长江口及其邻近陆架区沉积物的早期成岩作用

研究区位于长江口,水动力作用活跃。因直接受长江排泄的悬浮体堆积与影响,沉积速率较高,有机质丰富,是研究陆源碎屑沉积物早期成岩作用的较理想地区。通过水下浅层及近岸钻探取样,以及对样品的pH与Eh值、有机碳、生物细菌、孔隙水化学组分,自生矿物标型特征和稳定同位素值等的分析,本文拟从沉积物的水化学特征、化学作用与反应产物,以及早期成岩作用的标志作一初步探讨。     

紫阳黄柏树湾和竹山文峪河毒重石矿床锶同位素及碳氧同位素研究

紫阳黄柏树湾毒重石矿床和竹山文峪河毒重石-重晶石矿床呈层状或似层状产于下寒武统下部或其相当层位的硅质岩中,矿体受岩性和岩相控制作用明显.对矿床中毒重石、钡解石和方解石的锶同位素及碳氧同位素的研究结果表明,形成这些矿物的碳主要来自沉积物中的生物有机质在早期成岩阶段经降解、缩合及脱羧基作用所形成的烃类物质或生物气;而锶主要为沉积物孔隙水中海水锶与沉积物中火山碎屑物质蚀变过程中所释放的锶的混合.毒重石形成于早期成岩阶段沉积物的孔隙水介质中,形成毒重石的成矿流体主要为早期成岩阶段沉积物中由海水、有机质组分和火山物质组分相互叠加和混合而组成的孔隙水有机成矿流体.毒重石矿石中广泛发育的生物碎屑及粒屑结构说明生物作用通过生物成因重晶石 (bio- barite)的形式将海水中的 Ba2 浓集并沉降于海底,形成钡矿床的初始富集体.因而,海水中生物作用和沉积物的早期成岩作用是形成本区毒重石矿床的主要机制.     

长江水下三角洲沉积物磁性特征空间差异及其冲淤指示意义

三角洲冲淤具有空间异质性,而沉积物的磁性特征可灵敏地反映物源、沉积动力特征以及早期成岩作用影响,是揭示空间异质性的有效方法。选取长江水下三角洲20~35 m水深的四个约2 m长的柱样进行磁学和碳、硫地球化学分析,结合粒度及年代资料,探讨了长江水下三角洲沉积物柱样磁性特征空间差异及其冲淤指示意义。研究结果显示,粒度表征的动力分选影响沉积物的磁性特征,这在年代较新（<350 a）的柱样中表现尤为明显,即细颗粒沉积物中富集亚铁磁性矿物,从而具有较高的磁化率。铁、碳、硫及硫同位素特征揭示了长江水下三角洲沉积物较弱的硫酸盐还原特征。沉积物年龄及沉积速率影响沉积物成岩改造强度,进而导致了磁性特征垂向变化的空间差异,整体上看,远离现代沉积中心的柱样,成岩改造特征更为明显。磁化率值的大小、成岩分带的完整性及其反映的铁还原带和硫酸盐还原带转换深度,一定程度上可以揭示三角洲的淤积和侵蚀特征。     

内蒙古西部额济纳旗及邻区石炭系—二叠系的储集条件——石炭系—二叠系油气地质条件研究之二

通过对研究区石炭系—二叠系碎屑岩沉积相纵向演化与平面展布特征、岩石学特征、成岩作用、孔隙类型的研究,认为研究区石炭系—二叠系碎屑岩砂砾岩的发育程度、成分成熟度、结构成熟度等均受阿拉善古陆和马鬃山-拐子湖中间隆起带2个沉积物源的控制。南部以阿拉善古陆为主要沉积物源,砂砾岩发育,成分成熟度和结构成熟度均较高。由南向北阿拉善古陆作为物源的影响逐渐降低,砂砾岩发育程度逐渐变差,成分成熟度和结构成熟度亦逐渐变差。以粘土矿物及其相对含量、自生矿物特征等为主要依据,对成岩作用阶段进行划分,多数剖面以中成岩A期为主,研究区北部、北山地区和受阿尔金走滑断裂影响的雅干一带,受构造动力变质作用或岩浆热接触变质作用的影响进入中成岩B期。碎屑岩储集层孔隙演化受成岩作用的控制,多数以溶蚀孔（缝）为主,少数具有残余粒间孔,总体来看孔隙发育较差。除碎屑岩储集层外,各类碳酸盐岩、火山岩,以及华力西期风化壳的各类岩石均可能成为重要的储集层类型。     

