Deformation of intrasalt beds recorded by magnetic fabrics

R Issachar* (Corresponding Author), R Weinberger, G I Alsop, T Levi

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Intrasalt beds comprise sedimentary layers within a weak rock salt mass. Thick intrasalt beds (hundred meter scale) are common in salt structures, yet their internal deformation has not been investigated in detail as outcrops of such beds are rare. In this study, we explore the internal deformation of thick intrasalt beds exposed along the Sedom salt wall in the Dead Sea Basin. These beds are highly deformed and form a kilometer-scale recumbent fold. We measured the magnetic fabrics from six sites along these beds. Magnetic fabrics reflect the preferred alignment of crystals and grain shapes and are a proven kinematic marker in deformed rocks. Our analysis shows that the magnetic fabrics are mostly controlled by the preferred orientation of clay minerals. The orientations of the principal susceptibility axes vary along the salt wall regardless of the specific rock type. Minimum susceptibility axes (K 3 axes) are normal to bedding, whereas maximum susceptibility axes (K 1 axes) are subparallel to bedding strike. We suggest that the magnetic fabrics were acquired by strain imposed at a necked region along a subsurface fault, together with folding during passive diapirism. Generally, the magnetic fabrics have not been influenced by the later stage of active diapirism, which led to emergent beds at the surface. Nevertheless, in sites from the upper limb of the recumbent fold, the magnetic fabrics were further deformed by folding at the base of a salt glacier. Our results demonstrate that thick intrasalt beds are mechanically distinct from the encasing flowing salt and preserve information on salt tectonic processes operating at depth.

Original languageEnglish
JournalJournal of Geophysical Research: Solid Earth
Early online date23 Dec 2019
DOIs
Publication statusE-pub ahead of print - 23 Dec 2019

Fingerprint

magnetic fabric
beds
Salts
salt
salts
diapirism
Rocks
folding
Salt tectonics
magnetic permeability
salt tectonics
fold
Glaciers
weak rock
rock salt
preferred orientation
rocks
Clay minerals
rock
glaciers

Keywords

  • Anisotropy of Magnetic Susceptibility (AMS)
  • intrasalt beds
  • salt tectonics
  • salt wall
  • SEDOM DIAPIR
  • INTERNAL STRUCTURE
  • SEDIMENTS
  • SUSCEPTIBILITY LT-AMS
  • PULL-APART
  • DEAD-SEA BASIN
  • SALT TECTONICS
  • FAULT
  • LOW-TEMPERATURE ANISOTROPY
  • STRAIN

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

Deformation of intrasalt beds recorded by magnetic fabrics. / Issachar, R (Corresponding Author); Weinberger, R; Alsop, G I; Levi, T.

In: Journal of Geophysical Research: Solid Earth, 23.12.2019.

Research output: Contribution to journalArticle

@article{6429773e1bab4248ad64ff51e0c99a19,
title = "Deformation of intrasalt beds recorded by magnetic fabrics",
abstract = "Intrasalt beds comprise sedimentary layers within a weak rock salt mass. Thick intrasalt beds (hundred meter scale) are common in salt structures, yet their internal deformation has not been investigated in detail as outcrops of such beds are rare. In this study, we explore the internal deformation of thick intrasalt beds exposed along the Sedom salt wall in the Dead Sea Basin. These beds are highly deformed and form a kilometer-scale recumbent fold. We measured the magnetic fabrics from six sites along these beds. Magnetic fabrics reflect the preferred alignment of crystals and grain shapes and are a proven kinematic marker in deformed rocks. Our analysis shows that the magnetic fabrics are mostly controlled by the preferred orientation of clay minerals. The orientations of the principal susceptibility axes vary along the salt wall regardless of the specific rock type. Minimum susceptibility axes (K 3 axes) are normal to bedding, whereas maximum susceptibility axes (K 1 axes) are subparallel to bedding strike. We suggest that the magnetic fabrics were acquired by strain imposed at a necked region along a subsurface fault, together with folding during passive diapirism. Generally, the magnetic fabrics have not been influenced by the later stage of active diapirism, which led to emergent beds at the surface. Nevertheless, in sites from the upper limb of the recumbent fold, the magnetic fabrics were further deformed by folding at the base of a salt glacier. Our results demonstrate that thick intrasalt beds are mechanically distinct from the encasing flowing salt and preserve information on salt tectonic processes operating at depth.",
keywords = "Anisotropy of Magnetic Susceptibility (AMS), intrasalt beds, salt tectonics, salt wall, SEDOM DIAPIR, INTERNAL STRUCTURE, SEDIMENTS, SUSCEPTIBILITY LT-AMS, PULL-APART, DEAD-SEA BASIN, SALT TECTONICS, FAULT, LOW-TEMPERATURE ANISOTROPY, STRAIN",
author = "R Issachar and R Weinberger and Alsop, {G I} and T Levi",
note = "Funding Information Israel Science Foundation (ISF). Grant Number: 868/17 Israeli Government. Grant Number: 40706 Israel Science Foundation. Grant Number: 868/17",
year = "2019",
month = "12",
day = "23",
doi = "10.1029/2019JB018788",
language = "English",
journal = "Journal of Geophysical Research: Solid Earth",
issn = "2169-9313",
publisher = "Wiley-Blackwell",

