper aims to illustrate the use of infrared thermography as a non-destructive and non-contact technique to observe the phenomenological manifestation of damage in granite under unconfined compression. It allows records and observations in real time of heat patterns produced by the dissipation of energy generated by plasticity. The experimental results show that this technique, which couples mechanical and thermal energy, can be used for illustrating the onset of damage mechanism by stress concentration in weakness zones.

Minh-Phong Luong

2014-01-01

278

GRANITE- A steroscopic imaging Chernkov telescope system  

International Nuclear Information System (INIS)

A second 10 meter class imaging telescope was constructed on Mt. Hopkins, Arizona, the site of the original 10 meter Whipple Cherenkov telescope. The twin telescope system with a 140 meter base line will allow both a reduction in the energy threshold and an improvement in the rejection of the hardonic background. The new telescope started operation in December 1991. With the final completion of the first installation stage (GRANITE I) during spring 92, it is now operating simultaneously with the orginal reflector. We describe in this paper design and construction of the new instrument and demonstrate the capability of the experiment to record coincident events

279

A Distributed Network Intrusion Detection System with Active Surveillance Agent  

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Full Text Available A distributed network intrusion detection system (IDS called SA-NIDS is proposed based on the network-based intrusion detection architecture. It includes three basic components, Local Intrusion Detection Monitor (LIDM, Global Intrusion Detection Controller (GIDC, and Surveillance Agent (SA. Basically, the LIDM is used to do packets capturing, packets de-multiplexing, local intrusion detection and intrusion inferring. The GIDC is installed in administration center for communicating and managing LIDMs, it can also do the intrusion detection and intrusion inferring. The SA contains several optional functions for information gathering. After an attack behavior is discovered, the SA may be used to launch some kinds of information gathering to the attacker, so that the proposed SA-NIDS has the active surveillance ability. For the intrusion inferring, the pattern matching and the statistical approach are applied in SA-NIDS. The experimental results can satisfy the needs of network information safety.    

Bin Zeng

2013-10-01

280

NETWORK INTRUSION DETECTION AND PREVENTION ATTACKS  

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Full Text Available Intrusion detection is an important technology in business sector as well as an active area of research. It is an important tool for information security. A Network Intrusion Detection System is used to monitor networks for attacks or intrusions and report these intrusions to the administrator in order to take evasive action. Today computers are part of networked; distributed systems that may span multiple buildings sometimes located thousands of miles apart. The network of such a system is a pathway for communication between the computers in the distributed system. The network is also a pathway for intrusion. This system is designed to detect and combat some common attacks on network systems. It follows the signature based IDs methodology for ascertaining attacks. A signature based IDS will monitor packets on the network and compare them against a database of signatures or attributes from known malicious threats. In this system the attack log displays the list of attacks to the administrator for evasive action. This system works as an alert device in the event of attacks directed towards an entire network.

Harpreet kaur

2012-06-01

 
 
 
 
281

Intrusion problematic during water supply systems’ operation  

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Full Text Available Intrusion through leaks occurrence is a phenomenon when external fluid comes into water pipe systems. This phenomenon can cause contamination problems in drinking pipe systems. Hence, this paper focuses on the entry of external fluids across small leaks during normal operation conditions. This situation is especially important in elevated points of the pipe profile. Pressure variations can origin water volume losses and intrusion of contaminants into the drinking water pipes. This work focuses in obtaining up the physical representation on a specific case intrusion in a pipe water system. The combination of two factors is required to generate this kind of intrusion in a water supply system: on one hand the existence of at least a leak in the system; on the other hand, a pressure variation could occur during the operation of the system due to consumption variation, pump start-up or shutdown. The potential of intrusion during a dynamic or transient event is here analyzed. To obtain this objective an experimental case study of pressure transient scenario is analyzed with a small leak located nearby the transient source.

Jesus Mora-Rodriguez, P. Amparo López-Jimenez, Helena M. Ramos

2011-05-01

282

Category-Based Intrusion Detection Using PCA  

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Full Text Available Existing Intrusion Detection Systems (IDS examine all the network features to detect intrusion or misuse patterns. In feature-based intrusion detection, some selected features may found to be redundant, useless or less important than the rest. This paper proposes a category-based selection of effective parameters for intrusion detection using Principal Components Analysis (PCA. In this paper, 32 basic features from TCP/IP header, and 116 derived features from TCP dump are selected in a network traffic dataset. Attacks are categorized in four groups, Denial of Service (DoS, Remote to User attack (R2L, Remote to User attack (U2R and Probing attack. TCP dump from DARPA 1998 dataset is used in the experiments as the selected dataset. PCA method is used to determine an optimal feature set to make the detection process faster. Experimental results show that feature reduction can improve detection rate for the category-based detection approach while maintaining the detection accuracy within an acceptable range. In this paper KNN classification method is used for the classification of the attacks. Experimental results show that feature reduction will significantly speed up the train and the testing periods for identification of the intrusion attempts.

Gholam Reza Zargar

2012-10-01

283

A-type and I-type granitoids and mylonitic granites of Hassan Salaran area of SE Saqqez, Kurdistan, Iran  

Science.gov (United States)

The Hassan Salarn area is located 20km to southeast of Saqqez city in Kurdistan Province, western Iran. In this area there are two distinct granitic rock suites consisting A-type and I-type granites and also mylonitic granites. These A-type and I-type granites have various petrological and geochemical characteristics. They also have different origins and petrogenesis. A-type granitoids comprise alkali feldspar granite, syenogranite and quartz alkali feldspar syenite, whereas I-type granitoids are composed of monzogranite, granodiorite and tonalite. Geochemically, A-type granitoids are peralkaline and acmite-normative but I-type granitoids are subalkaline (calc-alkaline), metaluminous and diopside-normative. A-type granitoids are also ferroan alkali and ferroan alkali-calcic whereas I-type granitoids are magnesian and calcic. A-type granitoids resemble to within plate granites and post-orogenic granites whereas I-type granitoids resemble to volcanic arc granites. A-type granitoids contain higher concentrations of alkalies, Zr, Rb, Nb, Y, Th, Ce, high FeO/MgO ratios and lower concentrations of Mg, Ca and Sr, resembling post-orogenic A-type granites. It is possible that heat from a mantle-derived magma which intruded into the lower crust, and/or rapid crustal extension have been essential generation of approriate melts producing A-type granitoids. Thus we can conclude that A-type granitoids were generated from a mixed mantle-crust source. Negative Nb anomalies and low contents of Ti and P probably indicate a subduction-related origin for protolith of I-type granitoids. Negative Nb anomalies and enrichment in Ce relative to its adjacent elements can be related to involvement of continental crust in magmatic processes. I-type granitoids are also enriched in Rb, Ba, K, Th, Ce and depleted in Nb, Zr and Y, indicating that they have had interacted with crust. I-type granitoids may result from contamination of mantle-derived magmas by continental crust during a subduction event. The mylonitic granites are elongated masses with a NE-SW trend and their contacts with the A-type and I-type granitoids are fault contact. Hand specimens have a layered appearance with green bands made from chlorite and epidote and grey to white bands with quartz and feldspar. These rocks contain plagioclase, quartz and orthoclase under the microscope. Also fine-grained minerals such as quartz, sericite, epidote, chlorite and opaque minerals make the groundmass wrapping the porphyroclasts. Pressure shadows around porphyroclasts of plagioclase and quartz and crystallization of fine-grained quartz and sericite in these places along with intense alteration of plagioclase to epidote and sericite, existence of quartz with different sizes, andaluse extinction in quartz crystals, and elongation of chlorites, resulted from dynamic recrystallisation of biotites all indicate effect of stresses on the rocks. Considering the similar mineralogical composition of the mylonitic rocks with I-type granitoid, it could be concluded that the granodioritic magma, after intrusion and solidification, is changed to mylonite in a shear zone due to tectonical forces.

Abdullah, Fakhraddin Mohammad; Saeed Ahmad, Sheler

2014-05-01

284

A New Method for Intrusion Detection using Manifold Learning Algorithm  

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Full Text Available Computer and network security has received and will still receive much attention. Any unexpected intrusion will damage the network. It is therefore imperative to detect the network intrusion to ensure the normal operation of the internet. There are many studies in the intrusion detection and intrusion patter recognition. The artificial neural network (ANN has proven to be powerful for the intrusion detection. However, very little work has discussed the optimization of the input intrusion features for the ANN. Generally, the intrusion features contain a certain number of useless features, which is useless for the intrusion detection. Large dimensions of the feature data will also affect the intrusion detection performance of the ANN. In order to improve the ANN performance, a new approach for network intrusion detection based on nonlinear feature dimension reduction and ANN is proposed in this work. The manifold learning algorithm was used to reduce the intrusion feature vector. Then an ANN classifier was employed to identify the intrusion. The efficiency of the proposed method was evaluated with the real intrusion data. The test result shows that the proposed approach has good intrusion detection performance.

