Study On The Genetic Mechanism Of Dolomite In The Ordovician Ma 5₅ Sub-segment In The Eastern Part Of Sulige

In rdos Basin in the lower Paleozoic of Majiagou formation, contains the largest marine carbonate strata in natural gas geological reserves, in recent years, in combination according to the gas field have been made in the exploration of data, it was found that, lower Paleozoic Ma 5 subinterval contains abundant natural gas reserves, but Ma 5 dolomite Genesis has been controversial, dolomite flat body distribution of clutter.The 5^th submember of 5^th member, Majiagou Formation in the intertidal supratidal zone Yun Ping, dolomite beach body like an island distribution. The main diagenetic processes are: the role of dolomite, the role of the gypsum and the role of the cloud, the role of the role of the formation of dolomite, compaction and pressure dissolution, dissolution, filling effect, recrystallization and the role of yellow iron mineralization, etc..The 5^th submember of 5^th member, Majiagou Formation in east of Sulige area of Ordos Basin is belong to the system of sedimentary environments such as supratidal zone and intertidal zone, in the uplifted positions of Sedimentary micro-geomorphology, threr deposited penecontemporaneous dolostone. seepage-reflux dolomitization and burial dolomitization prompted Dolomite into Crystalline dolostone. In terms of the ratio of Mn/Sr, the latter ranges from 5 to 8, which indicates that the Crystalline dolostone is resulted from intense diagenesis, meanwhile, That contents of Mn increased and contents of Sr decreased also manifests the truth that Dolomite turn into the direction of increasing order degree during the course of compaction and burial diagenesia. With the transformation of mineral phases, the 18o and 13c content in the minerals will gradually decrease, the ?18o of dolomicrite is between -7.40 to -5.77 percent, and the ?13c is between -1.88 to -1.04 percent, as to the Crystalline dolostone, its ?18o is between-11.07 to-8.78 percent,and ?13c is between -2.33 to -2.06 percent, which illustrates that the Crystalline dolostone is a result of dolomicrite throuth compaction and burial diagenesia. The sedimentary micro highlands of 5^th submember of 5^th member, Majiagou Formation is favorable area of Dolomit-beech Complex. In large scale, the condition of development of dolomite of 6th submember of 5^th member, Majiagou Formation controlled the distribution of sedimentary micro highlands of 5^th submember of 5^th member, Majiagou Formation, the former one's formation thickness and the latter one's thickness of dolomite is positive correlated, the position of the thicker formation of 6th submember of 5^th member, Majiagou Formation corresponds to the sedimentary micro highlands of 5^th submember,therefore, the 6th submember's formation thickness can be applied to depict the characteristic of sedimentary microrelief and predict the distribution of Dolomit-beech Complex of 5^th submember of 5^th member, Majiagou Formation, and eventrually keeping on enlarging the areas of exploration and development.