济阳坳陷古近纪孔店组

一一沙四下亚段沉积期的原型盆地格局

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中图分类号：P618.130.2;TE121.1 文献标志码：A

Abstract：Basedonthe latest3Dseismicanddrilingdata，thisstudyreconstructs thesyndepositional tectonic framework， strataerosion thickness，andoriginalthickness，andcombind withtheregional tectonicbackground，clarifiestheprototype basin during the depositional period from the Ek Formation to the lower member of the Es4 Formation. The results show that the remaining strata from the Ek Formation to the lower Es4 member can be subdivided into four tectonic sub-layers：the third，second，and first members of Kongdian Formation，and the lower member of the Es4 Formation.From bottom to top， thedistributionrangeofresidualstrataincreases，whiletheir structural separationdecreases，reflectingthecombinedffects of originaldepositionandsubsequent erosion.During thedeposition periodofthethirdmemberof the Kongdian Formation， theJiyang Depresion exhibitedtwosmall，localized sub-sags，influencedbyLate Mesozicpaleogeomorphologyandanitial extensional tectonicsettng.Intheperiodof thesecondmember，theJiyangDepresionevolved intoanisolated，deperfault basin under a graduall intensifying extensional regime，which can be divided into three major deposition areas：the northeastern Zhanhuasag，the northeasternDongying sag，andthe southwestern Dongying-Huimin sag.With the depositionof the first member，the Jiyang Depresionfurtherdeepened，thedepositionalarea expanded，andstructuralsegmentation weakened under stronger extensional forces.During the deposition of the lower member of the Es 4 Formation， faulting continued and the lakebasin further expanded.The tectoniccharacteristicsand prototypebasinconfigurationofthe Jiyang Depresiondurig the deposition of the Kongdian Formation and lower Es4 member were both inherited from pre-existing Late Mesozoic structures， whilealso exhibiting unique features.Thesestrataexperienced significantpost-depositionaldenudation，mainlycontrolld by thefaultblocktiltingandgentleslopeupliftasociatedwithlateractivefaultstrending nearEWandNEdirection.All tectonic sub-layer tops show evidence of substantial erosion，with the denudation of the lower Es4 member being particularly widespread.

Keywords：prototype basin；sedimentary period of Ek Formation and the lower member of Es4 ；strata deposition and erosion; fault control basin； Jiyang Depression

渤海湾盆地新生代经历多幕式的构造演化，其中古近纪末期（ 23.3Ma ）和古近纪早期均存在显著的构造转型[1]，前者已为众多学者所认同，而后者目前还存在一定分歧，具体表现在： ① 转型的时限，目前存在沙四下亚段沉积末期、沙四段沉积末期[沙三段沉积末期4等观点； ② 转型前的活动断裂，主要有 NW 向断裂活动为主[5]、NW向 NE 向断裂转型[3]、NE向断裂活动为主[]等; ③ 转型前的区域伸展方向，主要有近 NS向[2]、NW-SE向[7-9]等，Zhu 等[10]认为古新世—早始新世在兰聊断裂以西主要为NW-SE向，而在兰聊断裂以东则为近NS向。（剩余17608字）