Facies and stratigraphic framework of a Khuff outcrop equivalent: Saiq and Mahil formations, Al Jabal al-Akhdar, Sultanate of Oman

Koehrer, Bastian; Zeller, Michael; Aigner, Thomas; Poeppelreiter, Michael; Milroy, Paul; Forke, Holger; Al-Kindi, Suleiman

doi:10.2113/geoarabia150291

Cited by 87 publications

(31 citation statements)

References 39 publications

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“…Lithology, biota, and transect key are provided in (A). Only Hindeodus parvus has been found so far in this section (18), and the conodont zones with dashed lines are identified from the d 13 C record and regional stratigraphy (36)(37)(38). Before EP1, d 13 C carb values began to decrease before reaching the minimum of the globally recognized negative CIE at the PTB (Fig.…”

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confidence: 79%

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Ocean acidification and the Permo-Triassic mass extinction

Clarkson

Kasemann

Wood

et al. 2015

Science

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154

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Ocean acidification triggered by Siberian Trap volcanism has been implicated as a kill18 mechanism for the Permo-Triassic mass extinction, but evidence for an acidification event 19 remains inconclusive. To address this, we present a high resolution seawater pH record across 20 this interval, utilizing boron isotope data combined with a quantitative modeling approach. In the 21 latest Permian, the alkalinity of the ocean increased, priming the Earth system with a low level of 22 atmospheric CO 2 and a high ocean buffering capacity. The first phase of extinction was 23 2 coincident with a slow injection of isotopically light carbon into the atmosphere-ocean, but the 24 ocean was well-buffered such that ocean pH remained stable. During the second extinction pulse, 25 however, a rapid and large injection of carbon overwhelmed the buffering capacity of the ocean, 26causing an abrupt and short-lived acidification event that drove the preferential loss of heavily 27 calcified marine biota. kyrs (2) and can be resolved into two distinct marine extinction pulses, with the respective kill 37 mechanisms appearing to be ecologically selective (3). The first occurred in the latest Permian 38 (Extinction Pulse 1; EP1) and was followed by an interval of temporary recovery before the 39 second pulse (EP2) which occurred in the earliest Triassic. The direct cause of the mass 40 extinction is widely debated with a diverse range of overlapping mechanisms proposed, 41 including widespread water column anoxia (4), euxinia (5), global warming (6) and ocean 42 acidification (7). 43Models of PTB ocean acidification suggest that a massive, and rapid, release of CO 2 from 44 Siberian Trap volcanism, acidified the ocean (7). Indirect evidence for acidification comes from 45 the interpretation of faunal turnover records (3, 8), potential dissolution surfaces (9) and Ca 46 3 isotope data (7). A rapid input of carbon is also potentially recorded in the negative carbon 47 isotope excursion (CIE) that characterizes the PTB (10, 11) . The interpretation of these records 48 is, however, debated (12), and of great importance to understanding the current threat of 49 anthropogenically-driven ocean acidification (11). 50Here, we test the ocean acidification hypothesis by presenting a novel proxy record of 51 ocean pH across the PTB, using the boron isotope composition of marine carbonates ( 11 additional counterbalancing alkalinity flux. This is consistent with independent proxy data (6). 129The alkalinity source may have been further increased through soil loss (26) carbon to the atmosphere, yet remarkably, the acidification event occurs after the decline in  13 C, 139when  13 C has rebounded somewhat and is essentially stable (Fig. 2). 140Unlike the first carbon injection, the lack of change in  13 C at this time rules out very 141 13 C-depleted carbon sources, because no counterbalancing strongly 13 C-enriched source exists.

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confidence: 79%

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confidence: 80%

Ocean acidification and the Permo-Triassic mass extinction

Clarkson

Kasemann

Wood

et al. 2015

Science

306

154

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“…Several papers have defined Arabian Plate Mid-Permian to Early Triassic T-R sequences adopting the term "Khuff" (abbreviated "KS"; e.g. Strohmenger et al, 2002;Vaslet et al, 2005;Insalaco et al, 2006;Alsharhan, 2006;Knaust, 2009;Maurer et al, 2009;Koehrer et al, 2010). Each Khuff Sequence is here given a type section from a published paper in which the biostratigraphy and high-resolution architecture are best documented.…”

Section: Nomenclature For Khuff Sequencesmentioning

confidence: 99%

“…These frameworks have provided important regional constraints for tying locally interpreted transgressiveregressive (T-R) sequences (e.g. Strohmenger et al, 2002;Osterloff et al, 2004;Vaslet et al, 2005;Alsharhan, 2006;Insalaco et al, 2006;Al-Husseini, 2008;Maurer et al, 2009;Koehrer et al, 2010) and biostratigraphic zones (e.g. Stephenson et al, 2003;Stephenson, 2006;Angiolini et al, 2004;Vachard et al, 2005;Crasquin-Soleau et al, 2006;Chirat et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…The first study spans the Upper Permian and Lower Triassic in the Fars-Zagros subsurface and outcrops in Iran (Insalaco et al, 2006; Figure 1a). The second covers the Middle Permian to Lower Triassic in the Saiq Plateau of Al Jabal al-Akhdar in Oman (Koehrer et al, 2010;Figure 1b). These two papers, taken together with other sequence-stratigraphic studies, provide an important opportunity to recalibrate the Middle In some localities, stage assignments are shown in color as indicated by the original authors (Chart).…”

Section: Introductionmentioning

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Calibrating Mid-Permian to Early Triassic Khuff sequences with orbital clocks

