Low-latitude and Southern Hemisphere origin of Anisian (Triassic) bedded chert in the Inuyama area, Mino terrane, central Japan

Paleomagnetic and paleontologic studies of Middle Triassic to earliest Jura ssic radiolarian bedded chert in the Inuyama area, southern Mine terrane of central Japan, have shown that the chert was deposited in an equatorial re gion with a paleolatitude between 10 degreesN and 10 degreesS, and in parti cular, the lower to middle Anisian chert depositional basin was situated in the Southern Hemisphere. The chert has four characteristic components of r emanent magnetization. The highest blocking temperature component, carried by hematite, shows positive fold and reversal tests and is regarded as the primary remanent magnetization acquired just after deposition. The other th ree components are interpreted as a present field overprint and two postfol ding remagnetizations. The absolute, tilt-corrected inclinations of the pri mary component are less than 20 degrees for all the samples of Middle Trias sic to earliest Jurassic age, with the mean inclination of the lower to mid dle Anisian chert being 11.0 degrees +/- 4.3 degrees. Paleomagnetic polarit y reversals observed for the lower to middle Anisian chert are well correla ted with those of the European Triassic sections, under paleontologic age c onstraints using radiolarians and conodonts, provided that the Anisian cher t in Inuyama was deposited in the Southern Hemisphere. This conclusion illu minates the paleogeographic evolution of the chert-bearing accretionary com plexes not only in Japan but along the eastern margin of Asia as well.