Signs of the record of geomagnetic reversal in permian–triassic trap intrusions of the Ergalakhsky complex, Norilsk region

Alternating intervals of normal and reversed polarity are revealed in the sections of two Permian–Triassic trap intrusions of the Ergalakhsky complex, Norilsk region. The near-contact zones of the intrusions are magnetized reversely, whereas magnetization in the central zones has normal polarity. The arguments are presented that this change in the polarity along the intrusions section is not due to the postmagmatic remagnetization or self-reversal of remanence but marks the reversal of the geomagnetic field that occurred during the emplacement of the intrusive bodies. Highly accurate age determination for the Ergalakhsky intrusions – the oldest intrusive trap complex in the Norilsk region – is vital for time correlation of the initial stage of magmatic activity. According to the paleomagnetic data, the studied sills intruded directly at the Permian–Triassic boundary at the very end of the Ivakinsky stage. The existing estimates for the durations of the reversals indicate that the cooling of the intrusions could last a few thousand years. In the future, the examined sills of the Ergalakhsky complex can be used as a unique object for exploring the structure of the geomagnetic field during the reversals, for reconstructing the thermal history of intrusions’ cooling, and as a reference for estimating the total duration of trap magmatism.

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Low Geomagnetic Field Paleointensity on the Permian–Triassic Boundary from Study of the Kuznetsk Basin Traps (Southern Siberia)

Russian Geology and Geophysics ◽

10.2113/rgg20204330 ◽

2021 ◽

Author(s):

A.A. Eliseev ◽

V.V. Shcherbakova ◽

D.V. Metelkin ◽

N.E. Mikhaltsov ◽

G.V. Zhidkov ◽

...

Keyword(s):

Geomagnetic Field ◽

Absolute Intensity ◽

Kuznetsk Basin ◽

Single Domain ◽

Large Igneous Province ◽

Triassic Boundary ◽

Mean Values ◽

Initial Stage ◽

Order Of Magnitude ◽

Permian Triassic Boundary

Abstract —Here we report the first data on the absolute intensity value of the geomagnetic field on the Permian–Triassic boundary from basalts of the Kuznetsk basin. The latter are considered as one of the manifestations of the initial stage of trap magmatism during the formation of the Siberian large igneous province. The good preservation of information on the ancient geomagnetic field in the Mal’tsevskaya Formation basalts is due to the presence of small single domain and pseudo-single domain grains of primary magmatic titanomagnetite in the groundmass. The paleointensity values obtained following the Thellier-Coe method correspond to the generally accepted criteria of reliability and indicate that the geomagnetic field intensity during the formation of the Kuznetsk basin traps on the Permian–Triassic boundary was almost an order of magnitude lower than the present-day one. Moreover, the mean values of the virtual dipole moment for the Kozhukhta and the Vlasov units in the lower and middle Mal’tsevskaya Formation ((1.9 ± 0.6) · 1022 A · m2 and (1.1 ± 0.7) · 1022 A · m2, respectively) are in good alignment with determinations of the paleointensity during the accumulation of the Ivakinsky Formation of the Norilsk Region in the Siberian province, which confirms the accuracy of traditional regional correlations.

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High-resolution stratigraphy of the Changhsingian (Late Permian) successions of NW Iran and the Transcaucasus based on lithological features, conodonts and ammonoids

Fossil Record ◽

10.5194/fr-17-41-2014 ◽

2014 ◽

Vol 17 (1) ◽

pp. 41-57 ◽

Cited By ~ 21

Author(s):

A. Ghaderi ◽

L. Leda ◽

M. Schobben ◽

D. Korn ◽

A. R. Ashouri

Keyword(s):

