辽宁东五家子金矿矿脉含矿性评价标志研究

辽宁东五家子金矿的矿脉由蚀变岩和石英脉透镜体构成,可采矿体均为硫化物石英脉型.工业矿脉中,石英为烟灰色,发育他形、半自形的细粒黄铁矿等硫化物,有较大规模的矿体.矿化脉中,石英为乳白色,发育粗粒、自形的浅色黄铁矿,无可采矿体.在工业矿脉、次要矿脉、矿化脉的蚀变岩和石英脉样品中,Au,Hg与其他元素的相关性有明显区别.用石英脉样品的As-Ni-Ba图解和蚀变岩样品的Au-Ag-Ba图解预测,矿区外围的西沟1号脉和西沟3号脉属于工业矿脉.     

Environmental Redox Changes of the Ancient Sea in the Yangtze Area during the Ordo-Silurian Transition

Extensive organic-matter （OM） rich facies （black shales） occur in the Ordo-Silurian boundary successions in the Yangtze area, South China. To investigate the redox changes of the Yangtze Sea during the Ordo-Silurian transition, two OM sections （Wangjiawan in Yichang, Hubei Province, and Sanjiaguan in Zhangjiajie, Hunan Province） straddling the Ordo-Silurian boundary are studied. The measurements finished in this study include contents of the total organic carbon （TOC）, pyrite sulphur, and different species of Fe, including dithionite-extractable Fe （FED）, pyrite Fe （FeP）, HCl-extractable Fe （FeH）, and total Fe （FeT）, in black shales, as well as other redox proxies, such as the SIC ratio, the ratio between highly reactive Fe （FeHR = FeD ＋ FeP） and FeT, and the FeP/（FeP ＋ FeH） ratio, known as the degree of pyritization （DOP）. In the Wangjiawan section, the Middle Ashgill sediments have high FeHR/FeT ratios （0.20-0.77; avg. 0.45）, high DOP values （0.21-0.72; avg. 0.54）, and a relatively constant sulfur content independent of the organic carbon content. By the contrast, the mid-early Hirnantian deposits generally have low FeHR/FeT ratios （0.10-0.35; avg. 0.21）, low DOP values （0.11- 0.40; avg. 0.28）, and SIC values are clustering on the normal marine value （SIC = 0.36）. The late Hirnantian and early Rhuddanian deposits, similar to those of the Middle Ashgill deposits, are characterized by high FeHR/FeT ratios （0.32-0.49; avg. 0.41）, high DOP values （0.46-0.68; avg. 0.53） and fairly constant sulfur contents. These data suggest the occurrences of marine anoxia on the Yangtze Sea shelf during intervals of the Mid Ashgill, Late Hirnantian and Early Rhuddanian, and ventilated and oxygenated marine conditions during the mid-early Hirnantian time. The mid-early Hirnantian ventilated event was concomitant with the global glacial period, likely resulted from the glacio-eustatic sea-level fall and subsequent circulation of cold, dense oxygenated waters     

大民屯凹陷烃源岩有机质丰度的恢复

烃源岩有机质丰度的恢复具有重要的现实和理论意义。笔者在对比多种方法的基础上,对大民屯凹陷的烃源岩的有机质丰度进行了恢复。     

New data on the correlation of skarn and gold mineralization at the Tardan deposit (northeastern Tuva)

Gold mineralization of the Tardan deposit is of different spatial occurrences and is related to different hydrothermal-metasomatic formations, the main ones being skarn-magnetite bodies, metasomatites of mineralized crush zones, and metasomatites of argillizitic-rock association. The formation of gold mineralization was a multistage process related to the repeated magmatism of the Tannu-Ola complex. It took place in a wide temperature range (400–150 °C), which determined the diversity of produced mineral assemblages. The gold mineralization associated with magnetite bodies shows a spatial correlation with magnesian and calcareous skarns and is localized in plagiogranites and gabbro-diorites of the Tannu-Ola complex intruded in the Late Ordovician. Gold mineralization that occurs in crush zones and along the fault sutures in moderate- and low-temperature hydrothermal-metasomatic rocks (propylites, beresites, serpentinites, and argillizites) formed somewhat later than skarns as a result of the intrusion of granite dike bodies. Comparative analysis of different types of gold mineralization showed both a change of mineral assemblages of the gold mineralization during the ore formation and some geochemical difference between gold and gold-bearing ores. In passing from early to late occurrences of native gold, its fineness decreases, the contents of admixtures correspondingly increase, and the gold composition changes. Gold of high-temperature rocks is rich in Cu (up to 17%), and gold of low-temperatures rocks has higher contents of Ag and Hg.     

