Magnetic fabric and paleomagnetism of the Middle Triassic siliciclastic rocks from the Nanpanjiang Basin, South China: Implications for sediment provenance and tectonic process

摘要: A combined magnetic fabric and paleomagnetic study has been carried out on the siliciclastic rocks gathered from a stratigraphic cross-section through Nanpanjiang Basin, South China, in an attempt to extract paleoflow information preserved and, thus, constrain possible origins of these clastic rocks. The sediments used for this were formed by sediment-gravity flows along southern margin China block Middle Triassic time (ca. 245-228 Ma). results show normal distribution both low field susceptibility values natural remanent magnetization intensities, which with monotonic detrital framework mode, mainly comprising quartz lithic particles, may suggest single provenance involved deposition deposits. Anisotropy (AMS) analysis acquires primarily sedimentary fabrics, which, study, reveal directions ranging NNW ENE overall mean orientation NE. Demagnetization part samples isolates characteristic component averaged at D = 44.8 degrees, I= 16.9 K 9.7, alpha(95) 6. 5 n 55, corresponding paleolatitude N8.6 degrees clockwise rotation ca. 45 since studied cross-section. This direction passes fold tests is consistent reference expected 95% confidence level. Restoring similar declination renders northward paleoflow, other evidence, suggests during time. In terms early Mesozoic plate southeastern Asia, tectonic scenario proposed here, whereby nearly N-S convergence Indochina blocks its related Indosinian orogeny caused formation foreland basin, was filled voluminous detritus shed uplifted orogenic belt side. (C) 2013 Elsevier Ltd. All rights reserved.