Assessment on Redox Conditions and Organic Burial of Siliciferous Sediments at the Latest Permian Dalong Formation in Shangsi,Sichuan,South China

The redox sensitive elements, molybdenum （Mo） and uranium （U）, in marine sediments from the latest Permian Dalong （大隆） Formation at the Shangsi （上寺） Section, Northeast Sichnan （四川）, South China, were analyzed by inductively coupled plasma mass spectrometry （ICP-MS） to determine their response to a range of redox conditions, and to estimate the organic carbon burial rate. On the basis of the correlation between anthigenic Mo abundance and organic carbon content in modern oceans, the organic carbon burial rates were calculated for the rocks at Dalong Formation, ranging from 0.48-125.83 mmol/（m^2.d）, which shows a larger range than the mineralization rate of organic carbon at the continental margins （1.6-4.23 mmol/（m^2-d））. The Zr-normalized Mo and U abundances show large fluctuations in the entire section. The maxima of Zr-normalized Mo abundance and thus the maxima of the organic carbon burial rates were observed at the interval between the 155th and 156th beds （404-407 m above the base of Middle Permian）. A decrease （the minimum） in U/Mo ratios is present in this interval. It is speculated that the oxygen-limited conditions and ultimately anoxia or euxinia may develop within this depth interval. In contrast, an enhanced enrichment of Zr-normalized U abundance is found, in association with less enrichment in Zr-normalized Mo abundance in the interval from the 151st to 154th beds （395-404 m above the base of Middle Permian）, inferring the dominance of a suboxic/anoxic depositional condition （denitrifying condition）, or without free H2S. The presence of small quantities of dissolved oxygen may have caused the solubilization and loss of Mo from sediments. It is proposed that the multiple cycles of abrupt oxidation and reduction due to the upwelling at this interval lead to the enhanced accumulation of authigenic U, but less enrichment of Mo. A decrease in the contents of U, Mo, and TOC is found above the 157th bed （407 m above the base of Middle Permian）, in association with the enhanced U/Mo ratio, suggesting the overall oxic conditions at the end of the Dalong Formation.

Carbon Isotope Records Indicative of Paleoceanographical Events at the Latest Permian Dalong Formation at Shangsi,Northeast Sichuan,China

Paired organic and carbonate carbon isotope compositions of Late Permian Wujiaping （吴家坪） and Dalong （大隆） formations at Shangsi （上寺）, Northeast Sichuan （四川） were analyzed by MAT 251. An abrupt negative excursion in the two isotope records was observed in the middle part of Dalong Formation, in association with a drop in the carbon isotope difference of the two records and an increase of total organic carbon （TOC） content. The negative drop of the paired carbon isotope records is suggestive of the input of 12C-enriched CO2. The molecular ratios of pristane to phytane and dibenzothiophene to phenanthrene indicate the anoxic condition in this interval. The enhanced TOC content is indicative of the elevated preservation of organic matter due to the anoxic condition. These isotopic and organic geochemical data probably infer the occurrence of the upwelling in this interval. The additional contribution of volcanism activity observed in South China cannot be excluded to the input of 12C-enriched CO2 and the negative shifts in carbon isotope composition of bulk organic matter and carbonate.

云南镇康打拢锡多金属矿区深部找矿预测研究

打拢锡多金属矿区位于保山地块南段之镇康复式背斜核部转折端一带,近年来矿区发现新找矿信息,显示深部找矿潜力巨大。在系统总结成矿地质背景、矿区地质、地球物理、地球化学、成矿地质体、成矿构造与成矿结构面、成矿作用特征标志等基础上,认为打拢锡多金属矿区矿化样式具二元空间结构,并对矿区深部成矿作用中心进行了初步识别,对打拢锡多金属矿区深部开展了定性和定量预测,提出了深部找矿建议,以期为深部找矿突破提供方向和依据。

全州县大龙矿区钻孔弯曲规律及应对措施分析

在施工过程中,钻孔的实际空间位置可能偏离设计空间位置,这种现象被称为钻孔弯曲,又称孔斜。孔斜是钻孔的6项评价指标之一,对钻孔质量起着决定性作用。钻孔弯曲一般受地质地层和钻探工艺影响。钻孔过度弯曲给施工带来困难,降低钻进效率,孔壁失稳引发卡钻、断钻、埋钻等孔内事故,更严重的是不能穿过设计的见矿点,从而得不到符合客观实际的地质资料,造成地质情况失真,影响矿床的合理评价。

