http://www.sciencedirect.com/science/article/pii/S1674987113001084

We report here for the first time the composition and mineralogical studies on a new meteorite,which fell in Dhayala ki Chappar(24°58'N,73°48'27"E) 5 km NW of Nathdwara in south Rajasthan,India,on Dec.25 th,2012.Mineralogical and compositional studies were carried out on a representative piece of the Nathdwara meteorite sample.The mineralogical composition of the meteorite has been found to be olivine(42-45 vol.%),feldspar(10-15 vol.%),orthopyroxene(23-25 vol.%),troilite(6-8 vol.%),and titanium bearing minerals(6-8 vol.%).Our investigations show that the Nathdwara meteorite belongs to H6 group of ordinary chondrites.     

The dilemma of the Jiaodong gold deposits: Are they unique?

The ca. 126e120 Ma Au deposits of the Jiaodong Peninsula, eastern China, define the country＇s largest gold province with an overall endowment estimated as＆gt;3000 t Au. The vein and disseminated ores are hosted by NE-to NNE-trending brittle normal faults that parallel the margins of ca. 165e150 Ma, deeply emplaced, lower crustal melt granites. The deposits are sited along the faults for many tens of kilometers and the larger orebodies are associated with dilatational jogs. Country rocks to the granites are Pre-cambrian high-grade metamorphic rocks located on both sides of a Triassic suture between the North and South China blocks. During early Mesozoic convergent deformation, the ore-hosting structures developed as ductile thrust faults that were subsequently reactivated during Early Cretaceous ＂Yan-shanian＂intracontinental extensional deformation and associated gold formation. 〈br〉 Classification of the gold deposits remains problematic. Many features resemble those typical of orogenic Au including the linear structural distribution of the deposits, mineralization style, ore and alteration assemblages, and ore fluid chemistry. However, Phanerozoic orogenic Au deposits are formed by prograde metamorphism of accreted oceanic rocks in Cordilleran-style orogens. The Jiaodong de-posits, in contrast, formed within two Precambrian blocks approximately 2 billion years after devolati-lization of the country rocks, and thus require a model that involves alternative fluid and metal sources for the ores. A widespread suite of ca. 130e123 Ma granodiorites overlaps temporally with the ores, but shows a poor spatial association with the deposits. Furthermore, the deposit distribution and mineral-ization style is atypical of ores formed from nearby magmas. The ore concentration requires fluid focusing during some type of sub-crustal thermal event, which could be broadly related to a combination of coeval lithospheric thinning, asthenospheric upwelling, paleo-Pacific plate subduction, and seismicity along the continental-scale Tan-Lu fault. Possible ore genesis scenarios include those where ore fluids were produced directly by the metamorphism of oceanic lithosphere and overlying sediment on the subducting paleo-Pacific slab, or by devolatilization of an enriched mantle wedge above the slab. Both the sulfur and gold could be sourced from either the oceanic sediments or the serpentinized mantle. A better understanding of the architecture of the paleo-Pacific slab during Early Cretaceous below the eastern margin of China is essential to determination of the validity of possible models.     

http://www.sciencedirect.com/science/article/pii/S1674987114000711

The West Junggar region,located in the loci of the Central Asian Orogenic Belt,is a highly endowed metallogenic province with >100 tonnes Au,>0.7 Mt Cu,>0.3 Mt Mo,and >2.3 Mt chromite as well as significant amounts of Be and U.The West Junggar region has three metallogenic belts distributed systematically from north to south:(1) late Paleozoic Saur Au-Cu belt;(2) early Paleozoic XiemisitaiSharburt Be-U-Cu-Zn belt;(3) late Paleozoic Barluk-Kelamay Au-Cu-Mo-Cr belt.These belts host a number of deposits belonging to at least eight economically important styles,including epithermal Au,granite-related Be-U,volcanogenic massive sulfide(VMS) Cu-Zn,podiform chromite,porphyry Cu,hydrothermal quartz vein Au,porphyry-greisen Mo(-W),and orogenic Au.These deposit styles are associated with the tectonics prevalent during their formation.Five tectonic-mineralized epochs can be recognized:(1) Ordovician subduction-related VMS Cu-Zn deposit;(2) Devonian ophiolite-related podiform chromite deposit;(3) early Carboniferous subduction-related epithermal Au and porphyry Cu deposits;(4) late Carboniferous subduction-related granite-related Be-U,porphyry Cu,and hydrothermal quartz vein Au deposits;and(5) late Carboniferous to early Permian subduction-related porphyry-greisen Mo(-W) and orogenic Au deposits.     

