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Pyrite Concretions in the Lower Cambrian Niutitang Formation,South China:Response to Hydrothermal Activity

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Journal of Earth Science 2023年第4期34卷 1053-1067页

作者： Zixuan Liu detian yan Xing Niu Key Laboratory of Tectonics and Petroleum Resources Ministry of EducationChina University of GeosciencesWuhan 430074China School of Geosciences Yangtze UniversityWuhan 434023China

The Early Cambrian Niutitang Formation is characterized by wide distribution of black shales on yangtze Block,South *** we have reported the pyrite concretions in the bottom of the Niutitang Formation deposited in the slope-basin environment of yangtze *** pyrite concretion was mainly composed of pyrite associated with hydrothermal minerals(barite,hyalophane,tetrahedrite),followed by quartz and organic *** elements Mo and U displayed significant enrichment(enrichment factors > 10),indicating the euxinic bottom water ***,Ni,and excess Ba concentrations were relatively high,denoting high primary ***-situ sulfur isotope compositions of pyrite concretions δ34Spy) showed little variations(13.2‰–19.4‰) and small fractionations compared to coeval seawater δ*** and geochemical analyses indicated the pyrite concretions were formed in the sediment-water interface during the early diagenesis,with H2S diffusing from the euxinic water,and influenced by hydrothermal activity leading to the coexistence of barite,hyalophane,and *** results imply euxinic bottom water featured by high primary productivity and increasing riverine flux of sulfate from chemical weathering during the Early Cambrian.

关键词： shale pyrites black shale pyrite concretion depositional environment.

Pore Structure and Multi-Scale Fractal Characteristics of Adsorbed Pores in Marine Shale:A Case Study of the Lower Silurian Longmaxi Shale in the Sichuan Basin,China

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Journal of Earth Science 2022年第5期33卷 1278-1290页

作者： Haijiao Fu detian yan Chenpeng Yao Xianbo Su Xiaoming Wang Hu Wang Yueguo Li School of Earth Resources China University of GeosciencesWuhan430074China Key Laboratory of Tectonics and Petroleum Resources China University of GeosciencesMinistry of EducationWuhan430074China School of Energy Science and Engineering Henan Polytechnic UniversityJiaozuo454000China

Exploration practice indicates that free gas is the key to the large-scale development of shale gas,while adsorbed gas is also of great significance to the sustainable development of shale gas,and thus systematic researches on absorbed pores are *** date,researches on pore structure and multi-scale fractal characteristics of absorbed pores in marine shale are obviously insufficient,limited the understanding of gas production behavior from shale *** this study,total organic carbon(TOC),X-ray diffraction(XRD),CH_(4) adsorption,field emission electron microscopy(FE-SEM),and low temperature gas(i.e.,CO_(2)and N_(2))adsorption/desorption analyses were conducted on 10 continuously core samples from the Lower Silurian Longmaxi shale in the Fuling region of Sichuan Basin,*** results indicate that the TOC content of marine shale samples changes from 0.95%to 4.55%with an average of 2.62%,showing an increasing trend with the increase of burial depth;moreover,quartz and clay are the dominated mineral compositions in marine shale,and they show a certain negative ***-SEM analysis indicates that almost all pore types in marine shale are related to organic matter(OM).Hysteresis loops of marine shale samples mainly belong to Type H2,further indicating that the pores in marine shale are mainly ink-bottle pores(i.e.,OM pores);moreover,adsorption isotherms obtained from CO_(2)adsorption data all belong to typeⅠ,indicating microporous properties for all shale *** analysis indicates that pore volume and pore surface area of adsorbed pores(<300 nm)is mainly provided by the pores within the pore range of 0.6–0.7,0.80–0.85,and 1.7–5.0 *** on the micropore filling model and the Frenkel-Halsey-Hill(FHH)model,multiscale fractal dimensions(D1,D2,and D3)are calculated from gas adsorption data(i.e.,CO_(2)and N_(2)),corresponding to part of micropore(0.6–1.1 nm),small-mesopore(1.7–5.0 nm),big-mespore and part of macropore(5.0–300 nm),respectiv

关键词： adsorbed pores Pore structure Fractal dimensions Marine shale Sichuan Basin petroleum geology

