We use 3D seismic reflection data from the Levant margin, offshore Lebanon to investigate the structural evolution of the Messinian evaporite sequence, and how intra-salt structure and strain varies within a thick salt sheet during early-stage salt tectonics. Intra-Messinian reflectivity reveals lithological heterogeneity within the otherwise halite-dominated sequence. This leads to rheological heterogeneity, with the different mechanical properties of the various units controlling strain accommodation within the deforming salt sheet. We assess the distribution and orientation of structures, and show how intra-salt strain varies both laterally and vertically along the margin. We argue that units appearing weakly strained in seismic data may in fact accommodate considerable subseismic or cryptic strain. We also discuss how the intra-salt stress state varies through time and space in response to the gravitational forces driving deformation. We conclude that efficient drilling through thick, heterogeneous salt requires a holistic understanding of the mechanical and kinematic development of the salt and its overburden. This will also enable us to build better velocity models that account for intra-salt lithological and structural complexity in order to accurately image sub-salt geological structures.

我们使用黎巴嫩近海黎凡特边缘的 3D 地震反射数据来研究墨西拿蒸发岩层序的结构演化，以及早期盐构造期间厚盐层内盐内结构和应变如何变化。墨西拿内部反射率揭示了岩盐占主导地位的序列内的岩性异质性。这导致流变异质性，不同单元的不同机械性能控制变形盐层内的应变调节。我们评估了结构的分布和方向，并展示了盐内应变如何沿边缘横向和垂直变化。我们认为，在地震数据中出现弱应变的单元实际上可能适应相当大的亚地震或隐蔽应变。我们还讨论了盐内应力状态如何随着重力驱动变形而随时间和空间变化。我们得出的结论是，有效钻探厚厚的非均质盐需要对盐及其覆盖层的机械和运动发展有全面的了解。这也将使我们能够建立更好的速度模型，以解释盐内岩性和结构的复杂性，以便准确地成像盐下地质结构。