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Geochemistry and depositional environment of fuchsite quartzites from Sargur Group,western Dharwar Craton,India
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作者 C.S.Sindhuja G.Harshitha +1 位作者 C.Manikyamba K.S.V.Subramanyam 《Acta Geochimica》 EI CAS CSCD 2024年第3期555-570,共16页
Meso-Neoarchean fuchsite quartzites are present in different stratigraphic positions of Dharwar Craton including the oldest(~3.3 Ga)Sargur Group of western Dharwar Craton.The present study deals with the petro-graphic... Meso-Neoarchean fuchsite quartzites are present in different stratigraphic positions of Dharwar Craton including the oldest(~3.3 Ga)Sargur Group of western Dharwar Craton.The present study deals with the petro-graphic and geochemical characteristics of the fuchsite quartzites from the Ghattihosahalli belt to evaluate their genesis,depositional setting and the enigma involved in the ancient sedimentation history.Their major mineral assemblages include quartz,fuchsite,and feldspars along with accessory kyanite and rutile.The geochemical com-positions are characterized by high SiO_(2),Al_(2)O_(3),low MgO,CaO,strongly enriched Cr(1326–6899 ppm),Ba(1165–3653 ppm),Sr(46–210 ppm),V(107–868 ppm)and Zn(11–158 ppm)contents compared to the upper continental crust(UCC).The UCC normalized rare earth element(REE)patterns are characterized by depleted light REE[(La/Sm)UCC=0.33–0.95]compared to heavy REE[(Gd/Yb)_(UCC)=0.42–1.65]with conspicuous positive Eu-anomalies(Eu/Eu^(*)=1.35–18.27)characteristic of hydrothermal solutions evidenced through the interlayered barites.The overall major and trace element systematics reflect a combined mafic-felsic provenance and suggest their deposition at a passive continental margin environ-ment.The comprehensivefield,petrographic,and geo-chemical studies indicate that these quartzites are infiltrated by Cr-richfluids released during high-grade metamorphism of associated ultramafic rocks.The Sargur and the subse-quent Dharwar orogeny amalgamated diverse lithounits from different tectonic settings,possibly leading to the release of Cr-richfluids and the formation of fuchsite quartzite during or after the orogeny.Thesefindings sug-gest a pre-existing stable crust prior to the Sargur Group and the link between orogenic events and various mineral deposits in the Dharwar Craton. 展开更多
关键词 dharwar Craton Ghattihosahalli Fuchsite quartzite PROVENANCE Depositional setting
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Geochemistry of Layered Ultramafic Rocks in J.C. Pura Schist Belt, Dharwar Craton, Karnataka, India
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作者 S. Santhosh B. G. Dayanand B. C. Prabhakar 《Open Journal of Geology》 CAS 2023年第2期189-202,共14页
The Jayachamarajapura schist belt in western Dharwar craton, southern India, is predominantly an ultramafics dominant terrain. These rocks have been extensively metamorphosed and altered to serpentinite. The komatiite... The Jayachamarajapura schist belt in western Dharwar craton, southern India, is predominantly an ultramafics dominant terrain. These rocks have been extensively metamorphosed and altered to serpentinite. The komatiite nature of ultramafics is conspicuous. In most of the areas of the belt these ultramafics are massive in nature. However, some of the ultramafic units show layered nature. But, their outcrops are encompassed within the massive komatiitic bodies. These komatiitic ultramafics are predominantly Mg-rich in nature. The layered rocks are also Mg-rich, and their field setting and geochemistry suggest their intermittent occurrence as sills, during the differentiation of peridotitic magma. The layered rocks, which have been intensely serpentinisation show homogenous nature. They are almost wholly made of serpentine with occasional relics of pyroxene. Secondary carbonate mineral is often noticed. Their higher MgO content indicates Mg-rich ultramafic magmatism during Archaean orogeny. 展开更多
关键词 Western dharwar Craton Layered Sequences KOMATIITE J.C. Pura Belt
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Eastern Dharwar Craton,India:Continental lithosphere growth by accretion of diverse plume and arc terranes 被引量:10
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作者 C.Manikyamba Robert Kerrich 《Geoscience Frontiers》 SCIE CAS 2012年第3期225-240,共16页
Abstract Greenstone belts of the eastern Dharwar Craton, India are reinterpreted as composite tecto- nostratigraphic terranes of accreted plume-derived and convergent margin-derived magmatic sequences based on new hig... Abstract Greenstone belts of the eastern Dharwar Craton, India are reinterpreted as composite tecto- nostratigraphic terranes of accreted plume-derived and convergent margin-derived magmatic sequences based on new high-precision elemental data. The former are dominated by a komatiite plus Mg-tholeiitic basalt volcanic association, with deep water siliciclastic and banded iron formation (BIF) sedimentary rocks. Plumes melted at 〈90 km under thin rifted continental lithosphere to preserve intrao- ceanic and continental margin aspects. Associated alkaline basalts record subduction-recycling of Me- soarchean oceanic crust, incubated in the