Sequence Stratigraphic Distribution Analysis of Methane-hydrate-bearing Submarine-fan Turbidite Sandstones in the Eastern Nankai Trough Area: Relationship between Turbidite Facies Distributions and BSR Occurrence
Sequence Stratigraphic Distribution Analysis of Methane-hydrate-bearing Submarine-fan Turbidite Sandstones in the Eastern Nankai Trough Area: Relationship between Turbidite Facies Distributions and BSR Occurrence
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南海海槽东部地区含甲烷水合物海底扇浊积砂岩层序地层分布分析：浊积岩相分布与BSR发生的关系
DOI：
10.5026/jgeography.118.776
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
T. Saeki
中科院分区：
文献类型：
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作者：
O. Takano;Mizue Nishimura;T. Fujii;T. Saeki
由于前期研究表明南海海槽东部地区甲烷水合物大部分赋存于浊积岩砂岩基质孔隙中，浊积砂岩相分布可能是评价南海海槽东部地区甲烷水合物分布和实际体积的重要关键之一。本文尝试重建海底扇浊积岩的沉积过程，并利用沉积学和层序地层学方法研究了浊积岩相分布与作为甲烷水合物代理的底部模拟反射体（BSR）产状之间的关系。首先，利用2D/3D地震勘探数据和井数据（包括岩心和测井数据）来识别浊积岩相、地震相和沉积层序。目标上里欧-更新世挂川群和小笠群可分为 17 个沉积层序，包括 6 个地震相，表明海底扇元素和周围斜坡到盆底环境。接下来，通过绘制地震相、3D 地震地貌和井相数据的所有信息来创建每个沉积层序单元的相图。获得的相图显示，11 个主要海底峡谷充当了来自日本大陆的位置固定的沉积物供应系统，沿着这些系统，在弧前盆地中形成了海底扇。上更新世海底扇沉积类型从辫状河道类型，经过小型径向扇、槽充式扇和泥质片扇类型，转变为河道-堤坝系统类型。最后，将每个沉积层序的相图与BSR分布进行叠加。重叠图表明 BSR 发生在海底扇的支流河道、分流河道和近叶上，表明甲烷水合物选择性地发生在海底扇的粗粒部分。由于挂川群下部主要由辫状河道型海底扇浊积岩组成，挂川下部层位是南海海槽东部地区甲烷水合物的主要层位之一。
Since previous research revealed that most of the methane hydrates in the eastern Nankai Trough area occur in matrix pores of turbidite sandstones, the facies distribution of turbidite sandstones may be one of the important keys to evaluate the distributions and actual volume of methane hydrates in the eastern Nankai Trough area. This paper attempts to reconstruct depositional processes of submarine-fan turbidites, and examines the relationship between turbidite facies distributions and bottom simulating reflector (BSR) occurrence as a proxy of methane hydrate using sedimentologic and sequence stratigraphic methodology. First, 2D/3D seismic survey data and well data including cores and logs were used to identify turbidite facies, seismic facies, and depositional sequences. The targeted Plio-Pleistocene Kakegawa and Ogasa Groups can be divided into 17 depositional sequences, and include six seismic facies indicating submarine-fan elements and surrounding slope to basin-floor environments. Next, facies maps for each depositional sequence unit were created by plotting all information on seismic facies, 3D seismic geomorphology, and well facies data. The obtained facies maps reveal that 11 major submarine canyons functioned as positionally fixed sediment supply systems from main land Japan, along which submarine fans were formed in the forearc basins. Submarine-fan depositional styles changed through Plio-Pleistocene from a braided channel type, through small radial fan, trough-fill fan, and muddy sheet fan types, to a channel-levee system type. Finally, the facies maps of each depositional sequence were overlaid with the BSR distribution. The overlaid maps indicate that the BSRs occur on feeder channels, distributary channels, and proximal lobes of submarine fans, suggesting that methane hydrates selectively occur in coarser grained portions of a submarine fan. Because the lower part of the Kakegawa Group is mainly composed of braided channel-type submarine fan turbidites, the lower Kakegawa horizon serves one of the major horizons bearing methane hydrates in the eastern Nankai Trough area.
日本中部滨松市外弧前斜坡的活动断层和构造（参考）
DOI：
--
发表时间：
2006
期刊：
Journal of the Geological Society of Japan 112-12
影响因子：
--
作者：
大森健太郎;妹尾大;Kosaku ARAI
通讯作者：
Kosaku ARAI