http://www.sciencedirect.com/science/article/pii/S1674987113001072

The late Permian Emeishan large igneous province(ELIP) covers ~0.3 x 106 km2 of the western margin of the Yangtze Block and Tibetan Plateau with displaced,correlative units in northern Vietnam(Song Da zone).The ELIP is of particular interest because it contains numerous world-class base metal deposits and is contemporaneous with the late Capitanian(~260 Ma) mass extinction.The flood basalts are the signature feature of the ELIP but there are also ultramafic and silicic volcanic rocks and layered maficultramafic and silicic plutonic rocks exposed.The ELIP is divided into three nearly concentric zones(i.e.inner,middle and outer) which correspond to progressively thicker crust from the inner to the outer zone.The eruptive age of the ELIP is constrained by geological,paleomagnetic and geochronological evidence to an interval of 3 Ma.The presence of picritic rocks and thick piles of flood basalts testifies to high temperature thermal regime however there is uncertainty as to whether these magmas were derived from the subcontinental lithospheric mantle or sub-lithospheric mantle(i.e.asthenosphere or mantle plume) sources or both.The range of Sr(I_(Sr) = 0.7040-0.7132),Nd(ε_(Nd)(t) ≈-14 to +8),Pb(~(206)Pb/~(204)Pb_1≈ 17.9-20.6) and Os(γ_(Os) =-5 to +11) isotope values of the ultramafic and mafic rocks does not permit a conclusive answer to ultimate source origin of the primitive rocks but it is clear that some rocks were affected by crustal contamination and the presence of near-depleted isotope compositions suggests that there is a sub-lithospheric mantle component in the system.The silicic rocks are derived by basaltic magmas/rocks through fractional crystallization or partial melting,crustal melting or by interactions between mafic and crustal melts.The formation of the Fe-Ti-V oxide-ore deposits is probably due to a combination of fractional crystallization of Ti-rich basalt and fluxing of C02-rich fluids whereas the Ni-Cu-(PGE) deposits are related to crystallization and crustal contamination of mafic or ultramafic magmas with subsequent segregation of a sulphide-rich portion.The ELIP is considered to be a mantle plume-derived LIP however the primary evidence for such a model is less convincing(e.g.uplift and geochemistry) and is far more complicated than previously suggested but is likely to be derived from a relatively short-lived,plume-like upwelling of mantle-derived magmas.The emplacement of the ELIP may have adversely affected the short-term environmental conditions and contributed to the decline in biota during the late Capitanian.     

http://www.sciencedirect.com/science/article/pii/S1674987114000589

At peak granulite-facies metamorphic conditions, lower continental crust is arguably fluxed by large amounts of two key low water activity fluids： （i） high-density CO2 and/or （ii） concentrated saline so- lutions. These fluids are either internally-derived, generated by mineral reactions or dehydration melting or, notably for CO2, externally-derived, issued from the underlying mantle. Postmetamorphic evolution results in complete disappearance of these fluids, except for minute remnants preserved in minerals as fluid inclusions. Two major processes are involved： （i） at peak conditions, granitoid magmas form, migrate upward, and crystallize as shallow intrusions in the upper crust （mineralized porphyry types or reduced intrusions）; （ii） during the rapid decompression which almost systematically follows a period of post-peak isobaric cooling, especially for ultrahigh-temperature granulites （anticlockwise P-T paths）, quartz-carbonate megashear zones are formed by repeated periods of seismic activity. Seismic activity may continue until all free fluids have disappeared, resulting in the ultramylonites and pseudotachylites that are found in many granulite domes. A great majority of vein-type Au deposits worldwide occur in the above-mentioned settings or nearby. We suggest that the Au has been scavenged by the granulite fluids, then redistributed and concentrated during the formation of veins and related phenomena.     

