China
Africa
Explore chapters and articles related to this topic
Sediments and Sedimentary Rocks
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Arkoses, such as the one shown in Figure 8.55, are sandstones that are generally reddish, orangish, or gray and contain more than 25% feldspar. Typical arkoses contain a mix of grain sizes, but coarse sand and some larger clasts are usually present in significant amounts. The arkose in Figure 8.55 contains conspicuous amounts of pebble-sized clasts besides the dominant sand. The reddish color of this sample, and most arkose, is due to the color of the K-feldspar clasts that it contains. Arkose most commonly forms from sediment produced by weathering of granitic rocks. The sediment must be buried rapidly or else chemical decomposition will replace the feldspar with clay minerals.
Diagenesis and Properties of Sedimentary Rocks
Published in Aurèle Parriaux, Geology, 2018
Arkose is a particular type of sandstone, generally with siliceous cement, produced by the diagenesis of granitic sand (Chap. 13). It is composed of granitic minerals that have been transported only short distances, thus preserving their crystalline appearance. Some very massive arkoses can strongly resemble granites, except that the arkoses can be stratified. Other types of cement can occur depending on the chemistry of the water that percolated through the sediment (Fig. 10.11).
Diagenesis and Properties of Sedimentary Rocks
Published in Aurèle Parriaux, Geology, 2018
Arkose is a particular type of sandstone, generally with siliceous cement, produced by the diagenesis of granitic sand (Chapt. 13). It is composed of granitic minerals that have been transported only short distances, thus preserving their crystalline appearance. Some very massive arkoses can strongly resemble granites, except that the arkoses can be stratified. Other types of cement can occur depending on the chemistry of the water that percolated through the sediment (Fig. 10.11).
Sediment provenance in the Murchison and Maruia basins, Aotearoa/New Zealand: a record of Neogene strike-slip displacement, convergence, and basement exhumation along the Australian–Pacific plate boundary
Published in New Zealand Journal of Geology and Geophysics, 2022
Matthew W. Sagar, Karen E. Higgs, Dominic P. Strogen, Kyle J. Bland, Greg H. Browne
Most samples are fine to medium sandstone with <10% matrix. Sorting ranges from poor to good (Table 2). Sandstone compositions range from quartzofeldspathic, through feldspathic, to rock fragment-rich, plotting as arkose, lithic arkose, feldspathic litharenite, or litharenite (Figure 2A). This reflects Q, F and R that range widely from 10% to 63%, 9% to 46% and 3% to 64%, respectively. Plagioclase is more abundant than K-feldspar in most samples (n = 20/25), with P/F in these samples ranging from 0.53 to 0.94 (Figure 2B). Proportions of rock fragments are highly variable, the only obvious pattern being that the majority (n = 21/25) contain >70% RmRmis + RiRmis; only four samples contain RsRmis > 30% (Figure 2C). Total mica ranges from 2% to 15% with biotite generally dominant. Total heavy minerals are generally <5%.