柴北缘冷湖五号构造中新统成岩作用及沉积环境  

Diagenesis and Sedimentary Environment of Miocene in Lenghu Ⅴ Tectonic Belt

作　　者：孙国强[1] 陈波[1,2] 郑永仙[3] 谢梅[3] 夏维民[3] 史基安[1] 

机构地区：[1]甘肃省油气资源研究重点实验室/中国科学院油气资源研究重点实验室,甘肃兰州730000 [2]中国科学院大学,北京100049 [3]中国石油青海油田公司勘探开发研究院,甘肃敦煌736202

出　　处：《天然气地球科学》2015年第4期679-688,共10页Natural Gas Geoscience

基　　金：中国科学院2012年度"西部之光"人才计划;甘肃省科技计划"自然科学基金"项目(编号:1308RJZA310);甘肃省重点实验室专项(编号:1309RTSA041)联合资助

摘　　要：综合运用岩石学、矿物学和元素地球化学等方法,对柴达木盆地北缘冷湖五号构造带中新统上干柴沟组碎屑岩的成岩作用、形成环境和物质来源等进行了系统研究。发现上干柴沟组碎屑岩颗粒间主要以点—线接触为主,颗粒间云母等塑性岩屑被挤压变形,说明经历过较强的压实作用。黏土矿物含量较高,平均达到了22.74%,主要以伊利石、绿泥石及伊/蒙混层为主。碳酸盐胶结物类型主要以方解石为主,仅含有少量白云石。碳酸盐胶结物的碳氧同位素含量测定表明,碳同位素(δ13C)值分布范围在-6.88‰^-3.8‰之间,平均为-5.39‰;氧同位素(δ18 O)值分布范围在-12.74‰^-6.98‰之间,平均为-10.18‰;根据碳氧同位素含量推算古盐度Z值分布范围为107.65~114.89,平均值为111.34;碳酸盐沉淀温度分布范围为52.34~88.93℃,平均值为72.08℃。结合对主量元素、微量元素及有机碳含量等地球化学元素的综合分析,冷湖五号构造带中新统上干柴沟组储集岩目前所处的成岩阶段主要为早成岩阶段B期至中成岩阶段A期,在沉积时期气候稳定且温暖湿润。Based on petrology, mineralogy and geochemistry, the diagenesis, depositional environment and origin of Miocene clastic rock of Shangganchaigou Formation in Lenghu V tectonic belt on the northern margin of the Qaidam Basin were studied. The experimental results demonstrated that particles of Miocene clastic rock of Shangganchaigou Formation mainly had point contact or line contact relationships, and had been suffered strong compaction;the elastic rock of Shangganchaigou Formation had high contents of clay minerals with average value was 22.74%,which were dominated by illite,chlorite and mixed layer of illite and montmorillonite;calcite was the main types of carbonate cements, and dolomite was minor; the carbon isotope （δ^13 C） of carbonate cements ranged from - 6.88‰ to - 3.8‰, and the average value was - 5.39‰ ; the oxygen isotope （δ^18O） ranged from -12.74‰to -6.98‰ ,and the average value was -10.18‰;Z-value of paleosalinity estimated by δ^13 C and δ^18O ranged from 107. 65 to 114. 89 and the average value was 111.34;and temperature of carbonate deposited ranged from 52.34℃ to 88.93℃ ,and the average value was 72.08℃. Above results,combined with the comprehensive analysis of some geochemical elements,such as major elements,trace elements and organic carbon content,suggested that main diagenetic stage of Miocene clastic rock of Shangganchaigou Formation in Lenghu V tectonic belt was in phase B of early diagenetic stage B or phase A of the middle diagenetic stage. The depositional environment of Miocene Shangganchai gou Formation in Lenghu V tectonic belt was dominated by stably warm and humid climate,and of which the main diagenesis of reservoirs currently are in period B of early diagenetic stage to period A of the mid dle diagenetic stage.

关 键 词：碳氧同位素 碳酸盐胶结物 上干柴沟组 冷湖五号构造带 

分 类 号：TE121.31[石油与天然气工程—油气勘探]