http://www.sciencedirect.com/science/article/pii/S1674987111000478

Convective heat transfer associated with the circulation of pore-fluid in porous rocks and fractures within the upper crust of the Earth is substantial when the temperature gradient is sufficiently high.In order to understand the process of Sn-polymetallic mineralization in the Dachang ore district of Guangxi,a finite element method has been used in this study to simulate both pore-fluid flow and heat transfer in this district.On the basis of related geological,tectonic and geophysical constraints,a computational model was established.It enables a computational simulation and sensitivity analysis to be carried out for investigating ore-forming pore-fluid flow and other key factors that may affect hydrothermal ore genesis in the district.The related simulation results have indicated that:(1) permeable fault zones in the Dachang ore district can serve as preferential pathways for pore-fluid flow on a regional-scale;and(2) the pore-fluid flow can affect the salinity distribution.This latter factor is part of the reason why Sn-polymetallic mineralization has taken place in this district.     

http://www.sciencedirect.com/science/article/pii/S1674987110000125

<正>Carbonatites are commonly related to the accumulation of economically valuable substances such as REE.Cu,and P.The debate over the origin of carbonatites and their relationship to associated silicate rocks has been ongoing for about 45 years.Worldwide,the rocks characteristically display more geochemical enrichments in Ba,Sr and REE than sedimentary carbonate rocks.However,carbonatite's geochemical features are disputed because of secondary mineral effects.Rock-forming carbonates from carbonatites at Qinling.Panxi region,and Bayan Obo in China show REE distribution patterns ranging from LREE enrichment to flat patterns.They are characterized by a Sr content more than 10 times higher than that of secondary carbonates.The coarse- and fine-grained dolomites from Bayan Obo H8 dolomite marbles also show similar high Sr abundance,indicating that they are of igneous origin.Some carbonates in Chinese carbonatites show REE(especially HREE) contents and distribution patterns similar to those of the whole rocks.These intrusive carbonatites display lower platinum group elements and stronger fractionation between Pt and Ir relative to high-Si extrusive carbonatite.This indicates that most intrusive carbonatites may be carbonate cumulates.Maoniuping and Daluxiang in Panxi region are large REE deposits.Hydrothermal fluorite ore veins occur outside of the carbonatite bodies and are emplaced in wallrock syenite.The fiuorite in Maoniuping has Sr and Nd isotopes similar to carbonatite.The Daluxiang fiuorite shows Sr and REE compositions different from those in Maoniuping.The difference is reflected by both the carbonatites and rock-forming carbonates,indicating that REE mineralization is related to carbonatites.The cumulate processes of carbonate minerals make fractionated fluids rich in volatiles and LREE as a result of low partition coefficients for REE between carbonate and carbonatite melt and an increase from LREE to HREE.The carbonatite-derived fluid has interacted with wallrock to form REE ore veins.The amount of carbonatite dykes occurring near the Bayan Obo orebodies may support the same mineralization model,i.e.that fluids evolved from the carbonatite dykes reacted with H8 dolomite marble,and thus the different REE and isotope compositions of coarse- and fine-grained dolomite may be related to reaction processes.     

