We study the crustal structure of Sri Lanka by analyzing data from a temporary seismic network deployed in 2016–2017 to shed light on the amalgamation process from a geophysical perspective. Rayleigh wave phase dispersion curves from ambient noise cross correlation and receiver functions were jointly inverted using a transdimensional Bayesian approach. The Moho depths in Sri Lanka range between 30 and 40 km, with the thickest crust (38–40 km) beneath the central Highland Complex (HC). The thinnest crust (30–35 km) is found along the west coast, which experienced crustal thinning associated with the formation of the Mannar Basin. V_P/V_S ratios lie within a range of 1.60–1.82 and predominantly favor a felsic to intermediate bulk crustal composition with a significant silica content of the rocks. A major intracrustal (18–27 km), slightly westward dipping (∼4.3°) interface with high V_S (∼4 km/s) underneath is prominent in the central HC, continuing into the western Vijayan Complex (VC). The discontinuity might have been part of the respective units prior to the collision and could be an indicator for the proposed tilting of the Wanni Complex/HC crustal sections. It might also be related to the deep crustal HC/VC thrust contact with the VC as an indenting promontory of high V_S. A low‐velocity zone in the central HC could have been caused by fluid influx generated by the thrusting process.

中文翻译：

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基于贝叶斯方法的表面波色散与接收函数联合反演的斯里兰卡地壳结构

我们通过分析2016-2017年部署的临时地震网络中的数据来研究斯里兰卡的地壳结构，以便从地球物理角度阐明合并过程。使用跨维贝叶斯方法，将来自环境噪声互相关和接收器函数的瑞利波相位弥散曲线联合反转。斯里兰卡的莫霍面深度在30到40公里之间，而高地综合体（HC）下方的地壳最厚（38-40公里）。在西海岸发现最薄的地壳（30-35公里），该地壳经历了与Mannar盆地形成有关的地壳变薄。V _P / V _S比例在1.60-1.82的范围内，主要有利于长英质到中等的散装地壳成分，且岩石中二氧化硅含量很高。在HC中部，主要的地壳内部（18–27 km），略微向西的倾斜（〜4.3°）界面和较高的V _S（〜4 km / s）在中央HC突出，并一直延伸到西部的Vijayan Complex（VC）。不连续性可能是碰撞前各个单元的一部分，并且可能是拟议的Wanni Complex / HC地壳剖面倾斜的指标。这也可能与地壳HC / VC与VC的深推力接触有关，这是高V _S的压痕。HC中心的低速带可能是由推进过程产生的流体涌入引起的。