Al-Husseini¹,

Matthews²

2010

GeoArabia

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The Middle East Geologic Time Scale (ME GTS) seeks to document and age-calibrate Arabian Plate transgressive-regressive (T-R) depositional sequences using: (1) Geological Time Scale of the International Commission on Stratigraphy (GTS), and (2) Arabian Orbital Stratigraphy time scale (AROS). AROS is based on an orbital-forcing glacio-eustatic model that offers three orbital clocks to date T-R sequences: (1) Stratons @ ca. 405 Ky; (2) Dozons @ ca. 4.86 My (12 stratons); and Orbitons @ ca. 14.58 My (36 stratons, three dozons). The Earth today is in Orbiton 0, which started ca. 1.5 Ma (SB 0); the ages of lower boundaries of orbitons can be estimated with the formula SB n = n × 14.58 + 1.5 Ma. This scheme was used to calibrate the Arabian Plate’s Mid-Permian to Early Triassic Khuff sequences, which contain one of the largest gas-bearing carbonate reservoirs in the World. The Khuff and equivalent formations have been interpreted by several authors in terms of six long-period sequences in outcrop belts and subsurface sections (Khuff sequences KS6 to KS1 in ascending order). Their type sections are briefly reviewed with emphasis on their boundaries, higher-order architecture and stage assignments. The age calibration starts at the basal Khuff Sequence Boundary (Khuff SB, Sub-Khuff Unconformity) defined in a type section in Al Huqf outcrop in Oman. Above the Khuff SB (ca. 268.9 Ma) the type sections of the oldest Khuff sequences KS6 (ca. 268.9–264.0 Ma) and KS5 (ca. 264.0–259.1 Ma) are defined in Oman and interpreted to each consist of twelve subsequences (stratons) with the predicted architecture of two consecutive dozons. By biostratigraphy they span the Mid-Permian (Guadalupian Epoch), Wordian and Capitanian stages. Type-Sequence KS4 (ca. 259.1–254.2 Ma) is defined in Iran and corresponds to the Wuchiapingian Stage. The Iranian type-Khuff Sequence KS3 (ca. 254.2–249.4 Ma) contains nine subsequences (stratons) grouped between two major exposure surfaces. By correlation to the Changhsingian Stage and Permian/Triassic Boundary (PTrB) type section in South China, it is interpreted as a dozon with three missing stratons. Khuff Sequence KS2 (ca. 249.4–247.8 Ma) contains the PTrB with an orbital age of ca. 249.0 Ma, compared to 251.0 ± 0.4 in GTS and 249.0–253.0 Ma by radiometric dating in its type section. Khuff sequences KS2 and KS1 contain 13 subsequences (stratons) between ca. 249.4–244.1 Ma spanning latest Permian and Early Triassic. The boundary of the Khuff with the overlying Sudair Formation, Sudair Sequence Boundary, is defined in Borehole SHD-1 (Central Saudi Arabia) and calibrated at ca. 244.1 Ma falling near the age of the Early/Mid-Triassic Boundary in GTS. The enclosed Chart shows a work-in-progress correlation of the six Khuff sequences across the Arabian Plate.

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New Permian Aliyak and Kariz Now formations, Alborz Basin, NE Iran: correlation with the Zagros Mountains and Oman

Fard

Davydov

2014

Geol. J.

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Two new Permian‐aged formations ‘Kariz Now Formation’ and ‘Aliyak Formation’ are proposed for a 65–150 m‐thick succession in the Kariz Now area, with the type section for both (79.5 m thick) located 9 km northeast of Aliyak village ca. 100 km southeast of Mashhad city, northeastern Iran. The lower Kariz Now Formation is composed of siliciclastics. The age of this Formation is poorly constrained but its correlation with the Shah Zeid Formation in the Central Alborz suggests a possible Asselian‐Hermagorian age for the Kariz Now Formation, which implies a hiatus of Yakhtashian–mid Midian (Artinskian–mid Capitanian) age between the siliciclastics of the Kariz Now Formation and carbonates of the disconformably overlying Aliyak Formation. There is also the possibility of a potential correlation of this Formation with the Kungurian Faraghan Formation in the Zagros area. The succeeding Aliyak Formation is mostly composed of carbonate rocks capped by a thin basaltic lava flow. The Aliyak Formation is unconformably overlain by dolostones that are correlated with the Middle Triassic Shotori Formation. Samples were collected from the Kariz Now and Aliyak formations, but fossils were only recovered from the Aliyak Formation. These include calcareous algae, small foraminiferans, fusulinids, crinoid stems and brachiopods. The recovered fusulinid assemblage from the Aliyak Formation is consistent with that of the upper Capitanian Monodiexodina kattaensis–Codonofusiella erki and Afghanella schencki–Sumatrina brevis zones of the Zagros Mountains and with the upper part of the Ruteh Fm in the Alborz Mountains. Although not radiometrically dated, the basaltic lava flow most probably corresponds to similar basaltic lava flows occurring in the uppermost part of the Ruteh Formation in Central Alborz. Thus, the Permian in the studied region developed in a basin that extended westward as far as the Central Alborz. A late Capitanian age for the Aliyak Formation implies it correlates with the Capitanian KS5 in Al Jabal Al‐Akhdar in Oman, with Aliyak Unit 5 potentially representing the Permian maximum flooding surface MFS P25. Copyright © 2014 John Wiley & Sons, Ltd.

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Facies and stratigraphic framework of a Khuff outcrop equivalent: Saiq and Mahil formations, Al Jabal al-Akhdar, Sultanate of Oman

Cited by 87 publications

References 39 publications

Ocean acidification and the Permo-Triassic mass extinction

Ocean acidification and the Permo-Triassic mass extinction

Calibrating Mid-Permian to Early Triassic Khuff sequences with orbital clocks

New Permian Aliyak and Kariz Now formations, Alborz Basin, NE Iran: correlation with the Zagros Mountains and Oman

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