Holocene climate reconstructions of Ulungur Lake (Xinjiang,China) inferred from ostracod species assemblages and stable isotopes

In this paper, the data on the paleoclimatic and paleoenvironmental changes during the Holocene are presented and a discussion is made on a 225-cm-long sediment core from Ulungur Lake, located in Northwest China. The chronology is constructed from six AMS radiocarbon dates on the bulk organic matter. On the basis of the analysis of ostracod assemblages and the shell stable isotopes, the core is divided into three paleoclimatic and paleoenvironmental evolution stages: 9 985–5 250 cal.aB.P. stage is the wettest phase of the core section. The climate changed from moderate-dry to cool-wet, and then to warm-wet in turn, and the lake level rose accordingly, showing the characteristic of a high lake level. 5 250–1 255 cal.aB.P. stage was the driest phase of the core sediment. The climate turned from the early warm-dry to the late warm-wet and the lake level fell and rose again. Finally, the 1 255 cal.aB.P. stage was the medium stage of the section. The temperature was low and then increased after the 1920s and the climate was dry. The whole climatic and environmental evolution records of Lake Ulungur were not only in agreement with the sporopollen record of the same core but also in agreement with the record of environmental changes of adjacent areas. It responded to regional environmental changes and global abrupt climate events, following the westerly climate change mode on 100-year-scale, primarily with cold-wet and warmdry characteristics. __________ Translated from Quaternary Sciences, 2007, 27(3):382–391 [译自:第四纪研究]     

A dynamic box model of bioactive elements in the southern Taiwan Strait

A dynamic box model was applied to study the characteristics of biogeochemical cycling of PO_4-P,NO_3-N,AOU,POC and PON in the southern Taiwan Strait region based on field data of the"Minnan Taiwan Bank Fishing Ground Upwelling Ecosystem Study" during the period of Dec.1987-Nov.1988.According to the unique hydrological and topographical features of the region,six boxesand three layers were considered in the model.The variation rates and fluxes of elements induced by hor-izontal current,upwelling,by diffusion,sinking of particles and biogeochemical processes were estimatedrespectively.Results further confirmed that upwellings had important effects in this region.Thenearshore upwelling areas had net input fluxes of nutrients brought by upwelling water,also had high de-pletion rates of nutrients and production rates of particulate organic matter and dissolved oxygen.Theabnormal net production of nutrients in the middle layer(10-30m) indicated the important role of bacte-ria in this high production region.Th     

Molecular and bulk isotopic analyses of organic matter in marls of the Mulhouse Basin (Tertiary, Alsace, France)

Contents of 13C in kerogens and carbonates in 21 samples from a core of the MAX borehole, Mulhouse Evaporite Basin, range from -27.3 to -23.5 and -3.7 to -1.8% vs PDB, respectively. Organic nitrogen in the same samples is enriched in 15N relative to atmospheric N2 by 12.2-15.7%. Hydrogen indices and delta values for kerogens vary systematically with facies, averaging 493 mg HC/g Corg and -25.7% in the most saline facies (dominated by inputs from aquatic sources) and 267 mg HC/g Corg and -23.7% in the least saline facies (50/50 aquatic/terrigenous). Values of delta were measured for individual aliphatic hydrocarbons from three samples representing three different organic facies. For all samples, terrigenous inputs were unusually rich in 13C, the estimated delta value for bulk terrigenous debris, apparently derived partly from CAM plants, being -22.5%. In the most saline facies, isotopic evidence indicates the mixing of 13C-depleted products of photosynthetic bacteria with 13C-enriched products of halotolerant eukaryotic algae. At lower salinities, a change in the producer community is marked by a decrease in the 13C content of algal lipids. The content of 13C in algal lipids increases in the least saline facies, due either to succession of different organisms or to decreased concentrations of dissolved CO2.     

