Martín Rodríguez Kacevas , Marcelo Assumpção , Leda Sánchez Bettucci , Meijian An , Mei Feng
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引用次数: 0
摘要
近年来,乌拉圭地震台网的发展使我们能够在一个很少开展此类地震研究的地区开展地壳结构研究。在这项工作中,我们更新了用 H-k 叠加法计算的地壳厚度和 Vp/Vs 比值,并根据接收函数和瑞利波群速度频散曲线的联合反演,提出了 S 波速度模型。一些有趣的结果是,在位于拉普拉塔河克拉通的一个站点下方存在一个 S 波速度高达 4.1 千米/秒的下地壳,而在乌拉圭巴拉那盆地最北端的站点存在一个过渡莫霍面,这或许表明存在局部的下沉物质。在 Dom Feliciano 地带的 Sierra Ballena 剪切带下发现了相对较厚的地壳,与周围站点相比为 41.8 千米。我们证实,当接近大洋海岸时,地壳厚度会减小,在乌拉圭东南部的莫霍深度为 36.3 千米。最后,根据计算得出的泊松比,可以推断乌拉圭大部分地区的地壳成分为长岩至中岩。
Crustal thicknesses in Uruguay from joint inversion of receiver functions and surface wave dispersion
The development of a seismic network in Uruguay in recent years has enabled studies of crustal structure in a region with few seismological studies of this type. In this work, we update the crustal thicknesses and Vp/Vs ratios calculated by H-k stack and present S-wave velocity models based on joint inversion of receiver functions and Rayleigh wave group velocity dispersion curves.
Some interesting results are the presence of a lower crust with a high S-wave velocity of 4.1 km/s below one of the stations located on the Río de la Plata Craton and the existence of a transitional Moho in Uruguay's northernmost station on the Paraná Basin, perhaps suggesting the presence of localized underplated material. A relatively thick crust, 41.8 km, compared to surrounding stations, was found beneath the Sierra Ballena Shear Zone in the Dom Feliciano Belt. We confirm the decrease in crustal thickness when approaching the oceanic coast, reaching a Moho depth of 36.3 km in SE Uruguay. Finally, the calculated Poisson's ratio allows inferring a crust of felsic to intermediate composition beneath most of Uruguay.
期刊介绍:
Papers must have a regional appeal and should present work of more than local significance. Research papers dealing with the regional geology of South American cratons and mobile belts, within the following research fields:
-Economic geology, metallogenesis and hydrocarbon genesis and reservoirs.
-Geophysics, geochemistry, volcanology, igneous and metamorphic petrology.
-Tectonics, neo- and seismotectonics and geodynamic modeling.
-Geomorphology, geological hazards, environmental geology, climate change in America and Antarctica, and soil research.
-Stratigraphy, sedimentology, structure and basin evolution.
-Paleontology, paleoecology, paleoclimatology and Quaternary geology.
New developments in already established regional projects and new initiatives dealing with the geology of the continent will be summarized and presented on a regular basis. Short notes, discussions, book reviews and conference and workshop reports will also be included when relevant.