asthenosphere, and erupted coevally with Mg basalts from a heterogeneous mantle plume. Together, komatiites-Mg basalts-alkaline basalts plot along the Phanero- zoic mantle array in Th/Yb versus Nb/Yb coordinate space, representing zoned plumes, establishing that these reservoirs were present in the Neoarchean mantle. Convergent margin magmatic associations are dominated by tholeiitic to calc-alkaline basalts compo- sitionally similar to recent intraoceanic arcs. As well, boninitic flows sourced in extremely depleted mantle are present, and the association of arc basalts with Mg-andesites-Nb enriched basalts-adakites documented from Cenozoic arcs characterized by subduction of young (〈20 Ma), hot, oceanic litho- sphere. Consequently, Cenozoic style "hot" subduction was operating in the Neoarchean. These diverse volcanic associations were assembled to give composite terranes in a subduction-accretion orogen at -2.7 Ga, coevally with a global accretionary orogen at -2.7 Ga, and associated orogenic gold mineralization. 展开更多
关键词 Continental lithospheregrowth Zoned plume Subduction-accretion Neoarchean mantle GEODYNAMICS Eastern dharwar Craton
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Tourmaline from the Archean G.R.Halli gold deposit,Chitradurga greenstone belt,Dharwar craton(India):Implications for the gold metallogeny 被引量:5
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作者 Susmita Gupta M.Jayananda Fareeduddin 《Geoscience Frontiers》 SCIE CAS CSCD 2014年第6期877-892,共16页
Tourmaline occurs as a minor but important mineral in the alteration zc,ne of the Archean orogenic gold deposit of Guddadarangavanahalli (G.R.Halli) in the Chitradurga greenst^ne belt of the western Dharwar craton, ... Tourmaline occurs as a minor but important mineral in the alteration zc,ne of the Archean orogenic gold deposit of Guddadarangavanahalli (G.R.Halli) in the Chitradurga greenst^ne belt of the western Dharwar craton, southern India. It occurs in the distal alteration halo of the G.R.Halli golcl deposit as (a) clusters of very fine grained aggregates which form a minor constituent in the natrix of the altered metabasalt (AMB tourmaline) and (b) in quartz-carbonate veins (vein tourmaline). ~['he vein tourmaline, based upon the association of specific carbonate minerals, is further grouped as (i) albite-tourmaline-ankerite-quartz veins (vein-1 tourmaline) and (ii) albite-tourmaline-calcite-quartz veins (vein-2 tourmaline). Both the AMB tourmaline and the vein tourmalines (vein-I and vein-2) belong to the alkali group and are clas- sified under schorl-dravite series. Tourmalines occurring in the veins are zoned while the AMB tour- malines are unzoned. Mineral chemistry and discrimination diagrams 1eveal that cores and rims of the vein tourmalines are distinctly different. Core composition of the ve:n tourmalines is similar to the composition of the AMB tourmaline. The formation of the AMB tourmaline and cores of the vein tour- malines are proposed to be related to the regional D1 deformational event associated with the emplacement of the adjoining ca. 2.61 Ga Chitradurga granite whilst rims of the vein tourmalines vis-a- vis gold mineralization is spatially linked to the juvenile magmatic accretion (2.56-2.50 Ga) east of the studied area in the western part of the eastern Dharwar craton. 展开更多
关键词 TOURMALINE G.R.HalIi Orogenic gold deposit dharwar craton ARCHEAN
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Magnetotelluric investigation of lithospheric electrical structure beneath the Dharwar Craton in south India:Evidence for mantle suture and plume-continental interaction 被引量:3
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作者 D. Malleswari K. Veeraswamy +4 位作者 K.K. Abdul Azeez A.K. Gupta Narendra Babu Prasanta K. Patro T. Harinarayana 《Geoscience Frontiers》 SCIE CAS CSCD 2019年第5期1915-1930,共16页
Broad-band and long period magnetotelluric measurements made at 63 locations along -500 km long Chikmagalur-Kavali profile,that cut across the Dharwar craton (DC) and Eastern Ghat Mobile Belt (EGMB) in south India,is ... Broad-band and long period magnetotelluric measurements made at 63 locations along -500 km long Chikmagalur-Kavali profile,that cut across the Dharwar craton (DC) and Eastern Ghat Mobile Belt (EGMB) in south India,is modelled to examine the lithosphere architecture of the cratonic domain and define tectonic boundaries.The 2-D resistivity model shows moderately conductive features that intersperse a highly resistive background of crystalline rocks and spatially connect to the exposed schist belts or granitic intrusions in the DC.These features are therefore interpreted as images of fossil pathways of the volcanic emplacements associated with the greenstone belt and granite suite formation exposed in the region.A near vertical conductive feature in the upper mantle under the Chitradurga Shear Zone represents the Archean suture between the western and eastern blocks of DC.Although thick (-200 km) cratonic (highly resistive) lithosphere is preserved,significant part of the cratonic lithosphere below the western DC is modified due to plume-continental lithosphere interactions during the CretaceouseTertiary period.A west-verging moderately conductive feature imaged beneath EGMB lithosphere is interpreted as the remnant of the Proterozoic collision process between the Indian land mass and East Antarctica.Thin (-120 km) lithosphere is seen below the EGMB,which form the exterior margin of the India shield subsequent to its separation from East Antarctica through rifting and opening of the Indian Ocean in the Cretaceous. 展开更多
