沉积学报2025，Vol.43Issue(5)：1642-1664,23.DOI:10.14027/j.issn.1000-0550.2025.038
刍议"台内滩"
"Intraplatform Shoals":Discussion
摘要
Abstract
[Objective]The shoal carbonate facies are of particular interests in the petroleum industry due to their potential high porosity.This paper intends to discuss whether the intraplatform shoals could be developed or not in the context of the restricted,low-energy hydrodynamic condition within platforms.[Methods]This study initially reviews the hydrodynamic conditions and facies zonation within modern platform interiors of different types,then examines the depositional environments/facies of Lower Paleozoic intraplatform grainstones in the Tarim Basin,and finally dis-cuss the artificial pitfall created likely by resetting of vertically-stacked,but laterallys-offset marginal shoal facies de-veloped in different time intervals as the intraplatform shoals within a low-resolution time framework when performing paleogeographic reconstruction.[Results and Conclusions](1)The positive seafloor reliefs of platform margins(whether rimmed margins or ramp margins)are acted as the main barriers upon which the platformward propagation of open marine wave currents was mostly blocked by the seafloor friction and subsequent wave surge and breaking,leading to an overall restricted low-energy condition in the back-shore platform interior.In this case,the positive reliefs within lagoons tends to result in island-like tidal flats(or tidal islands)rather than sandy shoals.(2)Grain-stones,or even conglomerates present in platform interior successions are potentially deposited in two depositional en-vironments:(a)in relatively large,deep back-shoal restricted lagoons,strong storm-induced density flows are trans-ported downdip below the storm wave base,resulting in sheet-or fan-shaped grainy tempestite beds dominated by well-sorted peloids with preserved hummocky and/or swaley cross stratification and/or graded bedding;(b)in the branching tidal channels/creeks that cut into the tidal flat,laying down intraclastic gravels or sands derived from sur-rounding microbial mats along the channel levees.thereby forming channelized microbial grainstone/conglomerate bodies with laterally or bidirectionally inclined bedding and local lag pebble deposits.(3)When reconstructing litho-facies paleogeography within a low-resolution time framework,an intraplatform shoal pattern could be artificially cre-ated by resetting the vertically-stacked and laterally-offset marginal shoals of different time intervals into the platform interior regime,if ignoring facies diachronicity,i.e.,in different parasequence sets(or systems tracts).Therefore,cautions should be paid to facies analysis on the grainy deposits of platform interior successions on the basis of sound scientific knowledge and solid observations,otherwise misleading interpretations would result in misunderstanding for the real facies patterns.关键词
碳酸盐台地内部/潟湖/潮坪/颗粒岩/风暴沉积/潮道Key words
platform interior/lagoon/tidal flat/grainstone/storm deposit/tidal channel分类
天文与地球科学引用本文复制引用
陈代钊,郭川,杨钹,丁一,唐攀,韩俊..刍议"台内滩"[J].沉积学报,2025,43(5):1642-1664,23.基金项目
多圈层相互作用的油气富集理论项目(THEMSIE04010101) （THEMSIE04010101）
国家重点研发计划(2017YFC0603103) （2017YFC0603103）
中国石油化工股份有限公司西北分公司委托项目(34400008-16-ZC0607-008)Project of Theory of Hydrocarbon Enrichment under Multi-spheric Interactions of the Earth,No.THEMSIE04010101 （34400008-16-ZC0607-008）
National Key Research and Development Program of China,No.2017YFC0603103 （）
SINOPEC Northwest Oil Company-sponsored Project,No.34400008-16-ZC0607-008 （）
