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

Abstract

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.

Permian Paleogeography of the Eastern CAOB: Paleomagnetic Constraints From Volcanic Rocks in Central Eastern Inner Mongolia, NE China

“…For the NCB, the post‐Late Permian APWP has been firmly established (e.g., Huang et al, ; Van der Voo et al, ; L. Wu et al, ; Yang & Besse, ); however, the Permo‐Carboniferous path is problematic due to the paucity of reliable paleomagnetic results. Published Early Carboniferous to Early Triassic data from the NCB since the1980s with Q ≥ 4 (Van der Voo, ) are summarized in supporting information Table S3 (Embleton et al, ; Fang et al, ; Huang et al, , ; Ma et al, ; Ma & Zhang, ; McElhinny et al, ; Tan et al, ; H. Wu et al, ; Yang et al, , T. Zhou et al, ). Running mean and Q ‐weighted spherical spline (smoothing factor = 300) APWPs for the NCB are generated using both uncorrected and IF‐corrected data (Table and Figures a and b; Torsvik et al, , ).…”

Late Pennsylvanian to Wuchiapingian palynostratigraphy of the Baode section in the Ordos Basin, North China

“…A significant magnetostratigraphic marker for the upper boundary of the Wordian stage (the Illawarra Reversal) (Jin and Shang, 2000), was delimited in the middle part of the Upper Shihhotze Formation. This lies slightly above the upper boundary of the Crenulata Biozone (Embleton et al, 1996;Menning and Jin, 1998), and so the Crenulata Biozone is likely to be of the late Kungurian to Wordian age. (Plate 7) 4.8.1.…”

“…Eight miospore biozones are erected and integrated with the marine microfossil record and magnetostratigraphic calibrations as proposed by Kong et al (1996) and Embleton et al (1996).…”

Geomagnetic reversal rates following Palaeozoic superchrons have a fast restart mechanism

“…3). The end of the Kiaman Superchron is shown in the West Texas/New Mexico data26, the Taiyuan section27 (Fig. 3) and in data from Japan28.…”