Compaction history of Upper Cretaceous shale and related tectonic framework, Arabian Plate, Eastern Oman Mountains

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Abstract

Shale of the Upper Cretaceous Al-Khod Formation intruded younger conglomerates of the same formation. Intrusion followed a preexisting fault that had been widened by extension. The fissility of the shale mimics the contact contours of the conglomeratic host rocks. Sandstone and conglomerate clasts are “floating” in the shale. Vertical postintrusive calcite veins are ptygmatically folded by compaction. These ptygmatically folded compaction veins display horizontal to gently dipping axial planes. Shortening amounts to ~ 40%, indicating that shale intrusion ensued with high water content. It also shows that an estimated amount of 35 to 45% of water content was expelled by compaction after vein formation. Countless, randomly oriented calcite veins in the conglomerate at the shale contact point to fluid expulsion from the shale into the conglomerate. Shale intrusion postdates the late Cretaceous obduction of the Semail Ophiolite. Intrusion most likely occurred during the Oligocene for which extension of the nearby Frontal Range Fault was due to gravitational collapse, associated with isostatic/elastic rebound. Shale dike formation is related to a widened fault within a sinistral negative flower structure with a minimum width of 100 m. Intrusion ensued at an overburden of approximately 100 m of the upper part of the Al-Khod Formation and approximately 900 m of the Paleogene limestone. Folding of calcite veins and the significant water loss was caused by corresponding compaction. Nontronite is the red shale’s main clay mineral. It derived from a source area of exposed and weathered mafic to ultramafic rocks.

Original languageEnglish
Article number444
JournalArabian Journal of Geosciences
Volume11
Issue number16
DOIs
Publication statusPublished - Aug 1 2018

Fingerprint

Arabian plate
compaction
shale
Cretaceous
tectonics
mountain
history
conglomerate
calcite
water content
fluid expulsion
nontronite
obduction
ultramafic rock
ophiolite
overburden
clast
Paleogene
host rock
folding

Keywords

  • Al-Khod Formation
  • Hajar Mountains
  • Negative flower structure
  • Ptygmatically folded compaction veins
  • Shale compaction history
  • Shale dike
  • Upper Cretaceous/Tertiary

ASJC Scopus subject areas

  • Environmental Science(all)
  • Earth and Planetary Sciences(all)

Cite this

@article{5d4c766bc9244b94a48bf3eb63f4ba09,
title = "Compaction history of Upper Cretaceous shale and related tectonic framework, Arabian Plate, Eastern Oman Mountains",
abstract = "Shale of the Upper Cretaceous Al-Khod Formation intruded younger conglomerates of the same formation. Intrusion followed a preexisting fault that had been widened by extension. The fissility of the shale mimics the contact contours of the conglomeratic host rocks. Sandstone and conglomerate clasts are “floating” in the shale. Vertical postintrusive calcite veins are ptygmatically folded by compaction. These ptygmatically folded compaction veins display horizontal to gently dipping axial planes. Shortening amounts to ~ 40{\%}, indicating that shale intrusion ensued with high water content. It also shows that an estimated amount of 35 to 45{\%} of water content was expelled by compaction after vein formation. Countless, randomly oriented calcite veins in the conglomerate at the shale contact point to fluid expulsion from the shale into the conglomerate. Shale intrusion postdates the late Cretaceous obduction of the Semail Ophiolite. Intrusion most likely occurred during the Oligocene for which extension of the nearby Frontal Range Fault was due to gravitational collapse, associated with isostatic/elastic rebound. Shale dike formation is related to a widened fault within a sinistral negative flower structure with a minimum width of 100 m. Intrusion ensued at an overburden of approximately 100 m of the upper part of the Al-Khod Formation and approximately 900 m of the Paleogene limestone. Folding of calcite veins and the significant water loss was caused by corresponding compaction. Nontronite is the red shale’s main clay mineral. It derived from a source area of exposed and weathered mafic to ultramafic rocks.",
keywords = "Al-Khod Formation, Hajar Mountains, Negative flower structure, Ptygmatically folded compaction veins, Shale compaction history, Shale dike, Upper Cretaceous/Tertiary",
author = "Frank Mattern and Andreas Scharf and M. Al-Sarmi and Bernhard Pracejus and Al-Hinaai, {A. S.} and Ali AL-Mamari",
year = "2018",
month = "8",
day = "1",
doi = "10.1007/s12517-018-3781-2",
language = "English",
volume = "11",
journal = "Arabian Journal of Geosciences",
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T1 - Compaction history of Upper Cretaceous shale and related tectonic framework, Arabian Plate, Eastern Oman Mountains