内蒙古西部额济纳旗及邻区石炭系-二叠系的储集条件——石炭系-二叠系油气地质条件研究之二

通过对研究区石炭系-二叠系碎屑岩沉积相纵向演化与平面展布特征、岩石学特征、成岩作用、孔隙类型的研究,认为研究区石炭系-二叠系碎屑岩砂砾岩的发育程度、成分成熟度、结构成熟度等均受阿拉善古陆和马鬃山-拐子湖中间隆起带2个沉积物源的控制.南部以阿拉善古陆为主要沉积物源,砂砾岩发育,成分成熟度和结构成熟度均较高.由南向北阿拉善古陆作为物源的影响逐渐降低,砂砾岩发育程度逐渐变差,成分成熟度和结构成熟度亦逐渐变差.以粘土矿物及其相对含量、自生矿物特征等为主要依据,对成岩作用阶段进行划分,多数剖面以中成岩A期为主,研究区北部、北山地区和受阿尔金走滑断裂影响的雅干一带,受构造动力变质作用或岩浆热接触变质作用的影响进入中成岩B期.碎屑岩储集层孔隙演化受成岩作用的控制,多数以溶蚀孔(缝)为主,少数具有残余粒间孔,总体来看孔隙发育较差.除碎屑岩储集层外,各类碳酸盐岩、火山岩,以及华力西期风化壳的各类岩石均可能成为重要的储集层类型.     

云贵湖泊现代沉积物早期成岩过程中微量重金属地球化学行为研究

云贵湖泊现代沉积物早期成岩过程中微量重金属地球化学行为研究＠马英军￥中国科学院地球化学研究所湖泊沉积物,孔隙水,微量重金属,早期成岩作用,地球化学相云贵湖泊现代沉积物早期成岩过程中微量重金属地球化学行为研究马英军（中国科学院地球化学研究所,贵阳５５０００２...     

致密砂岩储层成岩作用特征研究及其对储集性能的影响——以鄂尔多斯盆地东部上古生界盒8段天然气储层为例

通过各类薄片显微镜下精细研究与定量统计,利用图像孔喉分析、电镜扫描、阴极发光等多种分析测试手段,对鄂尔多斯盆地东部主力含气层盒8段致密砂岩的岩石学特征、孔隙发育特征及成岩作用特征进行研究,结合成岩演化分析其对盒8段各砂岩储层储集性能的影响。研究表明:盒8段砂岩以岩屑石英砂岩和岩屑砂岩为主,其次是石英砂岩,填隙物以高岭石、硅质和伊利石为主,孔隙类型以次生溶孔为主。储层各砂岩的岩石学特征、孔隙发育状况及其成岩演化过程存在一定的差异。差异性的成岩演化过程导致盒8段各砂岩胶结物成分及其含量不同,并导致各砂岩孔隙结构的不同,后者直接影响砂岩的储集性能。该研究对于探讨不同砂岩类型成岩演化对砂岩储层储集性能的影响具有重要的意义,可为研究区天然气的勘探指明方向。     