http://www.sciencedirect.com/science/article/pii/S1674987112000564

High-pressure（HP） granulites widely occur as enclaves within tonalite-trondhjemitegranodiorite （TTG） gneisses of the Early Precambrian metamorphic basement in the Shandong Peninsula, southeast part of the North China Craton（NCC）.Based on cathodoluminescence（CL）,laser Raman spectroscopy and in-situ U-Pb dating,we characterize the zircons from the HP granulites and group them into three main types:inherited（magmatic） zircon,HP metamorphic zircon and retrograde zircon.The inherited zircons with clear or weakly defined magmatic zoning contain inclusions of apatites,and ²⁰⁷Pb/²⁰⁶Pb ages of 2915—2890 Ma and 2763—2510 Ma,correlating with two magmatic events in the Archaean basement. The homogeneous HP metamorphic zircons contain index minerals of high-pressure metamorphism including garnet,clinopyroxene.plagioclase,quartz,rutile and apatite,and yield ²⁰⁷Pb/²⁰⁶Pb ages between 1900 and 1850 Ma,marking the timing of peak HP granulite fades metamorphism.The retrograde zircons contain inclusions of orthopyroxene.plagioclase.quartz,apatite and amphibole.and yield the youngest ²⁰⁷Pb/²⁰⁶Pb ages of 1840—1820 Ma among the three groups,which we correlate to the medium to low-pressure granulite fades retrograde metamorphism.The data presented in this study suggest subduction of Meso- and Neoarchean magmatic protoliths to lower crust depths where they were subjected to HP granulite facies metamorphism during Palaeoproterozoic（1900—1850 Ma）.Subsequently, the HP granulites were exhumated to upper crust levels,and were overprinted by medium to low-pressure granulite and amphibolite facies retrograde event at ca.1840—820 Ma.     

http://www.sciencedirect.com/science/article/pii/S1674987113000303

The Xinjie layered intrusion in the Panxi region,SW China,hosts both Fe-Ti oxide and platinum-group element（PGE） sulfide mineralization.The intrusion can be divided,from the base upward,into UnitsⅠ,ⅡandⅢ,in terms of mineral assemblages.UnitsⅠandⅡare mainly composed of wehrlite and clino-pyroxenite, whereas UnitⅢis mainly composed of gabbro.PGE sulfide-rich layers mainly occur in Unit I, whereas thick Fe-Ti oxide-rich layers mainly occur in UnitⅢ.An ilmenite-rich layer occurs at the top of UnitⅠ.Fe-Ti oxides include magnetite and ilmenite.Small amounts of cumulus and intercumulus magnetite occur in UnitsⅠandⅡ.Cumulus magnetite grains are commonly euhedral and enclosed within olivine and clinopyroxene.They have high Cr₂O₃ contents ranging from 6.02 to 22.5 wt.%,indicating that they are likely an early crystallized phase from magmas.Intercumulus magnetite that usually displays ilmenite exsolution occupies the interstices between cumulus olivine crystals and coexists with interstitial clinopyroxene and plagioclase.Intercumulus magnetite has Cr₂O₃ ranging from 1.65 to 6.18 wt.%, lower than cumulus magnetite.The intercumulus magnetite may have crystallized from the trapped liquid.Large amounts of magnetite in UnitⅢcontains Cr₂O₃（<0.28 wt.%） much lower than magnetite in UnitsⅠandⅡ.The magnetite in UnitⅢis proposed to be accumulated from a Fe-Ti-rich melt.The Fe-Ti-rich melt is estimated to contain 35.9 wt.%of SiO₂,26.9 wt.%of FeO^t,8.2 wt.%of TiO₂,13.2 wt.%of CaO, 8.3 wt.%of MgO,5.5 wt.%of Al₂O₃ and 1.0 wt.%of P₂O₅.The composition is comparable with the Fe-rich melts in the Skaergaard and Sept Iles intrusions.Paired non-reactive microstructures,granophyre pockets and ilmenite-rich intergrowths,are representative of Si-rich melt and Fe-Ti-rich melt,and are the direct evidence for the existence of an immiscible Fe-Ti-rich melt that formed from an evolved ferro-basaltic magma.     

