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首页> 外文期刊>Journal of sedimentary research >SUBLACUSTRINE GEOMORPHOLOGY AND MODERN SEDIMENTATION IN A GLACIAL SCOUR BASIN, JUNE LAKE, EASTERN SIERRA NEVADA, USA
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SUBLACUSTRINE GEOMORPHOLOGY AND MODERN SEDIMENTATION IN A GLACIAL SCOUR BASIN, JUNE LAKE, EASTERN SIERRA NEVADA, USA

机译：揭开冰川池，六月湖，东部塞拉尼亚，美国的冰川地貌和现代沉降

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摘要

Small sub-alpine glacial lakes are often targeted as Holocene paleoclimate archives, but their evolution as landforms and depositional basins is understudied. At June Lake in the eastern Sierra Nevada of California (USA), bathymetry, surface sediment composition, and seismic stratigraphy are studied to assess the modern sedimentary system and gain insight into the basin's origins. A basin-wide seismic survey reveals sublacustrine morphological features that attest to the role of ice in scouring the June Lake basin, including a prominent abraded bedrock shoal and an adjacent overdeepened depression. The seismic survey reveals four acoustically distinct stratigraphic units that reflect the history of sedimentation following glacial scouring. The youngest of these is represented in the recovered lacustrine core records as hemipelagically deposited, organic-rich, laminated diatomaceous oozes alternating with coarse tephra beds. The organic-rich oozes are characterized by low carbon and nitrogen stable-isotope values and occur in profundal areas of the modern lake floor. These sediments suggest an algae-dominated productivity regime and preservation of organic matter at depth. With no perennial streams entering June Lake, surface-sediment grain-size distribution and geochemistry are controlled by water depth and basin morphology. Additional modern facies types include poorly sorted coarse detrital landslide deposits below steep basin walls and volcaniclastic sandy gravel in windward littoral areas. These data provide a modern facies model for sedimentation in ice-scoured, hydrologically closed sub-alpine lakes and a baseline for future paleoclimate studies using June Lake sediment cores.
机译：小亚高山冰川湖泊往往是全新的古古怪档案，但他们被视为地貌和沉积盆地的演变。在June Lake在加利福尼亚州的东部塞拉尼亚（美国），沐浴浴，表面沉积物组成和地震地层，以评估现代沉积系统，并进入盆地的起源。一个盆地地震调查显示出证明冰在炼制六月湖盆地的作用，包括突出的磨损基岩浅滩和邻近的过度过度抑郁症。地震调查显示了四个声学上不同的地层单位，反映了冰川冲刷之后沉淀的历史。这些中最小的是在回收的湖泊核心记录中表示，作为血管沉积的有机含量的富含层压的硅藻土渗漏，与粗Tephra床交替。富含有机的渗漏的特征在于低碳和氮稳定同位素值，并发生在现代湖底的丰道地区。这些沉积物表明了一种藻类统治的生产力制度和深度有机质的保存。没有进入6月湖的多年生溪流，表面沉积物粒度分布和地球化学受水深度和盆地形态控制。额外的现代面部类型包括陡峭的盆地墙壁和迎风区宽敞地区的粗碎屑垫层沉积物。这些数据提供了一种用于冰冲刷，水文封闭的亚高山湖泊沉降的现代相板模型，以及使用六月湖沉积物核心的未来古气候研究的基准。

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