关键词 MAGNETOTELLURIC LITHOSPHERIC structure MANTLE PLUME MANTLE SUTURE dharwar CRATON
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AMS studies on a 450 km long 2216 Ma dyke from Dharwar craton, India:Implications to magma flow 被引量:2
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作者 E. Nagaraju V. Parashuramulu 《Geoscience Frontiers》 SCIE CAS CSCD 2019年第5期1931-1939,共9页
Anisotropy of magnetic susceptibility (AMS) studies were carried out on a precisely dated (2216.0 ± 0.9 Ma),450 km long NeS striking dyke in the Dharwar Craton,to determine the magma flow direction along the dyke... Anisotropy of magnetic susceptibility (AMS) studies were carried out on a precisely dated (2216.0 ± 0.9 Ma),450 km long NeS striking dyke in the Dharwar Craton,to determine the magma flow direction along the dyke length.In order to use the imbrication of the magnetic foliation,forty eight samples were collected from 13 locations along the length of the dyke.Magnetogranulometry studies show that AMS fabric is dominated by medium grained interstitial Ti-poor multidomain magnetite.The corrected anisotropy degree (Pj) of the samples was found to be low to moderate,between 1.007 and 1.072,which indicates primary magnetic fabric.The magnetic ellipsoid is either triaxial,prolate or oblate and clearly defines normal,intermediate and inverse magnetic fabrics related to magma flow during the dyke emplacement.The maximum susceptibility axes (Kmax) of the AMS tensor of the dyke is predominantly inclined at low angles (<30°),with no systematic variation in depth along the NeS profile,indicating sub-horizontal flow even at mid crustal levels which could probably be governed by location of the focal region of the magma source (mantle plume?),flow dynamics together with the compressive stresses exerted by the overlying crust. 展开更多
关键词 ANISOTROPY of magnetic SUSCEPTIBILITY dharwar CRATON DYKE SWARMS
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Detrital zircon U-Pb geochronology of stromatolitic carbonates from the greenstone belts of Dharwar Craton and Cuddapah basin of Peninsular India 被引量:2
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作者 Arubam C.Khelen C.Manikyamba +3 位作者 Li Tang M.Santosh K.S.V.Subramanyam Th Dhanakumar Singh 《Geoscience Frontiers》 SCIE CAS CSCD 2020年第1期229-242,共14页
Oldest rocks are sparsely distributed within the Dharwar Craton and little is known about their involvement in the sedimentary sequences which are present in the Archean greenstone successions and the Proterozoic Cudd... Oldest rocks are sparsely distributed within the Dharwar Craton and little is known about their involvement in the sedimentary sequences which are present in the Archean greenstone successions and the Proterozoic Cuddapah basin.Stromatolitic carbonates are well preserved in the Neoarchean greenstone belts of Dharwar Craton and Cuddapah Basin of Peninsular India displaying varied morphological and geochemical characteristics.In this study,we report results from U-Pb geochronology and trace element composition of the detrital zircons from stromatolitic carbonates present within the Dharwar Craton and Cuddapah basin to understand the provenance and time of accretion and deposition.The UPb ages of the detrital zircons from the Bhimasamudra and Marikanve stromatolites of the Chitradurga greenstone belt of Dharwar Craton display ages of 3426±26 Ma to 2650±38 Ma whereas the Sandur stromatolites gave an age of 3508±29 Ma to 2926±36 Ma suggesting Paleo-to Neoarchean provenance.The U-Pb detrital zircons of the Tadpatri stromatolites gave an age of 2761±31 Ma to1672±38 Ma suggesting Neoarchean to Mesoproterozoic provenance.The Rare Earth Element(REE)patterns of the studied detrital zircons from Archean Dharwar Craton and Proterozoic Cuddapah basin display depletion in light rare earth elements(LREE)and enrichment in heavy rare earth elements(HREE)with pronounced positive Ce and negative Eu anomalies,typical of magmatic zircons.The trace element composition and their relationship collectively indicate a mixed granitoid and mafic source for both the Dharwar and Cuddapah stromatolites.The 3508±29 Ma age of the detrital zircons support the existence of 3.5 Ga crust in the Western Dharwar Craton.The overall detrital zircon ages(3.5-2.7 Ga)obtained from the stromatolitic carbonates of Archean greenstone belts and Proterozoic Cuddapah basin(2.7-1.6 Ga)collectively reflect on^800-900 Ma duration for the Precambrian stromatolite deposition in the Dharwar Craton. 展开更多
关键词 STROMATOLITES ARCHEAN PROTEROZOIC dharwar Craton Cuddapah basin Detrital zircons
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New Data on the Mineralogy of Chromite from the Nuggihalli Schist Belt,Western Dharwar Craton,Karnataka,India:Petrogenetic Implications 被引量:2