AU - Mattern, Frank

AU - Scharf, Andreas

AU - Al-Sarmi, M.

AU - Pracejus, Bernhard

AU - Al-Hinaai, A. S.

AU - AL-Mamari, Ali

PY - 2018/8/1

Y1 - 2018/8/1

N2 - Shale of the Upper Cretaceous Al-Khod Formation intruded younger conglomerates of the same formation. Intrusion followed a preexisting fault that had been widened by extension. The fissility of the shale mimics the contact contours of the conglomeratic host rocks. Sandstone and conglomerate clasts are “floating” in the shale. Vertical postintrusive calcite veins are ptygmatically folded by compaction. These ptygmatically folded compaction veins display horizontal to gently dipping axial planes. Shortening amounts to ~ 40%, indicating that shale intrusion ensued with high water content. It also shows that an estimated amount of 35 to 45% of water content was expelled by compaction after vein formation. Countless, randomly oriented calcite veins in the conglomerate at the shale contact point to fluid expulsion from the shale into the conglomerate. Shale intrusion postdates the late Cretaceous obduction of the Semail Ophiolite. Intrusion most likely occurred during the Oligocene for which extension of the nearby Frontal Range Fault was due to gravitational collapse, associated with isostatic/elastic rebound. Shale dike formation is related to a widened fault within a sinistral negative flower structure with a minimum width of 100 m. Intrusion ensued at an overburden of approximately 100 m of the upper part of the Al-Khod Formation and approximately 900 m of the Paleogene limestone. Folding of calcite veins and the significant water loss was caused by corresponding compaction. Nontronite is the red shale’s main clay mineral. It derived from a source area of exposed and weathered mafic to ultramafic rocks.

AB - Shale of the Upper Cretaceous Al-Khod Formation intruded younger conglomerates of the same formation. Intrusion followed a preexisting fault that had been widened by extension. The fissility of the shale mimics the contact contours of the conglomeratic host rocks. Sandstone and conglomerate clasts are “floating” in the shale. Vertical postintrusive calcite veins are ptygmatically folded by compaction. These ptygmatically folded compaction veins display horizontal to gently dipping axial planes. Shortening amounts to ~ 40%, indicating that shale intrusion ensued with high water content. It also shows that an estimated amount of 35 to 45% of water content was expelled by compaction after vein formation. Countless, randomly oriented calcite veins in the conglomerate at the shale contact point to fluid expulsion from the shale into the conglomerate. Shale intrusion postdates the late Cretaceous obduction of the Semail Ophiolite. Intrusion most likely occurred during the Oligocene for which extension of the nearby Frontal Range Fault was due to gravitational collapse, associated with isostatic/elastic rebound. Shale dike formation is related to a widened fault within a sinistral negative flower structure with a minimum width of 100 m. Intrusion ensued at an overburden of approximately 100 m of the upper part of the Al-Khod Formation and approximately 900 m of the Paleogene limestone. Folding of calcite veins and the significant water loss was caused by corresponding compaction. Nontronite is the red shale’s main clay mineral. It derived from a source area of exposed and weathered mafic to ultramafic rocks.

KW - Al-Khod Formation

KW - Hajar Mountains

KW - Negative flower structure

KW - Ptygmatically folded compaction veins

KW - Shale compaction history

KW - Shale dike

KW - Upper Cretaceous/Tertiary

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U2 - 10.1007/s12517-018-3781-2

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