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利用薄片、碳氧稳定同位素、微量元素等测试资料,以巴楚大板塔格与阿克苏蓬莱坝剖面中下奥陶统碳酸盐岩为研究对象,系统报道了岩石学与地球化学的各种特征,分析了不同特征所表征的成岩环境。研究表明:(1)碳、氧同位素垂向上整体表现为埋藏成岩环境,鹰山组顶部、蓬莱坝组中部以及顶部呈现出淡水成岩环境特征,鹰山组中部与蓬莱坝组底部显示为海水成岩环境,鹰山组下部和上部表现为海水成岩环境背景下短期受到淡水影响,白云岩δ~(18) O值、δ~(13)C值高于灰岩,鹰山组白云岩δ~(13)C值低于蓬莱坝组白云岩;(2)不同类型白云岩Sr含量呈现规律性。还原环境敏感元素富集在鹰山组中—粗晶白云岩与蓬莱坝组顶部粉—细晶白云岩,氧化环境敏感元素富集在鹰山组藻砂屑云质灰岩、蓬莱坝组细晶夹自形中晶白云岩和砂屑幻影白云岩;(3)白云岩化的过程是LREE亏损的过程。一间房组生屑灰岩具较高的∑REE,MREE略富集,Ce负异常程度高,蓬莱坝组下部残余结构云岩REE配分继承颗粒灰岩。鹰山组下部藻泥晶砂屑灰岩与云质砂屑灰岩REE配分相似,∑REE具有随水体深度增加而减小的趋势,LREE富集,HREE亏损,Gd正异常。鹰山组中—粗晶白云岩与蓬莱坝组顶部粉—细晶白云岩REE配分相似,MREE富集。鹰山组与蓬莱坝组细晶—中晶白云岩具明显Eu负异常。
Based on the test data of thin slices, stable carbon and oxygen isotopes, trace elements and other test data, the Bachu Dabantag and Middle Aoxue Penglaoba Dam Middle-Lower Ordovician carbonates were systematically studied and systematically reported various kinds of petrology and geochemistry Characteristics of the diagenetic environment characterized by different characteristics. The results show that: (1) The carbon and oxygen isotopes are vertically buried in the diagenetic environment. The top of the Yingshan Formation and the middle and top of the Penglaibao Formation show the features of freshwater diagenesis. The bottom of the Yingshan Formation and the Penglai Dam Formation is characterized by seawater diagenesis In the lower part and the upper part of Yingshan Formation, seawater diagenesis environment is affected by freshwater in the lower part of the seafloor. The δ 18 O value and δ 13 C value of dolomite are higher than those of limestone and Yingshan Formation dolomite δ ~ ( 13) The C value is lower than that of the Penglai Dam dolomite; (2) The Sr content of different types of dolomites shows regularity. The enrichment of environmental sensitive elements in the Yingshan Formation - coarse crystalline dolomite and Penglaiba Formation top powder - fine crystalline dolomite, the oxidation of environmental sensitive elements enrichment in the Yingshan Formation algal sandstone cloud dolomite, Penglai dam group thin Crystal folder self-crystalline medium dolomite and silt phantom dolomite; (3) dolomitization process is LREE depletion process. A group of bioclastic limestone with a higher ΣREE, MREE slightly enriched, Ce negative anomaly, the lower part of the Penglai Dam residual REE distribution of dolostone succession granular limestone. The Yingshan Formation lower algae dolomitic sandstone limestone is similar to the dolomitic limestone REE distribution. ΣREE tends to decrease with the increase of water depth. LREE enrichment, HREE loss and Gd anomaly. Yingshan Formation - coarse crystalline dolomite and Penglaibang top of the powder - fine crystalline dolomite REE with similar points, MREE enrichment. The Yingshan Formation and Penglaiba Formation fine-grained dolomite have obvious Eu anomalies.