【作者】 杨平；

【导师】 刘大锰； 朱如凯；

【作者基本信息】 中国地质大学（北京） ， 能源地质工程， 2007， 博士

【摘要】 柴达木盆地第三系自下而上发育有古近系路乐河组、下干柴沟组、上干柴沟组,新近系下油砂山组、上油砂山组、狮子沟组共六套地层。层序生物地层学是层序地层学和生物地层学交叉的产物。高分辨层序地层的基准面旋回转换面与地震层序界面共同构成一个等时地层格架,在古生物化石限定一段地层的时代之后,地层界线就以基准面旋迴转换面为依据。各地层“组”的时间跨度均符合二级层序的年限,定义为长期旋迴,所以长期旋迴以现有的岩石地层单位为基准,其界面相当于T0～T5地震标准层。GR曲线有规律的波动和短期基准面旋迴叠加方式的改变是识别中期旋迴的有效依据。柴西七个泉构造可识别的高分辨率层序地层中期基准面旋迴数为:狮子沟组2个,命名为S1-2;上油组3个,命名为SY1-3;下油组4个,命名为XY1-4;上柴组3个,命名为SC1-3;下柴组上段5个,命名为XS1-5;下柴组下段3个,命名为XX1-3;红柳泉构造与此相似。在七个泉和红柳泉地区选择了四条过井地震剖面,构成一组“井”字形闭合剖面,化石标定时代,基准面旋迴确定分界。古近纪红深10井南、北至少各存在一个沉积凹陷,红深10井至七24井方向很可能是古近纪的一个断裂构造带,分割了七个泉和红柳泉两个沉积凹陷区。层序生物地层对比结果显示,中星介在下油组和上柴组均有分布,正星介在上油组和下油组均有分布。生态体系域是在层序地层演化过程中,以特有的古生物组合反映层序体系域环境属性的一套沉积体。本文划分了四个生态体系域(生态域),分别是:1.土星介生态域,2.球星介生态域,3.正星介生态域,4.轮藻生态域。土星介生态域主要与三级层序的TST相对应,正星介生态域对应HST或TST下部,斗星介生态域接近基准面下降-上升的转换点。轮藻生态域在TST和HST均能形成,但对水体的盐度要求是淡水-少盐水。生态体系域作为一个研究化石与环境关系的整体,其化石组成分子的出现就代表这一生态域的存在,生态体系域的存在为层序体系域的确立提供支持,同时可说明其环境属性,这就是生态体系域在层序体系域划分研究中的意义所在。更多还原

【Abstract】 Tertiary strata of Qaidam basin include Lulehe Formation, Lower Ganchaigou Formation, Upper Ganchaigou Formation of Paleogene, and Lower Youshashan Formation, Upper Youshashan Formation, Shizigou Formation of Neogene from bottom to top.The sequence biostratigraphy is a multidiscipline integrated sequence stratigraphy with biostratigraphy. The interface of the base level cycle of high-resolution sequence stratigraphy and the seismic sequence boundary jointly make up of an isochronous stratigraphic frame. After dating a member of stratum, using palaeontological fossils, the stratum borders can be determined according to the base level. The time span of the formations in each stratum is in accord with the age of the second-order sequence without exception, which is defined as a long-term cycle. Therefore, the long-term cycle is benchmarked on an existing lithostratigraphic unit, whose interface is equivalent to T0~T5 seismic markers. The disciplinarian fluctuation of GR curve and the change of superposition mode of short-term base level cycle are an effective basis for identifying the medium-term base level cycles.The number of the medium-term base level cycle identified in high-resolution sequence stratigraphy of Qigequan structure in Qaidam basin includes two cycles in Shizigou Formation (named as S1-2 ), three cycles in Upper Youshashan Formation (named as SY1-3), four cycles in Lower Youshashan Formation (named as XY1-4), three cycles in Upper Ganchaigou Formation (named as SC1-3), five cycles in Lower Ganchaigou Formation (named as XS1-5), and three cycles in lower member of Lower Ganchaigou Formation (named as XX1-3). The cycles in Hongliuquan Structure resemble those of the Qigequan structure.We chose four seismic profiles across wells in Qigequan and Hongliuquan regions, composing a group of closed netlike sections, and dated using fossils, confirmed the boundary by base level cycles. In south and north of well Hongshen 10 there at least exists a Paleocene depositional depression. In the region of well Hongshen 10 and well Qi 24 there likely exists an Paleocene fault zone, whichseparated the two depositional depressions of Qigequan and Hongliuquan. In a sequence biostratigraphic framework, the fossil Mediocypris distributes in the Lower Youshashan Formation and Upper Ganchaigou Formation and the fossil Cyprideis distributes in the Upper and Lower Youshashan Formations.Ecological system tract is a sedimentary body reflecting the environmental attribute of sequence system tracts using a proper palaeontology assemblage during a sequence stratigraphic evolutional process. The four ecological system tracts (biochore) in this paper are divided as follows: No.1 Ilyocypris ecological tract; No. 2 Cyclocypris ecological tract; No. 3 Cyprideis ecological tract; No. 4 Charophyte ecological tract. The Ilyocypris ecological tract mainly corresponds to the TST in the third-order sequence, and the Cyprideis ecological tract to the HST or the lower TST. The Cyclocypris ecological tract is close to the changing point of decline and rise of the base level. The Charophyte ecological tract can be formed in both TST and HST, while its salinity of water body is fresh to somewhat saline.The fossils of ecological tract reflecting an entire study of the relation of the fossils and environments indicate the existence of the tract which can support the confirmation of the tract of sequence stratigraphy and demonstrate its environmental attribute as well. This is the significance of the ecological system tract in the research of the classification of the system tracts of stratigraphic sequence.更多还原