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作者 Perumala V.S.RAJU Elapavalooru V.S.S.K.BABU Roland K.W.MERKLE 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2011年第1期107-115,共9页
The occurrence of rhythmic layering of chromite and host serpentinites in the deformed layered igneous complexes has been noticed in the Nuggihalli schist belt (NSB) in the western Dharwar craton, Karnataka, South I... The occurrence of rhythmic layering of chromite and host serpentinites in the deformed layered igneous complexes has been noticed in the Nuggihalli schist belt (NSB) in the western Dharwar craton, Karnataka, South India. For this study, the chromitite rock samples were collected from Jambur, Tagadur, Bhakatarhalli, Ranganbetta and Byrapur in the NSB. Petrography and ore microscopic studies on chromite show intense cataclasis and alteration to ferritchromite. The ferritchromite compositions are characterized by higher Cr number (Cr/[Cr+AI]) (0.68-0.98) and lower Mg number (Mg/[Mg+Fe]) (0.33-0.82) ratios in ferritchromite compared to that of parent chromite. The formation process for the ferritchromite is thought to be related to the exchange of Mg, AI, Cr, and Fe between the chromite, surrounding silicates (serpentines, chlorites), and fluid during serpentinization. 展开更多
关键词 CHROMITE ferritchromite Nuggihalli schist belt dharwar Craton INDIA
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Petrogenesis of 3.15 Ga old Banasandra komatiites from the Dharwar craton, India: Implications for early mantle heterogeneity 被引量:1
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作者 J.M.Maya Rajneesh Bhutani +1 位作者 S.Balakrishnan S.Rajee Sandhya 《Geoscience Frontiers》 SCIE CAS CSCD 2017年第3期467-481,共15页
Spinifex-textured, magnesian (MgO 〉25 wt.%) komatiites from Mesoarchean Banasandra greenstone belt of the Sargur Group in the Dharwar craton, India were analysed for major and trace elements and 147,146Sm-143,142Nd... Spinifex-textured, magnesian (MgO 〉25 wt.%) komatiites from Mesoarchean Banasandra greenstone belt of the Sargur Group in the Dharwar craton, India were analysed for major and trace elements and 147,146Sm-143,142Nd systematics to constrain age, petrogenesis and to understand the evolution of Archean mantle. Major and trace element ratios such as CaOJAl203, Al2O3JTiO2, GdJYb, LaJNb and NbJY suggest aluminium undepleted to enriched compositional range for these komatiites. The depth of melting is estimated to be varying from 120 to 240 km and trace-element modelling indicates that the mantle source would have undergone multiple episodes of melting prior to the generation of magmas parental to these komatiites. Ten samples of these komatiites together with the published results of four samples from the same belt yield 147Sm-143Nd isochron age of ca. 3.14 Ga with an initial ENd(t) value of +3.5. High precision measurements of 142Nd/144Nd ratios were carried out for six komatiite samples along with standards AMES and La Jolla. All results are within uncertainties of the terrestrial samples. The absence of 142Nd/144Nd anomaly indicates that the source of these komatiites formed after the extinction of 146Sm, i.e. 4.3 Ga ago. In order to evolve to the high eNd(t) value of +3.5 by 3.14 Ga the time-integrated ratio of 147Sm/144Nd should be 0.2178 at the minimum. This is higher than the ratios estimated, so far, for mantle during that time. These results indicate at least two events of mantle differentiation starting with the chondritic composition of the mantle. The first event occurred very early at ~ 4.53 Ga to create a global early depleted reservoir with superchondritic Sm/Nd ratio, The source of Isua greenstone rocks with positive ~42Nd anomaly was depleted during a second differentiation within the life time of 146Sm, i.e. prior to 4.46 Ga. The source mantle of the Banasandra komatiite was a result of a differentiation event that occurred after the extinction of the 146Sm, i,e. at 4.3 Ga and prior to 3,14 Ga. Banasandra komatiites therefore provide evidence for preservation of heterogeneities generated during mantle differentiation at 4,3 Ga. 展开更多
关键词 Komatiite dharwar craton Early mantle differentiation 142Nd/144Nd Sm-Nd geochronology
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REE geochemistry of auriferous quartz carbonate veins of Neoarchean Ajjanahalli gold deposit,Chitradurga schist belt,Dharwar Craton,India 被引量:1
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作者 S.Sarangi R.Srinivasan V.Balaram 《Geoscience Frontiers》 SCIE CAS CSCD 2013年第2期231-239,共9页
REE composition of the carbonates of the auriferous quartz carbonate veins(QCVs) of the Neoarchean Ajjanahalli gold deposit.Chitradurga schist belt.Dharwar Craton,is characterized by U-shaped chondrite normalized RE... REE composition of the carbonates of the auriferous quartz carbonate veins(QCVs) of the Neoarchean Ajjanahalli gold deposit.Chitradurga schist belt.Dharwar Craton,is characterized by U-shaped chondrite normalized REE patterns with both LREE and HREE enrichment and a distinct positive Eu anomaly.As positive Eu anomaly is associated with low oxygen fugacity,we propose that the auriferous fluids responsible for gold mineralization at Ajjanahalli could be from an oxygen depleted fluid.The observed positive Eu anomaly is interpreted to suggest the derivation of the auriferous fluids from a mantle reservoir.The location of Ajjanahalli gold deposit in a crustal scale shear zone is consistent with this interpretation. 展开更多
