东海西湖凹陷平湖组层序地层划分

共识别出平湖组5个三级层序界面T63、T53(Sb1)、T43(Sb2)、T23(Sb3)、T03(Sb4)和3个体系域界面f1、T33(f2)、f3。平湖组共有6个段,可划分出3个沉积旋回。平湖六段未见底,沉积旋回性不清,平湖五段为SⅢ1,平湖四段和三段组成SⅢ2,平湖二段和一段划分为SⅢ3。本区短周期(四级层序)海平面变化曲线的包络线(相当于三级层序)和全球海平面三级周期的变化曲线基本一致,反映全球海平面变化对本区层序发育有明显的影响。     

Carbonate Sequence Stratigraphy of a Back-Arc Basin： A Case Study of the Qom Formation in the Kashan Area, Central Iran

The Qom Formation comprises Oligo-Miocene deposits from a marine succession distributed in the Central Basin of Iran. It is composed of five members designated as A-F. Little previous work exists on the sequence stratigraphy. Based on an integrated study of sequence stratigraphy with outcrop data, wells and regional seismic profiles, the Qom Formation is interpreted as a carbonate succession deposited in a mid-Tertiary back-arc basin. There are two second-order sequences (designated as SS1 and SS2) and five third-order sequences (designated as S1-S5). Five distinct systems tracts including transgressive, highstand, forced regressive, slope margin and lowstand have been recognized. The relationship between the sequences and lithologic sub-units has been collated and defined (S1 to S5 individually corresponding to A-C1, C2-C4, D-E, the lower and upper portions of F); a relative sea level change curve and the sequence stratigraphic framework have been established and described in detail. The coincidence of relative sea level change between that of the determined back-arc basin and the world indicates that the sedimentary cycles of the Qom Formation are mainly controlled by eustatic cycles. The variable combination of the systems tracts and special tectonic-depositional setting causally underpin multiple sequence stratigraphic framework styles seen in the carbonates of the back-arc basin revealing: (1) a continental margin basin that developed some form of barrier, characterized by the development of multiple cycles of carbonate-evaporites; (2) a flat carbonate ramp, which occurred on the southern shelf formed by the lack of clastic supply from nearby magmatic islands plus mixed siliciclastics and carbonates that occurred on the northern shelf due to a sufficient clastics supply from the land; and (3) a forced regressive stratigraphic stacking pattern that occured on the southern shelf and in basin lows due to the uplifting of the southern shelf. Thick and widespread aggradational framework limestone usually occurs in the initial sequences (S1 and S3) of the supersequence, which led to preferential oil reservoir deposition but a lack of source and cap rocks, whereas the retrogradational and progradational framework limestone usually occurs in the later sequences (S2 and S4-S5) of the supersequence, which results in two perfect sets of source, reservoir and cap rock assemblies, so that the limestone in sub-member C2-C4 and the F-Member can be predicted as important objects for oil exploration.     

塔里木盆地志留系高分辨率层序地层格架研究

以高分辨率层序地层学理论为指导,对塔里木盆地志留系进行高分辨率层序地层学分析,总结出各层序地层单元及其界面在露头、岩心、测井和地震资料中的判识标志,识别出研究区短期、中期和长期3个级别的基准面旋回层序。在研究区内短期旋回层序可划分为向上“变深”非对称型和向上“变浅”非对称型2种基本结构类型。通过柯坪地区露头剖面与全区钻井剖面进行对比,结合塔中地区层序地层划分,将全盆地划分出了4个长期基准面旋回层序,建立了全区高分辨率层序地层格架,为塔里木盆地志留系进一步的等时追踪对比、砂体几何形态、沉积相研究和储层结构描述等精细地质研究奠定了基础。     

塔河地区志留系的对比

塔河地区遭受过多次的构造抬升和剥蚀，志留系分布不规则，地层划分对比是本区寻找志留系油气藏的难题之一。本文综合应用古生物、测井、地震和野外露头资料进行地层划分对比，首先通过疑源类古生物的分析，确认塔河地区井下志留系的存在；继而分析其地震反射特征，通过地震一测井地层对比，将其与东河砂岩予以区分；最后通过与柯坪野外露头剖面的岩石地层对比，确认塔河地区所钻遇的志留系确为下志留统的柯坪塔格组中段。     

四川盆地东部海相下—中三叠统界线的锶同位素年龄标定

中国西南地区海相下—中三叠统以火山碎屑岩为其直观界线,该年龄的标定可为区域地层年表和国际地层委员会全球标准年表研究提供重要的下—中三叠统界线年龄参考值.基于此,本文测试了四川盆地东部华蓥山下—中三叠统界线火山碎屑岩附近的石膏和硬石膏样品87Sr/86Sr比值,以及相应的Si、Ca、Mg、Mn、Sr以及SO42-的含量,根据锶同位素地层学的原理,尝试对下—中三叠统界线进行了年龄标定;同时评估了样品的成岩蚀变性、对海水信息的代表性以及年龄标定结果的可靠性.火山碎屑岩附近5个样品的87Sr/86Sr比值变化在0.708243~0.708391之间,标定的年龄值在240.5~242.5Ma的范围内,2个紧靠火山碎屑岩样品的年龄值在242Ma左右(分别为241.9Ma和242.5Ma),从而为华南地区以火山碎屑岩作为海相下—中三叠统界线的合理性提供了重要的化学地层学依据,也为全球下—中三叠统界线提供了一个新的年龄值.     

