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EVIDENCE FOR NON‐COLLISION GEOLOGY IN THE MIDDLE EAST
Author(s) -
Kashfi M.S.
Publication year - 1988
Publication title -
journal of petroleum geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.725
H-Index - 42
eISSN - 1747-5457
pISSN - 0141-6421
DOI - 10.1111/j.1747-5457.1988.tb00831.x
Subject(s) - geology , subduction , ophiolite , fibrous joint , oceanic crust , paleontology , seismology , eclogitization , precambrian , continental crust , basement , continental collision , crust , geochemistry , tectonics , medicine , civil engineering , engineering , anatomy
It is customary to interpret ophiolite belts, including those of the Middle East, as remnants of oceanic crust. However, the mere presence of an ophiolite belt by itself is not proof that it is the site of a former subduction zone. It is argued in this paper that no subduction zone is, or ever was, present in the Middle East. Earthquake‐intensity and earthquake‐epicentre maps show that shocks of magnitude 6.5 and greater (Richter scale) take place in many areas far removed from proposed subduction zones. Even the major proposed subduction zone of the Middle East‐the Zagros “suture” or Zagros “crush zone”‐ has no associated volcanic rocks, and therefore lacks the lithological suit which typifies so‐called subduction zones. Moreover, basement‐rock exposures and basement reached in deep boreholes indicate that at least the major part of the Zagros Fold Belt is underlain by continental, non‐oceanic crust. The fact that identical lithofacies of the same, late PreCambrian through Early Tertiary, are present on both sides of the alleged subduction zone should be enough to give one cause for thought. Well‐known and closely related faunas have been described from Early and Late Paleozoic strata on both sides of the Zagros suture for many decades. Disagreements among plate tectonicists are many. Some advocate the former presence of two or more plates in this region; others have postulated several microplates; other workers support island‐are interpretations; almost all favour the existence of at least one suture zone that marks the locus of a continent‐continent collision. Nearly all of these hypothese are mutually exclusive. Most would cease to exist if the field data were honoured. These data show that there is nothing in the geologic record to support a separation in the past of Arabia‐Africa from the remainder of the Middle East.