Qiao W.,Guizhou Geological Survey |
Lang X.,Peking University |
Peng Y.,Louisiana State University |
Jiang K.,Guizhou Geological Survey |
And 3 more authors.
Journal of Earth Science | Year: 2016
Phosphorite nodule beds are discovered in the black shale of basal Niutitang Formation throughout the Yangtze Platform in South China, recording an important phosphorite-generation event. Platform-wide phosphorite precipitation requires special oceanographic and geochemical conditions, thus the origin of the Niutitang phosphorite nodules may provide valuable information about the ocean chemistry in the Early Cambrian. In this study, we measured sulfur and oxygen isotopic compositions of sulfate extracted from phosphorite nodules collected from the basal Niutitang Formation. Phosphorite associated sulfate (PAS) is a trace amount of sulfate that incorporates into crystal lattice during phosphorite precipitation, accordingly PAS records the geochemical signals during phosphorite nodule formation. Sulfur isotopic composition of PAS (δ34SPAS) ranges from -1.16‰ to +24.48‰ (mean=+8.19‰, n=11), and oxygen isotopic value (δ18OPAS) varies between -5.3‰ and +26.3‰ (mean=+7.0‰, n=8). Most phosphorite nodules have low δ34SPAS and low δ18OPAS values, suggesting PAS mainly derived from anaerobic oxidation of H2S within suboxic sediment porewater. We propose that phosphate was delivered to the Yangtze Platform by a series of upwelling events, and was scavenged from seawater with the precipitation of FeOOH. The absorbed phosphate was released into suboxic porewater by the reduction of FeOOH at the oxic-suboxic redox boundary in sediments, and phosphorite nodule precipitated by the reaction of phosphate with Ca2+ diffused from the overlying seawater. The platform-wide deposition of phosphorite nodules in the basal Niutitang Formation implies the bottom water might be suboxic or even oxic, at least sporadically, in Early Cambrian. We speculate that the intensified ocean circulation as evident with frequent occurrences of upwelling events might be the primary reason for the episodic oxidation of the Yangtze Platform in Early Cambrian. © 2016, China University of Geosciences and Springer-Verlag Berlin Heidelberg.
Zhang J.,Guizhou Geological Survey |
Zhang J.,Chinese Academy of science |
Dai C.,Guizhou Geological Survey |
Huang Z.,Chinese Academy of science |
And 3 more authors.
Ore Geology Reviews | Year: 2015
Gejiu is geographically located near Gejiu city, SW China. It is one of the largest tin-polymetallic districts in the world and contains approximately 3milliontons (Mt) of Sn and smaller quantities of Cu, Pb, and Zn. The deposit primarily yields three different types of ore: skarn-hosted ore, basalt-hosted stratiform ore, and carbonate-hosted stratiform ore. Kafang is one of the primary ore deposits in the Gejiu district and is an unusual occurrence hosted in basaltic rocks. Genetic models of the Kafang deposit suggest that it is related either to Anisian (Lower stage of Middle Triassic) Gejiu basalts or to Cretaceous Gejiu granite. In this study, we performed zircon SIMS U-Pb dating, major and trace element analyses, and Sr-Nd-Pb isotopic analyses for the Gejiu basalts and S isotopic analyses for stratiform Cu ore. Our results and previous studies are used to interpret the petrogenesis of the Gejiu basalts and the origin of the basalt-hosted stratiform Cu deposit. The SIMS zircon U-Pb analyses of the Gejiu basalts yield an age of 244.4Ma. The trace element ratios of the Gejiu basalts are similar to those of ocean island basalt and have positive εNd(t) values (ranging from 0.6 to 2.5) and uniform (87Sr/86Sr)i values (ranging from 0.70424 to 0.70488). These ratios are close to those of the Permian Emeishan flood basalt. Thus, the Gejiu basalts may represent coeval volcanisms within the plate involving remelting of the Emeishan plume head through a stress relaxation process after the main plume event. The Pb and S isotopic compositions of the Gejiu basalts and the stratiform Cu ores indicate that the source of Cu and S is primarily derived from the Gejiu basalts. However, the age of sulfide mineralization (84.2-79.6Ma) and the age of hydrothermal alteration (85.5-81.9Ma) are temporally consistent with the age of the Cretaceous granite emplacement (85.5-83.3Ma). From a petrological and geochemical study, we determine that the Gejiu basalts may have been subjected to pervasive granite-related hydrothermal alteration during the emplacement of granite. These processes increase the K and Mg contents of basalt and probably caused the formation of the Cu ores. Thus, the Kafang stratiform Cu deposit can be considered as a granite-related hydrothermal deposit. © 2015 Elsevier B.V.
Early and Middle Triassic trends in diversity, evenness, and size of foraminifers on a carbonate platform in south China: Implications for tempo and mode of biotic recovery from the end-Permian mass extinction
Payne J.L.,Stanford University |
Summers M.,Stanford University |
Summers M.,University of California at San Diego |
Rego B.L.,Stanford University |
And 5 more authors.