致密砂岩储层孔隙结构成因机理分析及定量评价——以鄂尔多斯盆地姬塬地区长8油层组为例

利用普通薄片、铸体薄片、物性分析和压汞曲线等资料,对姬塬地区长8油层组储层的微观孔隙结构特征及其成因机理等进行了研究.结果表明沉积物在地质历史时期经历的压实、胶结、溶蚀和破裂等一系列成岩作用对储集岩孔喉特征影响显著,成岩作用的不均一性导致了储层宏观物性和微观孔隙结构的差异.通过视压实率、视胶结率、视溶蚀率和视微孔隙率等参数的计算阐明了压实、胶结、溶蚀等对排驱压力和分选系数等孔隙结构特征参数的定量控制.选取成岩综合系数作为成岩作用强度及其组合的定量表征参数,其与排驱压力、分选系数、储集层品质指数和分形维数等均具良好的统计相关关系,不同的孔隙结构类型具有不同的成岩作用组合特征以及成岩综合系数值,因此成岩综合系数可作为不同孔隙结构类型的定量表征参数.在对影响孔隙结构特征的成岩作用类型和强度组合深入剖析的基础上,通过成岩综合系数可实现储集岩孔隙结构的定性划分和定量评价.     

鄂尔多斯盆地巴汗淖地区马五_6段碳酸盐岩C、O同位素特征及其成岩意义

鄂尔多斯盆地北部巴汗淖地区马五6段为风化壳型碳酸盐岩地层,岩性以鲕粒灰岩、晶粒白云岩为主,次生孔隙发育,是重要的油气储集层。采用Finnigan MAT252气体同位素质谱仪分别对该段碳酸盐岩进行C、O同位素测试,详细分析了巴汗淖地区马五6段碳酸盐岩成岩环境及孔隙演化条件。样品分析结果表明:埋藏高温成岩环境使得δ18O值与奥陶纪海水的δ18O值相比明显偏负,且白云岩δ18O值与灰岩δ18O值相比偏负,主要是埋藏白云石化作用的结果;δ13C值与奥陶纪海水δ13C值相当,极个别数值偏负,说明研究区马五6段在成岩作用过程中受有机碳影响较小,表明成岩作用发生在浅-中埋藏条件下。研究区孔隙度、渗透率的相关关系明显,主要是大气淡水成岩作用的改造,优化了孔隙及渗流通道,提高了储层的物性。     

鄂尔多斯盆地中部姚店油田上三叠统长4＋5储层砂岩的成岩作用

根据砂岩薄片、铸体薄片、扫描电镜、X－衍射等分析,对姚店油田三叠系延长组长4+5油层砂体的岩石学特征、成岩作用阶段划分、成岩作用类型及其对孔隙的影响进行了研究。研究结果表明,该区长4+5储层储集砂体成分主要以长石砂岩为主。成岩作用类型包括压实作用、胶结作用和溶蚀作用。砂岩经历了早期成岩阶段A、B期和晚期成岩阶段A期（A1、A2 期）的成岩演化过程。早期的压实作用、多种矿物胶结作用是使物性变差的2个重要因素,但早成岩阶段形成的绿泥石膜保护了一些砂岩的原生孔隙;晚成岩阶段A期的溶蚀作用,特别是长石的溶蚀是储层物性变好的重要成岩控制因素     

柴达木盆地鄂博梁Ⅲ号中新统成岩作用及沉积环境

综合运用岩石学、矿物学和元素地球化学等方法,对柴达木盆地北缘构造带鄂博梁Ⅲ号构造中新统上干柴沟组碎屑岩的成岩作用、形成环境和物质来源等进行了系统研究。发现上干柴沟组碎屑岩中碎屑颗粒间主要以点-线接触关系为主,长粒矿物被定向排列,经历过较强的压实作用。其中黏土矿物含量较高,平均达到了35.03%,主要以伊利石,绿泥石及伊-蒙混层为主。碳酸盐胶结物类型主要以方解石为主,仅含有少量白云石。碳酸盐胶结物的碳氧同位素含量测定表明,碳同位素(δ13C)分布在-6.8‰~-4.0‰之间,平均为-5.0‰;氧同位素(δ18O)分布于-11.1‰~-5.4‰,平均为-8.7‰;根据碳氧同位素含量推算古盐度Z值分布于108.34~114.89,平均值为112.77;碳酸盐沉淀温度分布在43.36℃~77.84℃,平均值为62.30℃。结合对主量元素、微量元素及有机碳含量等地球化学元素的综合分析,认为鄂博梁Ⅲ号构造带中新统上干柴沟组目前所处的成岩阶段主要为早成岩阶段B期至中成岩阶段A期,在形成早期主要以干、冷的淡水-微咸水环境为主,晚期则以要对暖、湿的淡水环境为主。     

