晚第四纪MIS6以来柴达木盆地成盐作用对冰期气候的响应   总被引：2，自引：0，他引：2  

陈安东  郑绵平  宋高  王学锋  李洪普  韩光  袁文虎 《地质论评》2020,66(3):611-624

气候是控制柴达木盆地盐类沉积的主要因素之一,但是其作用机制尚待明确。作者以柴达木盆地察汗斯拉图盐湖的3个含盐剖面为研究对象,采用多接收电感耦合等离子质谱(MC-ICP-MS)铀系测年测定其沉积时代,并通过X射线粉晶衍射(XRD)分析测定其盐类矿物种类。铀系测年显示D18剖面石盐和芒硝层的沉积时代为13.1±2.0 ka BP～15.9±2.5 ka BP,其中芒硝沉积年代属于末次冰期MIS2晚期;MXK2剖面芒硝层的沉积时代分别为131.7±39.5 ka BP和158.3±10.8 ka BP,D12剖面芒硝层的沉积时代分别为166.6±20.2 ka BP和198.0±20.6 ka BP,可以对应于倒数第二次冰期MIS6。XRD分析确定了3个剖面的盐类矿物主要为芒硝、石盐和石膏。综合多个盐湖晚第四纪成盐数据,本文认为倒数第二次冰期MIS6和末次冰期MIS2是柴达木盆地晚第四纪重要的成盐期,冰期的冷干气候有利于石盐和芒硝等盐类沉积。柴达木盆地"冰期成盐"的根本原因,是由于冰期环境下盆地周边山体冰川规模的扩张以及干冷的冰期气候,共同造成了盐湖补给水量的减少。此外,晚第四纪MIS6和MIS2的冰期降温也是导致盆地中冷相盐类沉积的直接原因。  相似文献   

The influence of the Sabatayn Evaporites on the hydrocarbon prospectivity of the Eastern Shabwa Basin, Onshore Yemen     

T. Richard Seaborne 《Marine and Petroleum Geology》1996,13(8):963-972

The Shabwa Basin is the northeastern extension of the Marib-Al Jawf-Shabwa system of Mesozoic grabens, located onshore in the Republic of Yemen. An evaporitic sequence with an estimated maximum depositional thickness of 300 metres was deposited during the Tithonian. It is designated the Sabatayn Formation and exerts significant control on most of the play elements in the principal hydrocarbon play systems anticipated in the northeastern part of the basin. Migration of hydrocarbons from pre-salt source rocks into intra-and post-salt reservoirs is restricted by the evaporites. Localised heat flow perturbations introduced by the salt, increase the maturity of post-salt source rocks. Post and intra-salt reservoirs are structured by listric faulting on a salt detachment, salt pillowing due to post-depositional loading, by local salt dissolution and by late folding due to gravity sliding of the post-salt section on a salt detachment. Early dissolution and reprecipitation of salt is responsible for occlusion of porosity in intra-salt clastic reservoirs.  相似文献   

Occurrence and conceptual sedimentary model of Cambrian gypsum-bearing evaporites in the Sichuan Basin,SW China   总被引：1，自引：0，他引：1  

Hong Liu  Xiucheng Tan  Yonghao Li  Jian Cao  Bin Luo 《地学前缘(英文版)》2018,9(4):1179-1191

During the Cambrian, gypsum-bearing evaporites formed in the Sichuan Basin, SW China. These rocks are important for oil and gas sealing, but details of their distribution and origin are not well established. This study examines the regional distribution and origin of the gypsum-bearing evaporites using a comprehensive analysis of drilling data from 34 wells, 5 measured cross-sections in the basin and surrounding area, and 96 maps of area-survey data. Results show that in the stratigraphic succession, the gypsum-bearing evaporites occur mainly in the Lower Cambrian Longwangmiao Formation, the Middle Cambrian Douposi Formation, and the Middle-Upper Cambrian Xixiangchi Group. Geographically, the rocks are found mainly in the southeastern part of the basin, and the distribution of deposits shows an overall SW-NE trend. The sedimentary environments for evaporite formation were evaporative lagoon and inter-platform basin in a platform setting. Gypsum was generated by the underwater concentration of sea water in a strongly evaporative environment. Both an evaporative restricted platform and a mixeddeposition restricted platform model appear to be applicable to the development of gypsum in the Sichuan Basin. The gypsum-bearing evaporites with the best sealing capacity are located mostly in the southeastern part of the basin. These constraints can be applied directly to regional exploration, and have implications for the regional paleogeography and paleoclimate.  相似文献   