Guoping Hou

2013-07-01

285

Pan-African alkali granites and syenites of Kerala as imprints of taphrogenic magmatism in the South Indian shield  

Science.gov (United States)

Granite and syenite plutons with alkaline affinities ranging in age from 550 to 750 Ma sporadically puncture the Precambrian granulites of the Kerala region. All the bodies are small (20 to 60 sq km), E-W to NW-SE elongated elliptical intrusives with sharp contacts and lie on or close to major late Proterozoic lineaments. Geochemical plots of A-F-M and An-Ab-Or relations show an apparent alkali enrichment trend on the former, but the plutons define relatively distinct fields on the latter. Most of the plutons are adamellitic to granitic by chemistry. The variations of SiO2 with log sub 10 K2O/MgO (1) brings out the distinct alkaline nature of the plutons. Some of the granites are extremely potassic, like the Peralimala pluton, which shows up to 11.8 percent K2O. On a SiO2-Al2O3-Na2O+K2O (mol percent) plot, the plutons vary from peraluminous to peralkaline, but none are nepheline normative. Low MgO, low to moderate CaO and high Fe2O3/FeO values are other common characteristics. Among trace elements, depletion of Ba, Sr and Rb with high K/Ba and K/Rb values are typical. Overall, the plutons show a trend of decreasing K/Rb ratio with increasing K content. Individual plutons show more clearly defined trends similar to those from granitic masses characterized by plagioclase fractionation.

Santosh, M.; Drury, S. A.; Iyer, S. S.

1988-01-01

286

Mercury Concentrations in Coastal Sediment from Younger Lagoon, Central California  

Science.gov (United States)

Younger Lagoon Reserve, located in northern Monterey Bay, is one of the few relatively undisturbed wetlands that remain along the Central Coast of California. This lagoon system provides protected habitat for more than 100 bird species and for populations of fish, mammals, and invertebrates. Total mercury (HgT) concentrations in water within Younger Lagoon appear to vary with rainfall conditions and range from about 5-15 pM. These concentrations are similar to HgT in water from six nearby lagoon systems. However, Younger Lagoon contains elevated concentrations of dissolved organic carbon (~1 mM) and monomethylmercury (MMHg, ~1 pM) relative to our comparison lagoon sites (DOC < 0.5 mM and MMHg < 0.5 pM). We attribute Younger Lagoon's high DOC and MMHg to its restricted connection to the ocean and minor riverine contribution. Coastal lagoons in this region typically form at the mouth of streams. They behave as small estuaries during the wet season when surface water discharge keeps the mouth of the stream open to the ocean, and then transition into lagoons in the dry season when a sand berm develops and effectively cuts off surface water exchange. At Younger Lagoon, the sand berm remains intact throughout the year, breaching only during particularly high tides or intense rain events. Therefore, the lagoon's connection to nearshore seawater is primarily via surface water - groundwater interaction through the sand berm. Because Younger Lagoon is largely isolated from a surface water connection with the ocean, runoff from upgradient urban and agricultural land has an enhanced impact on water (and presumably sediment) quality. As a result, the lagoon is eutrophic and experiences annual algal blooms. Groundwater surveys suggest surface water, groundwater, and coastal seawater are hydraulically connected at Younger Lagoon, and mixing among these water masses appears to influence water geochemistry. To date, no chemical analyses have been conducted on sediment from Younger Lagoon. To address this data gap we collected sediment samples during a February 2013 field campaign. One set of sediment samples is from the bottom of the lagoon along a transect perpendicular to the shoreline and another set is from an approximately 1 m depth profile on the lagoon side of the sand berm (depth of the groundwater table at the time of collection). These samples are being analyzed for HgT, MMHg, and total organic carbon (TOC) and will provide a first glimpse into the distribution of mercury species and organic carbon in sediments from the Younger Lagoon Reserve. We will also collect and analyze sediment samples from another lagoon site with comparable watershed characteristics.

Hohn, R. A.; Ganguli, P. M.; Swarzenski, P. W.; Richardson, C. M.; Merckling, J.; Johnson, C.; Flegal, A. R.

2013-12-01

287

Trusted Computing Based Collaborative Intrusion Detection System  

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Full Text Available Collaboration and information sharing has obliged participating parties to look for improved detection accuracy and reaction speed in Distributed Intrusion Detection Systems (DIDS solutions. This is mainly due to the increasing number of attacks as well as increasingly sophisticated intrusions and more alarmingly various critical components of a system can be targeted. This is further exasperated by the fact that most DIDS models do not consider the attacks targeting the collaborative network itself. We specifically find this issue to be very critical and hence in this paper we propose a trust aware DIDS simulation model that is capable of categorizing each participating IDS expertise (i.e. speciality and competence, therefore helps collaborating organizations to consult our simulation model for choosing the right candidate for any type of intrusion. We call our Model as Consultative Trusted Computing-based Collaborative IDS (CTC IDS. We utilize the Trusted Platform Module (TPM for integrity evaluation and fine-tuning peer evaluation.

Jamalul-Lail Ab Manan

2012-01-01

288

An Architecture of Hybrid Intrusion Detection System  

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Full Text Available Intrusion Detection System (IDS is renowned and widely-deployed security tool to detect attacks and malicious activities in information system. It is an essential element of any contemporary information system. There are mainly two techniques for intrusion detection: i signature-based (misuse detection and ii anomaly-based detection technique. Both the techniques have their advantages and disadvantages. This paper presents research from an ongoing study on the use of features of both the intrusion detection techniques to design a novel and efficient hybrid IDS. An architecture and implementation details of our hybrid IDS are presented. Furthermore, unique characteristics of our hybrid IDS are described. This paper concludes with future research directions and challenges in IDS.

Kanubhai K Patel

2012-12-01

289

Advances in Intrusion Detection System for WLAN  

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Full Text Available A wireless network is not as secure as compare the wired network because the data is transferred on air so any intruder can use hacking techniques to access that data. Indeed it is difficult to protect the data and provide the user a secure information system for lifetime. An intrusions detection system aim to detect the different attacks against network and system. An intrusion detection system should be capable for detecting the misuse of the network whether it will be by the authenticated user or by an attacker. Cross layer based technique help to make decision based on two layer physical layer where we compute RSS value and on MAC layer where one compute RTS-CTS time taken. This will reduce the positive false rate.They detect attempts and active misuse either by legitimate users of the information systems or by external. The paper has higlighted the advances in intrusion detection in wireless local area network.

Ravneet Kaur

2011-10-01

290

Developing Mobile Agent for Intrusion Detection  

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Full Text Available Mobile agent is a certain agent actively able to move from one computer to another or even travel acrossnetwork to perform the task assigned. This research aimed to develop mobile agent model to detectdistributed intrusion (Distributed Intrusion Detection System.It was expected that the produced model was able to perform its task in nearly real time manner, to beimmune against attack, and also fairly small overhead at the host, either in memory consumption or CPUusage. In this research, the Aglets concept was also developed to aid intrusion detection. This approachwas also maintained to solve certain issues such as scalability, reliability, and configurability. Hence, theadvantages and limitations of agent-based approaches will be when it is applied in real world.

Bambang Sugiantoro

2013-05-01

291

An overview to Software Architecture in Intrusion Detection System  

CERN Document Server

Network intrusion detection systems provide proactive defense against security threats by detecting and blocking attack-related traffic. This task can be highly complex, and therefore, software based network intrusion detection systems have difficulty in handling high speed links. This paper reviews of many type of software architecture in intrusion detection systems and describes the design and implementation of a high-performance network intrusion detection system that combines the use of software-based network intrusion detection sensors and a network processor board. The network processor acts as a customized load balancing splitter that cooperates with a set of modified content-based network intrusion detection sensors in processing network traffic.

Bahrami, Mehdi

2012-01-01

292

Effective analysis of cloud based intrusion detection system  

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Full Text Available The goal of IDS is to analyze events on the network and identify attacks. The increasing number of network security related incidents makes it necessary for organizations to actively protect their sensitive data with the installation of intrusion detection systems (IDS. People are paid more attention on intrusion detection which as an important computer network security technology. According to the development trend of intrusion detection, detecting all kinds of intrusions effectively requires a global view of the monitored network, Here, discuss about new intrusion detection mechanism based on cloud computing, which can make up for the deficiency of traditional intrusion detection, and proved to be great scalable.

Sanjay Ram

2012-08-01

293

In-situ experiments in granite  

International Nuclear Information System (INIS)

In-stitu experiments in granite were started in 1983 as a three-year plan of research and development of the experimental techniques to aime at development of a site assessment methodology and to provide the data for the safety assessment of the disposal of radioactive waste. At the test site of granite, an experimental room was excavated for exclusive use and heater test, migration test and corrosion test were performed. The heater test showed good agreement between measured and calculated temperatures in the rock where no fracture was found, however, in fractured zone it showed that the heat transfer by the ground water could not be disregarded. Rock deformation and permiability change were found near the heater in the fractured zone. Nuclide transport along the fracture is much faster than the transport in the rock matrix, besides dispersion in the rock matrix has very important role from the migration test. Corrosion test used sensitized specimens showed that some samples have susceptibilities to stress corrosion cracking after 12 months. (author)

294

The 'Granite' collegial mission of dialogue. Report  

International Nuclear Information System (INIS)

The aim of the 'Granite' collegial mission of dialogue is to inform the French authorities, associations and population about the project of construction of an underground laboratory for the study of the disposal of high level and long-life radioactive wastes in a granitic environment. The aim of the dialogue was not to select a site but to collect the public reactions and advices about such a project. However, such a dialogue has partially failed because of a misunderstanding of the population about the aims of the mission. However, the mission has collected many point of views and questions which are developed in this report. The first and second chapters recall the process of the mission and its progress, while a third chapter stresses on the questions asked by the public and which concern the fear of nuclear wastes and the incompatibility between the disposal of wastes and the socio-economical development of the region concerned. Thanks to the lessons drawn from this experience, the mission has formulated some recommendations (chapter 4) concerning the need for a better information of the population about any topic in relation with the radioactive wastes. Some complementary information is provided in appendixes. (J.S.)

