The Gulf of Trieste (GT), northeastern Adriatic, sits at the rigid edge of the Adria microplate representing the foreland of the adjoining Meso-Cenozoic External Dinarides and Southeastern Alps. The Adria-Eurasia plate boundary extends along the GT eastern coastline, depicted by the Karst Thrust, outer ramp of the SW-verging Dinarides. This separates the Cretaceous-Paleogene carbonates outcropping hundreds of meters on the Karst Plateau (hanging-wall) from their counterparts buried in the eastern gulf. Although the thrust has no evidence of historical and instrumental seismicity, a detailed seismic velocity field is needed to quantify reliable geometries in the foredeep, embedded in a tectonically active area where Adria is moving NNW-ward. Availability of a newly acquired marine multichannel seismic dataset, allowed us to provide the first well-constrained 3D P-wave velocity and depth model in the footwall of the Karst Thrust. Two iterative techniques, traveltime reflection tomography and depth seismic imaging, were applied on the data surveying the Dinaric foredeep. Our findings provide mean velocity values of 1700 m/s for the Quaternary sediments, 2900 m/s for the upper Eocene flysch turbidites, 4500 m/s for the lower flysch, 5000 m/s for the upper carbonates. The maximum flysch unit thickness results in about 1500 m and the top carbonates depth reaches about 1600 m below sea level, 1.7 km offshore Trieste, revealing the thrust is responsible for a minimum 1600–1800 m vertical throw. This study provides benefits for Adria geodynamic models and give new constraints for the geological and tectonic setting assessment, in a region settled over a currently active continental margin.

中文翻译：

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位于亚得里亚板块东北边缘的里雅斯特湾（亚得里亚海）迪纳里克前深部多道地震的 3D 速度-深度模型

亚得里亚海东北部的里雅斯特湾 (GT) 位于亚得里亚海微板块的刚性边缘，代表着毗邻的中新生代外部迪纳里德斯和东南阿尔卑斯山的前陆。亚德里亚-欧亚板块边界沿着 GT 东海岸线延伸，由喀斯特逆冲断层、西南迪纳里德斯的外坡道描绘。这将喀斯特高原（上盘）上露头数百米的白垩纪-古近纪碳酸盐岩与埋藏在东部海湾的对应碳酸盐岩区分开来。尽管逆冲断层没有历史和仪器地震活动的证据，但需要详细的地震速度场来量化前深部的可靠几何形状，该前深部位于阿德里亚正在向西北方向移动的构造活跃区域。新获取的海洋多道地震数据集使我们能够在喀斯特冲断层下盘提供第一个约束良好的 3D P 波速度和深度模型。走时反射断层扫描和深度地震成像这两种迭代技术被应用于第纳里克前深部勘测数据。我们的研究结果提供了第四纪沉积物的平均速度值为 1700 m/s，上始新世复理石浊积岩为 2900 m/s，下复理石为 4500 m/s，上层碳酸盐岩为 5000 m/s。复理石单元的最大厚度约为 1500 m，顶部碳酸盐岩深度达到海平面以下约 1600 m，距离的里雅斯特近海 1.7 公里，表明推力造成了最小 1600-1800 m 的垂直落差。这项研究为阿德里亚地球动力学模型提供了好处，并为当前活跃大陆边缘地区的地质和构造环境评估提供了新的约束。