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首页> 外文期刊>Geological Society of America Bulletin >Deglacial and postglacial sedimentary architecture in a deeply incised paleovalley-paleofjord-The Pennsylvanian (late Carboniferous) Jejenes Formation,San Juan,Argentina
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Deglacial and postglacial sedimentary architecture in a deeply incised paleovalley-paleofjord-The Pennsylvanian (late Carboniferous) Jejenes Formation,San Juan,Argentina

机译：深度切开的古欧弗利-古峡湾-阿根廷圣胡安的宾夕法尼亚州（石炭纪晚期）杰耶尼斯组的冰期和冰期后沉积构造

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摘要

Quebrada de las Lajas,near San Juan,Argentina,preserves an early Pennsylvanian deglacial-postglacial succession in a highly confined paleofjord setting.The sedimentary succession records four distinct stages in the evolution of the valley fill.Stage 1 is represented by the deposits of subglacial diamic-tites,ice-contact deltas,and related deep-water lacustrine environments,including several subaqueous channels.Stage 2 records a glacio-eustatic marine transgression,and a slow-down of the clastic supply into the paleofjord.Stage 3 records a sandy,confined turbidite environment.Stage 4 consists of a coarse-grained delta,which represents a significant rejuvenation of the sedimentary system in the paleofjord.The transition from stage 1 to stage 2 was abrupt and basinwide,and has proven to be a good regional correlation marker.In this paleovalley,the glacio-eustatic rise probably caused floating and consequent rapid melting of the valley glacier.This resulted in a paleovalley-wide turbidite event that is up to 5 m thick and indicates an overall waning character.The rapid sediment emplacement in this event and resulting loading of the paleovalley sediments may have helped cause widespread mass-transport events at the stage 1-2 boundary.All stages show evidence of mass-transport-related deposits,but stage 1 records the most widespread mass transport,with a large spectrum of processes represented,including coherently slumped material,rafted blocks,and completely mixed debris-flow deposits.These mass-transport deposits range from a few meters to over 50 m thick,and up to hundreds of meters wide and long.Most of the large mass-transport deposits in the lower part of the fjord fill occurred at the transition to stage 2,implicating a rise in relative sea level as a possible trigger for the slope failures.Additionally,stage 3 deposits were affected by several thrust-sense dislocations that have large offsets relative to the scale of the sedimentary succession (tens to over 50 m vertically and hundreds of meters laterally); strata associated with the dislocations exhibit growth,indicating very early movement,and they are interpreted as the frontal ramp zones of mass-transport deposits.The abundance and size of mass-transport deposits in stages 1 and 3 helped control sediment pathways throughout the paleofjord.
机译：阿根廷圣胡安附近的奎布拉达·德·拉斯·拉哈斯（Quebrada de las Lajas）保留了宾夕法尼亚州早期的冰川-冰期-后冰期演替，处于高度狭窄的古峡湾环境。沉积演替记录了河谷填充物演化的四个不同阶段。钙钛矿，冰接触三角洲和相关的深水湖泊环境，包括几个水下通道。阶段2记录了冰川向海洋的海侵作用，碎屑供应减慢到了峡湾。阶段3记录了砂质。第4阶段由一个粗颗粒的三角洲组成，代表了古峡湾沉积系统的显着复兴。从第1阶段到第2阶段的过渡是突然的和流域范围的，并已证明是良好的区域相关性在该古卵谷中，冰川向水平面的上升可能导致山谷冰川漂浮并因此迅速融化。这导致了整个古卵谷中的浑浊厚达5 m的事件表明总体特征减弱，该事件中快速的沉积物沉积以及由此引起的古卵形沉积物的加载可能有助于在1-2阶段边界处引起大规模的物质传输事件。大量与运输有关的沉积物，但第1阶段记录了最广泛的大规模运输，所代表的过程范围很广，包括相干塌陷的物料，筏块和完全混合的泥石流沉积物。几米到50 m以上的厚度，以及长达几百米的宽度和长。峡湾填充物下部的大部分大型输运沉积物发生在第二阶段的过渡期，这意味着相对海平面上升。此外，第3阶段沉积物还受到数种逆向感测位错的影响，这些位错相对于沉积演替的规模有较大的偏移量（数十到50兆伏在垂直方向上和在侧面数百米处）;与位错相关的地层显示出增长，表明运动很早，并且被解释为大量沉积物的前斜坡带。第一和第三阶段大量沉积物的数量和大小有助于控制整个峡湾的沉积物路径。

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