Abstract We conduct the seismic signal analysis on vintage and recently collected multichannel seismic reflection profiles from the Ionian Basin to characterize the deep basin Messinian evaporites. These evaporites were deposited in deep and marginal Mediterranean sedimentary basins as a consequence of the “salinity crisis” between 5.97 and 5.33 Ma, a basin‐wide oceanographic and ecological crisis whose origin remains poorly understood. The seismic markers of the Messinian evaporites in the deep Mediterranean basins can be divided in two end‐members, one of which is the typical “trilogy” of gypsum and clastics (Lower Unit – LU), halite (Mobile Unit – MU) and upper anhydrite and marl layers (Upper Unit – UU) traced in the Western Mediterranean Basins. The other end‐member is a single MU unit subdivided in seven sub‐units by clastic interlayers located in the Levant Basin. The causes of these different seismic expressions of the Messinian salinity crisis (MSC) appear to be related to a morphological separation between the two basins by the structural regional sill of the Sicily Channel. With the aid of velocity analyses and seismic imaging via prestack migration in time and depth domains, we define for the first time the seismic signature of the Messinian evaporites in the deep Ionian Basin, which differs from the known end‐members. In addition, we identify different evaporitic depositional settings suggesting a laterally discontinuous deposition. With the information gathered we quantify the volume of evaporitic deposits in the deep Ionian Basin as 500,000 km3 ± 10%. This figure allows us to speculate that the total volume of salts in the Mediterranean basin is larger than commonly assumed. Different depositional units in the Ionian Basin suggest that during the MSC it was separated from the Western Mediterranean by physical thresholds, from the Po Plain/Northern Adriatic Basin, and the Levant Basin, likely reflecting different hydrological and climatic conditions. Finally, the evidence of erosional surfaces and V‐shaped valleys at the top of the MSC unit, together with sharp evaporites pinch out on evaporite‐free pre‐Messinian structural highs, suggest an extreme Messinian Stage 3 base level draw down in the Ionian Basin. Such evidence should be carefully evaluated in the light of Messinian and post‐Messinian vertical crustal movements in the area. The results of this study demonstrates the importance of extracting from seismic data the Messinian paleotopography, the paleomorphology and the detailed stratal architecture in the in order to advance in the understanding of the deep basins Messinian depositional environments.

中文翻译：

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爱奥尼亚盆地深处墨西拿盐度危机的地震标志

摘要 我们对来自爱奥尼亚盆地的老式和最近收集的多道地震反射剖面进行地震信号分析，以表征深盆地墨西拿蒸发岩。由于 5.97 至 5.33 Ma 之间的“盐度危机”，这些蒸发岩沉积在深部和边缘的地中海沉积盆地中，这是一场盆地范围的海洋和生态危机，其起源仍知之甚少。地中海深部盆地墨西拿蒸发岩的地震标志可分为两个端元，其中之一是典型的石膏和碎屑（下部单元-LU）、岩盐（移动单元-MU）和上部的“三部曲”。在西地中海盆地追踪的硬石膏和泥灰岩层（上单元 - UU）。另一个端元是一个单一的 MU 单元，被位于黎凡特盆地的碎屑夹层细分为七个子单元。墨西拿盐度危机 (MSC) 的这些不同地震表现的原因似乎与西西里海峡的结构区域基石在两个盆地之间的形态分离有关。借助时域和深度域叠前偏移的速度分析和地震成像，我们首次定义了与已知端元不同的爱奥尼亚盆地深部墨西拿蒸发岩的地震特征。此外，我们确定了不同的蒸发沉积环境，表明横向不连续沉积。根据收集到的信息，我们将爱奥尼亚盆地深处的蒸发沉积物的体积量化为 500,000 km3 ± 10%。这个数字使我们能够推测地中海盆地的盐总体积比通常假设的要大。爱奥尼亚盆地的不同沉积单元表明，在 MSC 期间，它通过物理阈值与西地中海、波平原/亚得里亚海盆地和黎凡特盆地分开，这可能反映了不同的水文和气候条件。最后，MSC 单元顶部的侵蚀面和 V 形山谷的证据，以及尖锐的蒸发岩在无蒸发岩的前墨西拿构造高点上尖刺，表明爱奥尼亚盆地的墨西拿第 3 阶段极端底面下降. 应根据该地区的墨西拿和后墨西拿垂直地壳运动仔细评估这些证据。