新疆库车坳陷侏罗系碎屑岩中粘土矿物粒径研究

选取库车坳陷侏罗系阿合组—齐古组的碎屑岩样品,采用跟进与离心相结合的方式将岩样进行5级分离,对分离后岩样SEM(EDS)分析观察到不同粒径粘土矿物的形貌特征。在20～2μm范围内的样品中,可见片状碎屑粘土矿物;在<2μm的样品中可见自生粘土矿物,以集合体形式存在。对不同粒级的粘土XRD分析表明,该区碎屑岩的主要粘土矿物类型为伊利石、高岭石、绿泥石和伊蒙混层,伊蒙混层主要出现在<0.2μm范围内。高岭石的含量随着岩样粒度的变粗呈现上升的趋势,而伊利石则相反。在气候温暖潮湿的早侏罗世和中侏罗世早期,高岭石的含量相对高;在气候干旱的中侏罗世晚期及晚侏罗世,高岭石的含量减少,伊利石则呈现相反趋势。区分不同成因的粘土矿物可以为进一步研究这一地区的沉积环境、成岩演化历史提供有力依据。     

库车坳陷库车河剖面重矿物分布特征及其地质意义

沉积物中的重矿物分布受物源、构造背景和古气候、古环境等多种因素影响,是盆山演化研究的良好指示剂.本文通过对库车坳陷库车河剖面中新生代地层的野外观察和重矿物分析,将库车坳陷中生代沉积与南天山隆升的分异作用分为4个阶段,即早中三叠世、晚三叠世至早白垩世、第三纪古新世至中新世、上新世(5 Ma)以来,并认为最后一个阶段南天山隆升作用最强烈.将库车坳陷中新生代古气候演化分为3个阶段,即早三叠世(干旱-半干旱)、中晚三叠世-中晚侏罗世(湿润-半湿润)、晚侏罗世以来(半干旱-干旱).     

碎屑重矿物组成对南天山白垩纪-新近纪剥蚀去顶过程的指示

通过对天山南缘库车坳陷内白垩系—新近系砂岩中碎屑石榴子石的电子探针分析,可以将石榴子石分为3部分,分别是高锰铝榴石组份的石榴子石、与西南天山高压变质岩中石榴子石组成相似的石榴子石和富铁镁铝榴石组份的石榴子石。与白垩系相比,古近系和新近系砂岩中的富锰铝榴石组份的石榴子石所占比例减少,而富铁镁铝榴石组份的石榴子石含量增加。白垩系砂岩中含有高压变质岩来源的多硅白云母和蓝闪石,而且与西南天山高压变质岩中石榴子石组成相似的碎屑石榴子石在白垩系中含量也较高,而随着地层时代的变新,与西南天山高压变质岩中石榴子石组成相似的碎屑石榴子石在地层中的含量减少。根据现今南天山水系的分析,西南天山高压变质岩在最高隆起带以北,已经不能向库车坳陷提供物源。这些研究结果说明,古近纪和新近纪以来,南天山逆冲带与西南天山含高压变质岩体的古生代俯冲杂岩之间存在差异隆升,南天山的快速隆升遮挡了西南天山高压变质岩对库车坳陷的物质贡献。     

碎屑重矿物分析对库车坳陷白垩—第三纪物源变化的指示

碎屑沉积是山脉隆升和盆地沉积的直接记录，包括碎屑重矿物研究在内的碎屑沉积物的分析是开展盆山耦合研究的必要手段。对库车坳陷白垩系—第三系砂岩中重矿物含量特征进行了系统的研究，并应用电子探针技术分析碎屑石榴石和钛铁矿的化学组成，研究表明库车坳陷白垩—第三系源区主要由沉积岩、变质岩和酸性火山岩组成。白垩系砂岩中的石榴石来自西南天山蓝片岩和低级变质岩的比例较大，而第三系砂岩中的石榴石中富铁铝榴石组分，多来自高级变质岩。白垩系砂岩中的钛铁矿多来自变质岩，上第三系砂岩中来自火成岩的钛铁矿比例增加。由此可以认为南天山的大规模隆升和剥蚀发生在第三纪以来，由于它的隆升遮挡了南天山北缘古生代增生杂岩体对库车坳陷的物质贡献，并且随着剥蚀的加深，高级变质岩和火成岩的出露越来越多。     