295

Perceived illness intrusion among patients on hemodialysis  

International Nuclear Information System (INIS)

Dialysis therapy is extremely stressful as it interferes with all spheres of daily activities of the patients. This study is aimed at understanding the perceived illness intrusion among patients on hemodialysis (HD) and to find the association between illness intrusion and patient demo-graphics as well as duration of dialysis. A cross sectional study involving 90 patients with chronic kidney disease (CKD) stage V, on HD was performed during the period from 2005 to 2006. The subjects included were above 18 years of age, willing, stable and on dialysis for at least two months. Patients with psychiatric co-morbidity were excluded. A semi-structured interview schedule covering sociodemographics and a 13 item illness intrusion checklist covering the various aspects of life was carried out. The study patients were asked to rate the illness intrusion and the extent. The data were analyzed statistically. The mean age of the subjects was 50.28 + - 13.69 years, males were predominant (85%), 73% were married, 50% belonged to Hindu religion, 25% had pre-degree education, 25% were employed and 22% were housewives. About 40% and 38% of the study patients belonged to middle and upper socio-economic strata respectively; 86% had urban background and lived in nuclear families. The mean duration on dialysis was 24 + - 29.6 months. All the subjects reported illness intrusion to a lesser or greater extent in various areas including: health (44%), work (70%) finance (55%), diet (50%) sexuawork (70%) finance (55%), diet (50%) sexual life (38%) and psychological status (25%). Illness had not intruded in areas of relationship with spouse (67%), friends (76%), family (79%), social (40%) and religious functions (72%). Statistically significant association was noted between illness intrusion and occupation (P= 0.02). (author)

296

An automatically tuning intrusion detection system.  

Science.gov (United States)

An intrusion detection system (IDS) is a security layer used to detect ongoing intrusive activities in information systems. Traditionally, intrusion detection relies on extensive knowledge of security experts, in particular, on their familiarity with the computer system to be protected. To reduce this dependence, various data-mining and machine learning techniques have been deployed for intrusion detection. An IDS is usually working in a dynamically changing environment, which forces continuous tuning of the intrusion detection model, in order to maintain sufficient performance. The manual tuning process required by current systems depends on the system operators in working out the tuning solution and in integrating it into the detection model. In this paper, an automatically tuning IDS (ATIDS) is presented. The proposed system will automatically tune the detection model on-the-fly according to the feedback provided by the system operator when false predictions are encountered. The system is evaluated using the KDDCup'99 intrusion detection dataset. Experimental results show that the system achieves up to 35% improvement in terms of misclassification cost when compared with a system lacking the tuning feature. If only 10% false predictions are used to tune the model, the system still achieves about 30% improvement. Moreover, when tuning is not delayed too long, the system can achieve about 20% improvement, with only 1.3% of the false predictions used to tune the model. The results of the experiments show that a practical system can be built based on ATIDS: system operators can focus on verification of predictions with low confidence, as only those predictions determined to be false will be used to tune the detection model. PMID:17416165

Yu, Zhenwei; Tsai, Jeffrey J P; Weigert, Thomas

2007-04-01

297

Perceived illness intrusion among patients on hemodialysis  

Directory of Open Access Journals (Sweden)

Full Text Available Dialysis therapy is extremely stressful as it interferes with all spheres of daily acti-vities of the patients. This study is aimed at understanding the perceived illness intrusion among pa-tients on hemodialysis (HD and to find the association between illness intrusion and patient demo-graphics as well as duration of dialysis. A cross sectional study involving 90 patients with chronic kidney disease (CKD stage V, on HD was performed during the period from 2005 to 2006. The subjects included were above 18 years of age, willing, stable and on dialysis for at least two months. Patients with psychiatric co-morbidity were excluded. A semi-structured interview schedule covering socio-demographics and a 13 item illness intrusion checklist covering the various aspects of life was ca-rried out. The study patients were asked to rate the illness intrusion and the extent. The data were ana-lyzed statistically. The mean age of the subjects was 50.28 ± 13.69 years, males were predominant (85%, 73% were married, 50% belonged to Hindu religion, 25% had pre-degree education, 25% were employed and 22% were housewives. About 40% and 38% of the study patients belonged to middle and upper socio-economic strata respectively; 86% had urban background and lived in nuclear fami-lies. The mean duration on dialysis was 24 ± 29.6 months. All the subjects reported illness intrusion to a lesser or greater extent in various areas including: health (44%, work (70% finance (55%, diet (50% sexual life (38% and psychological status (25%. Illness had not intruded in areas of rela-tionship with spouse (67%, friends (76%, family (79%, social (40% and religious functions (72%. Statistically significant association was noted between illness intrusion and occupation (P= 0.02.

Bapat Usha

2009-01-01

298

Perceived illness intrusion among patients on hemodialysis.  

Science.gov (United States)

Dialysis therapy is extremely stressful as it interferes with all spheres of daily activities of the patients. This study is aimed at understanding the perceived illness intrusion among pa-tients on hemodialysis (HD) and to find the association between illness intrusion and patient demographics as well as duration of dialysis. A cross sectional study involving 90 patients with chronic kidney disease (CKD) stage V, on HD was performed during the period from 2005 to 2006. The subjects included were above 18 years of age, willing, stable and on dialysis for at least two months. Patients with psychiatric co-morbidity were excluded. A semi-structured interview schedule covering socio-demographics and a 13 item illness intrusion checklist covering the various aspects of life was carried out. The study patients were asked to rate the illness intrusion and the extent. The data were analyzed statistically. The mean age of the subjects was 50.28 +/- 13.69 years, males were predominant (85%), 73% were married, 50% belonged to Hindu religion, 25% had pre-degree education, 25% were employed and 22% were housewives. About 40% and 38% of the study patients belonged to middle and upper socio-economic strata respectively; 86% had urban background and lived in nuclear families. The mean duration on dialysis was 24 +/- 29.6 months. All the subjects reported illness intrusion to a lesser or greater extent in various areas including: health (44%), work (70%) finance (55%), diet (50%) sexual life (38%) and psychological status (25%). Illness had not intruded in areas of relationship with spouse (67%), friends (76%), family (79%), social (40%) and religious functions (72%). Statistically significant association was noted between illness intrusion and occupation (P= 0.02). PMID:19414939

Bapat, Usha; Kedlaya, Prashanth G

2009-05-01

299

The Serra do Carambei Granite - PR and the uraniferous anomalism  

International Nuclear Information System (INIS)

The Serra do Carambei Granite forms a pluton relatively homogeneous, covering about 33 km2, cropping out as an elongate retangular body trending NE-SW, being emplaced in the Cunhaporanga Granitoid Complex. Its characteristics indicates a kind of hololeucocratic granite, equigranular, medium to coarse-grained, consisting predominantly of microperthitic alkali-feldspar, quartz and a small amount of biotite (less than 1%), thus being classified as an alaskite. Chemical data allows a classification in the group of granite with high contents of silica (74-76% Wt. SiO2), dominantly alkaline chemism and hypersolvus character, derived from a parental magma under saturated in water with distinguished features of granitoids from the magnetite series and types I and A granites. The pluton shows important chemical variations due to weathering processes. However detailed chemical studies reveal the presence of anomalous concentrations of trace elements such as U, Sn, Nb, Y, Zr, the Serra do Carambei Granite lacks economically important mineralizations because of the absence of well-developed tardi/pos-magmatic processes that could concentrate them. The SW side of the granite is cut by leucocratic rhyolite dykes that show some radiometric anomalies. These rocks, which are highly diferentiated, were emplaced contemporaneously to the Serra do Carambei Granite. Although petrographic and chronological similarities are found between the uraniferous alaskite of Roessing (Namibia) and the Serra do Carambei Granite anyhow it was not possible to establish any lateral continuity with the uranifeous Pan-African Province. (Author)

300

Paleomagnetism of 1.8 Ga shoshonitic intrusions in Lake Ladoga region, NW Russia  

Science.gov (United States)

