沉积物体积分配原理——高分辨率层序地层学的理论基础

基准面旋回期间沉积物以不同体积被分配到不同相域的过程及其伴随的可容纳空间的变化称为“沉积物体积分配” ,它反映了沉积过程响应系统遵循物质保存定律。沉积物体积分配在地层记录中的沉积学和地层学的响应表现为 :( 1)地层旋回的对称性随时间和空间的变化 ;( 2 )反映原始地貌要素保存程度的相分异作用 ;( 3)进积 /加积地层单元的叠加样式。这些沉积学与地层学属性无一不是高分辨率层序地层划分与对比的基础。根据沉积物体积分配原理 ,正确的年代地层对比应该是有时岩石与岩石、有时岩石与界面或界面与界面的对比 ,而不是等厚度对比和岩性地层对比。鄂尔多斯盆地上古生界海陆过渡相和渤海湾裂谷盆地东营组湖相沉积的地层对比说明了沉积物体积分配的过程及其在高分辨率地层划分和对比中的应用。

SEDIMENT VOLUME PARTITION PRINCIPLE: THEORY BASIS FOR HIGH-RESOLUTION SEQUENCE STRATIGRAPHY

Sediment volumes into different facies tracts during base|level cycles and accompanied accommodation changes are termed “sediment volume partition”, which reflects that stratigraphic process|response system obeys mass conservation law. Stratigraphic and sedimentary response of sediment volumetric partition includes: (1) the variation of symmetries of stratigraphic cycles with time and space;(2)facies differentiation reflecting degree of original geomorphic elements;(3)stacking patterns of progradational/aggradational stratigraphic units. Correct chronostratigraphic correlation should be that of rocks to rocks, rocks to surfaces or surfaces to surfaces according to sediment volumetric partition. High|resolution stratigraphic correlation frame in transition facies of Upper Paleozoic, Ordos Basin, and in lacustrine facies of Dongying Fm., Bohai Bay Basin illustrates volume partition process and its application.