TY - JOUR
T1 - Microfacies and composition of ferruginous beds at the platform-foreland basin transition (Late Albian to Turonian Natih Formation, Oman Mountains)
T2 - Forebulge dynamics and regional to global tectono-geochemical framework
AU - Mattern, Frank
AU - Pracejus, Bernhard
AU - Scharf, Andreas
AU - Frijia, Gianluca
AU - Al-Salmani, Moath
N1 - Funding Information:
We thank Editor Kasper Knight, Alistair Robertson and an anonymous reviewer for their constructive and supportive comments on the manuscript as well as Sarah Mattern for improving the English text. Moath Al-Salmani wrote an SQU Final-Year thesis about this study. We are grateful for the thin-section preparation by Hamdan Al-Zidi and Mohammed Al-Nadabi, SQU, and the XRD and XRF analyses by Khulood Al-Maimani, CAARU, SQU.
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2022/3/1
Y1 - 2022/3/1
N2 - Two forebulge successions exist in the Oman Mountains at the platform-foreland basin transition between the Late Albian to Turonian Natih Formation and the foreland basin shales of the Late Cretaceous Muti Formation. Forebulge creation is suggested by limestone microfacies analyses and analyses of ferruginous crusts and oolites, showing rapid changes in bathymetry and relative sedimentation rate. Each succession displays basal shallow subtidal limestone, passing upward directly to ferruginous crusts and then to Fe-rich oolites deposited in shallower and agitated water. Each succession is topped by clayey layers. Microfacies and lithological evolution of the two successions are alike, suggesting repetitively similar depositional and tectonic conditions. As both sequences occur at the same site, lateral forebulge migration possibly did not occur, suggesting an overall stationary vertical and stepwise forebulge development. The compositional evolution of the ferruginous crusts was complex and includes postdepositional diagenetic effects of the rocks. Both ferruginous crusts once consisted of iron sulfides, implying at least slightly reducing conditions during their formation, associated with water-deepening events. Both oolite levels contain chlorite, hematite, quartz, calcite and apatite. They also contain fragments of chlorite and hematite as nuclei, suggesting that these fragments derived from preexisting ferruginous crusts. Iron oxyhydroxides and clinochlore within the oolites reflects bathymetric changes to more oxidizing aqueous conditions, associated with water-shallowing events. Fe-rich anoxic to sub-oxic sea water of the marine foreland basin was the source for the crusts and oolites which coincided with a high rate of global Cretaceous ocean crust production and related hydrothermalism as well as the regional proximity of an active spreading axis. Fe was probably stabilized in ocean water as organic Fe complexes and Fe colloids.
AB - Two forebulge successions exist in the Oman Mountains at the platform-foreland basin transition between the Late Albian to Turonian Natih Formation and the foreland basin shales of the Late Cretaceous Muti Formation. Forebulge creation is suggested by limestone microfacies analyses and analyses of ferruginous crusts and oolites, showing rapid changes in bathymetry and relative sedimentation rate. Each succession displays basal shallow subtidal limestone, passing upward directly to ferruginous crusts and then to Fe-rich oolites deposited in shallower and agitated water. Each succession is topped by clayey layers. Microfacies and lithological evolution of the two successions are alike, suggesting repetitively similar depositional and tectonic conditions. As both sequences occur at the same site, lateral forebulge migration possibly did not occur, suggesting an overall stationary vertical and stepwise forebulge development. The compositional evolution of the ferruginous crusts was complex and includes postdepositional diagenetic effects of the rocks. Both ferruginous crusts once consisted of iron sulfides, implying at least slightly reducing conditions during their formation, associated with water-deepening events. Both oolite levels contain chlorite, hematite, quartz, calcite and apatite. They also contain fragments of chlorite and hematite as nuclei, suggesting that these fragments derived from preexisting ferruginous crusts. Iron oxyhydroxides and clinochlore within the oolites reflects bathymetric changes to more oxidizing aqueous conditions, associated with water-shallowing events. Fe-rich anoxic to sub-oxic sea water of the marine foreland basin was the source for the crusts and oolites which coincided with a high rate of global Cretaceous ocean crust production and related hydrothermalism as well as the regional proximity of an active spreading axis. Fe was probably stabilized in ocean water as organic Fe complexes and Fe colloids.
KW - Aruma Foreland Basin
KW - Ferruginous crusts
KW - Ferruginous oolites
KW - Forebulge sequences
KW - Gamma-radiation
KW - High oceanic crust production
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U2 - 10.1016/j.sedgeo.2021.106074
DO - 10.1016/j.sedgeo.2021.106074
M3 - Article
AN - SCOPUS:85122695723
SN - 0037-0738
VL - 429
JO - Sedimentary Geology
JF - Sedimentary Geology
M1 - 106074
ER -