川东地区华蓥山海相三叠系不同类型岩石对海水信息的保存性评估  

The capabilities of different Triassic marine rock types for preservation of coeval seawater information in the Huaying Mountain of eastern Sichuan

作　　者：胡作维[1] 黄思静[1] 魏文文[1] 刘辉伦[1] 刘涛[1] 

机构地区：[1]成都理工大学油气藏地质及开发工程国家重点实验室,沉积地质研究院,四川成都610059

出　　处：《岩石矿物学杂志》2011年第2期208-214,共7页Acta Petrologica et Mineralogica

基　　金：国家自然科学基金资助项目(40839908,40672072);教育部博士点基金资助项目(20050616005)

摘　　要：通过对川东地区华蓥山海相三叠系不同岩石类型样品的微观组构、阴极发光和微量元素等分析表明:川东地区华蓥山海相三叠系不同的岩石类型样品具有不同的抵抗成岩蚀变能力,其对海水信息的保存程度也不一致;钙质泥岩所记录的有关信息已基本不能代表海水,多数微晶灰岩所记录的有关信息可以较好地代表海水,而粉晶白云岩只有部分样品可以代表海水的信息,同时传统上被认为更容易遭受成岩蚀变的颗粒灰岩反而出现低Mn、高Sr和弱阴极发光等特征,其可能与早期海水胶结作用或者深埋藏条件下封闭海源流体作用有关。Different types of marine carbonate rocks have different capabilities of resisting diagenetic alteration and preserving coeval seawater information.Aragonite and high-magnesium calcite minerals,for example,are liable to suffering from relatively strong diagenetic alteration,and their preservation of the coeval seawater information is therefore relatively poor;by contrast,low-magnesium calcite mineral has much better capability for preservation of the coeval seawater information.It is thus thought that the evaluation of marine samples of different rock types for their diagenetic alteration and preservation of the coeval seawater information is a necessary basic work in sedimentary geochemistry and chemostratigraphy.The analyses of rock fabrics,cathodoluminescence and trace elements of Triassic marine samples of different rock types from the Huaying Mountains of eastern Sichuan were conducted in this paper to evaluate their capabilities for resisting diagenetic alteration and preserving coeval seawater information.The results indicate that the calcareous mudstone samples show strong luminescence,their average Mn concentration is higher than 800×10-6,average Sr concentration is only 280×10-6,average Mn/Sr ratio is higher than 3.3,which is the highest average Mn/Sr ratio in all the samples of different rock types.The micrite samples mostly show extremely weak or weak luminescence,with only a few samples showing moderate or strong luminescence,their average Mn concentration is 213×10-6,average Sr concentration is 704×10-6,and average Mn/Sr ratio is 0.44.The very fine-crystalline dolomite shows relatively weak luminescence,their average Mn concentration is 119×10-6,average Sr concentration is 86×10-6,which is the lowest average Sr concentration in all the samples,and average Mn/Sr ratio is 1.46.The grainstone samples show no luminescence,their average Mn concentrations is only 4×10-6,which is the lowest average Mn concentration in all the samples,average Sr concentrations is 1 015×10-6,which is the highest aver

关 键 词：海水信息 碳酸盐 成岩蚀变 三叠系 川东地区 

分 类 号：P588.2[天文地球—岩石学] P595[天文地球—地质学]