【作者】 时志强；

【导师】 彭大钧； 伊海生；

【作者基本信息】 成都理工大学 ， 矿产普查与勘探， 2004， 博士

【摘要】 高分辨率层序地层学以其全新的理论和技术方法受到石油地质学家的重视并被广泛应用于油气勘探和开发中；该理论在90年代中期引入我国，并迅速而广泛地用于陆相含油气盆地和陆相地层研究，而用于海相地层，尤其是海相碳酸盐岩地层的研究较少；对其研究也多局限在储层预测和油层的精细对比。本文首次将高分辨率层序地层的理论和方法用于羌塘盆地侏罗系地层的研究，借以探讨该理论在特提斯域碎屑岩与碳酸盐岩交互沉积的海相沉积当中的应用，并进行侏罗系地层高分辨率的等时对比。 用高分辨率层序地层学理论和技术方法将羌塘盆地侏罗系划分出3个超长期基准面旋同层序，其中中、上侏罗统可划分为2个超长期基准面旋回层序，并可进一步划分出7个长期、17个中期基准面旋回层序。结合野外实测剖面数据系统研究羌塘盆地剖面资料后，认为长期基准面旋回界面为：①盆地边缘地区（如那底冈日、双湖剖面）砂砾岩层底部，通常表现为各类滨岸上超和河道／潮道下切的冲刷间断面，与下伏地层呈突变式接触关系；②盆地大部分地区与基准面下降至最大位置时的潮上、蒸发泻湖相膏盐层的底部，反映着渐变的岩性、岩相界面；③潮上沉积的紫红色泥岩、膏溶角砾岩层的底部，一般显示为一定时期的沉积间断：④幕式运动基准面下降导致的明显暴露成因的古钙结壳、古土壤层，常在白云岩剖面中见此类沉积间断面；⑤在水深较大的地区反映连续沉积的整合界面，或为泥、粉砂岩连续沉积，或为泥微晶灰岩及颗粒灰岩的连续沉积。在以碎屑岩或碳酸盐岩为主的地层中各识别出3类短期基准面旋回层序的基本类型。并以中期基准面旋回层序为基础对盆地11个基干剖面高分辨率层序进行了划分与对比，建立了相应的盆地规模的高分辨率层序地层格架。研究表明，该理论能很好地用于海相地层研究，并对盆地生储盖组合的预测与对比具有实际意义；同时也验证了高分辨率层序地层学的广泛适用性，具有很大的理论意义。 论文用沉积学证据论证了羌塘盆地中侏罗世时期的盆地性质为陆缘盆地，存在于伸展性的大地构造背景。中侏罗世早期盆地存在着一系列地堑、地垒构造，二者之间的同沉积正断层发育，沿同沉积正断层砾岩沉积多见，且盆地内J₂q底部砾岩层厚度变化大。在详细研究雪山组的分布的基础上，认为在晚侏罗世显示为挤压性构造背景下的沉积物特征，晚侏罗世古羌塘海水从盆地北西及南东向方向双向退出研究区，且北西方向海退相对于南东方向更晚，表现为晚侏罗世提塘期（或延至早白垩世白里阿斯期）盆地西北部残留海相碳酸盐沉积，而盆地东南部为广阔的三角洲相沉积。 根据中期基准面界面的等时对比和岩相组合特征、相序特征，论文详细讨论了羌塘盆地侏罗纪岩相古地理演化。认为反映MSC1、MSC2和MSC3中期基准面旋回时期盆地古地形差异大、扇三角洲发育：MSC4、MSC5时期沉积物以潮坪相、滨浅海相碎屑岩为主：MSC6、MSC7、MSC8基准面旋回时期为碳酸盐台地沉积体系，和巴通期全球海平面上升有关；MSC9、MSC10中期基准面旋回时期为滨浅海相、潮坪相及三角洲相碎屑岩沉积发育：MSC11、MSC12和MSC13时期大致相当于晚侏罗世牛津-基末里期，古地理格局总体呈现出混积陆棚的特点：MSC14、MSC15和MSC16中期基准面旋回时期海水由北西及南东方向退出研究区，盆地内陆相沉积区逐步扩大。 与中亚、中东地区侏罗纪盆地地层对比后，本文认为羌塘盆地侏罗系可与伊朗kopetDagh盆地进行很好的对比。根据侏罗系高分辨率层序地层学特征、地层出露情况、生储盖层特征和组合、油气显示、构造条件和生油高峰与储盖层的匹配关系认为盆地东北缘斜坡和中央潜伏隆起区含油气远景差，羌北坳陷和羌南坳陷侏罗系生储盖配置良好，岩层受剥蚀程度较弱，含油气远景较好。并认为已发现油苗显示的羌南坳陷最有可能首先取得油气勘探的成果。提出羌塘盆地最有利的含油气远景区为：羌南坳陷内的比隆错—鄂雅错地区和羌北坳陷的吐坡错-确旦错地区、白滩湖-万安湖地区。更多还原

