Neotectonics and Climatic History of the Central Andes: High-Resolution Seismic Reflection Imaging of the Salar de Uyuni

9815062 McGeary这项研究涉及采集一套横跨玻利维亚高原乌尤尼盐湖的高分辨率地震反射剖面。 这个盐沼是世界上最大的盐滩，是晚更新世Minchin-Tauca湖的明显遗迹。 该项目有两个主要目标：（1）通过对300-500米深处的湖泥灰岩和盐层间层成像，为Altiplano南部盆地内的更新世沉积物提供地层和古气候记录;（2）记录第四纪湖泊地层受新构造变形影响的程度，无论是均衡反弹还是活动断裂横跨100公里宽的盐湖。 地震剖面将揭示重要地层边界的深度，预计主要反映在从盐沼下方回收的唯一深（120米）岩心中看到的交替泥灰岩和盐层。 泥灰岩沉积在深湖循环的稳定阶段（约100米水深），盐沉积在深湖循环的终止，当湖平面低或下降。 现在的盐湖表面在100 × 100公里的区域内平坦到1米以内。 埋藏盐单元顶部深度的横向变化主要反映了湖水和沉积物负荷的均衡响应，以及新构造变形的未知成分。 这些数据将解决的一个重要难题是，与最高的盐单元（向东变厚）和最高的明钦湖海岸线（向西倾斜）相关的区域倾斜的不协调指标。

9815062McGearyThis research involves the acquisition of a set of high-resolution seismic reflection profiles across the Salar de Uyuni in the Altiplano of Bolivia. This salar is the largest salt flat in the world and is a conspicuous remnant of the late Pleistocene Lake Minchin-Tauca. The project has two major objectives: (1) to produce a stratigraphic and paleoclimate record for Pleistocene deposits within the southern basin of the Altiplano by imaging interbedded layers of lake marls and salar salt down to depths of 300-500 meters and (2) to document the extent to which the Quaternary lake stratigraphy is affected by neotectonic deformation in the form of either isostatic rebound or active faulting across the 100-km wide salar. The seismic profiles will reveal depths to significant stratigraphic boundaries, which are expected to chiefly reflect the alternating marl and salt layers that were seen in the only deep (120 m) core that has been recovered from beneath the salar. The marl is deposited during stable phases of deep lake cycles (approximately 100-m water depth) and the salt is deposited during terminations of deep lake cycles, when lake level is low or falling. The present salar surface is flat to within 1 m over a 100 by 100-km area. Lateral variations in depth to the tops of buried salt units will mostly reflect isostatic response to lacustrine water and sediment loads, and an unknown component of neotectonic deformation. One of the significant puzzles these data will address is the discordant indicators of regional tilting associated with the uppermost salt unit, which thickens to the east, and the highest Lake Minchin shoreline, which tilts down to the west.