关键词 U-shaped REE pattern Eu anomaly Quartz carbonate veins(QCVs) Orogenic gold deposits dharwar Craton
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Petrology and Sr-Nd isotope systematics of the Ahobil kimberlite(Pipe-16)from the Wajrakarur field, Eastern Dharwar craton, southern India
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作者 Abhinay Sharma Alok Kumar +3 位作者 Praveer Pankaj Dinesh Pandit Ramananda Chakrabarti N.V.Chalapathi Rao 《Geoscience Frontiers》 SCIE CAS CSCD 2019年第3期1167-1186,共20页
Detailed mineralogical, bulk-rock geochemical and Sr-Nd isotopic data for the recently discovered Ahobil kimberlite(Pipe-16) from the Wajrakarur kimberlite field(WKF), Eastern Dharwar craton(EDC),southern India, are p... Detailed mineralogical, bulk-rock geochemical and Sr-Nd isotopic data for the recently discovered Ahobil kimberlite(Pipe-16) from the Wajrakarur kimberlite field(WKF), Eastern Dharwar craton(EDC),southern India, are presented. Two generations of compositionally distinct olivine, Ti-poor phlogopite showing orangeitic evolutionary trends, spinel displaying magmatic trend-1, abundant perovskite, Tirich hydrogarnet, calcite and serpentine are the various mineral constituents. On the basis of(i) liquidus mineral composition,(ii) bulk-rock chemistry, and(iii) Sr-Nd isotopic composition, we show that Ahobil kimberlite shares several characteristic features of archetypal kimberlites than orangeites and lamproites. Geochemical modelling indicate Ahobil kimberlite magma derivation from small-degree melting of a carbonated peridotite source having higher Gd/Yb and lower La/Sm in contrast to those of orangeites from the Eastern Dharwar and Bastar cratons of Indian shield. The T_(Dm) Nd model age(~2.0 Ga) of the Ahobil kimberlite is(i) significantly older than those(1.5~1.3 Ga) reported for Wajrakarur and Narayanpet kimberlites of EDC,(ii) indistinguishable from those of the Mesoproterozoic EDC lamproites,and(iii) strikingly coincides with the timing of the amalgamation of the Columbia supercontinent. High bulk-rock Fe-Ti contents and wide variation in oxygen fugacity fO_2, as inferred from perovskite oxybarometry, suggest non-prospective nature of the Ahobil kimberlite for diamond. 展开更多
关键词 PETROLOGY ISOTOPES KIMBERLITE Wajrakarur dharwar CRATON INDIA
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Nature and source of the ore-forming fluids associated with orogenic gold deposits in the Dharwar Craton
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作者 Biswajit Mishra Kamal Lochan Pruseth +1 位作者 Pranjit Hazarika Sakthi Saravanan Chinnasamy 《Geoscience Frontiers》 SCIE CAS CSCD 2018年第3期715-726,共12页
Neoarchean orogenic gold deposits, associated with the greenstone-granite milieus in the Dharwar Craton include(1) the famous Kolar mine and the world class Hutti deposit;(2) small mines at HiraBuddini, Uti, Ajjanahal... Neoarchean orogenic gold deposits, associated with the greenstone-granite milieus in the Dharwar Craton include(1) the famous Kolar mine and the world class Hutti deposit;(2) small mines at HiraBuddini, Uti, Ajjanahalli, and Guddadarangavanahalli;(3) prospects at Jonnagiri; and(4) old mining camps in the Gadag and Ramagiri-Penakacherla belts. The existing diametric views on the source of ore fluid for formation of these deposits include fluids exsolved from granitic melts and extracted by metamorphic devolatilization of the greenstone sequences. Lode gold mineralization occurs in structurally controlled higher order splays in variety of host rocks such as mafic/felsic greenstones, banded iron formations, volcaniclastic rocks and granitoids. Estimated metamorphic conditions of the greenstones vary from lower greenschist facies to mid-amphibolite facies and mineralizations in all the camps are associated with distinct hydrothermal alterations. Fluid inclusion microthermometric and Raman spectroscopic studies document low salinity aqueous-gaseous(H_2O + CO_2 ± CH_4 + NaCl) ore fluids,which precipitated gold and altered the host rocks in a narrow P-T window of 0.7-2.5 kbar and 215-320℃. While the calculated fluid O-and C-isotopic values are ambiguous, S-isotopic compositions of pyrite-precipitating fluid show distinct craton-scale uniformity in terms of its reduced nature and a suggested crustal sulfur source.Available ages on greenstone metamorphism, granitoid plutonism and mineralization in the Hutti Belt are tantamount, making a geochronology-based resolution of the existing debate on the metamorphic vs.magmatic fluid source impossible. In contrast, tourmaline geochemistry suggests involvement of single fluid in formation of gold mineralization, primarily derived by metamorphic devolatilization of mafic greenstones and interlayered sedimentary rocks, with minor magmatic contributions. Similarly, compositions of scheelite, pyrite and arsenopyrite point toward operation of fault-valves that caused pressure fluctuation-induced fluid phase separation, which acted as the dominant process of gold precipitation,apart from fluid-rock sulfidation reactions. Therefore, results from geochemistry of hydrothermal minerals and those from fluid inclusion microthermometry corroborate in constraining source of ore fluid,nature of gold transport(by Au-bisulfide complex) and mechanism of gold ore formation in the Dharwar Craton. 展开更多