【Abstract】 High-resolution sequence stratigraphy has been extensively applied to oil/gas exploration due to its bran-new theory, methods and high accuracy and predictability. It was introduced into China during the 1990s and then was widely used in the study of continental petroliferous basins and continental deposits. However, the applications of high-resolution sequence stratigraphy have been seldom reported on the marine depoits, especially the marine carbonate sediments in China. The paper for the first time applies the theory to the study of Jurassic sequence stratigraphy in Qiangtang Basin, Tibet, which was expected to reveal the practicality of the theory on the marine deposits containing both clastic rocks and carbonate rocks.Based on the theory of high-resolution sequence stratigraly, 3 super-long-term cycle sequences are identified from the Jurassic sediments in Qiangtang Basin, amony which 2 developes from middle-upper Jarassic. 7 long-term, 17 middle-term cycle sequences are distinguished from the 2 middle-upper Jurassic super-long-term cycle sequences. The systemic analysis of Jurassic outcrops shows that the interfaces of long-term cycle sequences are CD the scoured bases of coastal onlap and fluvial/tidel channels, which usually distribute at the marginal region of Qiangtang Basin and lie to the base of sandstone or conglomerate sediments, (2) the widely distributed base interfaces of supratidal or evaporitic lagoonal gypsum depoits, which implies the most falling of long-term cycle face, (3) the base interfaces of supratidal mudstones and breccia, which implies the sedimentary discontinuities, (4) palaeosoil and palaeocalcrete occurring in the dolostone, (5) conformable interfaces occurring in the area with relatively deep water. Three basic types of short-time cycle sequence are identified in this paper. Accurate high-resolution equitime correlation is made and sequence framework is established. The study shows that high-resolution sequence stratigraphy can be applied well to marine clastic even carbonate deposits and do well to the forcast and correlation of the combination of oil/gas source beds, reservoirs and cap formations.According to the sedimentological evidences the paper believes that Qiangtang Basin was a continental marginal basin during middle Jurassic time and was at an extensional architectonic setting. A series of garbens and horsts developed during the earliest period of middle Jurassic time and conglomerates deposited along the synsedimentary normal faults occurring at the margin of the garbens. Due to the study of upper-Jurassic Xweshan formation, it is also believed that sediments deposited with a compressional geotectonic setting during late Jurassic time. The palaeosea water exited northwestward and sowtheastward.Using the data of equitime correlation of base cycles, petrographical analysis, the Jurassicevolution of facies palaeogeography is revealed in this paper. During the MSC1 (when the first middle-term cycle developed), MSC2 and MSC3 period, the paleotopography varied and fan-deltas developed in Qiangtang Basin. During the MSC4 and MSC5 period, clastic rocks of tidel-flat facies and shore-shallow sea facies mainly deposited. Carbonate platform depositional system developed during the MSC6, MSC7 and MSC8 period and it was closely related to the rise of global sea level during the Bathonian period. During the MSC9 and MSC 10 period shore-shallow sea, tidel-flat and delta facies clastic rocks deposited. The MSC11, MSC12 and MSC 13 middle-term cycles developed during the later Jurassic Oxford and Kimerry period and mixed continental shelf sediment developed. During the MSC 14, MSC 15 and MSC 16 period the water of Jurassic Qiangtang sea exited from the researched region and the area of continental deposits extanded.With the high-resolution sequence stratigraphical analysis, data of outcrop formations, charaters and combination of oil/gas source rocks, reservoirs and cap rocks, oil/gas shows, tectonic conditions and the matched relation between oil/gas generating peak and sour更多还原