Embleton et al. (1996; hereafter referred to as EMMZL) EMMZL’s incorrect dating of the Illawarra Reversal resulted from a false correlation between the Upper Permian of Chinese detected the Late Permian Illawarra Reversal (IR: top of the Carboniferous–Permian reversed megazone, Kiaman, 265 Ma) chronostratigraphic schemes and that of Harland et al. (1990). The Upper Permian used in China is equivalent to the Lopingian in the lower Upper Shihezi (Shihhotse) Formation of North China. Series (Zhan, Zhaang & Li 1982; Sheng et al. 1982), while the Lower Permian is equivalent to the Chisian and the Maokouan In their stratigraphic scheme (Table 1 and Fig. 5, redrawn in our Fig. 1) the lower boundaries of the Upper Shihezi (Fig. 2). However, Harland et al.’s (1990) Upper Permian spans the Ufimian to the Changhsingian, and therefore closely Formation, Ufimian and Late Permian coincide. Consequently, EMMZL conclude that the Permo-Carboniferous reversed corresponds to the entire Permian succession that EMMZL identified in the Shanxi section. In the EMMZL scheme (Fig. 1) (Kiaman) superchron ends in mid-Ufimian time. This interpretation does not agree with the position of the IR in the the Lower Shihezi Formation corresponds to the entire Lower Permian, whereas in the Sheng & Jin (1994) scheme it is lower part of the type Tatarian on the East European Platform (Khramov 1963), which has been accepted for the last 30 years assigned to the upper Chihsian and the lower Maokouan and, combined with the Jin et al. (1994) scheme, corresponds to the and has been confirmed most recently by Gialanella et al. (1997). EMMZL do not mention this significant discrepancy middle part of the Permian (upper Kungurian plus Roadian plus Wordian; Fig. 2). (Fig. 1). We are certain that the difference can be explained better using a revised stratigraphic scheme than by suggesting EMMZL (p. 382) stated ‘The Shanxi Formation is rich in brachiopods, corals and fusulinids that date it as Late methodological insufficiencies or remagnetization. EMMZL use reliable palaeomagnetic equipment and Carboniferous’. This statement is untrue. In reality, the underlying Taiyuan Formation comprises normal marine sediments methodologies. Their magnetostratigraphic results are significant according to the sequences investigated, although no and contains fusulinids, corals and brachiopods, but the Shanxi (Shansi) Formation does not as it is of lacustrine origin fold test or conglomerate test is possible and mainly the red horizons of a grey/red Permian/Triassic succession yield (BGRM Shanxi 1989). The Shanxi (Shansi) Formation has never been assigned to the Late Carboniferous in the last stable remanent magnetizations. Plenty of facts support their magnetic zones. The Zijderfeld plots reflect continuous thermal decade. It is late Artinskian to post-Artinskian in age, because the upper part of the underlying Taiyuan Formation contains demagnetization and stable remanence (EMMZL, Fig. 2). Inclination and declination of the remanence are at the Artinskian conodonts such as Streptognathodus whitei (Wang et al. 1987) (Fig. 2). expected values; normal and reversed samples are grouped and bipolar (EMMZL, Fig. 3). A minimum of 13 polarity zones The plant fossils from the Upper Shihezi (Shihhotse) Formation and the Shiqianfeng (Shichienfeng) Formation are have been detected between the IR and the Permian/Triassic boundary. This number is in good agreement with data from referred to as the late stage of the Cathaysian flora (Li 1963). Indeed, the plant assemblage of the Shichienfeng (Shiqianfeng) the Salt Range (Haag & Heller 1991), Central Europe (Menning 1995) and Australia (Theveniaut et al. 1994). Formation contains some characteristic Zechstein species (Wang et al. 1989; also see Sheng & Jin 1994, p. 65). The different position of the IR within the Tatarian (Khramov 1963) and within the Ufimian (EMMZL) results Consequently, the Upper Shihhotse Formation (position of the IR of EMMZL) may correspond with part of the Upper from the stratigraphic schemes used by EMMZL (Table 1, Fig. 5). They refer their data to the ‘official Chinese stratiRotliegend (conformable below the Zechstein), where the IR is detected (Menning et al. 1988). graphic scheme’ (EMMZL, no details given) and the Harland et al. (1990) timescale (cf. Fig 1). On the other hand, the In the Sheng & Jin (1994) scheme the lower part of the Upper Shihhotse (Shihezi) Formation (position of the IR of magnetostratigraphic results of EMMZL and Khramov (1963) are consistent when referred to the correlation chart of Permian EMMZL) corresponds with the Upper Maokouan (Fig. 2). The IR has been expected within the Maokouan (Menning, deposits in China (Sheng et al. 1982; Sheng & Jin 1994) (Fig. 2).
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Apr 1, 2000
Imasiku A Nyambe + 1
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