Linked lowstand delta to basin-floor fan deposition, offshore Indonesia: An analog for deep-water reservoir systems
Linked lowstand delta to basin-floor fan deposition, offshore Indonesia: An analog for deep-water reservoir systems
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DOI：
10.1306/09030303003
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发表时间：
2004
期刊：
影响因子：
3.5
通讯作者：
A. Saller;Jesse T. Noah;Alif Prama Ruzuar;R. Schneider
中科院分区：
文献类型：
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作者：
A. Saller;Jesse T. Noah;Alif Prama Ruzuar;R. Schneider
在印度尼西亚东加里曼丹近海地区，三维地震反射镜可以追踪到从低洼三角洲到盆地底扇的下坡，从而深入了解沉积过程，这些沉积过程控制着许多古代深水环境中作为油气储集层的砂的分布。研究区间包括最近三个更新世旋回（10-330 ka，每110 ky）。陆架上的旋回主要是在高水位和上升海平面下降期间沉积的递进包体。平行反射体和海侵体系域的碳酸盐堆积分隔了递进包体。在最近的两个低洼期（18和130 ka），由于生长断裂和区域沉降阻止了低洼三角洲到达斜坡，粗碎屑没有沉积在深水环境中。在大约240 ka结束的海平面低潮期，一个三角洲在先前的陆架边缘推进，富含沙子的沉积物溢出到斜坡上。斜坡和盆地底部的地层显示了一个深水沉积体系是如何在海平面上升的单一旋回中演化的。斜坡上的峡谷将240 ka的低洼三角洲与同时期的盆地底扇连接起来。峡谷有一个弯曲的、分两部分的填充物，由一个下部的合并河道复合体和一个上部的河道-堤防复合体组成。坡脚处形成的盆底扇也由两部分组成。盆底扇地层下部的裂片较宽，反射面相对连续。地层上部为一条蜿蜒的河道-河堤复合体，在下部扇上推进，在最外层扇上供给片状裂片。斜坡上的合并河道填充物和盆底扇上的片状裂片具有中高振幅反射，推断为富砂的早期低洼沉积。斜坡和盆地底部的河道-堤防复合体以低振幅反射体为主，推断为晚低洼期富泥地层。与经典的层序地层模型不同，这些低洼地层并不覆盖在斜坡上；相反，深水碎屑从低地三角洲的最后一个斜形延伸而来。在这个系统中，低洼三角洲决定了富含沙子的沉积物何时何地进入斜坡上先前存在的峡谷，为盆地底扇提供食物。
In offshore East Kalimantan, Indonesia, three-dimensional seismic reflectors can be traced downslope from a lowstand delta to a basin-floor fan, giving insight into depositional processes controlling the distribution of sands that serve as hydrocarbon reservoirs in many ancient deep-water settings. The studied interval includes the last three Pleistocene cycles (10–330 ka; each 110 k.y. in duration). Cycles on the shelf are dominated by progradational packages deposited during highstands and falling eustatic sea level. Progradational packages are separated by parallel reflectors and carbonate buildups of the transgressive systems tracts. During the last two lowstands of sea level (18 and 130 ka), coarse clastics were not deposited in deep-water environments because growth faults and regional subsidence prevented lowstand deltas from reaching the slope. During the lowstand of sea level that ended at about 240 ka, a delta prograded over the previous shelf edge, and sand-rich sediments spilled onto the slope.Strata on the slope and basin floor show how a deep-water depositional system evolved during a single cycle of eustatic sea level. A canyon on the slope connects the 240-ka lowstand delta to a coeval basin-floor fan. The canyon has a sinuous, bipartite fill that consists of a lower, amalgamated channel complex and an upper channel-levee complex. The basin-floor fan formed at the toe of the slope also has two parts. The stratigraphically lower part of the basin-floor fan has broad lobes with relatively continuous reflectors. The stratigraphically higher part has a sinuous channel-levee complex that prograded over the lower fan and fed sheetlike lobes on the outermost fan. The amalgamated channel fills on the slope and sheetlike lobes on the basin-floor fan have moderate- to high-amplitude reflectors and are inferred to represent sand-rich, early lowstand deposits. The channel-levee complexes on the slope and basin floor are dominated by low-amplitude reflectors and are inferred to be mud-rich strata deposited during the late lowstand. Unlike classic sequence-stratigraphic models, these lowstand strata do not onlap the slope; instead, deep-water clastics extend from the last clinoforms of lowstand deltas. In this system, lowstand deltas determined when and where sand-rich sediments entered preexisting canyons on the slope to feed basin-floor fans.