Geological Society of America

T286 Statistical and Mathematical Approaches to Understanding Surface Processes and Stratigraphy

Wednesday, 25 September 2019
1:30 PM - 5:30 PM
Room 224A, North Building

GRAINSIZE DEPENDENT TRANSPORT AND DEPOSITION IN A LANDSCAPE EVOLUTION MODEL

Paper number: T286-13
Program: Technical Sessions
Time: 4:35 PM – 4:50 PM

Authors

Erica Emry Presenting Author
New Mexico Institute of Mining and Technology, Socorro, NM
Kyungdoe Han
New Mexico Institute of Mining and Technology, Socorro, NM
Michael Berry
New Mexico Institute of Mining and Technology, Socorro, NM
Jolante van Wijk
New Mexico Institute of Mining and Technology, Socorro, NM
John L. Wilson
New Mexico Institute of Mining and Technology, Socorro, NM
Ryan J. Leary
New Mexico Institute of Mining and Technology, Socorro, NM
Daniel Garcia-Castellanos
CSIC - Instituto de Ciencias de la Tierra Jaume Almera (ICTJA), Barcelona

Abstract

The sedimentary deposits within continental basins frequently exhibit spatially-variable sorting, with coarser clastics (gravel and sand) proximal to river outlets and fine-grained clastics located at greater distances into lakes and seas. This dependency on grain-size produces patterns that can have a significant effect on patterns of subsurface fluid transport, mineralization, and spring effluence. Here, we incorporate grain-size dependent transport and deposition into TISC (Tectonics, Isostasy, Surface processes, and Climate), a large-scale finite-difference landscape evolution model, in order to reproduce sediment sorting along streams and within lake-filled basins. For each fluvial transport model in TISC, clastic sediments of two, user-defined, grain sizes are transported and deposited according to one or two criteria, the first representing differing abilities to be entrained by streams and the second that represents differing grain settling distances. As each incremental coarse and fine-grained sediment layer is deposited, we calculate basic petrophysical properties from user-defined grain size and porosity. From this, we calculate intrinsic permeability, using the Kozeny-Carman equation assuming spherical grains. As sedimentary units are defined by age horizon within TISC, we calculate effective (upscaled) horizontal and vertical permeability for each incremental coarse and/or fine grain depositional event, maintaining our ability to detect and record thin aquitard layers which can affect hydrologic anisotropy. We find that with the additional capability to separate two clastic grain sizes, we can reproduce more realistic sedimentation patterns, where coarse grains settle near river outflows and fine grains settle at greater distances within a basin. We also find that in the regions where significant coarse and fine grain sediment are both deposited, predicted horizontal-to-vertical permeability ratios increase by 1-2 orders of magnitude. We show results from a range of tests for simplified continental basin structures, varying erosional, transport, and depositional parameters, surface runoff, and topographic relief.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-338819

© Copyright 2019 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.