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鄂西—黔南地区下寒武统页岩旋回地层学研究

沉积学报 2024年第3期42卷 823-838,I0001页

作者：魏小松严德天龚银牛杏梁万乐伏海蛟刘紫璇杨向荣张宝中国地质大学(武汉)构造与油气资源教育部重点实验室武汉430074 湖北地质局第七大队湖北宜昌443000 长江大学地球科学学院武汉430100

【目的】鄂西—黔南地区下寒武统富有机质页岩层系是页岩气勘探的重要目标,查明不同地区富有机质页岩层段的等时地层关系及其成因已成为页岩气勘探的关键问题。【方法】通过对鄂西ND1井及黔南HY1井下寒武统测井自然伽马数据的旋回地层... 详细信息

【目的】鄂西—黔南地区下寒武统富有机质页岩层系是页岩气勘探的重要目标,查明不同地区富有机质页岩层段的等时地层关系及其成因已成为页岩气勘探的关键问题。【方法】通过对鄂西ND1井及黔南HY1井下寒武统测井自然伽马数据的旋回地层学分析,识别出下寒武统主要的天文周期,以文献报道的锆石年龄作为锚点建立了两口井的天文年代标尺,并基于沉积噪音模型恢复了两口井下寒武统时期的相对海平面变化。【结果】ND1井牛蹄塘组36 m和9 m的沉积旋回及HY1井16.6 m和4.0 m的沉积旋回代表了轨道周期405 kyr和100 kyr偏心率;ND1井牛蹄塘组和HY1井九门冲组持续时间分别为3.30 Myr和2.64 Myr。给出两种方案的天文年代标尺,方案一以ND1井牛蹄塘组顶作为锚点起点,对应的天文年代标尺年龄区间处于535.20±1.70 Ma~538.50±1.70 Ma;方案二以HY1井九门冲组顶作为锚点起点,对应的天文年代标尺年龄区间处于535.20±1.70 Ma~537.84±1.70 Ma。经过对比分析,两口井海平面变化对应于1.20 Myr旋回和两个三级层序(SQ1和SQ2)。将下寒武统富有机质页岩总有机碳(Total Organic Carbon,TOC)含量和405 kyr旋回滤波及海平面变化曲线对比,结果显示TOC高值段对应于405 kyr旋回最大值,而ND1井TOC低值段对应于两个405 kyr旋回之间的低值。此外,TOC高值段既对应于海平面较高时期,也对应于海平面较低时期。【结论】由于太阳系的混沌行为,无法准确预测寒武纪早期理论轨道偏心率对富有机质页岩驱动的机制。假设偏心率最大值和总有机碳含量最大值对应,则更长的时间段内强季节性变化在某种程度上触发了黑色页岩的富集。此外,相对海平面变化和总有机碳含量对比表明海平面变化和有机质富集不具有因果关系。

关键词：牛蹄塘组九门冲组轨道驱动偏心率沉积噪音模型

准噶尔盆地玛湖凹陷中部地区多层系油气成藏条件及勘探前景

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石油学报 2024年第5期45卷 771-786,816页

作者：张磊魏小松唐勇郑孟林严德天张宝张铭轩袁铎恩中国石油新疆油田公司勘探开发研究院新疆克拉玛依834000 中国地质大学(武汉)构造与油气资源教育部重点实验室湖北武汉430074

玛湖凹陷中部(玛中)地区油气勘探在二叠系—侏罗系获得了工业油流和良好的油气显示,但目前其整体勘探程度较低,油气富集条件、成藏模式及主控因素的系统研究较为薄弱,深入认识玛中地区多层系油气的成藏条件与有利区分布,是提高油气勘探... 详细信息

