Direct calibration of salt sheet kinematics during gravity-driven deformation

Cartwright, Joe; Kirkham, Chris; Bertoni, Claudia; Hodgson, Neil; Rodriguez, Karyna

doi:10.1130/g40219.1

Cited by 30 publications

(107 citation statements)

References 19 publications

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“…A multitude of pockmarks and other seepage edifice have been identified over the last two decades across the Nile deep-sea fan and adjacent Levant Basin and Eratosthenes Seamount, with their scope continuously expanding as new data becomes available (e.g., [68][69][70][71][72][73]77,78]). Similar intra-to post-Messinian buried features are also abundant in the geophysical record [79][80][81][82][83]. Together these provide potential sources for hydrates formation in the EMS, at present or over climatic changes.…”

Section: Natural Gas and Hydrates In The Emsmentioning

confidence: 65%

Methane Hydrate Stability and Potential Resource in the Levant Basin, Southeastern Mediterranean Sea

et al. 2019

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To estimate the potential inventory of natural gas hydrates (NGH) in the Levant Basin, southeastern Mediterranean Sea, we correlated the gas hydrate stability zone (GHSZ), modeled with local thermodynamic parameters, with seismic indicators of gas. A compilation of the oceanographic measurements defines the >1 km deep water temperature and salinity to 13.8 °C and 38.8‰ respectively, predicting the top GHSZ at a water depth of ~1250 m. Assuming sub-seafloor hydrostatic pore-pressure, water-body salinity, and geothermal gradients ranging between 20 to 28.5 °C/km, yields a useful first-order GHSZ approximation. Our model predicts that the entire northwestern half of the Levant seafloor lies within the GHSZ, with a median sub-seafloor thickness of ~150 m. High amplitude seismic reflectivity (HASR), correlates with the active seafloor gas seepage and is distributed across the deep-sea fan of the Nile within the Levant Basin. Trends observed in the distribution of the HASR are suggested to represent: (1) Shallow gas and possibly hydrates within buried channel-lobe systems 25 to 100 mbsf; and (2) a regionally discontinuous bottom simulating reflection (BSR) broadly matching the modeled base of GHSZ. We therefore estimate the potential methane hydrates resources within the Levant Basin at ~100 trillion cubic feet (Tcf) and its carbon content at ~1.5 gigatonnes.

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Section: Natural Gas and Hydrates In The Emsmentioning

confidence: 65%

Methane Hydrate Stability and Potential Resource in the Levant Basin, Southeastern Mediterranean Sea

et al. 2019

View full text Add to dashboard Cite

show abstract

“…[81][82][83][84][85][86][87][88][89][90][91]). Similar intra-to post-Messinian buried features are also abundant in the geophysical record [92][93][94][95][96]. Together these provide potential sources for hydrates formation in the EMS, at present or over climatic changes.…”

Section: Introductionmentioning

confidence: 65%

Methane Hydrate Stability and Potential Reserves in the Levant Basin, Southeastern Mediterranean Sea

Tayber¹,

Meilijson²,

Ben‐Avraham³

et al. 2019

Preprint

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To estimate The potential inventory of natural gas hydrates in the Levant Basin we correlated the gas hydrate stability zone (GHSZ), modeled with locally estimated thermodynamic parameters, with seismic indicators of gas. Compilation of oceanographic measurements define the deep-water temperature and salinity to 13.8°C and 38.8&permil; respectively, predicting the top GHSZ at a water depth of 1250±5 m. Assuming beneath the seafloor a hydrostatic pore-pressure, the water body salinity, and geothermal gradients ranging between 20 to 28.5°C/km, yields a useful first-order base-GHSZ approximation. Our model predicts that the entire northwestern half of the Levant Basin lies within the GHSZ, with a median thickness of ~150 m.  High amplitude seismic reflectivity (HASR) imaged on an extensive 3D seismic dataset, consistently correlates with verified active seafloor gas seepage and is pervasively distributed across the deep-sea fan of the Nile within the Levant. Two main trends observed for the distribution of HASR are suggested to represent: (1) shallow gas and possibly hydrates, within buried channel-lobe systems 25 to 100 m beneath the seafloor; and (2) a regionally discontinuous bottom simulating reflection (BSR) broadly matching the modeled base GHSZ. We therefore estimate the potential methane hydrates reserve within the Levant Basin at ~4 Tcf.

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“…This is probably due to the dominance of Couette flow (simple shear) in the Messinian evaporites (see Fig. 8a), as recorded by fluid escape pipes within the salt and its overburden (Cartwright et al, 2018).…”

Section: Contraction 30mentioning

confidence: 99%

Deformation of intrasalt competent layers in different modes of salt tectonics

Rowan

Urai

Fiduk³

et al. 2019

Preprint

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Abstract. Layered evaporite sequences (LES) comprise interbedded weak layers (halite and, commonly, bittern salts) and strong layers (anhydrite and usually non-evaporite rocks such as carbonates and siliciclastics). This results in a strong rheological stratification, with a range of effective viscosity up to a factor of 105. We focus here on the deformation of competent intrasalt beds in different modes of salt tectonics using a combination of conceptual, numerical and analog models, and seismic data. In bedding-paralell extension, boudinage of the strong layers forms ruptured stringers, within a halite matrix, that become increasingly isolated with increasing strain. In bedding-parallel shortening, competent layers tend to maintain coherency while forming harmonic, disharmonic, and polyharmonic folds, with the rheological stratification leading to buckling and fold growth by bedding-parallel shear. In differential loading, extension and the resultant stringers dominate beneath suprasalt depocenters while folded competent beds characterize salt pillows. Finally, in tall passive diapirs, stringers generated by intrasalt extension are rotated to near vertical in tectonic melanges during upward flow of salt. In all cases, strong layers are progressively removed from areas of salt thinning and increasingly disrupted and folded in areas of salt growth as deformation intensifies. The varying styles of intrasalt deformation impact seismic imaging of LES and associated interpretations. Ruptured stringers are often visible where they have low dips, as in slightly extended salt layers or beneath depocenters, but are usually not imaged in tall passive diapirs due to steep dips. In contrast, areas of slightly to moderately shortened salt typically have well imaged, mostly continuous intrasalt reflectors, although seismic coherency decreases as deformation intensifies. Similarly, wells are most likely to penetrate strong layers in contractional structures and salt pillows, less likely in extended salt because they might drill between stringers, and unlikely in tall passive diapirs because the stringers are near-vertical. Thus, both seismic and well data may be interpreted to suggest that diapirs and other areas of more intense intrasalt deformation are more halite rich than is actually the case.

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Direct calibration of salt sheet kinematics during gravity-driven deformation

Cited by 30 publications

References 19 publications

Methane Hydrate Stability and Potential Resource in the Levant Basin, Southeastern Mediterranean Sea

Methane Hydrate Stability and Potential Resource in the Levant Basin, Southeastern Mediterranean Sea

Methane Hydrate Stability and Potential Reserves in the Levant Basin, Southeastern Mediterranean Sea

Deformation of intrasalt competent layers in different modes of salt tectonics

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