摘要
通过元素地球化学分析、X-衍射全岩分析、岩石薄片分析等试验方法对鄂尔多斯盆地延长组块状砂岩中"泥包砾"结构成因机制进行研究。结果表明:该结构中泥质包壳层Fe/Mn值较低、MnO_2含量较高,Th/U值较高、δU小于1,Sr/Ba值较低,反映近岸、偏氧化及低古盐度的浅水地球化学特征,和与其伴生的半深湖层状泥岩的沉积介质环境存在较大差异性;结构中内核的主要成分为砂质、泥质或白云石团块,形成于滨浅湖或三角洲前缘环境;"泥包砾"结构非瞬态形成,而是贯穿长7—长6_3期三角洲前缘砂泥岩软沉积物往深湖区块体搬运的全过程,经历浅湖相团块形成、结构初始形成、岩性混合转移、最终停积定型4个阶段。
The genetic mechanism of mud-coated intraclasts within deep-water massive sandstone in Yanchang Formation of Ordos Basin ＂was studied combining the test method of element geochemistry,XRD and rock thin section analysis. The find-ings of this study include the following： the Fe/Mn is low,the content of MnO2 is high,Th/U is high,the 8U is less than 1 , and the Sr/Ba is low in the argillaceous cladding layer,reflecting the geochemistry^ characteristics of shallow- water environ-ment are nearshore,oxidation and low salinity. There is a large difference in depositional environment with the associated layered mudstone of the semi-deep lake. The main components of the core of the mud-coated intraclasts are sandy, muddy or dolomitic lump, which were formed in shore-shallow lake or delta front environment. The formation process of mud-coated in-traclasts was long, in which the soft sandy or muddy sediments within the delta front were transported into deep lakes in clumps from Chang7 to Chang63 period through four stages ： lump formation of shallow lake facies, initial formation of structure ,mixed transfer of lithology and eventually deposition setting.
出处
《中国石油大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2017年第4期46-53,共8页
Journal of China University of Petroleum(Edition of Natural Science)
基金
国家科技重大专项(2011ZX05001-003)
关键词
“泥包砾”结构
延长组
沉积环境
地球化学
深水沉积
鄂尔多斯盆地
mud-coated intraclasts
Yanchang Formation
sedimentary environment
geochemistry
deep-water sedimentary
Ordos Basin
作者简介
廖建波（1979-）,男,高级工程师,博士研究生,研究方向为沉积学.E-mail：liao_jb@petrochina.com.cn
