柴达木盆地新近系中新统岩相古地理分析-古生物与地层学专业论文 word格式.docx

摘要
本文应用沉积学、高分辨率层序地层学、岩相古地理学、岩石学以及盆地分析、测井地层、地震地层等多学科相结合的方法与手段,研究柴达木盆地新近系中新统上干柴沟组的沉积特征,建立了层序地层格架,进行了层序界面的识别与对比,进而在层序格架内分析了柴达木盆地新近纪中新统的岩相古地理特征。
通过对柴达木盆地新近系中新统上干柴沟组地层变化与分布的研究,明确了各时期地层厚度展布规律,地层厚度呈现“西厚东薄,北厚南薄”的特点,总体则呈现南北展布东西分带特点。对柴达木盆地新近系中新统上干柴沟组三级层序界面进行研究,建立了层序地层格架,划分出 2 个三级层序。对沉积相标志特征和组合类型进行了深入分析,充分利用钻井岩心、各种测井资料,划分了沉积相类型和组合方式,结合物源方向分析、测井-录井相分析,建立了测井-录井相与沉积相之间的对应转化关系。研究表明,柴达木盆地新近系中新统上干柴沟组发育有冲积扇、河流、三角洲和湖泊 4 种沉积
体系类型。识别出 7 种沉积相和 12 种亚相类型。根据柴达木盆地新近系中新统上干柴沟组的砂泥分散体系及特征、粗砾屑分布规
律,结合重矿物分析、古气候分析以及古水流分析,采用优势相分析方法,对柴达木盆地新近系中新统进行了全盆地岩相古地理图的编制,结果表明层序 1 时,盆地面积最为广阔,沉积相主要表现为由南北的物源区向中心呈现冲积扇-辫状河-三角洲-滨湖-浅
湖-深湖相带的展布。层序 2 在全盆皆有发育,在靠近山前地区主要为浅水环境,至盆地内部沉积厚度变大,且以湖泊相沉积为主,在深湖区远离物源的水下隆起部位发育碳酸盐滩坝。
关键词:柴达木盆地、上干柴沟组、高分辨率层序地层、岩相古地理
Abstract
Using the method of bination of sedimentology, high-resolution sequence stratigraphy, lithofacies paleography, petrology and basin analysis, well logging, seismography and so on, this paper discussed the sedimentary characteristic of upper-Ganchaigou formation during Miocene series in Neozoic of Qaidam Basin, and set up sequence stratigraphy framework and made identification parison of the sequence surface, e to the analysis of the lithofacies paleographic characteristic of Miocene series in Neozoic of Qaidam Basin in the stratigraphy framework.
Though the research of the variation and distribution of stratum of upper-Ganchaigou formation during Miocene series in Neozoic of Qaidam Basin, it explicated the rule of distribution of stratum thickness in different period, that was the thickness of basin stratum presented the characteristic of “thick in the west and thin in the east, while thick in the north and thin in the south”, and spreading in south-north while zoning in east-west on the whole. It also analyzed the third-order sequence interface of upper-
Ganchaigou formation during Miocene series in Neozoic of Qaidam Basin, and bulit sequence stratigraphy framework, dividing out two third-order sequence.
What’s more, it analyzed the symbol characteristic o