}

TY - JOUR

T1 - Deformation of intrasalt beds recorded by magnetic fabrics

AU - Issachar, R

AU - Weinberger, R

AU - Alsop, G I

AU - Levi, T

N1 - Funding Information Israel Science Foundation (ISF). Grant Number: 868/17 Israeli Government. Grant Number: 40706 Israel Science Foundation. Grant Number: 868/17

PY - 2019/12/23

Y1 - 2019/12/23

N2 - Intrasalt beds comprise sedimentary layers within a weak rock salt mass. Thick intrasalt beds (hundred meter scale) are common in salt structures, yet their internal deformation has not been investigated in detail as outcrops of such beds are rare. In this study, we explore the internal deformation of thick intrasalt beds exposed along the Sedom salt wall in the Dead Sea Basin. These beds are highly deformed and form a kilometer-scale recumbent fold. We measured the magnetic fabrics from six sites along these beds. Magnetic fabrics reflect the preferred alignment of crystals and grain shapes and are a proven kinematic marker in deformed rocks. Our analysis shows that the magnetic fabrics are mostly controlled by the preferred orientation of clay minerals. The orientations of the principal susceptibility axes vary along the salt wall regardless of the specific rock type. Minimum susceptibility axes (K 3 axes) are normal to bedding, whereas maximum susceptibility axes (K 1 axes) are subparallel to bedding strike. We suggest that the magnetic fabrics were acquired by strain imposed at a necked region along a subsurface fault, together with folding during passive diapirism. Generally, the magnetic fabrics have not been influenced by the later stage of active diapirism, which led to emergent beds at the surface. Nevertheless, in sites from the upper limb of the recumbent fold, the magnetic fabrics were further deformed by folding at the base of a salt glacier. Our results demonstrate that thick intrasalt beds are mechanically distinct from the encasing flowing salt and preserve information on salt tectonic processes operating at depth.

AB - Intrasalt beds comprise sedimentary layers within a weak rock salt mass. Thick intrasalt beds (hundred meter scale) are common in salt structures, yet their internal deformation has not been investigated in detail as outcrops of such beds are rare. In this study, we explore the internal deformation of thick intrasalt beds exposed along the Sedom salt wall in the Dead Sea Basin. These beds are highly deformed and form a kilometer-scale recumbent fold. We measured the magnetic fabrics from six sites along these beds. Magnetic fabrics reflect the preferred alignment of crystals and grain shapes and are a proven kinematic marker in deformed rocks. Our analysis shows that the magnetic fabrics are mostly controlled by the preferred orientation of clay minerals. The orientations of the principal susceptibility axes vary along the salt wall regardless of the specific rock type. Minimum susceptibility axes (K 3 axes) are normal to bedding, whereas maximum susceptibility axes (K 1 axes) are subparallel to bedding strike. We suggest that the magnetic fabrics were acquired by strain imposed at a necked region along a subsurface fault, together with folding during passive diapirism. Generally, the magnetic fabrics have not been influenced by the later stage of active diapirism, which led to emergent beds at the surface. Nevertheless, in sites from the upper limb of the recumbent fold, the magnetic fabrics were further deformed by folding at the base of a salt glacier. Our results demonstrate that thick intrasalt beds are mechanically distinct from the encasing flowing salt and preserve information on salt tectonic processes operating at depth.

KW - Anisotropy of Magnetic Susceptibility (AMS)

KW - intrasalt beds

KW - salt tectonics

KW - salt wall

KW - SEDOM DIAPIR

KW - INTERNAL STRUCTURE

KW - SEDIMENTS

KW - SUSCEPTIBILITY LT-AMS

KW - PULL-APART

KW - DEAD-SEA BASIN

KW - SALT TECTONICS

KW - FAULT

KW - LOW-TEMPERATURE ANISOTROPY

KW - STRAIN

UR - http://www.scopus.com/inward/record.url?scp=85076883491&partnerID=8YFLogxK

U2 - 10.1029/2019JB018788

DO - 10.1029/2019JB018788

M3 - Article

JO - Journal of Geophysical Research: Solid Earth

JF - Journal of Geophysical Research: Solid Earth

SN - 2169-9313

ER -