西藏定日贡扎上白垩统锶同位素曲线及年代地层划分

根据从西藏定日贡扎上白垩统剖面中未经蚀变的海相碳酸盐样品中获得的50个锶同位素测试数据建立了对应于地层厚度的锶同位素演化曲线,与W.H.Burke等(1982)对应于地质年代建立的锶同位素曲线的同时代部分进行了对比,两条曲线极为相似,显示了地质历史中古海洋中的锶同位素组成具有全球一致的演化规律,为定日贡扎上白垩统剖面的年代地层划分提供了依据,同时还讨论了定日贡扎地区晚白垩世地层划分对比中的一些问题。     

Analyses of Sequence Stratigraphy and Environments across Permian—Triassic Boundary in Liaotian, Northwestern Jiangxi Province

Based on the study of lithology, sedimentology and paleontology at the Permian-Triassic boundary in Liaotian, Northwestern Jiangxi Province, the sequence stratigraphy and depositional environments across the boundary are reconstructed. The top part of the Upper Permian Changxing Formation is composed of very thick-bedded ligh-colored dolomitic limestone formed in high deposition rate on carbonate ramp,which indacates a transgression systems tract (TST). The Lower Triassic Qinglong Formation shows continuous deposition with the underlying Upper Permian. The lower member of Qinglong Formation consists of calcareous shale, shelly limestome and dolomitic limestone with abundant bivalves (Claraia sp.) and trace fossills (Chondrites). The calcareous shale at the bottom of Lower Triassic indicates a calm deep water environment to form the condensed section (CS). The shelly limestome and dolomitic limeston with shell fossils, intraclast, algal ooide show clean but turbulent environment of carbonate ramp, which produce the deposition of highstand systems tract (TST).     

南沙海区礼乐盆地沉积地层与构造特征分析

通过对地震剖面、钻井及拖网采样资料的分析,认为礼乐盆地发育有海相的中、新生代地层,存在晚白垩世与晚渐新世两个区域性不整合面,将沉积层分为三套构造层:下构造层较厚,为中生代地层,表现为翘倾断块和宽缓背斜两种构造样式;中构造层较薄甚至局部缺失,为古新世-早渐新世充填的张裂期沉积,表现为半地堑构造样式;上构造层为晚渐新统至第四系沉积,充填区域沉降期海相地层,地层较为平稳。在中构造层沉积过程中发育多排NE向控洼断裂,断裂倾向NW,形成多个半地堑,控制了新生代早期的沉积充填,同时也表现出礼乐盆地在新生代早期受明显的张裂作用。通过对各构造层的构造、沉积特征分析,认为礼乐盆地经历了挤压、拉张、漂移、区域沉降四个构造演化阶段,是一个以中生代地层为主的叠合盆地。     

从常规体系域到非常规体系域——河流相层序地层学研究的一个重要进展

在与海平面变化存在联系的近滨线河流相地层中,源于海岸碎屑沉积体系的层序地层学概念得到了较好的应用,从而在河流相地层中产生了低水位体系域(LST)、与海侵体系域类似的水进体系域(TST)及高水位体系域(HST)等常规体系域下的河流相层序地层划分方案。由于源于海岸沉积体系的早期体系域划分存在着概念体系的不协调,故常规体系域划分在河流相层序中的使用也就存在着概念体系的不协调。非常规体系域(低可容纳空间体系域,LAST;高可容纳空间体系域,HAST)的提出可避免这种概念体系的不协调,并为研究复杂的河流沉积过程和提取地层记录规律提供重要的线索和思路。     

陆相盐湖盆地层序地层学研究综述

陆相盐湖盆地层序地层学的研究，是层序地层学研究中的前缘课题。通常应用盐湖发育的环境变化参数、旋回年代学、古地磁反转和生物地层等方法，来研究盐湖沉积形成的条件、盐湖层序成因模式、盐湖演变与全球变化。目前在研究中存在的主要问题是陆相盐湖盆地的层序地层解释至今缺乏一个比较适用的模式或研究方法，其中的关键是如何解释盐岩沉积在层序发育中的地位和作用。