鄂尔多斯盆地南部奥陶系碳酸盐储层的胶结作用

鄂尔多斯盆地南部奥陶系马家沟组主要由原始沉积的碳酸盐岩和岩溶角砾岩组成。储集空间以次生孔隙为主。中奥陶世沉积作用之后不久,即发生了溶解作用、白云石沉淀、干化脱水作用、机械压实作用、岩溶作用和胶结作用。胶结作用很普遍,主要发生在中石炭世之后的埋藏条件下,是对储层重要的破坏作用。充填于硬石膏结核溶模孔和非组构选择性溶蚀孔、洞、缝的方解石和白云石是最常见的胶结物。这些方解石和白云石胶结物具泥晶、嵌晶状或粒状晶粒结构。泥晶白云石基质的δ18O值-10.98‰~-0.8‰,平均-5.54‰;δ13C值-4.76‰~5.77‰,平均1.51‰。充填于溶蚀孔、缝中的白云石的δ18O值-12.54‰~-2.67‰,平均-7.34‰;δ13C值-5.56
‰~3.48‰,平均0.28‰。充填于溶蚀孔、缝方解石的δ18O值-15.42‰~-6.02‰,平均-9.51‰;δ13C值-12.44‰~1.33‰,平均-3.20‰。总的来说,白云石和方解石胶结物的δ18O和δ13C值低于泥晶白云石基质的,原因是形成晚,受淡水淋滤、埋藏作用和有机质影响较大。泥晶白云石基质的Na含量0~350 μg/g,平均59 μg/g; Sr含量0~380 μg/g,平均10 μg/g;Fe含量0~14 570 μg/g,平均1 040 μg/g;Mn含量0~4 670 μg/g,平均183 μg/g。充填于次生孔隙中的胶结物的Na、Sr、Mn含量与泥晶白云石基质的差别不大,因这些元素含量均低。充填于次生孔隙的碳酸盐胶结物较泥晶白云石基质有明显高的Fe含量。胶结物包裹体的均一温度在90℃~140℃范围内。胶结物沉淀于埋藏较深,温度较高的还原条件下。流体包裹体的气相成分以CH4最为普遍,液相成分以H2O占绝大多数。早期胶结物形成于天然气形成前,晚期胶结物形成于天然气形成之后。岩溶洼地是胶结作用最发育的地带。     

A Reconstruction and Discussion of the Effect of Diagenetic Environment on Hydrocarbon Generation Based on Diagenetic Mineral Assemblage in Mudstone

