Intrasalt Structure and Strain Partitioning in Layered Evaporites: Implications for Drilling Through Messinian Salt in the Eastern Mediterranean

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Authors

Sian Evans , Christopher Aiden-Lee Jackson 

Abstract

We use 3D seismic reflection data from the Levant margin, offshore Lebanon to investigate the structural evolution of the Messinian evaporite sequence, and how intrasalt 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 intrasalt strain varies both laterally and vertically along the margin. We argue that units appearing weakly strained in seismic data, may in fact accommodate considerable sub-seismic or cryptic strain. We also argue that the intrasalt 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 intrasalt lithological and structural complexity in order to accurately image sub-salt geological structures.

DOI

https://doi.org/10.31223/osf.io/8pkbz

Subjects

Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure

Keywords

salt tectonics, Levant margin, Messinian salinity crisis

Dates

Published: 2020-06-18 11:56

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License

GNU Lesser General Public License (LGPL) 2.1

Additional Metadata

Data Availability (Reason not available):
Data is available under license from the Lebanese Petroleum Authority.

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