Paleomagnetic sampling was carried out on three undeformed ca. 1.8 Ga Svecofennian post-collisional shoshonitic intrusions in NW Lake Ladoga region in NW Russia. All the studied formations, Vuoksa, Ojajarvi and Elisenvaara show their own characteristic, stable remanence directions which are clearly separated from the low-coercivity present Earth s field direction. The quartz monzonites of the large Vuoksa intrusion (1802+/-17 Ma, U-Pb, zr., Konopelko and Ivanikov, 1996) yields SE declinations with intermediate negative inclinations (VGP:56.4N,222.7E, dp=6.7,dm=10.4, n=9 samples), while the quartz monzonites of the large Ojajarvi intrusion (1800-1805 Ma, K-Ar, amphibole, Ivanikov et al. 1996) yields NW declinations with intermediate positive inclinations (VGP:52.8N,231.3E, dp=6.5,dm=10.5, n=17 samples). In both intrusions, few samples show opposite directions. The combined pole, regarded to represent the primary 1.8 Ga remanence of the intrusions differs from the nearly coeval 1.77-1.79 Ga bipodal pole (VGP:39.7N,221.1E, Pisarevsky and Sokolov, 2001) obtained from the Shoksha sediments at Lake Onega further NE in NW Russia. The difference of poles may be due to slight tilting of the Lake Ladoga region caused by the emplacement of Subjotnian rapakivi granites and associated dykes at ca. 1.65-1.54 Ga. Alternatively, the difference may reflect diverging ages, the Lake Ladoga intrusions beeing ca. 10-20 Ma older than the sediments at Lake Onega. This alternative would mean a substantial plate movement of the Fennoscandian Shield in the post-collisional stage of the Svecofennian orogeny, not recognized before. Remanence directions of the Elisenvaara intrusion (1.80+/-6 Ma, U-Pb, zr., Kono-pelko and Vaasjoki, 2002, pers.comm.), which is exposed as two pipe-like bodies, differ from the directions of the Vuoksa and Ojajarvi intrusions. One of the studied sites, comprising of a variety of shoshonitic rock types, yields SE declinations with steep negative inclinations. By applying a tectonic correction, probably due to local tilting of the site, the remanence becomes aligned with the Vuoksa direction. The other Elisenvaara body of a homogenous syenite yields SW declinations with low inclinations (VGP:25.5N, 192.3E, dp=3.3,dm=6.6, n=6 samples), the pole beeing in agreement with the 1.54 Ga key pole of the Fennoscandian Shield. Hence, this Elisenvaara body was evidently totally remagnetized during Subjotnian. Similar directions were observed sporadically as partial overprints in the other Elisenvaara body as well as in some samples of the Vuoksa and Ojajarvi intrusions, thus reflecting the multistage geological history of the Lake Ladoga region.

Mertanen, S.; Ivanikov, V. V.; Philippov, N. B.; Bogatchev, V. A.

2003-04-01

 
 
 
 
301

Adaptive Genetic Algorithm Model for Intrusion Detection  

Directory of Open Access Journals (Sweden)

Full Text Available Intrusion detection systems are intelligent systems designed to identify and prevent the misuse of computer networks and systems. Various approaches to Intrusion Detection are currently being used, but they are relatively ineffective. Thus the emerging network security systems need be part of the life system and this ispossible only by embedding knowledge into the network. The Adaptive Genetic Algorithm Model - IDS comprising of K-Means clustering Algorithm, Genetic Algorithm and Neural Network techniques. Thetechnique is tested using multitude of background knowledge sets in DARPA network traffic datasets.

K. S. Anil Kumar

2012-09-01

302

Adaptive intrusion data system (AIDS) software routines  

International Nuclear Information System (INIS)

An Adaptive Intrusion Data System (AIDS) was developed to collect information from intrusion alarm sensors as part of an evaluation system to improve sensor performance. AIDS is a unique digital data-compression, storage, and formatting system; it also incorporates a capability for video selection and recording for assessment of the sensors monitored by the system. The system is software reprogrammable to numerous configurations that may be used for the collection of environmental, bilevel, analog, and video data. This report describes the software routines that control the different AIDS data-collection modes, the diagnostic programs to test the operating hardware, and the data format. Sample data printouts are also included

303

IRETHERM: The geothermal energy potential of Irish radiothermal granites  

Science.gov (United States)

The IRETHERM project is developing a strategic understanding of Ireland's deep geothermal energy potential through integrated modelling of new and existing geophysical and geological data. One aspect of IRETHERM's research focuses on Ireland's radiothermal granites, where increased concentrations of radioelements provide elevated heat-production (HP), surface heat-flow (SHF) and subsurface temperatures. An understanding of the contribution of granites to the thermal field of Ireland is important to assessing the geothermal energy potential of this low-enthalpy setting. This study focuses on the Galway granite in western Ireland, and the Leinster and the buried Kentstown granites in eastern Ireland. Shallow (magnetotelluric (MT) and audio-magnetotelluric (AMT) data acquisition across the three granite bodies, over three fieldwork seasons. MT and AMT data were collected at 59 locations along two profiles over the Leinster granite. Preliminary results show that the northern units of the Leinster granite (40 km SW of Dublin) extend to depths of 2-5 km. Preliminary results from the southern profile suggest a greater thickness of granite to a depth of 6-9 km beneath the Tullow pluton, 75 km SW of Dublin. Over the Galway granite, MT and AMT data have been collected at a total of 75 sites (33 consist of only AMT data acquisition, with both MT and AMT recorded at the remaining 42). Preliminary results show a deep resistor extending to depths of 15-20 km beneath the central block, with the resistive upper layer extending to depths of 3.5-7 km west of the Shannawona fault, a major structure that cuts the batholith. MT and AMT data acquired along a profile at 22 locations over the Kentstown granite suggests that this buried granite is at a depth of 400 m beneath the centre of the gravity anomaly. The MT and AMT data will be integrated with gravity and seismic refraction data (in the case of the Leinster granite) to identify deeply penetrating faults, which may provide conduits for hydrothermal fluids, and to produce a robust estimation of the volumetric extent of the granites, which is crucial in defining their geothermal energy potential. Thermal conductivity and geochemical data will be incorporated to constrain the heat contribution of granites to the Irish crust.

Farrell, Thomas; Jones, Alan; Muller, Mark; Feely, Martin; Brock, Andrew; Long, Mike; Waters, Tim

2014-05-01

304

Cue conditions and wayfinding in older and younger women.  

Science.gov (United States)

This study examined how varying the salience and complexity of environmental cues affects place learning in older versus younger women. Place learning is a critical cognitive function for wayfinding in new or changed environments that becomes impaired with age in many people. Environments such as nursing homes and assisted living facilities typically have poorly differentiated environments. Environmental modifications that influence how older adults learn places more effectively are not known. It was hypothesized that salient cues (prominent and distinctive) are particularly important to place learning. The Computer-Generated Arena was used to test this hypothesis in 20 healthy older (age 65+) women and 6 healthy younger (ages 18 to 35) women. Analyses of the data showed differences in place learning with respect to cue salience, complexity, and age, with younger women being much more proficient in the place learning task and with the best overall learning in the salient and complex cue conditions. PMID:20078000

Davis, Rebecca L; Therrien, Barbara A; West, Brady T

2008-10-01

305

The intrusive complexof the Island of Giglio: geomagnetic characteristics of plutonic facies with low susceptibility contrast  

Directory of Open Access Journals (Sweden)

Full Text Available Two main plutonic facies characterize the intrusive complex of the Island of Giglio, and the trend of their contact at depth has been modelled using a 2D½ analysis based on a detailed geomagnetic survey in order to verify the geological hypothesis of the subsurface geometry of this contact. The magnetic anomaly connected with the discontinuity is quite low, due to the small difference between the magnetic susceptibilities of the two granitic facies. Development of this model of inversion of the magnetic field, which is in good agreement with the geological interpretation, was made possible by: 1 accurate control of the geomagnetic time variations and consequent temporal reduction, 2 a very low level of the artificial magnetic noise, 3 high density of the magnetic survey, 4 detailed knowledge of the mapped geologic contact between facies and of their petrologic characteristics, and 5 direct local measurements of the magnetic susceptibilities of the key lithologies. The model shows the trends of the geological contact, as projected in three E-W sections, that dips eastward in the range between 210 and 540, supporting the geologic hypothesis that the Pietrabona facies represents an external shell of the shallowly emplaced Giglio monzogranite intrusion.

R. Cavallini

1998-06-01

306

Total exploitation of an ornamental granite quarry  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper we propose a methodology to estimate the recovery percentage for each of the products which can be obtained from the exploitation of an ornamental granite quarry: block, semiblock, masonry-transverse stone, and the smaller materials that can be used to obtain construction aggregates. This methodology ensures that quarry exploitation is exhaustive, thereby minimising the production of spoils and the consequent negative impact on the environment. The analysis is based on a detailed and exhaustive compilation of discontinuity data from the research fronts, which are then interpreted statistically and projected over the three weakness planes that are a particular feature of ornamental granite deposits. Using this information, and bearing in mind the minimum commercially viable sizes for each kind of granite, the corresponding recovery rates are calculated for each material in each plane. The results are then integrated using spatial techniques, and the result is an evaluation of quarry contents with a view to total exploitation. This methodology was applied to a quarry in the opening phase in order to carry out an a priori assessment of the economic feasibility of the quarry.

En este trabajo se propone una metodología para estimar el porcentaje de recuperación de cada uno de los productos que se pueden obtener en la explotación de una cantera de granito ornamental: bloque, semibloque, manpostería y per piaños, y material restante destinado a la obtención de áridos. De esta manera se logra un aprovechamiento integral de la cantera, evitándose la generación de estériles y el subsiguiente impacto ambiental producido por éstos. La metodología de análisis se basa en la recopilación detallada y exhaustiva de datos de discontinuidades en los frentes de investigación, que se interpretan estadísticamente y se proyectan sobre los tres planos de debilidad propios del granito ornamental. Con esta información, y las dimensiones mínimas comerciales de referencia para cada tipo de material, se realiza el cálculo de las recuperaciones correspondientes de cada material en cada plano y los resultados de recuperación sobre estos tres planos se integran mediante técnicas espaciales; obteniéndose la evaluación de los recursos en la cantera para su aprovechamiento integral. La metodología ha sido aplicada a una cantera en fase de apertura para realizar una valoración inicial de su viabililidad económica.

Taboada, J.