Late Permian ◽

Triassic Boundary ◽

Nw Iran ◽

The Earth ◽

Extinction Event ◽

History Of ◽

Mass Extinction Event ◽

Bottom To Top ◽

Permian Triassic Boundary ◽

North Western

Abstract. The Permian–Triassic boundary sections in north-western Iran belong to the most complete successions, in which the largest mass extinction event in the history of the Earth can be studied. We investigated the Changhsingian stage in six sections in the area of Julfa (Aras Valley) for their lithology, conodonts and ammonoids. Revision of the biostratigraphy led to the separation of 10 conodont zones (from bottom to top Clarkina orientalis–C. subcarinata interval zone, C. subcarinata, C. changxingensis, C. bachmanni, C. nodosa, C. yini, C. abadehensis, C. hauschkei, Hindeodus praeparvus–H. changxingensis and Merrilina ultima–Stepanovites ?mostleri zones) and 8 ammonoid zones (from bottom to top Iranites transcaucasius–Phisonites triangulus, Dzhulfites nodosus, Shevyrevites shevyrevi, Paratirolites trapezoidalis, P. waageni, Stoyanowites dieneri, Abichites stoyanowi and Arasella minuta zones). The new ammonoid genera Stoyanowites and Arasella are described.

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Magnetostratigraphy across the end-Permian mass extinction event from the Meishan sections, southeastern China

Geology ◽

10.1130/g49072.1 ◽

2021 ◽

Author(s):

Min Zhang ◽

Hua-Feng Qin ◽

Kuang He ◽

Yi-Fei Hou ◽

Quan-Feng Zheng ◽

...

Keyword(s):

Mass Extinction ◽

Southeastern China ◽

Triassic Boundary ◽

Biodiversity Crisis ◽

Normal Polarity ◽

Mass Extinction Event ◽

Geomagnetic Polarity ◽

Permian Mass Extinction ◽

Permian Triassic Boundary ◽

Geomagnetic Polarity Time Scale

The end-Permian mass extinction (EPME) has been recorded as the most severe biodiversity crisis in Earth’s history, although the timing of the marine and terrestrial extinctions remains debatable. We present a new high-resolution magnetostratigraphic succession across the EPME and the Permian-Triassic boundary (PTB) from the Meishan sections in southeastern China, which contain the global boundary stratotype section and point (GSSP) for the base of the Triassic (also the Induan Stage) and the base of the Changhsingian Stage. We identified five normal and five reverse magnetozones, including MS1n to MS5n and MS1r to MS5r, from oldest to youngest, in the Changhsingian and Induan Stages. The Induan Stage was determined to consist of two polarity intervals, where the upper one is reverse (MS5r), and the lower one is normal (MS5n). The Changhsingian Stage is dominated by normal polarity, intercalated with four short-term reverse magnetozones (MS1r to MS4r). Consequently, the PTB and the Wuchiapingian-Changhsingian boundary are clearly located in MS5n and MS1n, respectively. These new magnetostratigraphic results provide a potential reference geomagnetic polarity pattern with which to refine the geomagnetic polarity time scale for the EPME and the Permian-Triassic transition.

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DETERMINATION OF THE PERMIAN-TRIASSIC BOUNDARY IN AUSTRALIA FROM CARBON ISOTOPE STRATIGRAPHY

The APPEA Journal ◽

10.1071/aj93030 ◽

1994 ◽

Vol 34 (1) ◽

pp. 330 ◽

Cited By ~ 4

Author(s):

R. Morante ◽

J.J. Veevers ◽

A.S. Andrew ◽

P.J. Hamilton

Keyword(s):

Carbon Isotope ◽

Isotope Composition ◽

Time Correlation ◽

Depositional Environments ◽

Sedimentary Record ◽

Triassic Boundary ◽

Global Comparison ◽

Wide Range ◽

Isotope Stratigraphy ◽

Permian Triassic Boundary

Significant excursions in the carbon isotope composition of organic matter from sedimentary sections across the Permian/Triassic boundary are documented from the Bonaparte, Canning, Carnarvon, Perth, and Bowen Basins. The analysed sections represent a wide range of depositional environments from marine to non-marine, among which precise time correlation is uncertain. The sense and magnitude of the isotopic excursions are comparable to those found elsewhere around the world from marine carbonates at this time. Early Triassic sediments consistently bear carbon more depleted in the carbon-13 isotope than do latest Permian sediments. The isotope excursion provides an isochronous global datum in the sedimentary record at the palaeontologically determined Permian/Triassic boundary. This carbon isotope chemostratigraphic scheme has application for:correlation between different depositional environments, at scales ranging from intrabasinal to global;comparison of sedimentation rates; andrecognition of lacunas in the sedimentary record.