沉积物颜色和粘土矿物对库车坳陷第三纪气候变化的指示

库车坳陷第三纪连续的碎屑沉积,记录了丰富的古环境与古气候变化的信息。在详细的磁性地层年代学基础上,对库车坳陷北部第三系沉积剖面进行了系统的沉积物颜色测定和粘土矿物分析。结果表明,库车坳陷第三纪沉积物颜色变化与全球第三纪温度的变化有一致的趋势,随着全球气温的降低,沉积物的颜色的红色指数降低。粘土矿物的组合和含量变化在13 M a出现了一个转折,在此之前,库车坳陷泥岩样品中的粘土矿物组合为伊利石和绿泥石,指示干旱的气候环境。在13 M a之后,库车坳陷的粘土矿物组合变为蒙脱石、高岭石、绿泥石和伊利石,指示干冷与温湿交替的气候环境,与亚洲内陆季风气候加强相对应。由此,可以认为库车坳陷第三纪13M a的气候变化与青藏高原的隆升密切相关。     

库车坳陷同沉积演化的古地磁研究

运用古地磁学方法研究了库车坳陷第三系同沉积褶皱,同褶皱检验发现上新统和渐新统原生剩磁主要是同沉积剩磁,说明该区上新世和渐新世表现出较强的构造活动性;因而,对推断控制库车坳陷油气分布的构造格架和相关的构造形迹有十分重要的地质意义。     

库车坳陷脆性构造序列及其对构造古应力的指示

在对野外脆性构造(主要是节理和断层) 大量观测的基础上, 根据它们与应力的关系, 讨论了库车坳陷白垩纪末期以来的古构造应力时空变化.结果表明, 在库车坳陷脆性构造中, 早期隆升作用形成的主要发育在中生界的NEE-SWW向系统节理被晚期同构造期的在中生界与上第三系均发育的NNW-SSE向和NW-SE向节理切割并改造, 这是对区域上构造应力场在进入新近纪时从弱伸展变化到强烈挤压这一过程的响应.基于断层滑动分析的古应力反演结果显示, 此时盆山边界处以近N-S向伸展应力状态占主导, 而坳陷内部则表现为近N-S向和NW-SE向挤压应力状态.说明在进入新近纪后, 最大主应力(σ₁) 方向从垂向变成水平, 应力场发生了转变.此后的天山快速垂向隆升是库车坳陷北缘和内部应力状态存在差异的原因.      

新疆库车坳陷中部新近系－第四系沉积演化

新疆库车坳陷发育巨厚的新近系-第四系沉积物。本文通过考察野外露头、观察岩心和岩屑、分析测井曲线和地震资料,研究了该沉积层序及其演化规律。库车坳陷新近系吉迪克组及康村组沉积时期为浅水氧化湖泊环境,自北向南发育扇三角洲-湖泊沉积体系,为均衡沉积;新近系库车组-第四系广泛发育冲积扇沉积,自下而上冲积扇的规模不断增大,代表了盆地填平补齐的过程。库车坳陷新近纪剧烈构造活动期应从库车组末期开始,第四纪早期构造活动达到最剧烈时期。     