Paleobiology | Year: 2011
Delayed biotic recovery from the end-Permian mass extinction has long been interpreted to result from environmental inhibition. Recently, evidence of more rapid recovery has begun to emerge, suggesting the role of environmental inhibition was previously overestimated. However, there have been few high-resolution taxonomic and ecological studies spanning the full Early and Middle Triassic recovery interval, leaving the precise pattern of recovery and underlying mechanisms poorly constrained. In this study, we document Early and Middle Triassic trends in taxonomic diversity, assemblage evenness, and size distribution of benthic foraminifers on an exceptionally exposed carbonate platform in south China. We observe gradual increases in all metrics through Early Triassic and earliest Middle Triassic time, with stable values reached early in the Anisian. There is little support in our data set for a substantial Early Triassic lag interval during the recovery of foraminifers or for a stepwise recovery pattern. The recovery pattern of foraminifers on the GBG corresponds well with available global data for this taxon and appears to parallel that of many benthic invertebrate clades. Early Triassic diversity increase in foraminifers was more gradual than in ammonoids and conodonts. However, foraminifers continued to increase in diversity, size, and evenness into Middle Triassic time, whereas diversity of ammonoids and conodonts declined. These contrasts suggest decoupling of recovery between benthic and pelagic environments; it is unclear whether these discrepancies reflect inherent contrasts in their evolutionary dynamics or the differential impact of Early Triassic ocean anoxia or associated environmental parameters on benthic ecosystems. © 2011 The Paleontological Society. All rights reserved.
Wang G.,CAS Nanjing Institute of Geology and Palaeontology |
Li Y.,CAS Nanjing Institute of Geology and Palaeontology |
Kershaw S.,Brunel University |
Deng X.,Guizhou Geological Survey
GFF | Year: 2014
After the end-Ordovician mass extinction, reef recovery (size and biotic diversity) took several million years. On the Upper Yangtze Platform, South China Block, the initial reef reconstruction episode is recorded in limestone of middle Aeronian age in northern Guizhou Province. By late Aeronian, reefs were widespread on the Yangtze carbonate platform, today represented by patch reefs cropping out in a 10-km2 large area near Shuibatang, Tongzi County, where two stratigraphic intervals with reefs are recognized. Late Aeronian reefs constitute a complex and diverse reef community dominated by corals, and to a lesser extent stromatoporoids. They contain an accessory fauna of abundant bryozoans and crinoids and some brachiopods, trilobites, molluscs and calcimicrobes. These reefs correlate in time with similar reefs in Anticosti, Laurentia, palaeogeographically very distant from South China. Thus, there is good evidence that recovery and geographic expansion of reefs after the end-Ordovician extinction occur simultaneously in at least two continents. © 2013 © 2013 Taylor & Francis.
PubMed | Hefei University of Technology, Guizhou Geological Survey, CAS Institute of Geology and Geophysics and Louisiana State University
Type: | Journal: Scientific reports | Year: 2014
Investigation of climatic conditions prior to the Sturtian glaciations is critical to understanding the trigger mechanism for the series of Neoproterozoic global glaciations. In this study, we report high-resolution chemical index of alteration (CIA) records in the sediments of South China prior to the Sturtian glaciation (820~720 Ma). Our results showed there occurred multiple climate cooling before the Sturtian glaciations in South China: (1) a series of episodic and possibly global climate cooling periods from ca. 750 Ma to 725 Ma, which also caused some diachronous regional glaciations; (2) a permanent climate cooling period between ca. 800 Ma and 770 Ma, probably contemporaneous to the global Bitter Springs stage (13)C negative excursion; (3) a climate cooling period between ca. 815 Ma and 810 Ma. The three stages of climate cooling are also supported by their correspondence to previously reported extremely low (18)O records of igneous/metamorphic minerals from South China. These climate cooling periods also coincide with the magmatism and rifting events in South China. We argue that tectonic movements were the primary control on the climate cooling before the Neoproterozoic global glaciations.
Fu H.,Hubei University |
Ma D.,Guizhou Geological Survey |
Wu T.,Guizhou Geological Survey |
Xiong X.,Guizhou Geological Survey |
Zeng Y.,Guizhou Geological Survey
Geological Bulletin of China | Year: 2015
Pollen fossils such as Classopollis, Annulispora, and Chasmatosporites as well as abundant dinoflagellates like Systematophora cf., and Ctenidodinium, which indicate Middle-Upper Jurassic strata with a typical significance, were found in the formerly-regarded Middle Permian Xiala Formation within the Tarezeng area, Tibet. The findings show that at least part of Middle-Upper Jurassic strata has not been identified previously in the Xiala Formation. The assemblage characteristics of the rock, basic sequence, and fossil comparison show that this set of strata belongs to the Ringtor Formation. The determination of this formation provides basic information for the correlation of regional strata, the establishment of the stratigraphic framework and the investigation of the evolution of the Mesozoic basin. © 2015, Science Press. All right reserved.
