T98 High-Resolution Datasets for Fluvial and Hillslope Processes and Landforms: Frontiers of Remotely Sensed Data (Posters)

Monday, 5 November 2018
9:00 AM - 6:30 PM
Halls J-K

RIVERS RESPONSE TO TECTONICS IN EXTENSIONAL LANDSCAPES: A CASE OF STUDY IN THE JALISCO BLOCK (WEST-CENTRAL MEXICO) AND ADJACENT AREAS

Paper number: T98-2
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

  • Arturo Godínez-Tamay Presenting Author
    Posgrado en Ciencias de la Tierra, Universidad Nacional Autónoma de México, Ciudad de México
  • Miguel Castillo
    National Autonomous University of Mexico, Mexico City
  • Luca Ferrari
    Centro de Geociencias, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro
  • Fernando Ortega-Gutiérrez
    Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad de México

Abstract

Rivers are key elements of the landscape that capture changes in tectonic and/or climatic conditions. Many studies have used morphometric indexes of rivers to assess the tectonic forcing of landscape; however, the case for the response of rivers in extensional settings where volcanic activity has covered vast areas of the landscape has remained poorly documented. We evaluate the case of west-central Mexico where landscape results from an extensional tectonic regime initiated in the Miocene and continuing to the present, and where there is a marked volcanic activity of Eocene-Oligocene and Pliocene-Pleistocene age. We use the normalized channel steepness index (ksn) and compare this with other morphometric parameters such as the hillslope gradient, hillslope convexity, hillslope concavity, terrain rugosity and first order streams gradient (Fosg). Regressions of morphometric parameters as a function of ksn index have R2 greater in the Eocene-Oligocene volcanic landscapes (51% to 57%) in comparison to the Pliocene-Pleistocene volcanic landscapes (39% to 49%). The scaling between the hillslope concavity and ksn is the best among all the models tested, meaning that the incisional response dominates over the landscape. Tukey’s test show that the distribution of the concavity and the ksn index is not significantly different (p >0.05) among volcanic landscapes. The ANCOVA analysis also indicates that both concavity and rugosity are not significantly different among volcanic landscapes (p >0.05). Tukey’s test and the ANCOVA analysis also show that the distribution Fosg does not significantly differs among extensional landscapes (p >0.05). Our results indicate that even though volcanism might inhibit the response of rivers to tectonics, given the supply of large volumes of rock and sediment into the landscape, river incision is still mostly controlled by tectonic activity.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-315209

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