东岭地区营城组沉积层序与沉积相辨析

IDENTIFICATION AND ANALYSES OF THE STRATIGRAPHIC SEQUENCES AND DEPOSITIONAL FACIESES OF YINGCHENG FORMATION IN DONGLING AREA

东岭地区营城组由陆源碎屑沉积岩和火山岩夹层组成，陆源碎屑岩被火山岩分隔成2个三级层序，下部层序1位于火山岩下部，发育不完善，由薄层陆源碎屑岩组成，与下伏火石岭组呈明显角度不整合；上部层序2陆源碎屑岩发育较厚，是以火山岩顶面以及对应的沉积（不）整合面为层序界面的完整三级层序，发育低水位体系域、水进体系域、高水位体系域和强制水退体系域，相应沉积相类型主要为湖泊相、冲积扇相、水下冲积扇相以及辫状河三角洲相。与地壳沉积基准面升降旋回变化响应的沉积层序和沉积相实体共同演绎着东岭地区营城组的沉积演化历史。

Yingcheng Formation in Dongling area is composed of terrestrial clastic sedimentary rocks and volcanic intercalations, and the former is divided into two 3rd sequences by the later; the lower sequence-1 is composed of poor-developed thin terrestrial elastic rocks, which is below the volcanic rock and shown evident unconformity with the underlying Huoshiling Formation; the upper sequence-2 is a complete 3rd sequence, which has well-developed thick terrestrial elastic rocks and takes the top surface of volcanic rock and the correlative conformity or unconformity as the stratigraphic interfaces, and furthermore consist of lowstand system tract （ LST ） , transgressive system tract （ TST ）, highstand system tract （ HST ） and forced regressive system tract （ FRST ） ; their correlative sedimentary facieses include lacustrine, alluvial fan, subaqueous alluvial fan and braid river delta facieses. Both stratigraphic sequences and sedimentary facies that are associated with the changes of the base-level rising-falling of the crust to-gether dominate the depositional and evolutionary histories of Yingcheng Formation in Dongling area.