Devonian paleomagnetism of Yunnan Province across the Shan Thai‐South China Suture

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Abstract
A paleomagnetic study of Devonian sedimentary sequences from western and eastern Yunnan, China, yields contrasting paleolatitudes for these two areas. They indicate an equatorial position for eastern Yunnan, as part of the Yangtze Paraplatform or South China Block, and a paleolatitude of about 40° for western Yunnan as part of the Shan State (or Shan‐Thai) Block, which probably was part of the Gondwana supercontinent. The majority of samples is strongly overprinted by a present‐day field magnetization, but thermal demagnetization has been successful in isolating ancient, dual‐polarity characteristic directions of magnetization in rocks from eastern and western Yunnan, with results from the latter passing the fold test. The paleopole from eastern Yunnan is located at 8.9°N, 10.4°E (declination/inclination = 279.2°/+2.7°, k = 13, alpha 95 = 6.9°, N = 33 samples from 7 sites). The paleopole from western Yunnan is located at 66.5°N, 133.8°E (declination/inclination = 18.0°/+62.0°, k = 21, alpha 95 = 5.8°, N = 31 samples from 7 sites), yielding a paleolatitude of 42°. The two blocks studied are separated by the Red (Yuan) River and Lancang (Mekong) River fault zones, one of which is inferred to be an ancient suture.