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首页> 外文期刊>Physics of the Earth and Planetary Interiors: A Journal Devoted to Obsevational and Experimerntal Studies of the Chemistry and Physics of Planetary Interiors and Their Theoretical Interpretation >3D density model of the Central Andes
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3D density model of the Central Andes

机译：安第斯山脉中部的3D密度模型

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摘要

We developed a 3D density model of the continental crust, the subducted plate and the upper mantle of the Central Andes between 20-29 degrees S and 74-61 degrees W through the forward modelling of Bouguer anomaly. The goal of this contribution is to gain insight on the lithospheric structure integrating the available information (geophysical, geologic, petrologic, and geochemical) in a single model. The geometry of our model is defined and constrained by hypocentre location, reflection and refraction on and offshore seismic lines, travel time and attenuation tomography, receiver function analysis, magnetotelluric studies, thermal models and balanced structural cross-sections. The densities allocated to the different bodies are calculated considering petrologic and geochemical data and pressure and temperature conditions. The model consists of 31 parallel E-W vertical planes, where the continental crust comprises distinct bodies, which represent the different morphotectonic units of the Central Andes. We include a partial melting zone at midcrustal depths under the Altiplano-Puna (low-velocity zone) and consider the presence of a theologically strong block beneath the Salar de Atacama basin, according to recent seismic studies. Contour maps of the depth of the continental Moho, the thickness of the lower crust and the depth to the bottom of the lithosphere below South America are produced. The possible percentage of partial melt in the Central Andes low-velocity zone is estimated. The residual anomaly is calculated by subtracting from the Bouguer anomaly the gravimetric effect of the modelled subducted slab and of the modelled Moho. Isostatic anomalies are calculated from regional and local isostatic Mohos calculated with and without internal loads, derived from our gravity model, which are then compared to the modelled continental Moho. This study contributes to a more detailed knowledge of the lithospheric structure of this region of the Andes and provides an integrated 3D density model, which may be used by the geoscientific community as a tool that can help to understand and interpret the geodynamic features and processes acting along the Central Andes.
机译：通过布格异常的正演，我们开发了大陆壳，俯冲板块和安第斯山脉中部上地幔的3D密度模型，范围为南纬20-29度和南纬74-61度。该贡献的目的是获得对岩石圈结构的洞察力，将可用信息（地球物理，地质，岩石学和地球化学）整合到一个模型中。我们的模型的几何形状受震中位置，在和海上地震线上的反射和折射，传播时间和衰减层析成像，接收器功能分析，大地电磁研究，热模型和平衡的结构横截面的定义和约束。考虑岩石学和地球化学数据以及压力和温度条件，计算了分配给不同物体的密度。该模型由31个平行的E-W垂直平面组成，其中大陆壳包括不同的物体，代表了安第斯中部的不同构造单元。根据最近的地震研究，我们在Altiplano-Puna（低速带）下方的中地壳深度包括了一个局部融化带，并考虑在Salar de Atacama盆地下方存在一个在理论上很强的块体。绘制了莫霍面大陆深度，下地壳厚度以及南美洲下方岩石圈底部深度的等高线图。估计了安第斯中部低速带部分熔融的可能百分比。通过从布格异常中减去已建模的俯冲板块和已建模的Moho的重力效应，可以计算出残余异常。从重力模型导出的区域和局部等静线Mohos（通过内部和不通过内部载荷计算）来计算等静距异常，然后将其与模拟的大陆Moho相比较。这项研究有助于更详细地了解安第斯山脉地区的岩石圈结构，并提供了一个集成的3D密度模型，地球科学界可以将其用作可以帮助理解和解释地球动力学特征和作用过程的工具。沿安第斯山脉中部。

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