关键词 dharwar Gold FLUID INCLUSIONS ISOTOPES FLUID composition GREENSTONE METAMORPHISM
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Hydrothermal Hgbomite Associated with Vanadiferous-Titaniferous(V-Ti) Bearing Magnetite Bands in Bhakatarhalli Chromite Mine, Nuggihalli Greenstone Belt, Western Dharwar Craton, Karnataka, India
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作者 Raju V.S.PERUMALA Roland K.W.MERKLE 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2014年第3期845-853,共9页
Hogbomite,a rare exotic mineral,is found to be associated with the vanadiferous-titaniferous (V-Ti) bearing magnetite bands at Bhakatarhalli,Nuggihaifi greenstone belt,western Dharwar Craton,India.We report on a sec... Hogbomite,a rare exotic mineral,is found to be associated with the vanadiferous-titaniferous (V-Ti) bearing magnetite bands at Bhakatarhalli,Nuggihaifi greenstone belt,western Dharwar Craton,India.We report on a second occurrence of hogbomite from the Dharwar craton in Karnataka,which is the sixth documented occurrence of this mineral from India.We evaluate the chemical characteristics of hogbomite and associated Fe-Ti-minerals in an attempt to identify its formation as a primary hydrothermal mineral in a metamorphosed magnetite layer.We report here the presence of hogbomite as a complex oxide of Fe,Mg,Al and Ti with accessory of Zn,V and Sn.Petrographic studies suggest the (V-Ti) bearing magnetite (Mt) contain spinel,hogbomite,chlorite,martite,ilmenite (Ⅱ) and minor amounts of diaspore.The hogbomite displays euhedral to subhedral textures,and is up to 250 μm along the grain boundaries of magnetite and ilmenite.In the samples studied,hogbomite is prismatic,irregular and elongated in shape.The genesis of hogbomite in veins between magnetite and ilmenite implies its precipitation from fluids without involving complicated reactions.Several models were proposed for the formation of hogbomite; however,the subject is still debatable. 展开更多
关键词 Hogbomite western dharwar craton vanadium MAGNETITE EPMA INDIA
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Pb–Pb baddeleyite ages of mafic dyke swarms from the Dharwar Craton:Implications for Paleoproterozoic LIPs and diamond potential of mantle keel
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作者 D.Srinivasa Sarma V.Parashuramulu +2 位作者 M.Santosh E.Nagaraju N.Ramesh Babu 《Geoscience Frontiers》 SCIE CAS CSCD 2020年第6期2127-2139,共13页
The Dharwar Craton in Peninsular India was intruded by a series of mafic dykes during the Paleoproterozoic and these mafic magmatic events have important implications on continental rifting and LIPs.Here we report ten... The Dharwar Craton in Peninsular India was intruded by a series of mafic dykes during the Paleoproterozoic and these mafic magmatic events have important implications on continental rifting and LIPs.Here we report ten precise Pb-Pb TE-TIMS age determinations on baddeleyite grains separated from seven mafic dykes and three sills,intruding into Archean basement rocks and Proterozoic sedimentary formations of the Eastern Dharwar Craton respectively.The crystallization age of the baddeleyite shows 2366.3±1.1 Ma,and 2369.2±0.8 Ma for the NE-SW trending dykes,2368.1±0.6 Ma,2366.4±0.8 Ma,2207.2±0.7 Ma and 1887.3±1.0 Ma for the ENE-WNW to E-W striking dykes,1880.6±1.0 Ma,1864.3±0.6 Ma and 1863.6±0.9 Ma for Cuddapah sills,and 1861.8±1.4 Ma for the N-S trending dyke.Our results in conjunction with those from previous studies identify eight distinct stages of widespread Paleoproterozoic magmatism in the Dharwar craton.The mantle plume centres of the four radiating dyke swarms with ages of^2367 Ma,~2210 Ma,~2082 Ma,and^1886 Ma were traced to establish their proximity to the EDC kimberlite province.Though the^2367 Ma and^1886 Ma plume centres are inferred to be located to the west and east of the present day Dharwar craton respectively away from the kimberlite province,location of plume heads of the other two swarms with ages of^2207 Ma and^2082 Ma are in close proximity.In spite of the ubiquitous occurrence of dyke intrusions of all the seven generations in the kimberlite province,only few of these kimberlites are diamondiferous.Kimberlite occurrences elsewhere in the vicinity of older Large Igneous Provinces(LIPs)like the Mackenzie,Karoo,Parana-Etendeka and Yakutsk-Vilui are also non-diamondiferous.This has been attributed to the destruction of the lithospheric mantle keel(that hosts the diamonds)by the respective mantle plumes.The diamondiferous nature of the EDC kimberlites therefore suggests that plume activity does not always result in the destruction of the mantle keel. 展开更多
关键词 Paleoproterozoic mafic dykes Baddeleyite geochronology KIMBERLITE Large igneous province dharwar craton
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Lamprophyres from Southern Karnataka, Dharwar Craton, India: Insight on the Rodinia Break-up and Addition of Juvenile Crust