Inorganic minerals in mudstone are composed of clay minerals,carbonate and detrital minerals.Detrital minerals(such as quartz and feldspar)are mainly original deposit.However,clay minerals(kaolinite,illite,and chlorite)and carbonate(calcite and dolomite)are mostly diagenetic minerals.Furthermore,conversion of the four kinds of clay minerals are common.The formation of clay minerals and carbonate is controlled by temperature,pressure,p H,Eh and type of cations during diagenesis.Therefore mineral assemblage can indicate the characteristics and change of diagenetic environment.In addition to inorganic minerals,there are also organic matter of different sources and chemical properties in mudstone.Traditionally,it is considered that evolution of organic matter is controlled by thermal effect.Now studies show that inorganic and organic matter can interact with each other and form clay-organic complexes.This suggest that attention should be paid to the influence of diagenetic mineral assemblage and diagenetic environment on the evolution of organic matter* Samples of mudstone from 1500-4500m of the Palaeogene in the Dongying Depression,China,were collected to investigate the changes of mudstone diagenetic environment.XRD,thin section and SEM were used to detect diagenetic minerals and assemblage characteristics.Results showed that content of detrital minerals,which are floating in mud matrix or preserved as silt laminae,is basically unchanged from shallow to deep strata.Clay minerals which are gathered as argillaceous matrix or preserved as argillaceous laminae have growth and decline relation to carbonate which mainly appear as micropoikilitic ferriferous calcite and ferriferous dolomite.All these characteristics indicate that detrital minerals are exogenetic,whereas carbonate is diagenetic minerals.Based on the SEM analysis of the clay minerals,it was found that smectite present honeycomb and reticulate structure,while illite present filiform and schistose structure and there are growth and decline relationship between them.Nevertheless,hexagonal tabular and stratified kaolinite has the highest content from 2400m to3300m.Rosette and stratified chlorite shows increase trend when the burial depth is deeper than 3300m.These characteristics indicated that clay minerals are diagenetic minerals and there are conversions among the four types.Therefore form shallow to deep,three diagenetic mineral assemblage zones can be divided based on the characteristics of carbonate and clay minerals in mudstone.Namely,smectite+illite/smectite zone in the depth of 2000-2500m;kaolinite+illite/smectite zone in the depth of 2500-3300m and illite+chlorite+carbonate zone below 3300m.Previous studies showed that kaolinite is stable under acidic conditions,while other clay minerals and carbonate are stable under alkaline conditions.Hence according to mineral assemblages feature,it was inferred that diagenetic environment of mudstonehasundergonethechangeof alkaline-acid-alkaline.For the organic matter with different chemical properties in mudstone,the hydrocarbon generation will be different in the acidic and alkaline diagenetic environment even if the conditions of temperature and pressure are the same.Therefore,for hydrocarbon generation we should not only focus on thermal effect,but also pay more attention to the differences of diagenetic environment which have great significance for the understanding of hydrocarbon generation,hydrocarbon expulsion and reservoir formation in mudstone.     

东胜地区直罗组含铀砂岩中方解石的碳氧同位素组成及铀成矿意义

方解石是东胜地区直罗组含铀砂岩中重要的胶结物类型,同时碳酸盐化与铀成矿作用关系密切。通过方解石胶结物岩石学、矿物学、碳氧同位素分析,研究了含铀砂岩中方解石碳氧同位素组成、沉淀机制及铀成矿意义。研究表明,东胜地区砂岩类型为长石岩屑砂岩、岩屑砂岩和石英砂岩,粘土矿物主要由蒙皂石、伊利石、高岭石和绿泥石组成,方解石类型以含铁矿方解石为主,其次为铁方解石。方解石δ~(13)C_(PDB)为-15.7‰~-1.6‰,平均-9.08‰,δ~(18)O_(PDB)为-15.6‰~-10‰,平均-12.4‰,显示其形成与有机酸脱羧作用有关,碳来源为有机碳。碳氧同位素分析数据计算表明,与方解石平衡的水相氧同位素组成变化范围较宽,为-7.66%-9.71‰,推测较轻的同位素组成具有封存大气降水的特征,而较重同位素组成则反映成岩成矿过程中深部富含油气低温热流体的加入。综合分析认为,东胜地区直罗组砂岩中方解石是地表水和深部油气共同作用的结果:早期有机酸促使长石类骨架颗粒溶蚀,形成石英颗粒次生加大边,并伴随着自生高岭石沉淀;后期随着大量烃类注入砂岩中,成岩成矿环境由酸性向碱性转变,还原性增强,介质水中的CO_2与Ca~(2+)圾Fe~(2+)结合形成含铁为特征的方解石,沉淀在原生粒间孔和各类次生溶蚀孔隙中。整个过程都伴随有铀元素运移和沉淀,暗示东胜铀矿床是地表水和深部油气混合作用形成的。     

Geochemistry of Diagenesis of Organogenic Sediments: An Example of Small Lakes in Southern West Siberia and Western Baikal Area