白垩纪以来库车坳陷碎屑重矿物组成变化

碎屑沉积是山脉隆升和盆地沉积的直接记录,包括碎屑重矿物研究在内的碎屑沉积物的分析是开展盆山耦合研究的必要手段。本文对库车坳陷白垩系—新近系砂岩中重矿物含量特征进行了系统的研究,并应用电子探针技术分析碎屑石榴石和电气石的化学组成。研究表明:库车坳陷白垩-新近系源区主要由高级变质岩和沉积岩以及中-酸性火成岩组成。白垩纪和古近纪砂岩中的石榴石富钙镁铝榴石组份,与来自西南天山低温高压变质岩中石榴石组成相似,而新近系砂岩中的石榴石中富铁铝榴石组份,多来自高级变质沉积岩,而非高压变质岩。这些分析表明南天山的大规模隆升和剥蚀发生在渐新世以来,由于它的隆升遮挡了西南天山对库车坳陷的物质贡献。     

新疆库车坳陷晚白垩世沉积的地球化学特征及意义

库车坳陷广泛发育的晚白垩世巴什基奇克组是新疆塔里木盆地北部地区克拉苏大型气田的主要储层,其沉积环境一直存在争议。本文依据塔里木盆地北部地区库车坳陷巴什基奇克组地球化学资料,对塔北地区晚白垩世时期发育海侵沉积进行了分析。结合野外露头剖面和钻井剖面巴什基奇克组上段新发现的大量海相钙质超微化石和沉积相特点,认为塔北地区晚白垩世时期曾发生明显的海侵作用,海水分布范围向东可达库车河地区,但沉积环境比较闭塞,古盐度指数反映水介质为咸水,古气候以干旱高温为特点。这一研究为塔西南地区和塔北地区晚白垩世地层对比奠定了基础,对本区的油气勘探和远景分析具有重要意义。     

准噶尔盆地玛湖坳陷侏罗系储层

通过对玛湖坳陷侏罗系储层特征的研究,表明该区储层主要为辫状河三角洲、河流相砂体。孔隙以溶蚀孔隙、原生粒间孔隙和残余粒间孔隙为主。储集物性变化大,属中-低孔、中-低渗储层。储集性主要受成岩压实和塑性岩屑影响。最后,结合该地区评价标准,将层序D和B划分为较好储层,层序C和A为较差储层。     

塔里木盆地库车坳陷东部早-中侏罗统沉积物源分析

根据岩心观察、重矿物特征、单井岩性剖面及相关指数的综合研究,认为早-中侏罗世期间,库车坳陷东部主要接受南天山物源区提供的碎屑物,而塔北隆起提供的碎屑物则比较有限。根据下-中侏罗统碎屑岩中重矿物和碎屑组分的差异,进一步将各期物源区在东西方向上划分成4个物源补给亚区。此外,从下侏罗统阿合组、阳霞组到中侏罗统克孜勒努尔组,南天山物源区逐渐向南天山造山带的腹部扩展,反映夷平作用进一步加强,构造活动性相对比较稳定。     

川西坳陷侏罗系沉积岩相与生烃关系研究

笔者从生烃角度分析和研究了川西坳陷侏罗系沉积岩相,川西坳陷早侏罗世—中侏罗世早期最好的生烃沉积环境是长年湖,其次为时令湖。在对烃源岩的系统采样分析与研究的基础上,对有机碳、有机质类型、有机质演化程度、生气率、生聚系数和体积参数进行了深入的研究,并取得了可靠的参数。采用天然气有机碳发生率法与有机显微组分发生率法,计算了川西坳陷侏罗系生烃量为(292483.3~333425.0)×10⁸m³,生烃聚集的资源量为(3509.8~4001.1)×10⁸m³,这对侏罗系远源成藏聚集效率有不可忽视的重要作用。目前川西坳陷所获储量仅占远景资源量的10%,川西坳陷侏罗系勘探高峰远未来到,仍有大量的油气资源量待发现,储量仍将有一个高速增长期。笔者通过综合研究认为侏罗系为勘探前景与经济效益较好的区域。     

新疆哈密拗陷北部早侏罗世地层及其孢粉组合

哈密拗陷北部下侏罗统按其岩性、化石组合和地震波组等特征自下而上分为八道湾组和三工河组.根据两组所产的孢粉化石,建立了两个孢粉组合Osmundacidites Apiculatisporis Cycadopites组合和Cyathidites Pinuspollenites Cycadopites组合.根据孢粉组合特征及其对比,探讨了八道湾组和三工河组的地质时代.     