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Ammonoid stratigraphy and sedimentary evolution across the Permian–Triassic boundary in East Greenland

Geological Magazine ◽

10.1017/s0016756806002020 ◽

2006 ◽

Vol 143 (5) ◽

pp. 635-656 ◽

Cited By ~ 33

Author(s):

MORTEN BJERAGER ◽

LARS SEIDLER ◽

LARS STEMMERIK ◽

FINN SURLYK

Keyword(s):

Triassic Boundary ◽

East Greenland ◽

Sedimentary Evolution ◽

Environmental Perturbations ◽

Relative Dating ◽

Greenland Basin ◽

History Of ◽

Adaptive Radiations ◽

Chemical Anomalies ◽

Permian Triassic Boundary

East Greenland is a classical area for the study of the Permian–Triassic transition and the succession is one of the most expanded in the world. New ammonoid data from the Wordie Creek Formation have allowed us to better reconstruct the history of the East Greenland basin from semi-isolated basins with an endemic fauna during latest Permian–earliest Triassic H. triviale–H. martini zones time to well-connected open marine shelf basins during the Early Triassic M. subdemissum, O. commune, W. decipiens and B. rosenkrantzi Zone times. The East Greenland zonation can be correlated with Boreal zonations in Arctic Canada, Svalbard and northeastern Asia. It allows precise relative dating and correlation of important events across the Permian–Triassic boundary. The new ammonoid data indicate that deposition was continuous across the Permian–Triassic boundary and developed as a marine mudstone–mudstone contact in basinal areas of Hold With Hope, northern and southern Jameson Land. Correlation of the ammonoid stratigraphy with the FAD of Hindeodus parvus, which defines the base of the Triassic in Global Stratotype Section and Point (GSSP) in Meishan, China, suggests that the Hypophiceras triviale Zone is to be referred to the uppermost Permian, whereas the H. martini Zone is lowermost Triassic. Accordingly, the end-Permian marine and terrestrial extinctions and associated isotope changes as well as the subsequent adaptive radiations in East Greenland took place in latest Permian time. New Boreal faunas and floras were well established and diversified in the Hypophiceras triviale Zone prior to the beginning of the Triassic, and the Permian–Triassic boundary, in its present definition, is no longer reflecting major changes in the Earth system. It would have been fortunate if a GSSP were defined in a protracted section at a point of major environmental perturbations, marked by isotope excursions, chemical anomalies and mass extinction, rather than in the strongly condensed section like Meishan at a point which post-dates all significant events.

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The Permian–Triassic boundary in Antarctica

Antarctic Science ◽

10.1017/s0954102005002658 ◽

2005 ◽

Vol 17 (2) ◽

pp. 241-258 ◽

Cited By ~ 49

Author(s):

G.J. RETALLACK ◽

A.H. JAHREN ◽

N.D. SHELDON ◽

R. CHAKRABARTI ◽

C.A. METZGER ◽

...

Keyword(s):

Carbon Isotope ◽

Terrestrial Ecosystems ◽

Early Triassic ◽

Mass Extinctions ◽

Late Permian ◽

Triassic Boundary ◽

Marine Fossils ◽

History Of ◽

Stratotype Section ◽

Permian Triassic Boundary

The Permian ended with the largest of known mass extinctions in the history of life. This signal event has been difficult to recognize in Antarctic non-marine rocks, because the boundary with the Triassic is defined by marine fossils at a stratotype section in China. Late Permian leaves (Glossopteris) and roots Vertebraria), and Early Triassic leaves (Dicroidium) and vertebrates (Lystrosaurus) roughly constrain the Permian–Triassic boundary in Antarctica. Here we locate the boundary in Antarctica more precisely using carbon isotope chemostratigraphy and total organic carbon analyses in six measured sections from Allan Hills, Shapeless Mountain, Mount Crean, Portal Mountain, Coalsack Bluff and Graphite Peak. Palaeosols and root traces also are useful for recognizing the Permian–Triassic boundary because there was a complete turnover in terrestrial ecosystems and their soils. A distinctive kind of palaeosol with berthierine nodules, the Dolores pedotype, is restricted to Early Triassic rocks. Late Permian and Middle Triassic root traces are carbonaceous, whereas those of the Early Triassic are replaced by claystone or silica. Antarctic Permian–Triassic sequences are among the most complete known, judging from the fine structure and correlation of carbon isotope anomalies.

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