2005-09-01

307

A network-based realtime intrusion detection system  

International Nuclear Information System (INIS)

The author first reviews the background of Intrusion Detection (ID), then discusses the models and classifications of Intrusion Detection System (IDS). After detail the basic concepts to realize network-based realtime IDS, the analysis of authors' work are presented

308

A Novel Datamining Based Approach for Remote Intrusion Detection  

Directory of Open Access Journals (Sweden)

Full Text Available Today, as information systems are more open to the Internet,attacks and intrusions are also increasing rapidly so the importance of secure networks is also vital. New intelligent Intrusion Detection Systems which are based on sophisticated algorithms are in demand.Intrusion Detection System (IDS is an important detection used as a countermeasure to preserve data integrity and system availability from attacks. It is a combination of software and hardware that attempts to perform intrusion detection.In data mining based intrusion detection system, we should make use of particular domain knowledge in relation to intrusion detection in order to efficiently extract relative rules from large amounts of records.This paper proposes boosting method for intrusion detection and it is possible to detect the intrusions in all the Systems, without installing the Software in client System (like client-server via Web service (Apache tomcat by using the ip address of the client system.

Renu Deepti.S, Loshma.G

2012-06-01

309

Geologic map of the Granite 7.5' quadrangle, Lake and Chaffee Counties, Colorado  

Science.gov (United States)

The geologic map of the Granite 7.5' quadrangle, Lake and Chaffee Counties, Colorado, portrays the geology in the upper Arkansas valley and along the lower flanks of the Sawatch Range and Mosquito Range near the town of Granite. The oldest rocks, exposed in the southern and eastern parts of the quadrangle, include gneiss and plutonic rocks of Paleoproterozoic age. These rocks are intruded by younger plutonic rocks of Mesoproterozoic age. Felsic hypabyssal dikes, plugs, and plutons, ranging in age from Late Cretaceous or Paleocene to late Oligocene, locally intruded Proterozoic rocks. A small andesite lava flow of upper Oligocene age overlies Paleoproterozoic rock, just south of the Twin Lakes Reservoir. Gravelly fluvial and fan deposits of the Miocene and lower Pliocene(?) Dry Union Formation are preserved in the post-30 Ma upper Arkansas valley graben, a northern extension of the Rio Grande rift. Mostly north-northwest-trending faults displace deposits of the Dry Union Formation and older rock units. Light detection and ranging (lidar) imagery suggests that two short faults, near the Arkansas River, may displace surficial deposits as young as middle Pleistocene. Surficial deposits of middle Pleistocene to Holocene age are widespread in the Granite quadrangle, particularly in the major valleys and on slopes underlain by the Dry Union Formation. The main deposits are glacial outwash and post-glacial alluvium; mass-movement deposits transported by creep, debris flow, landsliding, and rockfall; till deposited during the Pinedale, Bull Lake, and pre-Bull Lake glaciations; rock-glacier deposits; and placer-tailings deposits formed by hydraulic mining and other mining methods used to concentrate native gold. Hydrologic and geologic processes locally affect use of the land and locally may be of concern regarding the stability of buildings and infrastructure, chiefly in low-lying areas along and near stream channels and locally in areas of moderate to steep slopes. Low-lying areas along major and minor streams are subject to periodic stream flooding. Mass-movement deposits and deposits of the Dry Union Formation that underlie moderate to steep slopes are locally subject to creep, debris-flow deposition, and landsliding. Proterozoic rocks that underlie steep slopes are locally subject to rockfall. Sand and gravel resources for construction and other uses in and near the Granite quadrangle are present in outwash-terrace deposits of middle and late Pleistocene age along the Arkansas River and along tributary streams in glaciated valleys.

Shroba, Ralph R.; Kellogg, Karl S.; Brandt, Theodore R.

2014-01-01

310

Towards better tamper&intrusion detection  

Energy Technology Data Exchange (ETDEWEB)

This presentation discusses in generic terms some of the work of the Vulnerability Assessment Team at Los Alamos National Laboratory in the area of tamper and intrusion detection. Novel security approaches are discussed. We also present preliminary results for a crude prototype of a high security ('Town Crier') monitoring system for securing moving cargo or stationary assets.

Johnston, R. G. (Roger G.); Garcia, A. R. E. (Anthony R. E.); Pacheco, A. N. (Adam N.)

2002-01-01

311

Chemical Observations of a Polar Vortex Intrusion  

Science.gov (United States)

An intrusion of vortex edge air in D the interior of the Arctic polar vortex was observed on the January 31,2005 flight of the NASA DC-8 aircraft. This intrusion was identified as anomalously high values of ozone by the AROTAL and DIAL lidars. Our analysis shows that this intrusion formed when a blocking feature near Iceland collapsed, allowing edge air to sweep into the vortex interior. along the DC-8 flight track also shows the intrusion in both ozone and HNO3. Polar Stratospheric Clouds (PSCs) were observed by the DIAL lidar on the DC-8. The spatial variability of the PSCs can be explained using MLS HNO3 and H2O observations and meteorological analysis temperatures. We also estimate vortex denitrification using the relationship between N2O and HNO3. Reverse domain fill back trajectory calculations are used to focus on the features in the MLS data. The trajectory results improve the agreement between lidar measured ozone and MLS ozone and also improve the agreement between the HNO3 measurements PSC locations. The back trajectory calculations allow us to compute the local denitrification rate and reduction of HCl within the filament. We estimate a denitrification rate of about lO%/day after exposure to below PSC formation temperature. Analysis of Aura MLS observations made

Schoeberl, M. R.; Kawa, S. R.; Douglass, A. R.; McGee, T. J.; Browell, E.; Waters, J.; Livesey, N.; Read, W.; Froidevaux, L.

2006-01-01

312

ON-LINE CALCULATOR: VAPOR INTRUSION MODELING  

Science.gov (United States)

Migration of volatile chemicals from the subsurface into overlying buildings is called vapor intrusion (VI). Volatile organic chemicals in contaminated soils or groundwater can emit vapors, which may migrate through subsurface soils and may enter the indoor air of overlying build...

313

Smart sensor systems for outdoor intrusion detection  

International Nuclear Information System (INIS)

A major improvement in outdoor perimeter security system probability of detection (PD) and reduction in false alarm rate (FAR) and nuisance alarm rate (NAR) may be obtained by analyzing the indications immediately preceding an event which might be interpreted as an intrusion. Existing systems go into alarm after crossing a threshold. Very slow changes, which accumulate until the threshold is reached, may be assessed falsely as an intrusion. A hierarchial program has begun at Stellar to develop a modular, expandable Smart Sensor system which may be interfaced to most types of sensor and alarm reporting systems. A major upgrade to the SSI Test Site is in progress so that intrusions may be simulated in a controlled and repeatable manner. A test platform is being constructed which will operate in conduction with a mobile instrumentation center with CCTVB, lighting control, weather and data monitoring and remote control of the test platform and intrusion simulators. Additional testing was contracted with an independent test facility to assess the effects of severe winter weather conditions

314

An Adaptive Database Intrusion Detection System  

Science.gov (United States)

Intrusion detection is difficult to accomplish when attempting to employ current methodologies when considering the database and the authorized entity. It is a common understanding that current methodologies focus on the network architecture rather than the database, which is not an adequate solution when considering the insider threat. Recent…

Barrios, Rita M.

2011-01-01

315

Intrusive [r] and Optimal Epenthetic Consonants  

Science.gov (United States)

This paper argues against the view of intrusive [r] as a synchronically arbitrary insertion process. Instead, it is seen as a phonologically natural process, which can be modelled within the framework of Optimality Theory (OT). Insertion of [r] in phonologically restricted environments is a consequence of a more general theory of consonant…

Uffmann, Christian

2007-01-01

316

Various Approaches for Detecting Attacks in Intrusion Detection System  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The rapid development of computer networks and more importantly internet has created many security problems such as ever growing new intrusions on computer network systems. To secure this systemstrong intrusion detection system has to be build. An intrusion detection system monitors all inbound and outbound network activity and identifies suspicious activities that attempting to break and violate security of system. In this paper we have taken review of various approaches of Intrusion detecti...

Prof. Priti Subramanium; Purva Adlakha

2013-01-01

317

An overview to Software Architecture in Intrusion Detection System  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Network intrusion detection systems provide proactive defense against security threats by detecting and blocking attack-related traffic. This task can be highly complex, and therefore, software-based network intrusion detection systems have difficulty in handling high speed links. This paper reviews of many type of software architecture in intrusion detection systems and describes the design and implementation of a high-performance network intrusion detection system that combines the use of s...

Mehdi Bahrami 1; Mohammad Bahrami 2

2011-01-01

318

How stratospheric are deep stratospheric intrusions?  