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作者 Kirtikumar R.Randive 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第S1期101-,共1页
The late Archean Dharwar Craton is an important part of the Archean and Proterozoic terrains in Peninsular India.Dharwar Craton consists of Western and Eastern Blocks,separated by the Chitradurga Shear Zone.Eastern
关键词 dharwar Craton Insight on the Rodinia Break-up and Addition of Juvenile Crust Lamprophyres from Southern Karnataka India
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Shear-Controlled Gold Mineralization of G. R. Halli Area of Chitradurga Schist Belt, Dharwar Craton: Insights from Fluid Inclusion Study
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作者 Govindappa Gopalakrishna Mohamed Shareef Poorigali Chowdaiah Nagesh 《Open Journal of Geology》 2018年第7期662-673,共12页
Gold mineralization at G. R. Halli is located along the Central shear zone of Chitradurga schist belt, extending from west of Gonur, through east of G. R. Halli and C. K. Halli to east of Honnemardi, roughly parallel ... Gold mineralization at G. R. Halli is located along the Central shear zone of Chitradurga schist belt, extending from west of Gonur, through east of G. R. Halli and C. K. Halli to east of Honnemardi, roughly parallel to stratigraphic units. The NNW-SSE trending shear zone has a width of 0.5 to 1.5 km shows extensive carbonatization of metabasalts and the associated lithologies confined to NNW-WNW trending arcuate brittle-ductile zone. The sheared and silicified contact zones between carbonaceous argillite and schistose metabasalt form the potential sites for localization of mineralization. The gold is associated with sulphides mainly pyrite, arsenopyrite, galena, sphalerite, minor chalcopyrite. Textural relationship indicates two stage sulphide mineral assemblages co-relatable with two stage fluid ascents having temperature of homogenization between 125&#176;C and 256&#176;C. It is a typical epigenetic lode gold system, which got affected by later deformation. 展开更多
关键词 G. R. Halli Chitradurga SCHIST BELT dharwar CRATON
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Petrological Characteristics of the Peddavura Schist Belt and Adjacent Rocks in Eastern Dharwar Craton in Parts of Nalgonda District, Telangana State
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作者 Lakshmi Pagidoju Naresh Bandari Narsing Rao Alwal 《Open Journal of Geology》 2018年第2期124-134,共11页
The Peddavura greenstone Linear Belt, NW-SE trending, is formed in the Eastern part of the Dharwar Craton of south India, extended over 62.5 sq&bull;km in Nalgonda and Guntur districts region. The entire belt is i... The Peddavura greenstone Linear Belt, NW-SE trending, is formed in the Eastern part of the Dharwar Craton of south India, extended over 62.5 sq&bull;km in Nalgonda and Guntur districts region. The entire belt is illustrated as Peninsular Gneiss. The Belt Study has attracted geologists for conducting further research to evaluate the crust forming process at the time of early volcanic eruption of Earth’s history. The South Indian Dharwar Craton depicts and exposes the crustal segments where geological activities took place consistently during the Precambrian. The PSB (Peddavura Schist Belt) mostly consists of meta volcanic (meta basalts), amphibolites, granites, dolerites, basaltic andesites, pegmatite and Banded Magnetite Quartzite’s (BMQ) rock types. The 20 represented rock samples made for thin section studies. Based on the Petrological studies minerals are showing uralitization, saussuritization in the granite with mylonite structures, perthite and dolerite are showing heavy metal such as rutile and other opaque minerals (Magnetite, hematite, and typical pyrite crystal) are present in different represented rock samples. The minerals are showing different alteration zones along with microstructures. Using the Petrological studies the minerals and rock types are identified in the study region. 展开更多
关键词 Transmitted LIGHT MICROSCOPY Reflected LIGHT MICROSCOPY Peddavura SCHIST BELT Eastern dharwar CRATON
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Palaeomagnetic and Rockmagnetic Behaviour of Dykes from Hyderabad Granitic Region, Part of Eastern Dharwar Craton, Southern India
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作者 B.Madhusudan RAO R.SANDHYA +1 位作者 M.R.GOUTHAM B.V.S.MURTHY 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第S1期41-,共1页
The dykes intruding the Hyderabad Granitic Region(HGR)which forms the part of eastern Dharwar Craton extending between northern and northwestern margins of the Cuddapah Basin and western margin of the Pakhal
关键词 Southern India Part of Eastern dharwar Craton Palaeomagnetic and Rockmagnetic Behaviour of Dykes from Hyderabad Granitic Region
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Geochemical constraints on komatiite volcanism from Sargur Group Nagamangala greenstone belt,western Dharwar craton,southern India:Implications for Mesoarchean mantle evolution and continental growth
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作者 Tushipokla M.Jayananda 《Geoscience Frontiers》 SCIE CAS CSCD 2013年第3期321-340,共20页
