Moho map of South America from receiver functions and surface waves
Moho map of South America from receiver functions and surface waves
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DOI：
10.1029/2009jb006829
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发表时间：
2010-11
影响因子：
--
通讯作者：
S. Lloyd;S. Lee;G. França;M. Assumpção;M. Feng
中科院分区：
文献类型：
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作者：
S. Lloyd;S. Lee;G. França;M. Assumpção;M. Feng
[1] 我们估计了南美洲大约 40°S 以北的地壳结构和厚度。为此，我们分析了巴西东部部署的 20 个相对较新的临时宽带地震台的接收器功能。在分析中，我们包括远震和一些区域事件，特别是对于记录了很少合适地震的台站。我们首先使用两种不同的叠加方法估计地壳厚度和平均泊松比。然后，我们将新的地壳约束与之前接收函数研究的结果结合起来。为了插值站位置之间的地壳厚度，我们联合反演这些莫霍面约束、瑞利波群速度以及区域 S 和瑞利波形，以获得莫霍面深度的连续图。新的层析莫霍面图表明，莫霍面深度和莫霍面起伏随着前寒武纪地壳内的年龄而略有变化。地壳厚度和地质年龄之间的正相关性是否源自预插值点约束在很大程度上取决于所选择的接收器函数子集。这意味着仅使用预插值点约束（接收器函数）不足以对地质年龄的空间变化进行采样。新的莫霍面地图还揭示了亚马逊克拉通最古老核心下方异常深的莫霍面。
[1] We estimate crustal structure and thickness of South America north of roughly 40°S. To this end, we analyzed receiver functions from 20 relatively new temporary broadband seismic stations deployed across eastern Brazil. In the analysis we include teleseismic and some regional events, particularly for stations that recorded few suitable earthquakes. We first estimate crustal thickness and average Poisson's ratio using two different stacking methods. We then combine the new crustal constraints with results from previous receiver function studies. To interpolate the crustal thickness between the station locations, we jointly invert these Moho point constraints, Rayleigh wave group velocities, and regional S and Rayleigh waveforms for a continuous map of Moho depth. The new tomographic Moho map suggests that Moho depth and Moho relief vary slightly with age within the Precambrian crust. Whether or not a positive correlation between crustal thickness and geologic age is derived from the pre-interpolation point constraints depends strongly on the selected subset of receiver functions. This implies that using only pre-interpolation point constraints (receiver functions) inadequately samples the spatial variation in geologic age. The new Moho map also reveals an anomalously deep Moho beneath the oldest core of the Amazonian Craton.