Directory of Open Access Journals (Sweden)

Full Text Available Preliminary attempts of quantifying the stratospheric ozone contribution in the observations at the Zugspitze summit (2962 m a.s.l. next to Garmisch-Partenkirchen in the German Alps had yielded an approximate doubling of the stratospheric fraction of the Zugspitze ozone during the time period 1978 and 2004. These investigations had been based on data filtering by using low relative humidity and elevated 7Be as the criteria for selecting half-hour intervals of ozone data representative of stratospheric intrusion air. For quantifying the residual stratospheric component in stratospherically influenced air masses, however, the mixing of tropospheric air into the stratospheric intrusion layers must be taken into account. In fact, the dew-point-mirror instrument at the Zugspitze summit station rarely registers relative humidity (RH values lower than 10% in stratospheric air intrusions. Since 2007 a programme of routine lidar sounding of ozone, water vapour and aerosol has been conducted in the Garmisch-Partenkirchen area. The lidar results demonstrate that the intrusion layers are dryer by roughly one order of magnitude than indicated in the in-situ measurements. Even in thin layers frequently RH values clearly below 1% have been observed. These thin, undiluted layers present an important challenge for atmospheric modelling. Although the ozone values never reach values typical of the lower-stratosphere it becomes, thus, obvious that, without strong wind shear or convective processes, mixing of stratospheric and tropospheric air must be very slow in most of the free troposphere. As a consequence, the analysis the Zugspitze data can be assumed to be more reliable than anticipated. Finally, the concentrations of Zugspitze carbon monoxide rarely drop inside intrusion layers and normally stay clearly above full stratospheric values. This indicates that most of the CO and, thus, the intrusion air mass originate in the shallow "mixing layer" around the thermal tropopause. The CO mixing ratio in these descending layers between 1990 and 2004 exhibits a slightly positive trend indicating some Asian influence on the lowermost stratosphere in the high-latitude source region of most intrusions reaching the station.

T. Trickl

2014-06-01

319

How stratospheric are deep stratospheric intrusions?  

Directory of Open Access Journals (Sweden)

Full Text Available Preliminary attempts of quantifying the stratospheric ozone contribution in the observations at the Zugspitze summit (2962 m a.s.l. next to Garmisch-Partenkirchen in the German Alps had yielded an approximate doubling of the stratospheric fraction of the Zugspitze ozone during the time period 1978 to 2004. These investigations had been based on data filtering by using low relative humidity (RH and elevated 7Be as the criteria for selecting half-hour intervals of ozone data representative of stratospheric intrusion air. To quantify the residual stratospheric component in stratospherically influenced air masses, however, the mixing of tropospheric air into the stratospheric intrusion layers must be taken into account. In fact, the dewpoint mirror instrument at the Zugspitze summit station rarely registers RH values lower than 10% in stratospheric air intrusions. Since 2007 a programme of routine lidar sounding of ozone, water vapour and aerosol has been conducted in the Garmisch-Partenkirchen area. The lidar results demonstrate that the intrusion layers are drier by roughly one order of magnitude than indicated in the in situ measurements. Even in thin layers RH values clearly below 1% have frequently been observed. These thin, undiluted layers present an important challenge for atmospheric modelling. Although the ozone values never reach values typical of the lower-stratosphere it becomes, thus, obvious that, without strong wind shear or convective processes, mixing of stratospheric and tropospheric air must be very slow in most of the free troposphere. As a consequence, the analysis the Zugspitze data can be assumed to be more reliable than anticipated. Finally, the concentrations of Zugspitze carbon monoxide rarely drop inside intrusion layers and normally stay clearly above full stratospheric values. This indicates that most of the CO, and thus the intrusion air mass, originates in the shallow "mixing layer" around the thermal tropopause. The CO mixing ratio in these descending layers between 1990 and 2004 exhibits a slightly positive trend indicating some Asian influence on the lowermost stratosphere in the high-latitude source region of most intrusions reaching the station.

T. Trickl

2014-09-01

320

How stratospheric are deep stratospheric intrusions?  

Science.gov (United States)

Preliminary attempts of quantifying the stratospheric ozone contribution in the observations at the Zugspitze summit (2962 m a.s.l.) next to Garmisch-Partenkirchen in the German Alps had yielded an approximate doubling of the stratospheric fraction of the Zugspitze ozone during the time period 1978 to 2004. These investigations had been based on data filtering by using low relative humidity (RH) and elevated 7Be as the criteria for selecting half-hour intervals of ozone data representative of stratospheric intrusion air. To quantify the residual stratospheric component in stratospherically influenced air masses, however, the mixing of tropospheric air into the stratospheric intrusion layers must be taken into account. In fact, the dewpoint mirror instrument at the Zugspitze summit station rarely registers RH values lower than 10% in stratospheric air intrusions. Since 2007 a programme of routine lidar sounding of ozone, water vapour and aerosol has been conducted in the Garmisch-Partenkirchen area. The lidar results demonstrate that the intrusion layers are drier by roughly one order of magnitude than indicated in the in situ measurements. Even in thin layers RH values clearly below 1% have frequently been observed. These thin, undiluted layers present an important challenge for atmospheric modelling. Although the ozone values never reach values typical of the lower-stratosphere it becomes, thus, obvious that, without strong wind shear or convective processes, mixing of stratospheric and tropospheric air must be very slow in most of the free troposphere. As a consequence, the analysis the Zugspitze data can be assumed to be more reliable than anticipated. Finally, the concentrations of Zugspitze carbon monoxide rarely drop inside intrusion layers and normally stay clearly above full stratospheric values. This indicates that most of the CO, and thus the intrusion air mass, originates in the shallow "mixing layer" around the thermal tropopause. The CO mixing ratio in these descending layers between 1990 and 2004 exhibits a slightly positive trend indicating some Asian influence on the lowermost stratosphere in the high-latitude source region of most intrusions reaching the station.

Trickl, T.; Vogelmann, H.; Giehl, H.; Scheel, H.-E.; Sprenger, M.; Stohl, A.

2014-09-01

 
 
 
 
321

Sorption of actinides in granitic rock  

International Nuclear Information System (INIS)

The sorption of americium (III), neptunium(V) and plutonium on geologic media under oxic conditions has been measured by a batch technique. The aqueous phase was a synthetic groundwater or 4M NaCl solution. The solid phase was a pure mineral, representative of igneous rocks, or granite. Altogether 40 different minerals and rocks were used. The effects of pH and the ionic strength of the aqueous phase as well as of the cation exchange capacity and the surface/mass ratio of the solid sorbent are discussed. Empirical equations giving the distribution coefficient as a function of pH in the environmental pH-range 7-9 are suggested. Some observations and conclusions concerning sorption mechanisms are given. (author)

322

Diffusion data in granite. Recommended values  

International Nuclear Information System (INIS)

Diffusion data for radionuclide transport in the porous matrix of rock are proposed for Swedish rock and ground waters, for performance assessment. Suggested data are based on an experimental diffusion study, where tritiated water was used as noninteracting diffusing species in stationary diffusion experiments in Aespoe fine grained granite and diorite. These data, for tritiated water, were used as reference in our study. For other species the effective diffusivities could be predicted from knowledge of the relative behaviour of these species to that of tritiated water. The behaviour is influenced by the difference in free water diffusivity and sometimes the existence of anion exclusion of surface diffusion. Apparent diffusivities are also calculated using sorption data, in addition to the effective diffusivities. Data are proposed for high saline and low saline ground water conditions

323

Diffusion data in granite. Recommended values  

Energy Technology Data Exchange (ETDEWEB)

Diffusion data for radionuclide transport in the porous matrix of rock are proposed for Swedish rock and ground waters, for performance assessment. Suggested data are based on an experimental diffusion study, where tritiated water was used as noninteracting diffusing species in stationary diffusion experiments in Aespoe fine grained granite and diorite. These data, for tritiated water, were used as reference in our study. For other species the effective diffusivities could be predicted from knowledge of the relative behaviour of these species to that of tritiated water. The behaviour is influenced by the difference in free water diffusivity and sometimes the existence of anion exclusion of surface diffusion. Apparent diffusivities are also calculated using sorption data, in addition to the effective diffusivities. Data are proposed for high saline and low saline ground water conditions. 38 refs, 6 figs, 4 tabs.

Ohlsson, Yvonne; Neretniks, I. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Chemical Engineering and Technology

1997-10-01

324

Permeability reduction in granite under hydrothermal conditions  

Science.gov (United States)

The formation of impermeable fault seals between earthquake events is a feature of many models of earthquake generation, suggesting that earthquake recurrence may depend in part on the rate of permeability reduction of fault zone materials under hydrothermal conditions. In this study, permeability measurements were conducted on intact, fractured, and gouge-bearing Westerly granite at an effective pressure of 50 MPa and at temperatures from 150° to 500°C, simulating conditions in the earthquake-generating portions of fault zones. Pore fluids were cycled back and forth under a 2 MPa pressure differential for periods of up to 40 days. Permeability of the granite decreased with time t, following the exponential relation k=c(10-rt). For intact samples run between 250° and 500°C the time constant for permeability decrease r was proportional to temperature and ranged between 0.001 and 0.1 days-1 (i.e., between 0.4 and 40 decades year-1 loss of permeability). Values of r for the lower-temperature experiments differed little from the 250°C runs. In contrast, prefractured samples showed higher rates of permeability decrease at a given temperature. The surfaces of the fractured samples showed evidence of dissolution and mineral growth that increased in abundance with both temperature and time. The experimentally grown mineral assemblages varied with temperature and were consistent with a rock-dominated hydrothermal system. As such mineral deposits progressively seal the fractured samples, their rates of permeability decrease approach the rates for intact rocks at the same temperature. These results place constraints on models of precipitation sealing and suggest that fault rocks may seal at a rate consistent with earthquake recurrence intervals of typical fault zones.

Morrow, C. A.; Moore, D. E.; Lockner, D. A.