We present field, petrographic, major and trace element data for komatiites and komatiite basalts from Sargur Group Nagamangala greenstone belt, western Dharwar craton. Field evidences such as crude pillow structure i... We present field, petrographic, major and trace element data for komatiites and komatiite basalts from Sargur Group Nagamangala greenstone belt, western Dharwar craton. Field evidences such as crude pillow structure indicate their eruption in a marine environment whilst spinifex texture reveals their komatiite nature. Petrographic data suggest that the primary mineralogy has been completely altered during post-magmatic processes associated with metamorphism corresponding to greenschist to lower amphibolite facies conditions. The studied komatiites contain serpentine, talc, tremolite, actinolite and chlorite whilst tremolite, actinolite with minor plagioclase in komatiitic basalts. Based on the published Sm-Nd whole rock isochron ages of adjoining Banasandra komatiites (northern extension of Naga- mangala belt) and further northwest in Nuggihafli belt and Kalyadi belt we speculate ca. 3.2-3.15 Ga for komatiite eruption in Nagamangala belt. Trace element characteristics particularly HFSE and REE patterns suggest that most of the primary geochemical characteristics are preserved with minor influ- ence of post-magmatic alteration and[or contamination. About 1[3 of studied komatiites show AI- depletion whilst remaining komatiites and komatiite basalts are Al-undepleted. Several samples despite high MgO, (Gd]Yb)N ratios show low CaO/AI203 ratios. Such anomalous values could be related to removal of CaO from komatiites during fluid-driven hydrothermal alteration, thus lowering CaOJAI203 ratios. The elemental characteristics of Al-depleted komatiites such as higher (Gd/Yb)N (〉 1.0), CaO/AI203 (〉1.0), Al203frio2 (〈18) together with lower HREE, Y, Zr and Hf indicate their derivation from deeper upper mantle with minor garnet (majorite?) involvement in residue whereas lower (GdIYb)N (〈1.0), CaO/AI203 (〈0.9), higher A1203]TiO2 (〉18) together with higher HREE, Y, Zr suggest their derivation from shallower upper mantle without garnet involvement in residue. The observed chemical characteristics (CaO/AI203, AI203]TiO2, MgO, Ni, Cr, Nb, Zr, Y, Hf, and REE) indicate derivation of the komatiite and komatiite basalt magmas from heterogeneous mantle (depleted to primitive mantle) at different depths in hot spot environments possibly with a rising plume. The low content of incompatible elements in studied komatiites suggest existence of depleted mantle during ca. 3.2 Ga which in turn imply an earlier episode of mantle differentiation, greenstone volcanism and continental growth probably during ca. 3.6-3.3 Ga which is substantiated by Nd and Pb isotope data of gneisses and komatiites in western Dharwar craton (WDC). 展开更多
关键词 Komatiites dharwar craton Geochemistry Greenstone volcanism Mantle evolution
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Geochemistry of Late Archaean shaly BIF formed by oxic exogenic processes: an example from Ramagiri schist belt,Dharwar Craton, India 被引量:1
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作者 Meenal Mishra 《Chinese Journal Of Geochemistry》 EI CAS CSCD 2015年第3期362-378,共17页
The central block of the auriferous Ramagiri schist belt, in the Eastern Dharwar Craton, India consists of bimodal volcanics(mafic-felsic), shaly BIF and metasedimentary rocks. Geochemical studies of the associated sh... The central block of the auriferous Ramagiri schist belt, in the Eastern Dharwar Craton, India consists of bimodal volcanics(mafic-felsic), shaly BIF and metasedimentary rocks. Geochemical studies of the associated shaly BIF have indicated the enrichment of the major and trace elements such as Si O2, Al2O3, Ti O2, K2 O, Mg O, Fe2O3(T),Zr, Y, Cr, Ni, alkali and alkaline earth elements indicates that the clastic component of the shaly BIF had their contribution from the contemporaneous bimodal volcanics.The concave chondrite normalized REE patterns share ubiquitously anomalous positive cerium anomaly, absence of positive europium anomaly and the overall HREE enrichment. The REE patterns resemble those from the modern day sea water, except for positive Ce anomaly. The data suggests that arc related bimodal volcanism had been the plausible source of Fe, silica, REE and other trace elements. The coherent behaviour of Fe, Ti, Mn and P with the REEs indicates that they got incorporated from Fe–Ti–Mn bearing primary minerals and secondary products like clays. The variability of REE patterns in the BIF formation samples probably results from the differences in scavenging efficiency. The BIF bears signatures of mixing of the contemporaneous clastic and chemical processes, as well as the changes accompanying diagenesis and metamorphism.The precipitation of Fe did not stop during the sedimentation in an island arc related tectonic setting. The BIF strongly lacks the signatures from hydrothermal input. The presence of positive cerium anomalies and the absence of positive europium anomalies in the shaly banded ironformations imply that iron oxidation during BIF deposition took place in shallow waters rather than at depth, at oxicanoxic boundary. 展开更多
关键词 地球化学 二氧化硅 克拉通 晚太古代 岩带 印度 力作用 双峰式火山岩
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