Climatic and sea‐level control of Jurassic (Pliensbachian) clay mineral sedimentation in the Cardigan Bay Basin,Llanbedr (Mochras Farm) borehole,Wales

Early Jurassic climate is characterized by alternating cold and warm periods highlighted by studies based notably on oxygen isotopes measured on belemnite guards and other marine invertebrate shells. These climatic changes include changes in the hydrological cycle, and consequently weathering and runoff conditions. In order to clarify the erosion and weathering conditions during the Pliensbachian, this study determined the mineralogical composition of the clay fraction of 132 samples taken from the entire stage drilled in the Llanbedr (Mochras Farm) borehole (Cardigan Bay Basin). The clay mineral assemblages are composed of various proportions of chlorite, illite, illite/smectite mixed‐layers (R1 I–S), smectite and kaolinite, with possibly occasional traces of berthierine. The occurrence of abundant smectite indicates that the maximum burial temperature never exceeded 70°C. Consequently, clay minerals are considered mainly detrital, and their fluctuations likely reflect environmental changes. The variations in the proportions of smectite and kaolinite are opposite to each other. Kaolinite is particularly abundant at the base of the jamesoni Zone, in part coinciding with the δ¹³C negative excursion corresponding to the Sinemurian/Pliensbachian Boundary Event, and through the davoei Zone, whilst smectite is abundant in the upper part of jamesoni and base of ibex zones and through the subnodosus/gibbosus subzones of the margaritatus Zone. The kaolinite‐rich intervals reflect an intensification of hydrolysis and an acceleration of the hydrological cycle, while the smectite‐rich intervals indicate a more arid climate. The spinatum Zone is characterized by a distinct clay assemblage with abundant primary minerals, R1 I–S, kaolinite reworked from previously deposited sediments or from Palaeozoic rocks, and probably berthierine originating from contemporaneous ironstone‐generating environments of shallower waters. This mineralogical change by the end of the Pliensbachian likely reflects a transition from a dominant chemical weathering to a deeper physical erosion of the continent, probably related to a significant sea‐level fall consistent with a glacio‐eustatic origin.     

Characteristics of clay minerals in sediments of Hemudu area,Zhejiang, China in Holocene and their environmental significance

The Ningshao Plain experienced sea-level fluctuation and climate change in the Holocene and gave birth to a Neolithic Civilization, the Hemudu Culture (about 5000 BC). Using XRD method, this paper studied the clay mineralogy of sediments in core HMD-1301 from Hemudu Site area in Ningshao Plain. Results show that the clay mineral assemblages in all samples are quite consistent. They are dominated by illite (about 57%) and smectite (about 26%), and a small amount of kaolinite (about 6%) and chlorite (about 9%). In addition, illite, chlorite, and kaolinite are originated mainly from eolian loesses. Smectite is resulted mainly from chemical weathering of local volcanic rocks outcropped. Illite crystallinity indicates the climatic characteristics of the source region, and illite chemistry index reflects the climate nature of the sedimentary area. It is our understanding that water medium properties in a sedimentary environment affect clay mineral assemblage and the distribution, based on which were cognized the Holocene transgression-regression events in the Hemudu Site area. These mineral indices are well comparable with geochemical indicators in identifying the transgression-regression events. We believe that these events affected the ancient civilization of the ancient residential communities at the time.©2019 China Geology Editorial Office.     

