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首页> 外文期刊>Brazilian Journal of Geology >Seismic expression of depositional elements associated with a strongly progradational shelf margin: northern Santos Basin, southeastern Brazil
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Seismic expression of depositional elements associated with a strongly progradational shelf margin: northern Santos Basin, southeastern Brazil

机译：与强积架边缘相关的沉积元素的地震表达：巴西东南部的桑托斯盆地北部

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Seismic facies analysis and seismic geomorphology are important tools for the analysis of depositional elements in subsurface. This paper aimed to investigate the character and genesis of depositional elements and erosive features associated with an Eocene progradational shelf margin in northern Santos Basin. Identified seismic facies are interpreted as shelf-margin deltas/shoreface deposits, tangential (oblique) clinoforms, sigmoidal clinoforms, topset reflectors, mass-transport deposits and turbidites. These facies are grouped into four associations representing periods of relatively constant environmental conditions. Association 1 is composed of shelf-margin deltas/shoreface deposits, tangential clinoforms and extensive sand-rich turbidites disposed as submarine channels and frontal splays. A progressive increase in clinoform angle within this association has been identified, culminating in high-relief sigmoidal clinoforms with less voluminous turbidites of facies association 2. Association 3 is composed by subparallel to divergent topset reflectors, interpreted as continental to shelfal deposits placed during base-level rises. These are always truncated basinward by slump scars, formed as a consequence of sediment overload at the shelf margin during aggradations. Association 4 is composed of sigmoidal clinoforms, mass-transport deposits and turbidites. Early clinoforms are steeper as a consequence of the topography of the slump scars. Subsequently, dip angles become progressively gentler as the system approach to the equilibrium profile. The steep physiography was favorable for canyon incision, which played an important role in turbidite deposition. Mass-transport deposits, formed subsequent to slope collapse, are composed of mud-rich diamictites, and show strong internal deformation.
机译：地震相分析和地震地貌学是分析地下沉积元素的重要工具。本文旨在调查与北部桑托斯盆地始新世的陆架边缘相关的沉积元素的特征，成因和侵蚀特征。识别出的地震相被解释为陆缘三角洲/海岸沉积，切向（斜）斜斜形，S形斜斜形，顶反射体，大量沉积物和浊质。这些相分为四个关联，分别代表相对恒定的环境条件时期。协会1由陆缘三角洲/海岸沉积物，切向斜斜形和大量富含沙子的浊质组成，它们被设置为海底通道和额叶。已确定该组合中斜形角度逐渐增加，最终形成了高浮雕的乙状斜形，且相缔合体2的浊度较小。组合3由平行于发散的顶反射体组成，解释为陆基沉积至陆架沉积。级别上升。这些总是被塌陷疤向盆地截断，塌陷疤痕是由于沉积过程中架子边缘的沉积物超载而形成的。关联4由S型斜线形，大量沉积物和浊石组成。由于塌陷疤痕的地形，早期的斜形陡峭。随后，随着系统接近平衡曲线，倾角逐渐变得平缓。陡峭的地貌有利于峡谷切割，这在浊积岩沉积中起着重要作用。边坡坍塌后形成的大量输运沉积物，由富含泥浆的铁矾土组成，并表现出强烈的内部变形。

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