埃迪卡拉系微生物碳酸盐岩沉积特征及其地质意义:以川中磨溪8井区灯影组四段为例  

Sedimentary characteristics of the Ediacaran microbial carbonates and their geological implications:a case study of the Member 4 of Dengying Formation from Wellblock MX8 in central Sichuan Basin

作　　者：罗垚 谭秀成[1,2] 赵东方 罗文军[3] 刘耘 肖笛[1,2] 乔占峰 曾伟[1,2] Luo Yao;Tan Xiu-Cheng;Zhao Dong-Fang;Luo Wen-Jun;Liu Yun;Xiao Di;Qiao Zhan-Feng;Zeng Wei(State Key Laboratory of Oil and Gas Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China;Research Branch of Southwest Petroleum University,Key Laboratory of Carbonate Reservoirs,CNPC,Chengdu 610500,China;Research Institute of Exploration and Development,Petro China Southwest Oil&Gasfield Company,Chengdu 610041,China;Key Laboratory of Carbonate Reseviors,CNPC,Hangzhou 310023,China)

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点实验室,四川成都610500 [2]中国石油集团碳酸盐岩储层重点实验室西南石油大学研究分室,四川成都610500 [3]中国石油西南油气田分公司勘探开发研究院,四川成都610041 [4]中国石油集团碳酸盐岩储层重点实验室,浙江杭州310023

出　　处：《古地理学报》2022年第2期278-291,共14页Journal of Palaeogeography：Chinese Edition

基　　金：中国石油—西南石油大学创新联合体科技合作项目(编号:2020CX010300);中国石油集团公司上游领域基础性前瞻性项目(编号:2021DJ0501)共同资助。

摘　　要：四川盆地高石梯—磨溪地区埃迪卡拉系灯影组广泛发育一套微生物碳酸盐岩。以磨溪8井区灯影组四段(灯四段)为例,通过精细解析高频向上变浅序列的岩石学特征,发现灯四段微生物云岩及序列建造具有如下特征:(1)向上变浅序列主要由凝块石云岩、叠层石云岩和(含微生物)泥晶云岩3类构成,伴以少量微生物粘结颗粒云岩;(2)完整的典型向上变浅序列自下而上由(含微生物)泥晶云岩(A段)、平直状叠层石云岩(B段)、小型丘状叠层石云岩(C段)、分散状凝块石云岩(D段)、格架状凝块石云岩(E段)、微生物粘结颗粒云岩(F段)等6个岩性单元构成,但大量的序列由A-C-E、A-C-D、B-D、B-C-D-E等不完整的岩性单元构成,且序列顶底皆以凝块石云岩/(含微生物)泥晶云岩、叠层石云岩/(含微生物)泥晶云岩等不平整的岩性突变面或暴露面区分;(3)埃迪卡拉系微生物碳酸盐岩发育于浪基面之上至平均海平面附近的相对高能区域,且凝块石云岩较叠层石云岩形成的环境能量高。该研究结果不仅揭示出较高能的浅水环境控制了规模性微生物岩分布这一规律,而且对区域储集层预测具有指导意义,同时也因建立了有别于现代微生物的环境分布模式而具有重要的沉积学意义。The Ediacaran microbial carbonate rocks are widely developed in the Dengying Formation in the Gaoshiti-Moxi area of the Sichuan Basin.This paper takes the Member 4 of the Dengying Formation in Wellblock MX8 as an example.By analyzing the macroscopic and microscopic petrological characteris-tics of the high-frequency upward shallowing sequence,it is found that the microbial dolomite and se-quence construction in the Member 4 of Dengying Formation have the following characteristics:(1)The upward shallowing sequence is mainly composed of thrombolites,stromatolites,microbial dolomicrite and a small amount of microbial bonded granular dolomite.(2)The complete typical upward shallowing se-quence is composed of six lithologic units from bottom to top,including microbial dolomicrite(A),flat stromatolite(B),small hummocky stromatolite(C),dispersed thrombolite(D),latticed thrombolite(E),microbial bonded granular dolomite(F).A large number of sequences are composed of incomplete lithologic units such as A-C-E,A-C-D,B-D,B-C-D-E,and the top and bottom of the sequence are distinguished by uneven lithologic mutation surfaces or exposure surfaces such as thrombolites-microbial do-lomicrite,stromatolites-microbial dolomicrite.(3)The Ediacaran microbial carbonates were developed in relatively high energy areas above the wave base to near the average sea level,and the environmental energy of the thrombolites are much higher than that of the stromatolites.The results reveal that the high-energy shallow water environment not only controls the distribution of large-scale microbial rocks,but also provides guidance for regional reservoir prediction.Meanwhile,the results are of great sedimentological significance in the establishment of an environmental distribution model that is different from modern microorganisms.

关 键 词：微生物岩 微生物丘 沉积模式 灯影组 震旦系 四川盆地 

分 类 号：P588.245[天文地球—岩石学]