Meteoric diagenesis and dedolomite fabrics in precursor primary dolomicrite in a mixed carbonate–evaporite system     

《Sedimentology》2018,65(6):1827-1858

Dedolomitization is a common diagenetic process in shallow burial environments and is often associated with sulphates in mixed carbonate‐evaporite successions. In these settings, elevated Ca²⁺/Mg²⁺ ratios necessary for dedolomitization result from the dissolution of sulphate phases by the incursion of undersaturated groundwater. Reported dedolomite textures from other studies are varied, but the most prevalent is a rhombic texture interpreted to result from the partial to complete pseudomorphic replacement of secondary dolomite rhombs formed in the burial diagenetic realm. In this study of primary cryptocrystalline to finely crystalline dolomicrites in the Prairie Evaporite Formation of north‐eastern Alberta, dedolomitization has resulted in sutured to loosely packed mosaics of dedolomite that range from subhedral to distinctly euhedral (rhombic) crystal fabrics; however, no prior aggrading neomorphism producing dolomite rhombs is evident in the precursor dolomicrites. Non‐pseudomorphic dedolomitization of the dolomicrites results in textures that include rhombic dedolomite crystals with cloudy cores comprising remnant dolomicrite and clear rims. These textures are similar to those observed in the pseudomorphic dedolomitization of secondary dolomite rhombs. The Prairie Evaporite Formation of north‐eastern Alberta has experienced extensive karstification near the erosional margin of the sedimentary succession. Dedolomitization of dolomicrites occurs in marker beds within the Prairie Evaporite succession associated with evaporite karstification. Along with stratigraphic and petrographic considerations, stable isotope results support the interpretation of a shallow dedolomitization event influenced by meteoric waters derived from the basin margin. Negative δ ¹⁸O and low δ ¹³C values (averages of −13·6‰_VPDB and 0·5‰_VPDB, respectively) of the dedolomite, compared with those of the primary dolomicrite (averages of −6·0‰_VPDB and 1·2‰_VPDB, respectively), point to isotopically light diagenetic fluids. These results show that rhombic dedolomite textures can form through shallow, non‐pseudomorphic dedolomitization of dolomicrites by meteoric fluids in the presence of sulphates, with resulting textures that are similar to the pseudomorphic dedolomitization of secondary dolomite rhombs.  相似文献   

四川盆地东部地区早中三叠世蒸发岩的锶同位素特征及其地质意义          下载免费PDF全文

丁婷  袁苗  刘成林  赵艳军  朱志军  杨庆坤 《岩石矿物学杂志》2023,42(6):868-877

锶同位素已经成为全球海平面变化、造山运动、古气候和古环境等全球地质事件研究与对比的有效工具之一。本文以四川盆地东部地区早中三叠世蒸发岩的野外剖面和钻孔岩心为主要研究对象,测试了碳酸盐岩、硫酸盐岩和石盐岩的锶同位素组成,并建立了相应的锶同位素演化曲线。研究结果显示,碳酸盐岩的⁸⁷Sr/⁸⁶Sr值平均为0.707 895,硬石膏岩的⁸⁷Sr/⁸⁶Sr值平均为0.708 174,石盐岩的⁸⁷Sr/⁸⁶Sr值平均为0.708 177,同时碳酸盐岩的⁸⁷Sr/⁸⁶Sr值从早三叠世的0.707 413快速增加到中三叠世早期的0.708 515,而后呈现下降趋势。从总体上看,这些⁸⁷Sr/⁸⁶Sr值与全球早中三叠世同期的⁸⁷Sr/⁸⁶Sr值数据接近,说明四川盆地东部地区早中三叠世钾盐的物质来源大部分为海水,并沉积于海相沉积环境,同时由于火山...  相似文献   

大汶口盆地漕河崖矿段岩盐矿地质特征及岩相分布规律     

朱猛 《山东国土资源》2014,30(11)

