Early‐stage rifting of the northern Tyrrhenian Sea Basin: Results from a combined wide‐angle and multichannel seismic study
Early‐stage rifting of the northern Tyrrhenian Sea Basin: Results from a combined wide‐angle and multichannel seismic study
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第勒尼安海盆地北部的早期裂谷：广角和多道地震联合研究的结果
DOI：
10.1002/ggge.20180
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
R. de Franco
中科院分区：
文献类型：
--
作者：
Moeller;I. Grevemeyer;C. R. Ranero;C. Berndt;D. Klaeschen;V. Sallares;N. Zitellini;R. de Franco
大陆岩石圈的伸展导致裂谷盆地的形成，最终可能形成被动大陆边缘。在地壳伸展的早期阶段起作用的机制仍然存在激烈的争论。本文介绍了横贯第勒尼安海盆地北部的多通道地震和广角地震剖面的结果。剖面横跨科西嘉盆地（法国）到拉丁边缘（意大利），在那里盆地的早期裂谷阶段保存完好。我们发现了两个域，每个域都有不同的构造风格、热流和地壳厚度。西部的科西嘉盆地形成于第勒尼安海北部主裂谷期（~ 8-4 Ma）之前。第二域为裂谷陆壳，以中部和拉丁边缘的倾斜块体和半地堑构造为特征。这两个区域被科西嘉盆地东部的一个深（~ 10公里）沉积复合体隔开。广角地震数据的走时层析成像揭示了地壳结构和盆地下方15-17±1 km深的莫霍面结构。为了估计水平伸展量，我们确定了构造前、构造同期和构造后的沉积单元，并计算了断层的相对位移。我们发现主要断层的起始角度为45°-50°，裂陷区域的水平拉伸系数为β ~ 1.3 （~ 8-10 mm/a）。地壳从~ 24 km减薄到~ 17 km，表明有相似的延伸量（~ 30%）。该样带代表了早期裂谷的最佳成像之一，并表明地壳尺度分离的形成，或长寿命的低角度正断层，并不是控制大陆地壳裂谷起始的一般特征。其他年轻的裂谷盆地，如科林斯湾、苏伊士裂谷或贝加尔湖，显示出类似于北部第勒尼安盆地的特征，这表明半地堑构造和分布均匀的地壳减薄是裂谷形成过程中的共同特征。
Extension of the continental lithosphere leads to the formation of rift basins and ultimately may create passive continental margins. The mechanisms that operate during the early stage of crustal extension are still intensely debated. We present the results from coincident multichannel seismic and wide‐angle seismic profiles that transect across the northern Tyrrhenian Sea Basin. The profiles cross the Corsica Basin (France) to the Latium Margin (Italy) where the early‐rift stage of the basin is well preserved. We found two domains, each with a distinct tectonic style, heat flow and crustal thickness. One domain is the Corsica Basin in the west that formed before the main rift phase of the northern Tyrrhenian Sea opening (∼8–4 Ma). The second domain is rifted continental crust characterized by tilted blocks and half‐graben structures in the central region and at the Latium Margin. These two domains are separated by a deep (∼10 km) sedimentary complex of the eastern portion of the Corsica Basin. Travel‐time tomography of wide‐angle seismic data reveals the crustal architecture and a subhorizontal 15–17 ± 1 km deep Moho discontinuity under the basin. To estimate the amount of horizontal extension we have identified the pre‐, syn‐, and post‐tectonic sedimentary units and calculated the relative displacement of faults. We found that major faults initiated at angles of 45°–50° and that the rifted domain is horizontally stretched by a factor ofβ∼ 1.3 (∼8–10 mm/a). The crust has been thinned from ∼24 to ∼17 km indicating a similar amount of extension (∼30%). The transect represents one of the best imaged early rifts and implies that the formation of crustal‐scale detachments, or long‐lived low‐angle normal faults, is not a general feature that controls the rift initiation of continental crust. Other young rift basins, like the Gulf of Corinth, the Suez Rift or Lake Baikal, display features resembling the northern Tyrrhenian Basin, suggesting that half‐graben formations and distributed homogeneous crustal thinning are a common feature during rift initiation.
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