玛湖凹陷中部(玛中)地区油气勘探在二叠系—侏罗系获得了工业油流和良好的油气显示,但目前其整体勘探程度较低,油气富集条件、成藏模式及主控因素的系统研究较为薄弱,深入认识玛中地区多层系油气的成藏条件与有利区分布,是提高油气勘探成效的关键。基于最新岩心、测井、连井和地震资料分析以及岩石薄片观察等,系统论述了玛中地区的烃源岩特征、主要目的层系(二叠系下乌尔禾组、三叠系百口泉组和白碱滩组以及侏罗系八道湾组)的沉积特征和储层控制因素,明确了多层系油气富集层位及油气的立体成藏模式,为下一步勘探提供了前瞻性预测。研究结果表明,广泛发育的走滑断裂体系沟通了下伏二叠系烃源岩,断层和不整合面将油气垂向或侧向输运到二叠系下乌尔禾组和三叠系百口泉组,并进一步通过断层输送至浅层形成油气聚集;下乌尔禾组和百口泉组中,呈广覆式分布的扇三角洲前缘相贫泥砾岩储层和退积型扇三角洲相与晚期大套泥岩组成的良好储-盖组合是玛湖凹陷获得大面积油气成藏的关键;白碱滩组和八道湾组的薄层砂砾岩储层与大套泥岩组成的良好储-盖组合是玛中地区浅层油气成藏的关键。综合分析认为,玛中地区百口泉组一段上亚段及下乌尔禾组扇三角洲前缘砂体可发育优质储层,具备形成大型地层圈闭的条件;玛中地区白碱滩组二段和八道湾组一段辫状河三角洲前缘薄层砂砾岩发育优质储层,具备形成岩性圈闭的条件;以上均为玛中地区下一步油气勘探重点层系。

关键词：玛湖凹陷百口泉组下乌尔禾组白碱滩组八道湾组成藏模式

Combining indicators analysis and chemometrics to trace the geographical origin of crude oil

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Petroleum Research 2023年第4期8卷 524-530页

作者： Tong Li detian yan Wenjie Liang Xiaosong Wei Key Laboratory of Structure and Oil and Gas Resources Ministry of EducationChina University of Geosciences(Wuhan)Wuhan 430074Hubei ProvinceChina

Geographic traceability is crucial to global oil trade *** study discusses the possibility of using multivariate statistical methods combined with multi-indicator analysis to identify samples of crude oil imports from five major countries to *** physicochemical properties and trace elements of crude oil were detected by Petroleum product standards and inductively coupled plasma atomic emission spectrometry(ICP-AES).Eight indexes(moisture,density,sulfur content,acid value,organochlorine,carbon residual,V,and Ni)were *** component analysis(PCA),hierarchical clustering analysis(HCA),Orthogonal projections to lateen structures-discriminant analysis(OPLS-DA),and other multivariate data analysis methods were used to determine the geographical origin of crude oil *** results have been obtained using PCA to reduce the dimensions of the indicators of crude oil from different *** allows the reduction of 8 variables to 3 principal components and accounts for 80.06%of the total *** HCA shows five clusters corresponding to five sources of crude *** will help to improve the utilization rate of crude oil with different characteristics,improve the quality of crude oil trade,and ensure the high quality of crude oil *** the sample set used for modeling,the model's accuracy was 97.19%after OPLS-DA *** results show that the combination of multi-index analysis and stoichiometry is an effective tool for identifying crude oil origin,which fills the technical gap in the rapid identification of crude oil origin.

关键词： Crude oil Origintraceability PCA HCA OPLS-DA

Insights into Pore Structure and Fractal Characteristics of the Lower Cambrian Niutitang Formation Shale on the yangtze Platform,South China

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Journal of Earth Science 2020年第1期31卷 169-180页

作者： Zixuan Liu detian yan Xing Niu Key Laboratory of Tectonics and Petroleum Resources Ministry of EducationChina University of GeosciencesWuhan 430074China School of Earth Resources China University of GeosciencesWuhan 430074China Sedimentary Basin Research Center Yangtze UniversityWuhan 430074China

Shales from the Lower Cambrian Niutitang Formation of yangtze Platform have been widely investigated due to its shale gas *** better illustrate the pore structure and fractal characteristics of shale,a series of experiments were conducted on outcrop samples from the Lower Cambrian Niutitang Formation on yangtze Platform,including X-ray diffraction(XRD),field-emission scanning electron microscopy(FE-SEM) and low-temperature nitrogen ***-Halsey-Hill(FHH) model was adopted to calculate the fractal ***,the relationships between fractal dimensions and pore structure parameters and mineral composition are ***-SEM observation results show that interparticle pores are most developed in shale,followed by intraparticle *** study identified the fractal dimensions D1(ranging from 2.558 0 to 2.710 2) and D2(ranging from 2.541 5 to 2.765 2).The pore structure of the Niutitang Formation shale is primarily controlled by quartz and clay *** dimensions are able to characterize the pore structure complexity of Niutitang Formation shale because D1 and D2 correlate well with average pore diameter and quartz content.

