藏南古错地区上侏罗统上部和下白垩统沉积相?

基于野外剖面和室内沉积学研究，对古错地区侏罗纪末期-早白垩世地层进行详细描述和修订，识别出6种主要岩相类型：红褐色（风化色）石英砾岩、灰色－黄绿色岩屑砾岩、灰白色石英砂岩、灰色－黄绿色岩屑砂岩、灰色－黄绿色长石岩屑砂岩、灰色、深灰色、黑色页岩。发现粒序层理、水平层理、平行层理、板状交错层理、丘状交错层理等层理构造、波痕和槽模层面构造、重荷模和砂岩岩墙变形构造以及侵蚀面构造、叠瓦状构造、硬底、结核等沉积构造和生物遗迹。识别出三角洲（包括三角洲前缘亚相和前三角洲亚相）和陆棚（包括受风暴影响的陆棚相亚相和深水陆棚相亚相）两类沉积相，其中三角洲前缘亚相进一步划分为水下分流河道、分流河口砂坝和远砂坝等微相。建立了侏罗纪末期-早白垩世沉积相序及其演化，并在此基础上分析了沉积环境变化。

Sedimentary facies of the uppermost Jurassic and Lower Cretaceous in Gucuo area, southern Tibet

Based on the detailed field observation and sedimentological studies,the strata of the Late Jurassic-Early Cretaceous in the Gucuo area,southern Tibet were described and amended. Six types of lithofacies were recognized including rufous(weathered color) quartzose conglomerates,gray greenish pyroclastic conglomerates,gray-whitish sandstones,gray-greenish pyroclastic sandstones,gray-greenish lithic arenite,gray and dark gray black shales. Many sedimentary structures were discovered including normal grading beds,parallel lamination,planar cross-bedding,low-angle cross bedding,hummocky cross-bedding,ripples,flute cast,load casts,sandstone dikes,erosion surface,imbrications,hard grounds,as well as lots of concretions and bioturbations. Two types of sedimentary facies were recognized in the Gucuo area,i.e.delta (including delta front and prodelta) and shelf (including storm-influenced shelf and open deep shelf). The delta front facies can be further divided into subaqueous distributary channels,mouth bar,and far bar. The vertical facies association of the Gucuo section was established,which allows us to discuss the evolution of the sedimentary environments.