2001-01-01

325

Inclusões fluidas crepitadas, fluidos hipersalinos e aquo-carbônicos em quartzo associado a rochas micáceas no Granito Xinguara - Terreno Granito-Greenstone de Rio Maria, PA Decrepitated fluid inclusions, aqueous-carbonic and hypersaline fluids in quartz associated to micaceous rocks in the Xinguara Granite - Rio Maria Granite - Greenstone terrain, Pará, Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available As rochas micáceas encontradas no Granito Xinguara, terreno Granito-Greenstone de Rio Maria, Pará, são compostas por muscovita e clorita com níveis de quartzo intercalados, que formam uma xistosidade bem desenvolvida. Essa xistosidade é cortada por veios de quartzo. Ambas as gerações de quartzo apresentam os mesmos tipos de inclusões fluidas em halos ou trilhas secundárias de composições variadas entre aquosas, aquo-carbônicas e saturadas em torno de grandes inclusões primárias crepitadas ou em trilhas transgranulares secundárias. A grande variação de temperaturas de homogeneização, a alta salinidade, as evidências de estrangulamento e a existência das inclusões crepitadas permitem supor forte influência de alterações pós-formacionais e reequilíbrio relacionados à intrusão do granito. Essas rochas foliadas são, portanto, enclaves metassedimentares afetados por fluidos graníticos hipersalinos aquo-carbônicos.The micaceous rocks occurring in the Xinguara Granite, Rio Maria Granite-Greenstone terrain, Pará State, Brazil, are composed of muscovite and chlorite with quartz levels intercalated forming a well developed schistosity. This schistosity is cut by quartz veins. Both quartz generations show the same aqueous, aqueous-carbonic and halite-bearing fluid inclusions either in secondary inclusions halos and trails surrounding decrepitated primary fluid inclusions or in transgranular secondary trails. A wide variation of homogenization temperatures, high salinity, necking down and the decrepitated inclusions existence indicates strong influence of post-formational alteration and reequilibration linked to the granite intrusion. These foliated rocks are metasedimentary enclaves affected by late hypersaline aqueous-carbonic granitic fluids.

Marcelo Leopoldo Weber

2008-03-01

326

Media use by children younger than 2 years.  

Science.gov (United States)

In 1999, the American Academy of Pediatrics (AAP) issued a policy statement addressing media use in children. The purpose of that statement was to educate parents about the effects that media--both the amount and the content--may have on children. In one part of that statement, the AAP recommended that "pediatricians should urge parents to avoid television viewing for children under the age of two years." The wording of the policy specifically discouraged media use in this age group, although it is frequently misquoted by media outlets as no media exposure in this age group. The AAP believed that there were significantly more potential negative effects of media than positive ones for this age group and, thus, advised families to thoughtfully consider media use for infants. This policy statement reaffirms the 1999 statement with respect to media use in infants and children younger than 2 years and provides updated research findings to support it. This statement addresses (1) the lack of evidence supporting educational or developmental benefits for media use by children younger than 2 years, (2) the potential adverse health and developmental effects of media use by children younger than 2 years, and (3) adverse effects of parental media use (background media) on children younger than 2 years. PMID:22007002

Brown, Ari

2011-11-01

327

Older and Younger Workers: The Equalling Effects of Health  

Science.gov (United States)

Purpose: The purpose of this paper is to consider the statistical evidence on the effects that ill health has on labour market participation and opportunities for younger and older workers in the East Midlands (UK). Design/methodology/approach: A statistical analysis of Labour Force Survey data was undertaken to demonstrate that health issues…

Beck, Vanessa; Quinn, Martin

2012-01-01

328

Chronic pain: its treatment in geriatric and younger patients.  

Science.gov (United States)

The response of geriatric patients to a multidisciplinary chronic pain rehabilitation program was measured by comparing outcome data on 17 older patients (55 to 78 years) to data on 20 younger patients (29 to 48 years) treated in the same program. Pretreatment data were obtained at an initial evaluation, and posttreatment data were obtained at the most recent follow-up contact, usually at 12 months after treatment. Treatment outcome was assessed on the basis of eight quantitative measures: pain ratings; health care utilization; activity tolerance; daily "up time"; hours per week spent in paid employment, housework, volunteer work, or school; medication intake; SCL-90R somatization, depression, and anxiety scores; and an overall summary measure. Pretreatment data indicated that older and younger groups were similar on both demographic variables and clinical status. There was a larger percentage of women in the older group. The older patients were initially somewhat more impaired than the younger ones, with nearly four times the rate of health care utilization and almost two times higher medication intake. Both groups improved significantly from pretreatment to posttreatment on most of the eight measures. Older patients showed a greater decrease in health care utilization. Women and men did not respond differentially to treatment. The data indicated that geriatric patients can benefit from chronic pain rehabilitation programs at least as much as, if not more than, younger patients. PMID:3214260

Middaugh, S J; Levin, R B; Kee, W G; Barchiesi, F D; Roberts, J M

1988-12-01

329

New Data Mining Algorithm for Intrusion Detection in Networks?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An intrusion detection system is a mechanism that monitors network or system activities formalicious activities. Intrusion detection and prevention systems (IDPS) are primarily focused on identifyingpossible incidents, logging information about them and reporting attempts .In organizations use IDPS forother purposes, such as identifying problems with security policies and deterring individuals from violatingsecurity policies. Intrusion detection systems have become a necessary addition to the...

Penchala Praveen, M.; Sambath, M.; Ravi?, S.

2013-01-01

330

On Younger Stakeholders and Decommissioning of Nuclear Facilities  

International Nuclear Information System (INIS)

In modern democratic countries, information sharing and effective and open communication concerning dismantling and decommissioning of of nuclear facilities as well as the management of nuclear waste are essential for the task to build the confidence required for any further development of nuclear energy. At the same time, it is often perceived that all decision making processes about nuclear energy policies are probably increasingly influenced by public opinion. Nuclear and radiation safety Authorities have a clear role in this regard to provide unbiased information on any health and safety related issues. In order to meet this need, it is necessary for Authorities and others to understand the values and opinions of the citizens, and especially the younger ones. They hold the key to the future at the same time as their perspective on these issues is the least understood. The need of greater public participation in decision making is becoming increasingly recognised the scientific as well as the political community. Many activities are carried out in order to stimulate to higher levels of public involvement in decision making in this active research area. Younger citizens is a stakeholder group that is often excluded in decision- making processes. The existence of large gaps between the involvement of older and younger stakeholders in decision making processes needs to be addressed, since such imbalances might otherwise lead to unequal opportunities between generations and limit the future consumption level of the coming generations. Another demanding task for the present generation is to assure that appropriate financial resources are injected into the Swedish Nuclear Waste Fund. It will thereby be possible for coming generations to undertake efficient measures in the decommissioning and dismantling of older nuclear facilities. To undertake such measures in line with the environmental and health codex is essential. An appropriate balance in this regard must be based on a proper understanding of the values and value functions of younger citizens. Such information must thus be an integral part of the knowledge base to be used when plans and processes are being developed for dismantling and decommissioning of nuclear power plants and other older nuclear facilities. In the present project, empirical data have been collected and compiled in a survey of the values of younger citizens with regard to decommissioning and dismantling of older nuclear facilities. The survey constitutes a stratified sample from three towns in Poland. They are Lublin, Olsztyn and Gdansk. A total of 780 students in the age group 14-19 years participated in the Survey. The results are compared to those from a similar study in the County of Kalmar in Sweden in the year 2006. The results include some major lesson learned. These may be summarised as follows: - Younger citizens tend to base their values regarding decommissioning on safety, and environmental aspects. Aspects like future economic growth and technological processes are less influential on the values. - Younger citizens tend to express a lack of information and debate as a basis of their value functions. Likewise, they tend to express interest in the topic and are open to become more included in the processes. - Younger citizens have suggestions on how more information can be made accessible to the general public. - Younger citizens need to be better included in the stakeholder process. This can be achieved by allowances from the Swedish Nuclear Waste Fund to support groups of younger citizens to follow the Swedish process of research, development and demonstration of a concept for the management of spent nuclear fuel. Less than fully accessible information campaigns about nuclear power and associated nuclear waste may result in differences in confidence levels between different groups of stakeholders. By finding out more about the values of different stakeholders it will be possible for the Swedish Radiation Safety Authority as well as for Society as a whole to enhance the possibility t o de

331

Clinical Analysis of Lung Cancer Patients Younger Than 30 Years  

Directory of Open Access Journals (Sweden)

Full Text Available Background and objective It is common recognized that young patients of lung cancer have poor prognosis due to relatively higher malignancy and more invasive growth. In the past most studies on young patients of lung cancer selected patients younger than 40 or 45 years old, and there were few clinical materials for younger patients under 30 years. This study retrospectively described the the disease history, stage, treatment and pathology features of lung cancer patients younger than 30 years and aimed to provide references for these patients. Methods Those patients younger than 30 years, once admitted in the General Hospital of the People's Liberation Army for lung cancer from 1993 to date, were sought in medical record system, and 53 patients were found in total. In this group, there were 34 non-small cell lung cancer (NSCLC patients and 19 small cell lung cacer (SCLC patients. The male/female ratio was 1.5:1. In the NSCLC patients, there were 27 adenocarcinomas, 6 squamous carcinomas and 1 adenosquamous carcinoma, with no large cell carcinoma involved. In these patients, 12 patients received operations while 38 patients got chemo- and/or radiotherapy and 3 quited any treatment. Results There was no death in hospital, however, in the 12 patients who got operation, only 8 patients got complete resection while 4 patients got palliative resection. Conclusion Lung cancer patients younger than 30 years had a high fraction of adenocarcinoma and small cell type pathologically and most of them were in late stage when presenting with symptoms in hospital and would have a dismal prognosis. The routine health examination and early diagnosis should be emphasized to improve the prognosis of these patients.