辽宁大隆矿区矿井巷道空气温度的数值模拟与分析

为解决深部开采带来的巷道内温度过高而没有对热量加以利用的问题,采用传热学、计算流体力学理论,对巷道围岩—空气换热系统进行了三维数值计算,研究了在渗流和无渗流条件下巷道内部温度场随巷道空气入口雷诺数的变化规律。计算结果表明:在巷道长度方向0～50m范围内温升不明显,超过50m后温度增加明显,并且随着长度增加温度相应增加;渗流情况下,巷道空气出口平均温度高于无渗流情况下巷道空气出口平均温度;渗流情况下,雷诺数在1.3×105～3.5×105、11.33×105～3.5×105间平均总传热系数大于无渗流情况下平均总传热系数。控制巷道空气入口雷诺数是解决巷道内温度过高和对热量加以利用的关键。以上结论为矿井热害的综合治理、基于巷道风热量利用的空气源热泵系统的优化设计提供了重要依据。

井田的构造应力及影响

以大隆井田为例，应用地质动力区划方法划分了井田I～V级断裂．以I～V级断裂构成的井田地质断块为基础，采用有限单元法弹性力学平面应变模型，获得了井田构造应力的最大主应力和最小主应力等值线图．根据大隆矿构造应力分布状况，分析了井田井构造应力对巷规划设计的影响．

Geochemical characteristics of the Permian marine mudstone and constraints on its provenance and paleoenvironment in the Fenghai area,Fujian Province, southeastern China

Permian marine strata have gradually become a research focus in the world.The marine strata of the Late Permian Dalong Formation(P3d)in the Fenghai area,Fujian Province,have become more and more important as their geochemical characteristics record important geological information and are a good indicator for recovering and reconstructing the paleosedimentary environments and tectonic attributes.The major elements,trace elements and rare earth elements were analyzed by XRF and ICP-MS,respectively.Based on the results of detailed field geological surveys,profile measurements as well as typical sample collection,the tectonic setting and provenance of Permian marine mudstone were comprehensively discussed.The results showed that the Dalong Formation(P3d)was deposited in an active continental margin tectonic environment as revealed by the relation between Fe2O3 + MgO and TiO2 and Al2O3/SiO2.The fingerprint characteristics of Mn,Fe,Co,Ni and REE and the ratio of U/Th,V/Cr,Sr/Ba,(La/Yb)N and V/(V +Ni)indicated that the sedimentary provenance was mainly derived from potassium feldspar,followed by muscovite.Sedimentary water bodies showed a gradually decreasing depositional rate trend,water depth gradually shallowing and paleo-salinity and productivity gradually increasing.Moreover,since transient delamination occurred during sedimentary processes,sedimentary water bodies showed obvious neritic characteristics.It was consistent with the results revealed by lithological and geochemical characteristics.Calcareous mudstone and siltstone transitioned into fine sandstone from bottom to top,indicating paleo-water bodies became shallow.The research results provided good reference and guidance for understanding Permian paleo-sedimentary environments and tectonic attributes of the Yong’an area,Fujian Province,southeastern China.

Composition and distribution of NSO compounds in two different shales at the early maturity stage characterized by negative ion electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry

Gas chromatography/mass spectrometry （GC/MS） can only analyze volatile molecular compounds, and it has limitations when applied to determine the complex components of crude oils and hydrocarbon source rocks. Based on Fourier transform ion cyclotron resonance mass spectrometry （FT-ICR-MS） and GC/MS analyses, the molecular compositions of NSO compounds in extracts from the Permian Dalong Formation, Sichuan Basin and the Permian Lucaogou Formation, Junggar Basin in China were compared. Analyses of types of heteroatoms present （S~, $2, $3, OS, OS2, 02S, NS, and NOS compounds） suggest that marine shales from the Dalong Formation are mainly composed of carboxylic acids （02 com- pounds） with a high abundance of fatty acids, indicating a marine phytoplankton organic source. However, lacustrine shales from the Lucaogou Formation are dominated by pyrrolic compounds （N1 compounds） with abundant dibenzocar- bazole. It suggests that the organic source materials may be derived from lower aquatic organisms and lacustrine algae. Overall, FT-ICR-MS has potential for applications in analyses and determination of depositional environments and organic sources in petroleum geology.

