T343 Modern and Ancient Sediment Transport on Earth and Planetary Surfaces (Posters)

Wednesday, 28 September 2016
9:00 AM - 6:30 PM
Exhibit Hall E/F

PROVENANCE OF FLUVIAL-LACUSTRINE SANDSTONES OF LOWER PERMIAN LUCAOGOU LOW-ORDER CYCLE, BOGDA MOUNTAINS, NW CHINA

Paper number: T343-10
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

  • Xiaowei Peng Presenting Author
    Missouri University of Science and Technology, Rolla, MO
  • Wan Yang
    Missouri University of Science and Technology, Rolla, MO

Abstract

Compositional and textural maturity of sandstones can reflect provenance lithology and sediment transport distance, useful paleogeographic reconstruction. 18 sandstones from Taodonggou, SW Tarlong (TL), S TL and N TL sections were studied to investigate the fluvial-lacustrine sandstone provenance in lower Permian Lucaogou (LCG) low-order cycle, Bogda Mountains, NW China. The sections are 83, 84, 112 and 106 m thick, respectively, in a half graben covering 88 km2. 400 points were counted in each thin section. The sandstones include 6 lithic arenites, 7 lithic subarenites and 5 lithic wackes with an average composition of Q3F11L86, Q4F7L89 and Q6F11L83. Volcanic lithics (Lv) dominate with minor sedimentary lithics (Ls) with an average Lv/Ls ratio of 5:1. Abundant basaltic lithics indicate an uplifted oceanic crust source, probably the N Tianshan suture zone to the south. Upsection trend in compositional and textural maturity varies among sections. Taodonggou and N TL sections have an average composition of Q4F6L90 and Q1F8L91, respectively, with higher compositional maturity upsection. The similarity in composition and trend indicates a similar source. However, samples from SW TL have an average composition of Q5F8L87, a 1:1 Lv/Ls ratio, and an upsection decrease in compositional maturity. Abundance of Ls indicates a local sedimentary source. Samples of S TL have an average composition of Q8F14L78 and the highest compositional maturity in the middle part, suggesting source variation during deposition. Texturally, sandstones of N TL are poorly-moderately well sorted with 4.6% matrix on average, while those in the other sections have variable matrix content of 12-16% on average. The higher textural maturity of N TL sandstones implies longer transport distance. Grain size trend varies in each section: fining upward in lower LCG in all sections. However, in upper LCG, grain size fines upward in Taodonggou and SW TL sections, but coarsens up in N and S TL sections. This suggests that transport distance increased during deposition of lower LCG, and kept increasing for Taodonggou and SW TL sections but became shorter for N and S TL sections during deposition of upper LCG. Grain size trend may also be affected by depositional environments of sandstones.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-285784

© Copyright 2016 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.