塔中地区良里塔格组海平面变化对高频层序和沉积演化的控制  

Control of sea level changes on high-frequency sequence and sedimentary evolution of Lianglitage Formation in the Tazhong Area

作　　者：高达[1,2] 王明敏 陶叶 黄理力 孙春燕 黄鑫淼[1,2] 武建伟 GAO Da;WANG Mingmin;TAO Ye;HUANG Lili;SUN Chunyan;HUANG Xinmiao;WU Jianwei(School of Geosciences,Yangtze University,Wuhan 430100,Hubei,China;Key Laboratory of Exploration Technologies for Oil and Gas Resources,Ministry of Education,Yangtze University,Wuhan 430100,Hubei,China;South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China;PetroChina Hangzhou Research Institute of Geology,Hangzhou 310023,Zhejiang,China;Research Institute of Petroleum Exploration and production,Tarim Oilfield Company,PetroChina,Korla 841000,Xinjiang,China)

机构地区：[1]长江大学地球科学学院,湖北武汉430100 [2]油气资源与勘探技术教育部重点实验室,湖北武汉430100 [3]中国科学院南海海洋研究所,广东广州510301 [4]中国科学院大学,北京100049 [5]中国石油杭州地质研究院,浙江杭州310023 [6]中国石油塔里木油田分公司勘探开发研究院,新疆库尔勒841000

出　　处：《中国地质》2022年第6期1936-1950,共15页Geology in China

基　　金：国家自然科学基金(41502104);湖北省自然科学基金(2017CFB533);油气资源与勘探技术教育部重点实验室开放基金(K2018-06)联合资助。

摘　　要：【研究目的】碳酸盐岩地层易受海平面变化影响而发育高频层序,但是反映海平面变化的地化指标的精度不足,导致高频层序对海平面振荡的响应认识不够深入,高频海平面变化对台地边缘礁滩沉积的高频层序和沉积演化的控制尚不明确。【研究方法】论文研究选取塔里木盆地塔中地区某钻井的上奥陶统良里塔格组连续取心资料,通过密集取样开展微相分析和碳、氧同位素测试分析。【研究结果】该井良里塔格组中上部发育7种微相类型,沉积演化分析表明良里塔格组沉积中—晚期,沉积环境由潮坪向生物礁-颗粒滩再到较深水的开阔台地演化。碳、氧同位素测试显示δ^(13)C为0.5993‰~1.6228‰(均值1.^(13)9‰),δ^(18)O值为-8.3608‰~-5.1452‰(均值为-6.790‰);δ^(13)C和δ^(18)O的振荡变化与微相变化和沉积旋回对应良好。古海洋条件分析表明,良里塔格组沉积时期气候温热,礁、滩体发育层段样品的古温度值最高,代表着高的碳酸盐产率;Z值所反映的古盐度在底部潮坪沉积段最高,在高频旋回的顶部古盐度均明显减小,指示可能存在大气淡水的影响。与塔北地区南缘和巴楚地区的δ^(13)C和δ^(18)O存在一定差异,主要受控于沉积环境和古水深。【结论】良里塔格组中—上部存在至少3个完整的海平面升降变化周期,内部又包括至少2个次级周期;不同级别的海平面振荡主要受古气候变化驱动,并控制了高频层序的发育。海平面先缓慢上升再持续稳定或小规模振荡,是连续厚层的生物碎屑和砂屑颗粒滩沉积发育的有利条件;良里塔格组沉积晚期海平面快速上升,沉积环境向滩间洼地和较深水的开阔台地转变。在高频层序顶部海平面的小规模下降导致的早期岩溶作用是礁滩体储层质量改善的重要因素。This paper is the result of oil and gas exploration engineering.[Objective]Carbonate strata are susceptible to sea-level changes and thus develop high-frequency sequences.However,the accuracy of geochemical indicators reflecting sea-level changes is insufficient,resulting in poor understanding about the highfrequency sea-level fluctuation.The controls of sea-level changes on the high-frequency sequence and sedimentary evolution of the platform-margin reef-shoal deposits remain unclear.[Methods]Continuous core data from a well in the Upper Ordovician Lianglitage Formation in the Tarim Basin were selected for microfacies analysis,carbon and oxygen isotope analyses by denselycollected samples.[Results]Seven microfacies types developed in the middle and upper part of Lianglitage Formation.The analysis of the sedimentary evolution shows that the sedimentary environment evolved from tidal flat to reef and shoal,and to deeper platform during the middle to late period of deposition.The carbon and oxygen isotope values ranges from:δ^(13)C is 0.5993‰-1.6228‰(average 1.^(13)9‰) and δ^(18)O value is-8.3608‰--5.1452‰(average-6.790‰).The changes of the δ^(13)C and δ^(18)O correspond well with the evolution of microfacies and sedimentary cycles.The analysis of paleo-ocean conditions shows that the Lianglitage Formation was deposited under warm climate and the reef and shoal samples recorded high paleo-temperature,representing a high rate of carbonate production.The paleo-salinity reflected by the Z-value is high according to the samples at the bottom of the tidal flat,and it is relatively low at the top of high-frequency cycles,probably indicating the influence of meteoric water.The range of δ^(13)C and δ^(18)O values differ from the Tazhong area,the southern margin of Tabei area,and Bachu area,which is mainly related to the difference in environment and water depth.[Conclusions]At least three cycles of sea-level change and two secondary cycles exit in the middle to upper parts of the Lianglitage Formation.Dif

关 键 词：碳、氧同位素 礁滩相 海平面变化 碳酸盐岩微相 高频层序 良里塔格组 奥陶系 油气勘查工程 

分 类 号：P618.13[天文地球—矿床学]