Guangjie HOU

2011-05-01

332

SHRIMP ion probe zircon geochronology and Sr and Nd isotope geochemistry for southern Longwood Range and Bluff Peninsula intrusive rocks of Southland, New Zealand  

International Nuclear Information System (INIS)

Permian-Jurassic ultramafic to felsic intrusive complexes at Bluff Peninsula and in the southern Longwood Range along the Southland coast represent a series of intra-oceanic magmatic arcs with ages spanning a time interval of 110 m.y. New SHRIMP U-Pb zircon data for a quartz diorite from the Flat Hill complex, Bluff Peninsula, yield an age of 259 ± 4 Ma, consistent with other geochronological and paleontological evidence confirming a Late Permian age. The new data are consistent with an age of c. 260 Ma for the intrusive rocks of the Brook Street Terrane. SHRIMP U-Pb zircon ages for the southern Longwood Range confirm that intrusions become progressively younger from east to west across the complex. A gabbro at Oraka Point (eastern end of coastal section) has an age of 245 ± 4 Ma and shows virtually no evidence of zircon inheritance. The age is significantly different from that of the Brook Street Terrane intrusives. Zircon ages from the western parts of the section are younger and more varied (203-227 Ma), indicating more complex magmatic histories. A leucogabbro dike from Pahia Point gives the youngest emplacement age of 142 Ma, which is similar to published U-Pb zircon ages for the Anglem Complex and Paterson Group on Stewart Island. (author). 44 refs., 6 figs., 2 tabs

333

Uranium mapping of a zircon crystal from Erzgebirge granites  

International Nuclear Information System (INIS)

By induced fission track uranium mapping of a zircon crystal from the Kirchberg granite (Western Erzgebirge) different U concentrations in the core and an outer zone have been determined. The U concentrations in the core and the outer zone differ by a factor of 12. The estimated partition coefficient between zircon and a granitic groundmass amounts to K?1800. From these data the concentration of U in the progenitor of Western Erzgebirge, Older Granite Suite, was deduced to be 0.7 ppm. (orig.)

334

Derivation of S and Pb in phanerozoic intrusion-related metal deposits from neoproterozoic sedimentary pyrite, Great Basin, United States  

Science.gov (United States)

The thick (???8 km), regionally extensive section of Neoproterozoic siliciclastic strata (terrigenous detrital succession, TDS) in the central and eastern Great Basin contains sedimentary pyrite characterized by mostly high d34S values (-11.6 to 40.8%, Pb isotopes ( 207Pb/204Pb Pb-Zn-Cu-Ag-Au deposits associated with Jurassic, Cretaceous, and Tertiary granitic intrusions (intrusion-related metal deposits) contain galena and other sulfide minerals with S and Pb isotope compositions similar to those of TDS sedimentary pyrite, consistent with derivation of deposit S and Pb from TDS pyrite. Minor element abundances in TDS pyrite (e.g., Pb, Zn, Cu, Ag, and Au) compared to sedimentary and hydrothermal pyrite elsewhere are not noticeably elevated, implying that enrichment in source minerals is not a precondition for intrusion-related metal deposits. Three mechanisms for transferring components of TDS sedimentary pyrite to intrusion-related metal deposits are qualitatively evaluated. One mechanism involves (1) decomposition of TDS pyrite in thermal aureoles of intruding magmas, and (2) aqueous transport and precipitation in thermal or fluid mixing gradients of isotopically heavy S, radiogenic Pb, and possibly other sedimentary pyrite and detrital mineral components, as sulfide minerals in intrusion-related metal deposits. A second mechanism invokes mixing and S isotope exchange in thermal aureoles of Pb and S exsolved from magma and derived from decomposition of sedimentary pyrite. A third mechanism entails melting of TDS strata or assimilation of TDS strata by crustal or mantle magmas. TDS-derived or assimilated magmas ascend, decompress, and exsolve a mixture of TDS volatiles, including isotopically heavy S and radiogenic Pb from sedimentary pyrite, and volatiles acquired from deeper crustal or mantle sources. In the central and eastern Great Basin, the wide distribution and high density of small to mid-sized vein, replacement, and skarn intrusion-related metal deposits in lower Paleozoic rocks that contain TDS sedimentary pyrite S and Pb reflect (1) prolific Jurassic, Cretaceous, and Tertiary magmatism, (2) a regional, substrate reservoir of S and Pb in permeable and homogeneous siliciclastic strata, and (3) relatively small scale concentration of substrate and magmatic components. Large intrusion-related metal deposits in the central and eastern Great Basin acquired S and most Pb from thicker lithospheric sections. ?? 2011 Society of Economic Geologists, Inc.

Vikre, P. G.; Poulson, S. R.; Koenig, A. E.

2011-01-01

335

The state of the art in intrusion prevention and detection  

CERN Document Server

The State of the Art in Intrusion Prevention and Detection analyzes the latest trends and issues surrounding intrusion detection systems in computer networks, especially in communications networks. Its broad scope of coverage includes wired, wireless, and mobile networks; next-generation converged networks; and intrusion in social networks.Presenting cutting-edge research, the book presents novel schemes for intrusion detection and prevention. It discusses tracing back mobile attackers, secure routing with intrusion prevention, anomaly detection, and AI-based techniques. It also includes infor

Pathan, Al-Sakib Khan

2013-01-01

336

Intrusion detection networks a key to collaborative security  

CERN Document Server

The rapidly increasing sophistication of cyber intrusions makes them nearly impossible to detect without the use of a collaborative intrusion detection network (IDN). Using overlay networks that allow an intrusion detection system (IDS) to exchange information, IDNs can dramatically improve your overall intrusion detection accuracy.Intrusion Detection Networks: A Key to Collaborative Security focuses on the design of IDNs and explains how to leverage effective and efficient collaboration between participant IDSs. Providing a complete introduction to IDSs and IDNs, it explains the benefits of b

Fung, Carol

2013-01-01

337

Intrusion Detection in Data Mining With Classification Algorithm  

Directory of Open Access Journals (Sweden)

Full Text Available In the research of intrusion detection there are so manyattacks in the real life and some IDS System to detect it like network-based IDS, host-based IDS and application-based IDS to detect the Intrusion. In this paper, one frame work is introduce to detect an intrusion data with the help of data mining, a framework for intrusion detection system for filtering data set to network attacks. We also talk about the basic data mining technology for finding intrusion data for the data set. Detection in the field of data mining for intrusion detection. We also discuss some of the common algorithms for intrusion detection, such as decision trees, Naive Bayes, Naive Bayes (CFSGSW, NBTree improved adaptive NBTree it.

PATEL HEMANT, BHARAT SARKHEDI, HIREN VAGHAMSHI

2013-07-01

338

Distributed fiber optic moisture intrusion sensing system  

Science.gov (United States)

Method and system for monitoring and identifying moisture intrusion in soil such as is contained in landfills housing radioactive and/or hazardous waste. The invention utilizes the principle that moist or wet soil has a higher thermal conductance than dry soil. The invention employs optical time delay reflectometry in connection with a distributed temperature sensing system together with heating means in order to identify discrete areas within a volume of soil wherein temperature is lower. According to the invention an optical element and, optionally, a heating element may be included in a cable or other similar structure and arranged in a serpentine fashion within a volume of soil to achieve efficient temperature detection across a large area or three dimensional volume of soil. Remediation, moisture countermeasures, or other responsive action may then be coordinated based on the assumption that cooler regions within a soil volume may signal moisture intrusion where those regions are located.

Weiss, Jonathan D. (Albuquerque, NM)

2003-06-24

339

Using Jquery with Snort to Visualize Intrusion  

Directory of Open Access Journals (Sweden)

Full Text Available The explosive growth of malicious activities on worldwide communication networks, such as the Internet, has highlighted the need for efficient intrusion detection systems. The efficiency of traditional intrusion detection systems is limited by their inability to effectively relay relevant information due to their lack of interactive / immersive technologies. Visualized information is a technique that can encode large amounts of complex interrelated data, being at the same time easily quantified, manipulated, and processed by a human user. Authors have found that the representations can be quite effective at conveying the needed information and resolving the relationships extremely rapidly. To facilitate the creation of novel visualizations this paper presents a new framework that is designed with using data visualization technique by using Jquery Php for analysis and visualizes snort result data for user.

Alaa El - Din Riad

2012-01-01

340

A Survey on VANET Intrusion Detection Systems  

Directory of Open Access Journals (Sweden)

Full Text Available In recent years, the security issues on Vehicular ad hoc networks (VANETs have become one of the primary concerns. The VANET is inherently very vulnerable to attacks than wired network because it is characterized by high mobility, shared wireless medium and the absence of centralized security services offered by dedicated equipment such as firewalls and authentication servers. Attackcountermeasures such as digital signature and encryption, can be used as the first line of defense for reducing the possibilities of attacks. However, these techniques have limited prevention in general, and they are designed for a set of known attacks. They are unlikely to avoid most recent attacks that are designed to circumvent existing security measures. For this reason, there is a need of second technique to “detect and notify” these newer attacks, i.e. “intrusion detection”. This article aims to present and classifycurrent techniques of Intrusion Detection System (IDS aware VANETs.

Mohammed ERRITALI

2013-04-01