通过对漕河崖矿段进行勘探工作,发现该区岩盐矿层赋存较多,矿层厚度在0.40~14.72 m,Na Cl平均品位86.39%,属厚度较稳定,品位均匀矿层;岩盐矿层不仅局限在F2,F3,F43个断层的切割范围内,在F3断层北部尚有岩盐层赋存。  相似文献   

大汶口盆地漕河崖矿段岩盐矿地质特征及岩相分布规律     

朱猛 《山东地质》2014,(11):24-27

通过对漕河崖矿段进行勘探工作,发现该区岩盐矿层赋存较多,矿层厚度在0．40～14．72 m,NaCl 平均品位86．39％,属厚度较稳定,品位均匀矿层;岩盐矿层不仅局限在 F2,F3,F43个断层的切割范围内,在 F3断层北部尚有岩盐层赋存。  相似文献   

中国陆块海相盆地成钾条件与预测研究进展综述          下载免费PDF全文

刘成林  吴驰华  王立成  方小敏  赵艳军  颜茂都  张永生  曹养同  张华  吕凤琳 《地球学报》2016,37(5):581-606

中国古代海相钾盐找矿是一个"久攻不破"的难题,古代海相及海陆交互相盆地能否成钾也是长期争议的问题,也就是中国小陆块能否成钾、成大钾矿的关键问题。为此,本文以板块构造运动为主线,对中国主要小陆块漂移历史、成盆构造、古气候、古地理及海相/海陆交互相蒸发岩沉积特征进行了系统梳理和总结;在此基础上,基于盆地"构造-物源-气候"三要素耦合成钾理论,分析中国小陆块海相盆地成钾条件、成矿机理;同时,总结和借鉴全球海相钾盐成矿标志,建立钾盐成矿评价指标体系。基于这些研究基础,借助对主要陆块的区域构造和古地理特征、物质来源、古气候面貌等恢复及分析,对主要陆块的海相成钾潜力进行评价,同时预测找钾战略靶区。钾盐成矿模式研究表明:兰坪—思茅盆地白垩系、上扬子陆块四川盆地中—下三叠统、华北陆块陕北盆地中奥陶统及塔里木陆块库车盆地古近系等盆地及其层位具有较大的成钾潜力。结合成钾指标对比分析,优选圈定了思茅盆地南部、四川盆地中东部及塔里木的库车盆地等战略靶区内较为明确的重点靶区,可以进一步开展钻探验证。这些研究成果为在中国继续开展海相钾盐成矿研究和找钾提供科学依据。  相似文献   

中国中新生代咸化湖盆烃源岩沉积的问题及相关进展   总被引：8，自引：0，他引：8  

金强  朱光有 《高校地质学报》2006,12(4):483-492

我国东部断陷湖盆和西部坳陷湖盆第三系均有蒸发岩与烃源岩共生现象。前者水体深、咸化范围小，在氯化盐和碳酸盐沉积环境中形成了优质烃源岩，后者水体浅、咸化范围大，在氯化盐和硫酸盐沉积环境中发育了优质烃源岩，作者认为两种湖盆出现的水体分层是有机质堆积和保存的重要条件。济阳坳陷和柴达木盆地为两类咸化湖盆的典型代表，对它们的研究可以深化蒸发岩-烃源岩共生区油气地质的认识、促进勘探发展。  相似文献   

四川盆地三叠系蒸发岩的变质作用与富钾卤水的成因   总被引：5，自引：0，他引：5  

李亚文  蔡克勤 《现代地质》1998,12(2):222-228

在四川盆地三叠系蒸发岩建造中已发现钾盐镁矾、无水钾镁矾、软钾镁矾、杂卤石、钾石膏、多钙钾石膏、钙芒硝等矿物,并在多处发现富钾卤水。已有的资料表明,这些矿物组合是已沉积的固体钾盐层在成岩期水溶变质作用过程中形成的变质矿物组合。在此过程中大量的钾质转入水溶液,形成了富钾卤水。这种富钾卤水是可综合利用的ＫＣｌ、ＮａＣｌ和Ｌｉ、Ｓｒ、Ｃｓ、Ｒｂ、Ｂ、Ｂｒ、Ｉ的优质盐化工业原料卤水。  相似文献