Palaeoclimate indicators (clay minerals,calcareous nannofossils,stable isotopes) compared from two successions in the late Jurassic of the Volga Basin (SE Russia)

A study of clay mineral and calcareous nannofossil abundances in late Jurassic–early Cretaceous sediments from the Volga Basin, SE Russia, is presented. From these results, we are able to compare some general patterns of mineralogical and palaeontological change for the Volga Basin to the palaeoclimate models developed for northern Europe and beyond. The two successions examined comprise calcareous mudstones with black organic‐rich shale horizons, overlain by a series of phosphatic silty sands. Clay mineralogical results show a progressive decrease in kaolinite and the concomitant increase of smectite and illite through the middle Volgian, followed by an abrupt increase in kaolinite in the late Volgian. The clay mineral evidence suggests increasing aridity at the end of the Jurassic, similar, in part, to many western European successions. Because of differential settling of clay minerals, superimposed upon this possible climatic signature is likely to be the effect of relative sea‐level change. Calcareous nannofossil analysis from a single section reveals a shift through the middle Volgian from low nutrient, warm water assemblages dominated by Watznaueria to cooler surface water and high nutrient assemblages dominated by Biscutum constans. These observations suggest that increased aridity is also associated with climatic cooling. Black shales are associated with increased productivity, higher sea levels and increases in smectite content. Hence, periods of low (chemical) hinterland weathering during semi‐arid conditions are paradoxically associated with relatively nutrient‐rich waters, and organic‐rich shales. Comparison of published carbon and oxygen stable isotope results from this and other sections to the clay mineral and nannofossil data confirms the palaeoclimatic interpretation. This study significantly improves the published biostratigraphically constrained clay mineral database for this time period, because other European and North American successions are either non‐marine (and thus poorly dated), absent (through penecontemporaneous erosion) or condensed. Copyright © 2002 John Wiley & Sons, Ltd.     

鄂尔多斯盆地白垩系粘土矿物的分布特征及其沉积-成岩环境意义

系统地分析了鄂尔多斯盆地白垩系粘土矿物的特征及其沉积、成岩环境意义。研究结果表明:白垩系砂岩、泥质岩的粘土矿物组合以I+C+I/S型、I+C型为主,具有高伊利石含量,较高绿泥石、伊/蒙混层矿物含量的粘土矿物组成特点;其中泥质岩粘土矿物主要为陆源碎屑成因,次为沉积成岩过程中形成的自生粘土矿物,而砂岩粘土矿物兼有陆源碎屑成因和沉积成岩过程自生成因的特征;白垩系沉积时气候总体特征为干旱—半干旱,但局部时段发生干—湿气候波动而处于短暂的湿热气候环境;白垩系沉积物源富含长石等硅酸盐矿物,沉积物质主要自北、南、西向盆地内部搬运沉积;白垩系沉积和埋藏成岩过程中水介质整体上具有盐度较高,偏碱性,富K+、Fe2+、Mg2+的特点,且总体上盆地南部水介质中的这些指标都高于北部。     

鄂尔多斯盆地白垩系粘土矿物的分布特征及其沉积-成岩环境意义

系统地分析了鄂尔多斯盆地白垩系粘土矿物的特征及其沉积、成岩环境意义。研究结果表明：白垩系砂岩、泥质岩的粘土矿物组合以I+C+I/S型、I+C型为主,具有高伊利石含量,较高绿泥石、伊/蒙混层矿物含量的粘土矿物组成特点;其中泥质岩粘土矿物主要为陆源碎屑成因,次为沉积成岩过程中形成的自生粘土矿物,而砂岩粘土矿物兼有陆源碎屑成因和沉积成岩过程自生成因的特征;白垩系沉积时气候总体特征为干旱—半干旱,但局部时段发生干—湿气候波动而处于短暂的湿热气候环境;白垩系沉积物源富含长石等硅酸盐矿物,沉积物质主要自北、南、西向盆地内部搬运沉积;白垩系沉积和埋藏成岩过程中水介质整体上具有盐度较高,偏碱性,富K+、Fe2+、Mg2+的特点,且总体上盆地南部水介质中的这些指标都高于北部。