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洪浩尔舒特凹陷下白垩统近岸水下扇沉积特征
Sedimentary Characteristics of Near-shore Subaqueous Fans of the Lower Cretaceous in the Honghaoershute Depression
【摘要】 通过对岩芯、录井、测井及地震等资料的综合分析,明确了洪浩尔舒特凹陷陡坡带下白垩统近岸水下扇的沉积序列、展布特征、演化规律及扇体发育的控制因素。本区近岸水下扇可被划分为内扇、中扇及外扇三个亚相,主要发育具块状层理、递变层理的碎屑支撑中、细砾岩,具鲍马序列的浊积岩以及具滑塌构造的滑塌岩,另可见到震积岩。扇体自早白垩世阿尔善组沉积晚期开始发育,至腾一段时期规模达到最大且向北东迁移3.5 km左右;腾二段时期构造活动减弱,湖盆开始萎缩,扇体规模随之缩小,且至腾二段末期扇体逐渐向扇三角洲沉积过渡。近岸水下扇的沉积特征及其分布演化规律主要受控于该区多期强烈的构造活动和潮湿炎热的古气候因素。陡坡带发育的板式边界断层,断面陡峭平直、活动剧烈,为近岸水下扇的发育提供了有利的构造背景。
【Abstract】 The sedimentary characteristics,distribution characteristics,evolution laws and the controlling factors of the development of the Lower Cretaceous near-shore subaqueous fan,located in the steep slope of the Eastern Honghaoershute depression,were defined clearly based on the integrated information including cores,well-logging,logging and seismic data. The results show that three kinds of sub-facies,including upper fan,mid-fan and lower fan,can be identified in the nearshore subaqueous fan in the study area,the glutenite deposition is the most important deposition,including massive or grading middle-fine clast-supported conglomerate,turbidite bearing Bouma Sequence and slumps with slump structures. Besides,we also can find some seismite deposition. In the study area,the subaqueous fan began to develop from the upper part of the Aershan Formation,and it became the largest and shifted towards the north-east at the lower part of Tengger Formation by 3.5 km,however,the scale of the fan in the upper part of the Tengger Formation began to reduce with the weak of the tectonic activities and the shrink age of the basin and then the subaqueous fan became gradually changing into fan-delta deposition. The sedimentary characteristics,distribution and evolution laws were controlled by the multiple-staged tectonic activities and the palaeo-climates,which was hot and humid. The plate type boundary fault which is steep and active provides the favorable tectonic setting for the development of the near-shore subaqueous fans in the steep slope.
【Key words】 near-shore subaqueous fan; sedimentary characteristics; controlling factors; Lower Cretaceous; Honghaoershute depression;
- 【文献出处】 沉积学报 ,Acta Sedimentologica Sinica , 编辑部邮箱 ,2015年03期
- 【分类号】P618.13
- 【被引频次】5
- 【下载频次】327