关键词： Niutitang Formation yangtze area shale pore structure fractal features

Geochemistry of the Middle to Late Permian limestones from the marginal zone of an isolated platform(Laibin,South China)

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Science China Earth Sciences 2013年第10期56卷 1688-1700页

作者： QIU Zhen WANG QingChen yan detian State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of Sciences PetroChina Research Institute of Petroleum Exploration and Development Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education University of Geosciences

Major, trace and rare earth elements were measured in 27 samples of the Middle to Late Permian limestones from the Tieqiao section located on the marginal zone of an isolated platform （Laibin, South China）. Shale-normalized REE＋Y patterns of all samples show notably negative Ce anomalies （0.21-0.66, average 0.33）, slightly positive Gd anomalies （1.08-1.30, average 1.20）, and positive Y anomalies with superchondritic Y/Ho ratios （36-91, average 55）, which are consistent with those of modern shallow seawater. Their relative LREEs enrichment with higher NdsN/YbsN ratios （0.58-1.80） than those of modern shallow seawater （0.21-0.50） suggests complicated sources of REEs for all samples. Compared with geochemical features of sediments influenced by terrigenous particles and hydrothermal fluids, it is concluded that ambient shallow seawater was the primary source of REEs in these limestones. Comparing the indicators of REE＋Y elements （ZREE, NdsN/YbsN, Ce/Ce＊, Gd/Gd＊, Eu/Eu＊ and Y/Ho） in limestones with those in bedded cherts from the Tieqiao section, we consider that limestone and bedded chert have similar sources of REE＋Y elements： ambient shallow seawater with more or less hydrothermal fluids. In addition, there is a completely negative correlation between CaCO3 and SiO2 contents in limestones and bedded cherts. These results imply that precipitation of CaCO3 was inhibited by that of SiO2 which was derived mainly from hydrothermal fluid, es- pecially in bedded cherts from the Tieqiao section.

关键词： geochemistry rare earth element limestone the Middle to Late Permian South China

Geochemical changes across the Ordovician-Silurian transition on the yangtze Platform,South China

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Science China Earth Sciences 2009年第1期52卷 38-54页

作者： yan detian CHEN DaiZhao WANG QingChen WANG JianGuo Key Laboratory of Tectonics and Petroleum Resources Ministry of EducationChina University of GeosciencesWuhan 430074China State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China

The trace element and rare earth element(REE) variations across the Ordovician-Silurian succession are presented from two outcrop sections on the yangtze Platform:the Nanbazi section,Guizhou Province,deposited in a shallow platform interior setting,and the Wangjiawan section,Hubei Province,deposited in a deeper basinal *** analysis of closely spaced samples through three intervals,the Wufeng,Guanyinqiao and Longmaxi,revealed vast palaeoceanographic *** geochemical proxies,including Th/U,Ni/Co,V/Cr,and V/(V+Ni) ratios,together with sedimentary facies and biotic data,indicate that an anoxic condition on the most of the yangtze Platform during the Wufeng and Longmaxi intervals,but an oxic condition during the Guanyinqiao *** shift of the anoxic to the oxic environment during the Guanyinqiao time coincided with a global sea-level lowstand,in parallel with the global *** Longmaxian anoxic environment was a result of a global sea-level rise,which may be synchronized with a mainly catastrophic event in the latest *** the two sections generally show similar variation patterns of trace and REE concentrations and some element ratios,a minor difference occurs between the Wangjiawan and Nanbazi sections,likely reflecting a difference in depositional setting during the *** an oceanic oxygen-level variation may add a useful constraint to the current arguments on the cause and consequence of the latest Ordovician mass extinction.

关键词： rare earth elements trace elements paleo-redox proxies mass extinction Ordovician-Silurian boundary yangtze Platform

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

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Acta Geologica Sinica(English Edition) 2008年第3期82卷 679-689页

作者： yan detian CHEN Daizhao WANG Qingchen WANG Jianguo CHU yang State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 Key Laboratory of Tectonics and Petroleum Resources China University of Geosciences Ministry of Education Wuhan 430074

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 upon the shelf seabed. Acco

关键词： oceanic anoxia water column stratification Fe-S geochemistry organic carbon Late Ordovician Early Silurian yangtze Sea South China