【作者】 武振杰；

【导师】 姚建新；

【作者基本信息】 中国地质科学院 ， 古生物学与地层学， 2009， 博士

【摘要】 塔里木盆地是我国最大的内陆盆地,也是国内最后一个油气勘探程度较低的大型沉积盆地,面积达56万km~2,是国家能源重点勘探地区。但由于盆地经历多次构造变动,加上所处自然条件恶劣,给油气勘探带来一定的困难。本文以塔西北缘柯坪地区为研究区,以露头层序地层学、旋回地层学和沉积学为理论指导,以米级旋回研究为切入点,通过对不同露头点岩性、岩相、相序的研究,弄清研究区内高频层序发育特征及其叠加形式,在此基础上进一步的研究层序发育的不同周期和级次,并由点及线,由线及面,对柯坪地区奥陶系—泥盆系层序地层格架与沉积相开展研究。本文的研究取得以下认识:1.在研究究区内奥陶纪—泥盆纪地层中可以识别出3种沉积相类型:滨岸沉积、陆棚沉积和碳酸盐台地沉积。2.柯坪地区奥陶系中可划分6个三级层序,并可以归并到一个二级层序之中。这些三级层序的基本组成结构为“TST(海侵体系域)+HST(高水位体系域)”,其中均不发育低水位体系域或陆架边缘体系域,凝缩段(CS)仅见于层序3中。在一些层序中高水体体系域可以细分为早期高水体体系域(LHST)和晚期高水位体系域(LHST)。奥陶系6个层序在四石厂一带发育较全,向东至通古斯布隆利苏巴什一带地层厚度变薄,层序尖灭为3个,层序地层格架反映了在相对海平面变化过程中,中上奥陶统自东向西发生超覆。3.在柯坪地区志留系出露较全,泥盆系仅中、下统出露。连续沉积的志留系和泥盆系中一共可以划分出7个三级层序,其中层序1—层序5属志留系沉积,层序6和层序7为中、下泥盆统沉积。4.阿克苏地区中、上奥陶统碳酸盐岩磁化率测量测量结果表明,碳酸盐岩沉积环境与其磁化率曲线之间有一定的相关性:一般情况下,深水环境磁化率值较低,且曲线平直;水体变浅时测量值开始振荡,并有变大的趋势;浅滩等水体较浅环境中碳酸盐岩磁化率则出现异常高值。同时,碳酸盐岩磁化率曲线与层序界面、准层序(组)和层序之间有着一定的对应关系:与淹没型层序界面下部地层相比,上部地层中磁化率测量值值明显变小。在准层序组(组)中,其下部单元的磁化率一般较低,曲线较为平直;上部单元磁化率通常为明显变大,曲线呈高频振荡状。更多还原

【Abstract】 Tarim Basin is the largest inland basin in China, covering an area of 560,000 km2, and also the last domestic large sedimentary basin which is insufficiently studied in terms of oil and gas exploration. Thus this basin is the focus of the national energy exploration. However, the exploration is impeded by arduous natural condition and the multiple tectonic changes which the basin has experienced.The lithoogy, lithofacies and phase sequence in the Keping area in northern margin of Tarim has been studied in this paper, in order to understand the characteristics and the stacking pattern of meter-scale cycles. The study focus is the meter-scale cycles under the theory of outcrop sequence stratigraphy, cyclic stratigraphy and sedimentology. Furthermore, the different cycles and hierarchic rank of the development of sequences are analyzed; the Ordovician to Devonian sequence framework and sedimentary facies in particular localites, along expedition routes as well as large areas in Keping area. The following conclusions have been reached:Three sedimentary facies could be recognized in Ordovician to Devonian strata in studied area: shore facies, shelf and carbonate platform deposits.The Ordovician in Keping could be divided into three 3^rd sequences under one 2^nd sequence. These 3^rd sequences mainly comprise TST and HST, lacking **** and ***. In certain sequences, HST could be subdivided into LHST an LHST. CS is only observed in sequence 3. The six Ordovician sequences are well developed in Sishichang area. Eastwards to Gusibulong and Subashi area, they decrease to three sequences. The framework of sequences suggests that, in the sea-level fluctuation, the middle and upper Ordovician transgressed from east to west.In the middle and lower part of the Silurian and Devonian in Keping, seven 3^rd sequences could be established. The sequence 1-5 are Silurian and the remaining is early to middle Devonian.In Akesu area, measurement of magnetic susceptibility of middle to late Ordovician carbonates reveals that the sedimentary environment of carbonates is related to their magnetic susceptibility. In general, deep water environment resulted in low magnetic susceptibility. The magnetic susceptibility fluctuated and show the trend of increase as the water become shallow. The shallow water, such as shore, produced exceptionally high magnetic susceptibility. Meanwhile, magnetic susceptibility of carbonates is also related to the sequence boundary, parasequence and sequence. Compared with the strata under the submerged sequence boundary, strata above the boundary has obviously lower magnetic susceptibility. In parasequence formation, the lower part generally has low magnetic susceptibility and straight curve, but the converse is true for the upper part.更多还原