Seismic stratigraphy, buried beach ridges and contourite drifts: the Late Quaternary history of the closed Lago Cardiel basin, Argentina (49°S)
Seismic stratigraphy, buried beach ridges and contourite drifts: the Late Quaternary history of the closed Lago Cardiel basin, Argentina (49°S)
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地震地层学、埋藏的海滩山脊和等高线漂移：阿根廷封闭的拉戈卡迪尔盆地的晚第四纪历史（南纬 49°）
DOI：
10.1111/j.1365-3091.2004.00677.x
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发表时间：
2004
期刊：
影响因子：
3.5
通讯作者：
V. Markgraf
中科院分区：
文献类型：
--
作者：
A. Gilli;F. Anselmetti;D. Arizteguí;M. Beres;J. Mckenzie;V. Markgraf
报道了南美洲最南端封闭湖盆地拉戈卡迪尔 (Lago Cardiel) 的地震地层分析结果。从该地区获得的跨越晚第四纪的高分辨率大陆记录非常少。地震层序地层分析可以重建湖泊水位变化。盆地早期演化过程中出现了两次年龄不明的重大间断，在此期间在有限区域内沉积了冲积扇。随着晚更新世相对浅的湖泊的发展以及距今 11 220 14C yr BP 附近的短暂干燥脉冲，在全新世初期发生了超过 135 m 的海侵。这次海侵与海滩山脊的形成有关，这些海滩山脊保存在现代卡迪尔湖底部四个不同海拔的湖地层中。大部分未改造的海滩山脊的保存表明湖水位在逐步上升。没有地震证据表明在整个全新世期间，该湖的水位大幅下降到现代水平以下。全新世中期以来的沉积以沉积物堆积的强烈横向差异为特征，沉积中心略位于盆地中点以北，并呈明显的丘状分布。地震反射几何形状以及沉积学特征表明，湖相等高线漂移覆盖了 80-100km2 的面积。由于拉戈卡迪尔湖受到西风的影响，这些很可能推动了湖泊循环。淹没海滩山脊和等高线漂移的识别表明，高分辨率地震地层学不仅是重建封闭湖盆过去湖水位高程的有力工具，而且还可以提供有关湖水位变化率以及湖流的存在和强度的信息。
The results of a seismic stratigraphic analysis of a closed lake basin, Lago Cardiel, in southernmost South America are reported. Very few high‐resolution, continental records spanning the Late Quaternary have been obtained from this region. Seismic sequence stratigraphic analysis allows a reconstruction of lake level variations. Two major hiatuses of unknown age occurred during the early evolution of the basin with the deposition of an alluvial fan in a restricted area in the intervening time period. Following the development of a relatively shallow lake during the late Pleistocene and a short desiccation pulse around 11 220 14C yr BP, a transgression of over 135 m occurred at the beginning of the Holocene. The transgression was associated with the formation of beach ridges preserved in the lake stratigraphy on the floor of the modern Lago Cardiel at four different elevations. The preservation of largely unreworked beach ridges indicates a stepwise rise in the lake level. There is no seismic evidence of a major lowering of the lake below modern level during the entire Holocene. Deposition since the mid‐Holocene is marked by strong lateral differences in sediment accumulation with a depocentre slightly to the north of the basin midpoint and a pronounced mounded distribution. Seismic reflection geometries, as well as sedimentological characteristics indicate a lacustrine contourite drift covering an area of 80–100 km2. As Lago Cardiel is under the influence of westerly winds, these most likely drove lake circulation. The identification of drowned beach ridges and of contourite drifts illustrates that high‐resolution seismic stratigraphy is not only a powerful tool in reconstructing past lake level elevations for closed lake basins, but it can also provide information about the rate of lake level changes and the presence and strength of lake currents.