Earthquake-induced clastic dikes detected by anisotropy of magnetic susceptibility

Tsafrir Levi, Ram Weinberger, Tahar Aïfa, Yehuda Eyal, Shmuel Marco

Research output: Contribution to journalArticlepeer-review

58 Scopus citations

Abstract

Clastic dikes form either by passive deposition of elastic material into preexisting fissures or by fracturing and injection of clastic material during seismic shaking or passive overpressure. Because of their similar final geometry, the origin of elastic dikes is commonly ambiguous. We studied the mechanisms of elastic dike formation within the seismically active Dead Sea basin, where hundreds of clastic dikes crosscut soft rock of the late Pleistocene lacustrine Lisan Formation. We analyzed the anisotropy of magnetic susceptibility (AMS) of clastic dikes of known origin and defined characteristic AMS signatures of depositional or injection filling. We discovered that passively filled dikes, which contain brownish silt resembling local surface sediments, are characterized by an oblate AMS ellipsoid and vertical minimum susceptibility axis V3. Dikes that contain green clayey sediment connected to a mineralogically identical detrital layer of the Lisan Formation are characterized by a triaxial AMS ellipsoid, well grouped subhorizontal and parallel to the dike walls' maximum susceptibility axis V1, and subvertical intermediate susceptibility axis V2. Field evidence and AMS analysis indicate that most of these dikes were emplaced by injection inferred to be due to seismically triggered fluidization. This novel application of the AMS provides a petrofabric tool for distinguishing passively filled dikes from injection dikes and, where appropriate, for identifying the latter as seismites.

Original languageEnglish
Pages (from-to)69-72
Number of pages4
JournalGeology
Volume34
Issue number2
DOIs
StatePublished - 1 Feb 2006

Keywords

  • Anisotropy of magnetic susceptibility
  • Clastic dikes
  • Dead Sea transform
  • Seismites

ASJC Scopus subject areas

  • Geology

Fingerprint

Dive into the research topics of 'Earthquake-induced clastic dikes detected by anisotropy of magnetic susceptibility'. Together they form a unique fingerprint.

Cite this