TY - JOUR

T1 - Late Jurassic to Cretaceous evolution of the eastern Tethyan Hawasina Basin (Oman Mountains)

AU - Wohlwend, Stephan

AU - Celestino, Ricardo

AU - Reháková, Daniela

AU - Huck, Stefan

AU - Weissert, Helmut

N1 - Funding information: We thank Irene Meier, Reto Grischott, Maria Isabel Millán and Bas den Brock for their help in the Oman Mountains during field campaigns in 2011 to 2014. We also thank Stewart Bishop, Maria Coray-Strasser and Madalina Jaggi (ETH) for laboratory assistance, and Frowin Pirovino and Remy Lüchinger (ETH) for thin-section preparation. This study was supported by a Swiss National Science Foundation grant (200020_132775 & 200020_149168), by ETH Zurich and by the Grant Agency of the Slovak Republik (APVV-14-01-18, VEGA 2/0034). Furthermore, we thank the Associate Editor M.R. Petrizzo and two anonymous reviewers for their critical comments and constructive contributions.

PY - 2016/11/30

Y1 - 2016/11/30

N2 - Remnants of a Mesozoic continental margin can be studied today in the nappe pile of the Oman Mountains. Successions of the Arabian carbonate platform and the adjacent deep Hawasina Basin are preserved in the nappe pile and in the foothills of this Mountain range. The Jurassic–Cretaceous sediment successions of the Hawasina Basin (Sumeini and Hamrat Duru Group) are focus of this study. These basinal archives contain information on the response of an eastern Tethyan equatorial ocean system to multiple perturbations of the carbon cycle and of climate during the Cretaceous. Turbiditic continental slope and basinal successions formed near the Calcite Compensation Depth are difficult to date with biostratigraphy and sequence stratigraphy. The available stratigraphic framework for the Hawasina successions was not sufficient for tracing palaeoceanography through the time window of interest in this study. Therefore, existing sequence stratigraphy and biostratigraphy are complemented by additional biostratigraphic data and with a newly established carbon and strontium isotope chemostratigraphy. The Hawasina Basin was affected by sea-level variations, by changes in oceanography and also by regional tectonics. A first major modification of oceanography occurred at the end of the Jurassic when pelagic Maiolica-type sediments were accumulated in the deep basin and on adjacent submarine highs (Lower Member of Huwar and Sid'r formations). Pelagic to hemipelagic conditions existed until the Valanginian, marked by a major carbon isotope excursion. Pelagic sediments were replaced afterwards by a succession of fine to coarse-grained turbidites of Hauterivian to Aptian age. The transition into the mid-Cretaceous is marked by a sudden shift to fine-grained siliceous or chert deposits, at a time when sediments enriched in organic carbon were accumulated in the western Tethys and Atlantic Oceans. The continental slope as well as the Hawasina Basin seemed to have been well-ventilated during Early and mid-Cretaceous time. Siliceous limestones and chert are indicators of well-mixed and nutrient-rich surface water, while the absence of black shales suggests young and oxygenated deep water with a possible source on the vast Arabian platform. These peculiar oceanographic conditions were most pronounced during the onset of the extreme greenhouse episodes of the Oceanic Anoxic Event 1a.

AB - Remnants of a Mesozoic continental margin can be studied today in the nappe pile of the Oman Mountains. Successions of the Arabian carbonate platform and the adjacent deep Hawasina Basin are preserved in the nappe pile and in the foothills of this Mountain range. The Jurassic–Cretaceous sediment successions of the Hawasina Basin (Sumeini and Hamrat Duru Group) are focus of this study. These basinal archives contain information on the response of an eastern Tethyan equatorial ocean system to multiple perturbations of the carbon cycle and of climate during the Cretaceous. Turbiditic continental slope and basinal successions formed near the Calcite Compensation Depth are difficult to date with biostratigraphy and sequence stratigraphy. The available stratigraphic framework for the Hawasina successions was not sufficient for tracing palaeoceanography through the time window of interest in this study. Therefore, existing sequence stratigraphy and biostratigraphy are complemented by additional biostratigraphic data and with a newly established carbon and strontium isotope chemostratigraphy. The Hawasina Basin was affected by sea-level variations, by changes in oceanography and also by regional tectonics. A first major modification of oceanography occurred at the end of the Jurassic when pelagic Maiolica-type sediments were accumulated in the deep basin and on adjacent submarine highs (Lower Member of Huwar and Sid'r formations). Pelagic to hemipelagic conditions existed until the Valanginian, marked by a major carbon isotope excursion. Pelagic sediments were replaced afterwards by a succession of fine to coarse-grained turbidites of Hauterivian to Aptian age. The transition into the mid-Cretaceous is marked by a sudden shift to fine-grained siliceous or chert deposits, at a time when sediments enriched in organic carbon were accumulated in the western Tethys and Atlantic Oceans. The continental slope as well as the Hawasina Basin seemed to have been well-ventilated during Early and mid-Cretaceous time. Siliceous limestones and chert are indicators of well-mixed and nutrient-rich surface water, while the absence of black shales suggests young and oxygenated deep water with a possible source on the vast Arabian platform. These peculiar oceanographic conditions were most pronounced during the onset of the extreme greenhouse episodes of the Oceanic Anoxic Event 1a.

KW - Carbon cycle

KW - Cretaceous

KW - eastern equatorial Tethys

KW - Hawasina Basin

KW - OAEs

KW - Oman Mountains

KW - palaeoceanography

KW - Sumeini and Hamrat Duru Group

UR - http://www.scopus.com/inward/record.url?scp=85006117635&partnerID=8YFLogxK

U2 - 10.1111/sed.12326

DO - 10.1111/sed.12326

M3 - Article

AN - SCOPUS:85006117635

VL - 64

SP - 87

EP - 110

JO - SEDIMENTOLOGY

JF - SEDIMENTOLOGY

SN - 0037-0746

IS - 1

ER -