Organogenic sediments (sapropels) in lakes are characterized by a reduced type of diagenesis, during which organic compounds are decomposed, the chemical composition of the pore waters is modified, and authigenic minerals (first of all, pyrite) are formed. Pyrolysis data indicate that organic matter undergoes radical transformatons already in the uppermost sapropel layers, and the composition of this organic matter is principally different from the composition of the organic matter of the its producers. The sapropels contain kerogen, whose macromolecular structure starts to develop during the very early stages of diagenesis, in the horizon of unconsolidated sediment (0–5 cm). The main role in the diagenetic transformations of organic matter in sediments is played by various physiological groups of microorganisms, first of all, heterotrophic, which amonifying, and sulfate-reducing bacteria. SO₄^2? and Fe²⁺ concentrations in the pore waters of the sediments are determined to decrease (because of bacterial sulfate reduction), while concentrations of reduced Fe and S species (pyrite) in the solid phase of the sediment, conversely, increase. Comparative analysis shows that, unlike sapropels in lakes in the Baikal area, sapropels in southern West Siberia are affected by more active sulfate reduction, which can depend on both the composition of the organic matter and the SO₄^2? concentration in the pore waters.     

铝硅酸盐矿物成岩演化对形成过渡带气的影响

生油成气的过程不只是简单的有机物之间的转化，而是无机和有机两个系统综合运动的产物，它们之间相互联系相互制约。成岩作用伊始，两系统独立演化，均受成岩环境的制约。一旦环境适合于有机物裂化分解，两系统就共同发挥作用，通过质子的转移而相互作用。由于生物热催化过渡带气埋藏浅、热演化程度不高等特点，铝硅酸盐矿物成岩作用主要表现为:砂质岩以机械压实作用、胶结作用、溶解作用、矿化交代、自生矿物充填作用为主，泥质岩最显著的变化就是矿物的成岩演化，即蒙脱石→伊／蒙混层→伊利石，及蒙脱石→绿／蒙→绿泥石的成岩演化，其实质是有机与无机相互作用，即赋存在粘土中有机质的有机酸使砂质岩发生溶解，和碎屑岩溶解孔隙水中的Ａｌ３＋替代蒙脱石晶层间的Ｓｉ４＋，形成质子酸，对有机质形成过渡带气起着催化作用。     

Very early diagenesis in a calcareous,organic-rich mudrock from Jordan

The diagenesis in the organic-rich Cretaceous to Eocene Al Hisa Phosphorite Formation (AHP), Muwaqqar Chalk Marl Formation (MCM) and Umm Rijam Chert-Limestone Formation (URC) formations of Jordan can be linked directly to the fluctuating sedimentary environment of this shelf depositional system in the Middle to Late Eocene, and its influence on the composition of the deposited sediment and the early burial diagenetic environment. Most cementation was early, mostly within the first 10 m of burial, perhaps entirely within the first 100 m of burial. We propose that the siliceous cements are derived from biogenic silica, probably of diatoms, deposited in a shelf of enhanced productivity. Volumetrically, the most important processes were the redistribution of biogenic opal-A (diatoms) and calcite to form pervasive, layered and nodular cements. The formation of the silica and carbonate cements is closely linked through the effects their dissolution and precipitation have on pore fluid chemistry and pH. The chert beds have a biogenic silica origin, formed through replacement of diatoms and radiolaria by opal-CT, and subsequently by quartz. Calcite cement has carbonate derived from microbial diagenesis of organic matter and calcium derived from seawater. The Mg for early dolomite may have been generated by replacement of opal-CT by quartz, ore dissolution of unstable high Mg calcite bioclasts. The silica and carbonate diagenetic processes are both linked to microbial diagenesis of organic matter, and are intimately linked in both time and space, with pH possibly influencing whether a silica or a carbonate mineral precipitates. The paucity of metal cations capable of precipitating as sulphides is crucial to the creation of acidic pore water favourable to silica precipitation, either as opal-CT, chalcedony or quartz. The lack of clay minerals as a sink for the Mg required for opal-CT polymerisation is the principal factor responsible for the remarkably early silica cementation. All the diagenetic processes, with the probable exception of the opal-CT to quartz transition are early, almost certainly within the first 10 m of burial, possibly much less. A paragenetic sequence is presented here based on these two cores that should be tested against a wider core distribution to see whether this diagenetic history can be generalised throughout the basin. Warm bottom water temperatures probably led to silica diagenesis at much shallower burial depths than occurs in many other sedimentary basins. Silicified layers, in turn, commonly host fractures, suggesting that mechanical properties of the strata began to differentiate at a very early stage in the burial cycle. This has wide implications for processes linking diagenesis to deformation.     