The “Zero-order Model” revisited: Paul Schindler's influence on the development of trace metal scavenging models

In 1975 Paul Schindler produced the first oceanic trace metal scavenging model to explicitly include the role of surface chemistry as a control on trace metal water column residence times. The eighteen years that have elapsed since the publication of Schindler's seminal paper have seen the development of a variety of oceanic scavenging models; yet, the fundamental insight of his Zero-order Model remains the benchmark. This paper describes the role of Paul Schindler's work on surface chemistry in providing a framework for the current generation of trace element scavenging models.     

Multi-stage metallogeny in the southwestern part of South China,and paleotectonic and climatic implications: A high precision geochronologic study

The South China Block (SCB) is among the large-scale W-Sn mineralized regions of the globe. The Laojunshan W-Sn-dominant ore area (LOA) in the western part of the SCB preserves the records of the tectonic history of the Tethys realm extending through North Vietnam, and Yangtze to Cathaysia blocks, with coeval formation of giant metallic deposits. The prolonged tectonic activities and their control on the genesis and spatio-temporal distribution of giant metallic deposits in the LOA provide a window for a holistic understanding of the tectono-metallogenesis of the SCB. In this study, we present results from a multi-chronologic study to determine the timing of formation of the cassiterite-wolframite-scheelite mineralization. The results suggest three distinct tectono-metallogenic periods in the LOA during the geodynamic evolution of the surrounding tectonic units. The opening of the Proto-Tethys Ocean between the Yangtze-Indochina blocks and the westward Paleo-Pacific subduction beneath the Cathaysia block (420–380 Ma) jointly contributed to the Silurian to early Devonian intracontinental orogeny in the middle of the SCB that involved top-to-the-north thrusting along NE-striking shear zones. This event generated the Dulong-Song Chay granitoids, together with the formation of Xinzhai Sn deposit related to sheared mylonitic granites (ca. 419 Ma) and pegmatites (ca. 389 Ma), which include the early-stage Sn-sulfide skarn (ca. 418 Ma) and the late-stage Sn-bearing schist (ca. 389 Ma). During the Late Permian to Late Triassic (260–220 Ma), with the closure of the Proto-Tethys oceans in the west and ongoing Paleo-Pacific westward subduction in the east, the SCB and Indochina Block (IB) were amalgamated which also marks the time of formation of the Nanwenhe scheelite skarn deposit. The subducted Paleo-Tethys oceanic crust was likely entrained by the nearby rising Emeishan mantle plume (270–259 Ma), which formed the Maguan diabase (ca. 260 Ma) that shows significantly older Re-Os model age of ca. 268 Ma, suggesting that the Nanwenhe mineralization is potentially derived from ca. 260 Ma source. Furthermore, the intraplate shortening induced thin skinned crustal deformation and low grade metamorphism (ca. 230 Ma), with the main stage of scheelite-Sn-Mo mineralization (229.9, 229.8 and 219 Ma) and contemporary formation of the pegmatite (230.7 Ma). The Late Cretaceous involved two episodes of alternate extension and shortening, driven by the subduction polarity change from northwestward subduction of the Okhotomorsk block to northward subduction of the NeoTethys seafloor. The evolution of the LOA consists of the NW–SE transpression ending ca. 100 Ma, the WNW–ESE extension in the earlier episode lasting from 100 Ma to 86 Ma, the WNW–ESE transpression beginning at ca. 85 Ma and the NS extension in the later episode during the latest Cretaceous, which produced the extension-related three periods of Laojunshan granitic magmatism and coeval Sn-W mineralization, with ages in the range of 90–89 Ma, 87–85 Ma and 83–79 Ma. We also evaluate the implications of magmatic-metamorphic-metallogenic degassing on the regional paleoclimatic history.     

碳中和目标下关键矿产在清洁能源转型中的作用、供需分析及其建议

在"碳中和"目标的驱动下，全球能源系统向清洁化、低碳化甚至无碳化发展已是大势所趋。针对向清洁能源转型的需求，采用了统计对比、分类汇总、综合分析等方法，分析研究了关键矿产在电池、电网、低碳发电和氢能等行业中的作用和需求。结合当前关键矿产产量的地理集中度高、项目开发周期长、资源质量下降等矿产供应和投资计划不能满足清洁能源转型的需求等问题，提出确保关键矿产多样性供应，推动价值链各环节的技术创新，扩大回收利用，增强供应链弹性和市场透明度，将更高的环境、社会和治理标准纳入主流程及加强生产者和消费者之间的国际合作等建议。