湖南省大垄铅锌矿成矿地质特征及找矿前景浅析

茶陵县大垅铅锌矿属湖南省国土资源厅组织编制的《湖南茶陵锡田锡铅锌多金属矿整装勘查实施方案》中整合规划的保留矿山。本文作者探讨了湖南省茶陵县大垄矿区大垅、八团铅锌矿的找矿前景。

Paleo-productivity evolution across the Permian-Triassic boundary and quantitative calculation of primary productivity of black rock series from the Dalong Formation, South China

The change of the primary productivity across the Permian-Triassic boundary （PTB） remains controversial. In this study, records from two deep-water sections in South China （Xiakou and Xinmin sections） show the primary productivity decreased gradually from the latest Permian to the earliest Triassic, and five evolutionary stages Increase-Decrease-Recovery-Recession- Stagnation） can be observed from Clarkina changxingensis-C, deflecta to Hindeodus parvus-lsarcicella isarcica zones. Pri- mary productivity decreased abruptly from the base of C. meishanensis zone. Besides, for adjusting to the deterioration of the oceanic environment, the primary producers in the oceanic surface had changed to acritarch and cyanobacteria, which were more tolerant of stressful environment. Then the producers were under huge stagnation in the H. parvus-L isarcica zone. The values of quantitative calculation of the primary productivity from the black rock series in the Dalong Formation were very high, corresponding to that of an upwelling area in modern ocean, which shows that the strata of the Dalong Formation in the study region are potential hydrocarbon source-rocks. This result may come from the fact that South China craton was located at the equatorial upwelling area during the Permian-Triassic transitions. But organic matter contents were different in various sections because they could be affected by redox conditions and diagenesis process after burial.

Latest Wuchiapingian to Earliest Triassic Conodont Zones and δ13 Ccarb Isotope Excursions from Deep-Water Sections in Western Hubei Province, South China

Deep-water facies sections have advantages of recording complete information across the Permian-Triassic boundary(PTB). Here we present a detailed study on the conodont biostratigraphy and carbon isotope profile ranges from the Wuchiapingian-Changhsingian boundary(WCB) to the PTB of two deep-water facies sections at Zhuqiao and Shiligou in the Middle Yangtze region, western Hubei, South China. Fifteen species and three genera are identified. Eight conodont zones are recognized which in ascending order are the Clarkina orientalis, C. wangi, C. subcarinata, C. changxingensis, C. yini, C. meishanensis, Hindeodus parvus and Isarcicella isarcica zones. The onset of deposition of the deep-water siliceous strata of Dalong Formation in western Hubei began in the Late Wuchiapingian and persisted to the Late Changhsingian. Carbon isotope negative excursions occur near both the WCB and PTB in both sections. The WCB δ13 Ccarb negative excursion is in the C. orientalis and C. wangi zones. The PTB δ13 Ccarb negative excursion began in the C. yini Zone and extended to the I. isarcica Zone. The absence of several Changhsingian zones may indicate the difficulty of extracting conodonts from siliceous strata or the presence of an intra-Changhsingian hiatus.

Late Changhsingian (Latest Permian) Radiolarians from Chaohu,Anhui

This article reports a radiolarian fauna from the upper Dalong（大隆） Formation,Ping-dingshan（平顶山）,Chaohu（巢湖）,Anhui（安徽） Province,which includes 15 genera and 23 species.One new species,Copicyntra tongi Gui and Feng n.sp.,is described.Comparison of the fauna,lithology and biotic associations with those from Meishan（煤山） D and Dongpan（东攀） sections shows that the Dalong Formation in the Pingdingshan Section is deposited in a deep-water shelf basin,about 60-200 m in depth.On the basis of the biotic composition,diversity and morphology,the microfossil fauna from the Pingdingshan Section can be divided into three sedimentary assemblages and the extinction proc-esses of the assemblages are discussed.