Selective blackening of bioclasts via mixing‐zone aragonite neomorphism in Late Triassic limestone,Zlatibor Mountains,Serbia

A peculiar facies of the Norian–Rhaetian Dachstein‐type platform carbonates, which contains large amounts of blackened bioclasts and dissolutional cavities filled by cements and internal sediments, occurs in the Zlatibor Mountains, Serbia. Microfacies investigations revealed that the blackened bioclasts are predominantly Solenoporaceae, with a finely crystalline, originally aragonite skeleton of fine cellular structure. Blackening of other bioclasts also occurs subordinately. Solenoporacean‐dominated reefs, developed behind the platform margin patch‐reef tract, were the main source of sand‐sized detritus. The blackened and other non‐blackened bioclasts are incorporated in automicrite cement. Radiaxial fibrous calcite cements in the dissolutional cavities are also black, dark grey or white. Reworked black pebbles were reported from many occurrences of peritidal deposits; in those cases, the blackening took place under pedogenic, meteoric diagenetic conditions. In contrast, in the inner platform deposits of the Ilid?a Limestone, the blackening of bioclasts occurred in a marine–meteoric mixing‐zone, as indicated by petrographic features and geochemical data of the skeleton‐replacing calcite crystals. Attributes of mixing‐zone pore waters were controlled by mixing corrosion, different solubility of carbonate minerals and microbial decomposition of organic matter. In the moderate‐energy inner platform environment, large amounts of microbial organic tissue were accumulated and subsequently decomposed, triggering selective blackening in the course of early, shallow burial diagenesis. The δ¹⁸O and δ¹³C values of the mixing‐zone precipitates and replacive calcite do not produce a linear mixing trend. Variation mainly resulted from microbial decomposition of organic matter that occurred under mixing‐zone conditions. The paragenetic sequence implies cyclic diagenetic conditions that were determined by marine, meteoric and mixing‐zone pore fluids. The diagenetic cycles were controlled by sea‐level fluctuations of moderate amplitude under a semi‐arid to semi‐humid climate.     

苏北溱潼凹陷戴南组二段成岩作用与次生孔隙预测

成岩作用研究表明,戴南组二段成岩作用类型主要有机械压实、胶结、交代、溶解、粘土矿物充填等,并进行了各成岩作用对孔隙改造规模的统计。成岩作用阶段的划分,采纳了中华人民共和国石油天然气行业标准,将戴南组二段划分为早成岩Ｂ期和晚成岩Ａ期两个阶段。次生孔隙的发育、分布与泥岩压实曲线的紧密压实、大量脱水阶段或有机质的成熟阶段、生油门限以及混层粘土的第一迅速转化带有着密切联系,从而成为次生孔隙预测的着眼点。     

泥质岩成岩作用中的黏土矿物研究

文章通过对泥质岩的黏土质矿物组分、成岩作用中黏土质矿物变化综合研究,认为泥质岩中存在大量黏土矿物,且泥质沉积物由松散到固结成岩实质上是黏土矿物组成的变化。泥质岩中主要黏土矿物包括高岭石、蒙皂石、绿泥石、伊利石以及其组成的混层型矿物伊利石/蒙皂石、绿泥石/蒙皂石,其成岩过程可划分为成岩早期的压实阶段、成岩晚期的黏土矿物转化阶段。压实阶段的泥质沉积物中黏土矿物具有物源的继承性、沉积水体古环境指示意义;受压实作用孔隙水、层间水被排出,原生絮凝团被压破,使片状质点趋于平行排列,黏土矿物与孔隙水发生反应,亦形成少量的新生作用矿物,因而黏土矿物具继承源和新生作用源特性。成岩晚期阶段发生层间水释放及层间阳离子交换,从而使得矿物晶体结构与成分发生变化,主要表现为一元黏土矿物向二元混层型转化,最后再到一元型黏土矿物的转化,最终形成转变源黏土矿物。