Dai C.,Guizhou Geological Survey |
Zheng Q.,Guizhou Geological Survey |
Chen J.,Guizhou Geological Survey |
Wang M.,Guizhou Geological Survey |
Zhang H.,Guizhou Geological Survey
Earth Science Frontiers | Year: 2013
After the Wuling tectonic movement, a depositional pattern consisting of platform sediments, ramp turbidities, and deep basin sediments developed in Guizhou Province during the Xuefeng to the Caledonian tectonic cycles, which represent an evolution history from rifting oceanic basin turning to foreland basin. The rifting had resulted in numerous magmatic rocks. The Guangxi movement formed the Caledonian orogen, when the eastern, middle, and western portions of Guizhou were located in the orogenic inner belt, outer belt, and foreland part, respectively; from east to west, the regional metamorphic grade decreases gradually. Meanwhile, thrusts and metamorphic core complexes(MCCs) were developed. The rifting and foreland basins controlled the sedimentary and sedimentary exhalative(SEDEX) deposits, such as manganese, phosphorus, barite, nickel-molybdenum-vanadium, and lead-zinc ores, as well as hydrocarbon source rocks and shale gas etc. On the other hand, MCC structure and intraplate magmatism had controlled the mineralization of endogenic hydrothermal ores and reworked sedimentary ores including gold, copper, lead-zinc, and diamond deposits.
Zhang X.-J.,Guizhou Geological Survey |
Yang S.-F.,Guizhou Geological Survey |
Zhang H.,Geological Party 113 |
Li J.-B.,Guizhou Geological Survey
Wutan Huatan Jisuan Jishu | Year: 2015
Guizhou iron(rare earth) polymetallic deposit resources reserves is rich. However, the exploration has certain challenging because of its special geological condition. In this place, developing experimental study of geophysical methods to explore iron (rare earth) polymetallic deposit, it has an important guiding significance for the future exploration work. This paper briefly introduces the AMT working methods, as well as the geological and geophysical characteristics of Guizhou Weining Changgou area. The application of the exploration iron(rare earth) polymetallic deposit using AMT is discussed in Changgou area. Through the comprehensive inference and interpretation on resistivity section diagram, it has divided between the Permian Wuanwei group, emei mountain basalt group strata interface. It has circled the ore bearing favorable position. The drilling re-sults showing, it has obtained better prospecting results.
Lin M.,Wuhan University |
Peng S.,Wuhan University |
Peng S.,China Three Gorges University |
Qiao W.,Guizhou Geological Survey |
And 2 more authors.
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | Year: 2014
Researches on the Cenozoic volcanic rocks of the Mangbang Formation in the Mangbang area of the Tengchong block, South China, reveals many granulite xenoliths of felsic granulite and two-pyroxene granulite in trachyandesite. The granulite xenoliths range 3-5 cm in diameters, featured with aligned formation and blastic texture. Equilibrium temperature and pressure estimates for the felsic granulite xenoliths and two-pyroxene granulite xenoliths are 869-969 °C, 0.94-1.00 GPa and 841-972 °C respectively, indicating that they are high temperature granulites. The crystallization temperature and pressure of trachyandesite phenocryst is 1 008-1 059 °C, 1.26-1.33 GPa, indicating that they were formed in and originated from the lower crust to the top of the upper mantle. Electron backscatter diffraction(EBSD) analyses of two-pyroxene granulite xenoliths show that orthopyroxene and clinopyroxene have obvious lattice preferred orientation (LPO), and the main slip systems are: (010)  and (100) , (010)  respectively. The deformation mechanism is dislocation creep, which indicates that granulite xenoliths experienced a strong plastic deformation and metamorphism. The discovery of high temperature granulite in Cenozoic volcanic rocks suggests that Tengchong Cenozoic magmatic activity may be related with volcanic magamatism and high temperature metamorphism in the lower crustal caused by post-collisional extensional collapse, delamination and slab break-off after subduction and collision of the Indian Plate and the Tengchong block.
Tao P.,Guizhou Geological Survey |
Chen Q.,Guizhou Geological Survey |
Wang L.,Guizhou Geological Survey |
Hu C.,Guizhou Geological Survey
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2013
Gold deposits are of low-exploration and study degree in the Tianzhu-Jinping-Liping area, southeastern Guizhou Province. To carry out mineral prediction of gold mineral resources in this area, some special topic studies should be concerned such as the geological background, metallogenic regularity, geophysical, geochemical and remote sensing, prospecting indicators, etc. Some main factors affecting mineral prediction, for example, the geological background and metallogenic regularity must be identified. When the prediction conditions are not ripe in these areas, the potential assessment of mineral resources in ore field or deposit scale can be carried out, the prospecting perspective of each gold field can be evaluated and the possibility to find new deposit can be analyzed. The authors use the sum of weight of various forecasting elements to locate predicted mineral resources, instead of carrying out quantitative prediction based on GIS, intended to emphasize the importance of special topic researcher, and to explore the possibility of simplifying the process of mineral prediction. The simplified process of the location prediction for ore fields that suitable for this area includes studying on related topics and prediction elements, calculating the probability of mineral occurrence, classifying exploration prospective area and potential assessment of mineral resources for ore fields. According to this method, ten prospecting areas are determined including four class A, three class B and three class C.