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首页> 外文期刊>Research in Geophysics >Crustal thickness and Moho sharpness beneath the Midcontinent rift from receiver functions
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Crustal thickness and Moho sharpness beneath the Midcontinent rift from receiver functions

机译：接收器功能在中大陆裂谷以下的地壳厚度和莫霍面锐度

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The Mesoproterozoic Midcontinent rift (MCR) in the central US is an approximately 2000 km long, 100 km wide structure from Kansas to Michigan. During the 20-40 million years of rifting, a thick (up to 20 km) layer of basaltic lava was deposited in the rift valleys. Quantifying the effects of the rifting and associated volcanic eruptions on the structure and composition of the crust and mantle beneath the MCR is important for the understanding of the evolution of continental lithosphere. In this study we measure the crustal thickness (H), and the sharpness of the Moho (R) at about 24 portable and permanent stations in Iowa, Kansas, and South Dakota by stacking Pto- S converted waves (PmS) and their multiples (PPmS and PSmS). Under the assumption that the crustal mean velocity in the study area is the same as the IASP91 earth model, we find a significantly thickened crust beneath the MCR of about 53 km. The crustal V p /V s ratios increases from about 1.80 off rift to as large as 1.95 within the rift, which corresponds to an increase of Poisson’s ratio from 0.28 to 0.32, suggesting a more mafic crust beneath the MCR. The R measurements are spatially variable and are relatively small in the vicinity of the MCR, indicating the disturbance of the original sharp Moho by the rifting and magmatic intrusion and volcanic eruption.
机译：从美国堪萨斯州到密歇根州的中部中元古代中陆裂谷（MCR）约为2000公里，宽100公里。在20-40百万年的裂谷过程中，裂谷中沉积了厚厚的（达20 km）玄武岩熔岩层。量化裂谷作用和相关的火山喷发对MCR之下的地壳和地幔的结构和成分的影响，对于理解大陆岩石圈的演化非常重要。在这项研究中，我们通过叠加Pto-S转换波（PmS）及其倍数，测量了衣阿华州，堪萨斯州和南达科他州约24个便携式站和永久站的地壳厚度（H）和Moho的锐度（R） PPmS和PSmS）。在研究区域的地壳平均速度与IASP91地球模型相同的假设下，我们发现MCR下方的地壳明显增厚了约53 km。地壳的V p / V s比值从裂谷处的约1.80增加到裂谷内的1.95，这对应于泊松比从0.28增加到0.32，这表明MCR下方的镁铁矿壳更多。 R的测量值在空间上是可变的，并且在MCR附近相对较小，表明原始的锋利莫霍面受到裂谷，岩浆侵入和火山喷发的干扰。

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