http://www.sciencedirect.com/science/article/pii/S1674987112000886

Six national-scale, or near national-scale, geochemical data sets for soils or stream sediments exist for the United States. The earliest of these, here termed the ‘Shacklette’ data set, was generated by a U.S. Geological Survey (USGS) project conducted from 1961 to 1975. This project used soil collected from a depth of about 20 cm as the sampling medium at 1323 sites throughout the conterminous U.S. The National Uranium Resource Evaluation Hydrogeochemical and Stream Sediment Reconnaissance (NURE-HSSR) Program of the U.S. Department of Energy was conducted from 1975 to 1984 and collected either stream sediments, lake sediments, or soils at more than 378,000 sites in both the conterminous U.S. and Alaska. The sampled area represented about 65% of the nation. The Natural Resources Conservation Service (NRCS), from 1978 to 1982, collected samples from multiple soil horizons at sites within the major crop-growing regions of the conterminous U.S. This data set contains analyses of more than 3000 samples. The National Geochemical Survey, a USGS project conducted from 1997 to 2009, used a subset of the NURE-HSSR archival samples as its starting point and then collected primarily stream sediments, with occasional soils, in the parts of the U.S. not covered by the NURE-HSSR Program. This data set contains chemical analyses for more than 70,000 samples. The USGS, in collaboration with the Mexican Geological Survey and the Geological Survey of Canada, initiated soil sampling for the North American Soil Geochemical Landscapes Project in 2007. Sampling of three horizons or depths at more than 4800 sites in the U.S. was completed in 2010, and chemical analyses are currently ongoing. The NRCS initiated a project in the 1990s to analyze the various soil horizons from selected pedons throughout the U.S. This data set currently contains data from more than 1400 sites. This paper (1) discusses each data set in terms of its purpose, sample collection protocols, and analytical methods; and (2) evaluates each data set in terms of its appropriateness as a national-scale geochemical database and its usefulness for national-scale geochemical mapping.     

http://www.sciencedirect.com/science/article/pii/S1674987111000235

In this paper we present a review of mineral systems in northern Xinjiang,NW China,focussing on the Tianshan,West and East Junggar and Altay orogenic belts,all of which are part of the greater Central Asian Orogenic Belt(CAOB).The CAOB is a complex collage of ancient microcontinents,island arcs,oceanic plateaux and oceanic plates,which were amalgamated and accreted in Early Palaeozoic to Early Permian times.The establishment of the CAOB collage was followed by strike-slip movements and affected by intrap...     

http://www.sciencedirect.com/science/article/pii/S1674987111000193

Geochemical subsoil data obtained from China and European laboratories have been compared in this study. 787 C horizon subsoil samples from FOREGS (Forum of European Geological Surveys) geochemical baselines mapping project were sent to China’s IGGE (Institute of Geophysical and Geochemical Exploration) laboratory and composited to 190 samples according to the 160 km 160 km GNT (Global Terrestrial Network) cells. In addition to the FOREGS elemental analysis package, Au, Pt, Pd, B, Ge, Br, Cl, Se, N, Li and F were also analyzed by using the IGGE’s 76 element analytical scheme. Geochemical data statistics, scatter plotting, and geochemical map compilation techniques have been employed to investigate differences between FOREGS and IGGE analytical results. The results of two datasets, the IGGE’s analysis data for composited samples, and the FOREGS average data of samples in each GNT cell, agree extremely well for about 23 elements, viz: SiO2, Sr, Al2O3, Zr, Ba, Fe2O3, Ti, Rb, Mn, Gd, CaO, Ga, MgO, P, Pb, Na2O, Y, Th, As, U Sc, Cr, and Co. There are slight differences between-laboratory biases shown as proportional errors between the datasets for Ni, K2O, Tb, Tl, Cu, S, Sm, La, Ce, Pr, Nd, Eu, Ho, Er, Tm, Yb, Lu, Ta, Nb, Hf, and Dy. For Cd, Cs, Be, Sb, In, Mo, I, Sn, and Te, the correlation of the two datasets and the similarity of the geochemical maps are fairly good, but obvious biases exist between the two datasets at values near detection limits. Sensitivities of FOREGS analytical methods for W, Bi, Sn, Te, Be, and I are insufficient to produce reportable values in at least 80% of the samples. Although the detection limits of Ag for both FOREGS and IGGE are sufficient to provide reportable values, a large bias was found between the two datasets. This study demonstrates that consistent analytical data for certain elements of global geochemical mapping samples can be achieved by different qualified laboratories, such as China’s IGGE laboratory and some European laboratories. For some elements, such as Ag, further research on the selection of the proper analytical methods and on the development of quality control methods should be undertakendwith final recommendations adhered to by all participants of the global geochemical mapping program.     

