Abstract

This new seismic tomography study for the crust of southern Crimea and the northeastern Black Sea based on low-magnitude (M ≤ 3) earthquakes indicates significant heterogeneity of the crust at depths of 15–35 km. In the present paper we discuss the velocity distribution for P- and S-waves and give geological and tectonic interpretations in the context of collisional interaction between the Black Sea microplate and the Scythian plate. The joint use of data on both types of waves (P- and S-waves) increases the reliability of the interpretation and allows us to estimate the crustal composition of Mountainous Crimea (MC) and subcrustal mantle of the northeastern Black Sea. We have detected high velocity regions in the MC crust (Vp = 6.5‒6.8 km/s, Vs = 3.7‒3.9 km/s, Vp/Vs = 1.75‒1.9), which have complex configurations and can be deep sources of mid-Mesozoic intrusions known in the MC (Ayu-Dag and Castel). The high-velocity area is separated from eastern Crimea by a linear nearly north–south low-velocity zone located between the cities of Sudak and Feodosiya. The latter is interpreted as a weakened crustal zone associated with the Korsak–Feodosiya fault. The high-velocity region beneath the Black Sea (south of Kerch Peninsula) at depths of 25–40 km most likely belongs to the subcrustal mantle (Vp/Vs = 1.80–1.85) that underlies a thin suboceanic crust of the East Black Basin. The resulting crustal model for southern Crimea and adjacent part of the Black Sea is consistent with the parameters of other geophysical fields.

中文翻译：

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南部克里米亚和北部北部黑海地壳的地震层析成像模型

摘要

对克里米亚南部和东北部黑海的基于低幅度（地壳这种新的地震层析成像研究中号≤3）地震表明，在15-35公里深处的地壳显著异质性。在本文中，我们讨论了P波和S波的速度分布，并在黑海微板块与Scythian板块之间的碰撞相互作用的背景下给出了地质和构造解释。两种波（P-和S波浪）增加了解释的可靠性，并使我们能够估算出克里米亚山脉（MC）和东北黑海东北部地幔的地壳成分。我们在MC地壳中检测到了高速区域（Vp = 6.5‒6.8 km / s，Vs = 3.7‒3.9 km / s，Vp / Vs= 1.75‒1.9），具有复杂的构造，并且可能是MC中已知的中生代侵入岩的深层来源（Ayu-Dag和Castel）。高速区域与克里米亚东部之间被位于Sudak和Feodosiya市之间的线性近北-南低速区隔开。后者被解释为与Korsak-Feodosiya断层有关的地壳弱化带。黑海（刻赤半岛南部）25至40公里深度处的高速区域最有可能属于东黑盆地东海薄海底壳之下的地壳下地幔（Vp / Vs = 1.80-1.85）。由此产生的克里米亚南部和黑海邻近地区的地壳模型与其他地球物理场的参数一致。