古地理学报 ›› 2021, Vol. 23 ›› Issue (5): 983-998. doi: 10.7605/gdlxb.2021.05.063

• 地球化学与沉积环境 • 上一篇    下一篇

塔里木盆地乌什地区上震旦统奇格布拉克组地球化学特征及其地质意义*

郑剑锋1,2, 刘禹1,3, 朱永进1,2, 梁峰1,2   

  1. 1 中国石油集团碳酸盐岩储层重点实验室,浙江杭州 310023;
    2 中国石油杭州地质研究院,浙江杭州 310023;
    3 中国石油大学(北京)地球科学学院,北京 102249
  • 收稿日期:2021-03-08 修回日期:2021-05-20 出版日期:2021-10-01 发布日期:2021-09-29
  • 通讯作者: 刘禹,男,1997年生,中国石油大学(北京)地球科学学院硕士研究生,地质工程专业,主要从事沉积岩石学和沉积化学研究。E-mail: 912498894@qq.com。
  • 作者简介:郑剑锋,男,1977年生,硕士,高级工程师,主要从事碳酸盐岩沉积和储层研究。E-mail: zhengjf_hz@petroChina.com.cn。
  • 基金资助:
    *国家科技重大专项(编号: 2016ZX05004-002)和中国石油重大科技项目(编号: 2016B-0405)联合资助

Geochemical features and its geological significances of the Upper Sinian Qigeblak Formation in Wushi area,Tarim Basin

Zheng Jian-Feng1,2, Liu Yu1,3, Zhu Yong-Jing1,2, Liang Feng1,2   

  1. 1 Key Laboratory of Carbonate Reservoir,CNPC,Hangzhou 310023,China;
    2 PetroChina Hangzhou Research Institute of Geology,Hangzhou 310023,China;
    3 College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China
  • Received:2021-03-08 Revised:2021-05-20 Online:2021-10-01 Published:2021-09-29
  • Contact: Liu Yu,born in 1997,is a master degree candidate of China University of Petroleum(Beijing). Now he is mainly engaged in researches of sedimentary petrology and sedimentary geochemistry. E-mail: 9121498894@qq.com.
  • About author:Zheng Jian-Feng,born in 1977,is a senior engineer in PetroChina Hangzhou Research Institute of Geology,and is mainly engaged in research of carbonate sedimentation and reservoir. E-mail: zhengjf_hz@petroChina.com.cn.
  • Supported by:
    Co-funded by the National Science and Technology Major Project of China(No.2016ZX05004-002)and Major Science and Technology Project of PetroChina(No.2016B-0405)

摘要: 塔里木盆地寒武系盐下地层资源量巨大,上震旦统奇格布拉克组是该领域风险勘探的重要层系之一,但当前该层系勘探尚未取得重大突破,其中岩相古地理格局及储集层主控因素认识不深是制约勘探突破的重要因素之一。文中以乌什地区昆盖阔坦剖面为研究对象,通过地层精细描述和104块岩石薄片分析,并优选样品开展常微量元素、稀土元素、碳氧锶同位素、白云石有序度及U-Pb同位素年龄测试,分析了奇格布拉克组沉积环境及白云岩成因。结果表明: (1)塔里木盆地乌什地区昆盖阔坦剖面奇格布拉克组厚约141 m,主要发育叠层石、凝块石、泡沫绵层石3种微生物白云岩和鲕粒、粘结颗粒2种与微生物作用相关的颗粒岩,并根据相序组合可以划分为4个段,自下而上构成碳酸盐缓坡背景下的内缓坡潮坪—微生物丘滩沉积序列;(2)地球化学分析表明,奇格布拉克组沉积时期研究区整体处于温暖、干旱气候条件下的近岸浅水环境,海水具有较高盐度、较高水温和氧化—弱氧化特征,海平面先逐渐上升后快速下降;(3)奇格布拉克组白云岩形成于准同生—浅埋藏期,白云石化流体为具有较高盐度的海水。该研究成果不仅可以为塔里木盆地晚震旦世岩相古地理研究提供依据,还可以为储集层主控因素分析提供依据。

关键词: 塔里木盆地, 奇格布拉克组, 地球化学特征, 沉积环境, 白云石化

Abstract: The Cambrian subsalt formation in Tarim Basin is rich in abundant hydrocarbon resource. The Upper Sinian Qigeblak Formation is one of the important exploration targets in this field. However,no exploration breakthrough has been made so far in this formation. The limited knowledge of lithofacies paleogeography and reservoir genesis led to the restriction of exploration breakthrough. In this paper,the Kungaikuotan outcrop of Wushi area located at NW Tarim Basin is selected as the study region. Based on detailed stratigraphic description,analysis on 104 petrographic thin sections,and multi-parameters geochemical data analysis(major and trace elements,REEs,carbon-oxygen and strontium isotope,the order degree of dolomite and in-situ U-Pb dating),the sedimentary environment of Qigeblak Formation and genesis of dolomite have been studied. It was found that: (1)the Qigeblak Formation of the Kungaikuotan section in the Wushi area of Tarim Basin has the thickness of 141 m,developing three kinds of microbial dolomite(e.g.,stromatolite,clotted limestone,foam laminated stone),two kinds of grainstone related with microbial action(oolite dolomite and grain dolomite). The Qigeblak Formation can be divided into four sections according to the combination of facies sequence,forming the lithofacies assemblage in carbonate gentle slope from inner ramp tidal flat to inner ramp microbial mound/shoal from bottom to up;(2)The sedimentary period of Qigeblak Formation was in a shallow sea water under warm and dry climate background. Seawater has high salinity,high water temperature and oxidation-weak oxidation characteristics and the sea level firstly gradually rised and then declined rapidly;(3)Dolomitization of the Qigeblak Formation took place in penecontemporaneous-early diagenetic period and the dolomitization fluid was the seawater with high salinity. These research results are of great significance to lithofacies palaeogeographic mapping in Late Sinian,Tarim Basin and analysis of reservoir genesis.

Key words: Tarim Basin, Qigeblak Formation, geochemical characteristics, sedimentary environment, dolomitization

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