http://www.sciencedirect.com/science/article/pii/S1674987111000211

Arid and semi-arid regions are susceptible to high levels of erosion.A rapid and cost effective methodological erosion assessment for these regions is required to describe and monitor the processes that control erosion.This study uses remote sensing to describe the contribution of several factors that control erosion.Topography,land use,vegetation density,soil properties and climatic proxies are used to determine erosion risk and to provide basic maps of water and soil conservation practices. A hierarchi...     

http://www.sciencedirect.com/science/article/pii/S167498711500002X

Discovery rates for all metals,including gold,are declining,the cost per significant discovery is increasing sharply,and the economic situation of the industry is one of low base rate.The current hierarchical structure of the exploration and mining industry makes this situation difficult to redress.Economic geologists can do little to influence the required changes to the overall structure and philosophy of an industry driven by business rather than geological principles.However,it should be possible to follow the lead of the oil industry and improve the success rate of greenfield exploration,necessary for the next group of lower-exploration-spend significant mineral deposit discoveries.Here we promote the concept that mineral explorers need to carefully consider the scale at which their exploration targets are viewed.It is necessary to carefully assess the potential of drill targets in terms of terrane to province to district scale,rather than deposit scale,where most current economic geology research and conceptual thinking is concentrated.If otogenic,IRGD,Carlin-style and 10 CG gold-rich systems are viewed at the deposit scale,they appear quite different in terms of conventionally adopted research parameters.However,recent models for these deposit styles show increasingly similar source-region parameters when viewed at the lithosphere scale,suggesting common tectonic settings.It is only by assessing individual targets in their tectonic context that they can be more reliably ranked in terms of potential to provide a significant drill discovery.Targets adjacent to craton margins,other lithosphere boundaries,and suture zones are clearly favoured for all of these gold deposit styles,and such exploration could lead to incidental discovery of major deposits of other metals sited along the same tectonic boundaries.     

http://www.sciencedirect.com/science/article/pii/S1674987110000162

<正>Fault-block structures of the Altay-Sayan folded area(ASFA) southeastern Siberia of Russia were used as the basis for creating a 3-D model.The surface structures were projected to depths by previous correlations between long and deep faults,with all layers and deformation factors defined. The mean deformation factor(Ds) is 0.12 unit/km~3 in the upper layer,0.012 unit/km~3 in the intermediate layer,and 0.007 unit/km~3 in the lower layer of the 3-D ASFA neotectonic model.Ds allows correlation of the three distinguished layers with rheological bodies that differ in their potential for accumulating elastic energy.3-D modeling can be used as a methodological approach to projections in seismic prone areas such as the Krasnoyarsk region,for earthquake-hazard monitoring.     

http://www.sciencedirect.com/science/article/pii/S1674987111001034

A comprehensive methodology that integrates Revised Universal Soil Loss Equation（RUSLE） model and Geographic Information System（GIS） techniques was adopted to determine the soil erosion vulnerability of a forested mountainous sub-watershed in Kerala,India.The spatial pattern of annual soil erosion rate was obtained by integrating geo-environmental variables in a raster based GIS method.GIS data layers including,rainfall erosivity（R）,soil erodability（K）,slope length and steepness（LS）,cover management （C） and conservation practice（P） factors were computed to determine their effects on average annual soil loss in the area.The resultant map of annual soil erosion shows a maximum soil loss of 17.73 t h^-1 y^-1 with a close relation to grass land areas,degraded forests and deciduous forests on the steep side-slopes（with high LS ）.The spatial erosion maps generated with RUSLE method and GIS can serve as effective inputs in deriving strategies for land planning and management in the environmentally sensitive mountainous areas.     

http://www.sciencedirect.com/science/article/pii/S1674987111000272

We present here a thermodynamic model for predicting multi-phase equilibrium of methane hydrate liquid and vapor phases under conditions of different temperature,pressure,salinity and pore sizes.The model is based on the 1959 van der Waals—Platteeuw model,angle-dependent ab initio intermolecular potentials,the DMW-92 equation of state and Pitzer theory.Comparison with all available experimental data shows that this model can accurately predict the effects of temperature,pressure, salinity and capillary r...     

http://www.sciencedirect.com/science/article/pii/S1674987114000644

正1.Introduction This special issue of Geoscience Frontiers is a tribute volume honoring the life and career of Jacques Touret.A set of research papers has been assembled,which broadly reflect his research interests over his 50 plus year career.These papers focus on the role that fluids play during the formation and evolution of the Earth's crust.Below I provide a brief summary of the life of Jacques Touret,along with a select bibliography of his more important papers.This is then followed by a brief introduction to the papers assembled for this special issue.     

