Contrasting sedimentary processes along a convergent margin: the Lesser Antilles arc system
Contrasting sedimentary processes along a convergent margin: the Lesser Antilles arc system
复制标题
沿汇聚边缘对比沉积过程：小安的列斯群岛弧系统
DOI：
10.1007/s00367-006-0046-y
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发表时间：
2006
影响因子：
2.1
通讯作者：
G. Boudon
中科院分区：
文献类型：
--
作者：
M. Picard;J. Schneider;G. Boudon
小安的列斯群岛岛弧很好地说明了发生在活跃会聚环境中的沉积过程。边缘与北美和/或南美板块向西俯冲到加勒比板块之下有关。从东到西，弧可细分为几个构造-沉积域：增生棱柱体，弧前盆地，弧台和弧间盆地，格林纳达弧后盆地。格林纳达弧后盆地、弧前盆地（托巴哥海槽）和火山弧东侧的增生棱柱体构成了弧台和南美大陆来源颗粒的圈闭。火山弧是火山活动的，提供了大量的火山碎屑沉积物，这些沉积物主要通过火山碎屑重力流（火山碎屑雪崩、碎屑流、浊流）积聚在格林纳达盆地，少量通过沉降物积聚。相比之下，边缘的东侧则由火山灰沉降物和小型火山碎屑浊积岩提供。在这一地区，沉积物的主要成分是远洋起源，或来自南美洲（硅质浊积岩）。岛屿架是碳酸盐沉积的位置，例如在边缘北方的石灰岩加勒比海中发育的大型台地。浊流对碳酸盐物质的改造也使边缘东部盆地的数量减少。这种弧台两侧沿着边缘形成的沉积对比是由几个相互作用的因素控制的，包括盆地形态、火山生产力、风和深海流模式以及海平面变化。盆地形态似乎是最主要的因素。弧形台地的西坡比东坡陡，因此有利于重力流过程。
Sedimentation processes occurring in an active convergent setting are well illustrated in the Lesser Antilles island arc. The margin is related to westward subduction of the North and/or the South America plates beneath the Caribbean plate. From east to west, the arc can be subdivided into several tectono-sedimentary depositional domains: the accretionary prism, the fore-arc basin, the arc platform and inter-arc basin, and the Grenada back-arc basin. The Grenada back-arc basin, the fore-arc basin (Tobago Trough) and the accretionary prism on the east side of the volcanic arc constitute traps for particles derived from the arc platform and the South American continent. The arc is volcanically active, and provides large volumes of volcaniclastic sediments which accumulate mainly in the Grenada basin by volcaniclastic gravity flows (volcanic debris avalanches, debris flows, turbiditic flows) and minor amounts by fallout. By contrast, the eastern side of the margin is fed by ash fallout and minor volcaniclastic turbidites. In this area, the dominant component of the sediments is pelagic in origin, or derived from South America (siliciclastic turbidites). Insular shelves are the locations of carbonate sedimentation, such as large platforms which develop in the Limestone Caribbees in the northern part of the margin. Reworking of carbonate material by turbidity currents also delivers lesser amounts to eastern basins of the margin. This contrasting sedimentation on both sides of the arc platform along the margin is controlled by several interacting factors including basin morphology, volcanic productivity, wind and deep-sea current patterns, and sea-level changes. Basin morphology appears to be the most dominant factor. The western slopes of the arc platform are steeper than the eastern ones, thus favouring gravity flow processes.