Permo-Triassic magnetostratigraphy in China: northern Tarim

McFadden, P. L.; Ma, Xinghua; McElhinny, M. W.; Zhang, Z.K.

doi:10.1016/0012-821x(88)90071-4

Cited by 84 publications

(19 citation statements)

References 15 publications

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“…A great number of paleo-magnetism measurements indicate that the Tarim block was at a southern latitude in the Sinian and continually drifted northward to a northern latitude (e.g. McFadden et al, 1988;Sharps et al, 1989;Chen et al, 1992;Fang et al, 1998;Fang and Shen, 2001;Jia et al, 2007). After the formation of the crystalline basement of the Tarim Plate in the Mesoproterozoic, the Paleo-plate was at a latitude of 20°S (Jia et al, 2007).…”

Section: Temperature Datamentioning

confidence: 96%

Paleo-heat flow evolution of the Tabei Uplift in Tarim Basin, northwest China

Wang

Chen

et al. 2010

Journal of Asian Earth Sciences

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Section: Temperature Datamentioning

confidence: 96%

Paleo-heat flow evolution of the Tabei Uplift in Tarim Basin, northwest China

Wang

Chen

et al. 2010

Journal of Asian Earth Sciences

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“…We have followed similar rejection criteria to those of Enkin et al (1992) and have omitted the result by Lin ( 1984) from the Shiqianfeng Formation at Liaoning because the normal and reverse directions are not at all antipodal and it appears that there may be some effects resulting from local rotations. However, we are able to include some of the results of smaller collections (< 10 samples) because we then combine the data separately for the Lower Triassic and Upper Permian using the method for combining groups of palaeomagnetic directions or poles of McFadden & McElhinny (1995). In this method the result is essentially weighted towards those with the greatest number of measurements.…”

Section: Shiqinnfengfupper Shihezimentioning

confidence: 99%

Permo-Triassic magnetostratigraphy in China: the type section near Taiyuan, Shanxi Province, North China

Embleton

McElhinny

et al. 1996

Geophysical Journal International

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S U M M A R YA palaeomagnetic study has been made of samples collected from the Permo-Triassic type section near Taiyuan, Shanxi Province in the North China Block. No results were obtained from the Upper Carboniferous Shanxi and Taiyuan Formations. Results from the Permian Lower and Upper Shihezi and Shiqianfeng Formations and from the Lower Triassic Liujiagou Formation were restricted mainly to the red shale and red mudstone horizons that were preferentially sampled for this study. After thermal demagnetization, the following pole positions were obtained: Lower Permian (Lower Shihezi Formation, N = 11 samples) 20.9"N, 1.4"E with d p = 6.1" and dm = 12.2"; Upper Permian (combined Upper Shihezi and Shiqianfeng Formations, N = 89 samples) 47.8"N, 357.4"E with d p = 2.3" and dm = 4.3"; Lower Triassic (Liujiagou Formation, N = 25 samples) 50.0°N, 351.O"E with d p = 3.7" and dm = 7.0". The sequence crosses the younger boundary of the Permo-Carboniferous reversed (Kiaman) superchron, and the polarity sequence observed suggests that this superchron ended in mid-Ufimian times. A minimum of 13 polarity zones (seven normal and six reverse) then follow before the Permo-Triassic boundary. This is in excellent agreement with currently available observations worldwide.

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“…A minimum of three points (4 for planes) defined a stable endpoint magnetization, and anchored fits were avoided due to the anomalously low uncertainty estimations (Heslop and Roberts, 2016). Where MAD values were greater than 15°, or where samples did not reach stable endpoints, the arc method of McFadden and McElhinny (1988) was used to isolate the primary component of magnetization. Final iterative directions along the arc constraints were combined with lines for the stratigraphic polarity interpretation.…”

Section: Geologic Backgroundmentioning

confidence: 99%

“…Several periods of stable field polarity have been observed, the longest of which is known as the Kiaman Reverse Superchron (KRS; Fig. 3), which lasted more than 50 million years (Alva-Valdivia et al, 2002;Belica et al, 2017;Diehl and Shive, 1979;Diehl and Shive, 1981;DiVenere and Opdyke, 1990;DiVenere and Opdyke, 1991;Gialanella et al, 1997;Gose and Helsley, 1972;Irving and Parry, 1963;Khramov and Tarling, 1987;Lozovsky and Molostovsky, 1993;McFadden et al, 1988;Menning et al, 1988;Nawrocki, 1997;Opdyke and Channell, 1996;Opdyke et al, 2001;Opdyke et al, 2000;Steiner, 2006;Steiner et al, 1993;Szurlies et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Refining the chronostratigraphy of the Karoo Basin, South Africa: magnetostratigraphic constraints support an early Permian age for the Ecca Group

Belica¹,

Tohver²,

Poyatos‐Moré

et al. 2017

Geophysical Journal International

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Summary:The Beaufort Group of the Karoo Basin, South Africa provides an important chrono-and biostratigraphic record of vertebrate turnovers that have been attributed to the End-Permian mass extinction events at ca. 252 Ma and ca. 260 Ma. However, an unresolved controversy exists over the age of the Beaufort Group due to a large dataset of published U-Pb SHRIMP zircon results that indicate a ca. 274-250 Ma age range for deposition of the underlying Ecca Group. This age range requires the application of a highly diachronous sedimentation model to the Karoo Basin stratigraphy and is not supported by published paleontologic and palynologic data. This study tested the strength of these U-Pb isotopic datasets using a magnetostratigraphic approach. Here we present a composite ~1500 m section through a large part of the Ecca Group from the Tanqua depocentre, located in the southwestern segment of the Karoo Basin. After the removal of two normal polarity overprints, a likely primary magnetic signal was isolated at temperatures above 450°C. This section is restricted to a reverse polarity, indicating that it formed during the Kiaman Reverse Superchron (ca. 318-265 Ma), a distinctive magnetostratigraphic marker for Early−Middle Permian rocks. The Ecca Group has a corresponding paleomagnetic pole at 40.8°S, 77.4°E (A95 = 5.5°). UPb SHRIMP ages on zircons are presented here for comparison with prior isotopic studies of the Ecca Group. A weighted mean U-Pb age of 269.5 ± 1.2 Ma was determined from a volcanic ash bed located in the uppermost Tierberg Formation sampled from the OR1 research core. The age is interpreted here as a minimum constraint due to a proposed Pb-loss event that has likely influenced a number of published results. A comparison with the Geomagnetic Polarity Time Scale as well as published U-Pb TIMS ages from the overlying Beaufort Group supports a ca. 290-265 Ma age for deposition of the Ecca Group.

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Permo-Triassic magnetostratigraphy in China: northern Tarim

Cited by 84 publications

References 15 publications

Paleo-heat flow evolution of the Tabei Uplift in Tarim Basin, northwest China

Paleo-heat flow evolution of the Tabei Uplift in Tarim Basin, northwest China

Permo-Triassic magnetostratigraphy in China: the type section near Taiyuan, Shanxi Province, North China

Refining the chronostratigraphy of the Karoo Basin, South Africa: magnetostratigraphic constraints support an early Permian age for the Ecca Group

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