A review of the ～1600 Ma sedimentation, volcanism, and tectono-thermal events in the Singhbhum craton, Eastern India

The Palaeoproterozoic–Mesoproterozoic transition (～1600 Ma) is a significant event in the Earth history as a global thermal perturbation affected the pre-1600 Ma landmasses. Like other cratonic blocks of the world, lithospheric thinning, sedimentation, magmatism, metamorphism and crustal melting/anatexis are associated with this significant geological event in the Singhbhum cratonic province of India. This paper is a review of sedimentological, magmatic and tectono-thermal events in the Singhbhum craton at ～1600 Ma. The Palaeo-Mesoproterozoic sedimentation and volcanism in the Singhbhum craton took place in a terrestrial intracontinental rift setting. The available geochronological data are indicative of late Palaeoproterozoic to Neoproterozoic tectono-thermal events in the Chhotanagpur Granite Gneissic Complex (CGGC), an east–west trending arcuate belt of granite gneisses, migmatites and metasedimentary rocks. A detailed multidisciplinary geo-scientific investigation of the Dalma volcanic belt and the area to its north (Chandil Formation) and further north in CGGC will enable us to constrain the extant surface processes and crust-mantle interactions, the collision events between the North and South Indian cratonic blocks, and the position of India in the Columbia supercontinent.     

http://www.sciencedirect.com/science/article/pii/S1674987112000679

Quasi-integrity of continental crust between Mid-Archaean and Ediacaran times is demonstrated by conformity of palaeomagnetic poles to near-static positions between～2.7-2.2 Ca,～1.5-1.2 Ga and～0.75-0.6 Ga.Intervening data accord to coherent APW loops turning at "hairpins" focused near a continental-centric location.Although peripheral adjustments occurred during Early Proterozoic （～2.2 Ga） and Grenville（～1.1 Ga） times,the crust retained a low order symmetrical crescent-shaped form constrained to a single global hemisphere until break-up in Ediacaran times.Conformity of palaeomagnetic data to specific Eulerian parameters enables definition of a master Precambrian APW path used to estimate the root mean square velocity(v_RMS) of continental crust between 2.8 and 0.6 Ga.A long interval of little polar movement between～2.7 and 2.2 Ga correlates with global magmatic shutdown between～2.45 and 2.2 Ga,whilst this interval and later slowdown at～0.75-0.6 Ga to velocities of <2 cm/year correlate with episodes of widespread glaciation implying that these prolonged climatic anomalies had an internal origin;the reduced input of volcanically-derived atmospheric greenhouse gases is inferred to have permitted freeze-over conditions with active ice sheets extending into equatorial latitudes as established by low magnetic inclinations in glaciogenic deposits.v_RMS variations through Precambrian times correspond to the distribution of U-Pb ages in orogenic granitoids and detrital zircons and demonstrate that mobility of continental crust has been closely related to crustal tectonism and incrementation.Both periods of near-stillstand were followed by rapid v_RMS recording massive heat release from beneath the continental lid at～2.2 and 0.6 Ga.The first coincided with the Lomagundi-Jatuli isotopic event and led to prolonged orogenesis accompanied by continental flooding and reconfiguration of the crust on the Earth’s surface;the second led to continental break-up and instigated the comprehensive Plate Tectonics that has characterised Phanerozoic times.The Mesoproterozoic interval characterised by anorogenic magmatism correlates with low v_RMS between～1.5 and 1.1 Ga.Insulation of the sub-continental mantle evidently permitted high temperature melting and weakening of the crustal lid to enable buoyant emplacement of large plutons at high crustal levels during this magmatic event unique to Mesoproterozoic and early Neoproterozoic times.