T228 The Effects of Discharge Variability on Alluvial Stratigraphy: Toward a New Facies Model

Tuesday, 27 September 2016
1:30 PM - 5:30 PM
Room 401

FLUVIAL CONTROLS ON SOIL MOISTURE TRENDS OBSERVED IN NACIMIENTO FORMATION PALEOSOLS, SAN JUAN BASIN, USA

Paper number: T228-15
Program: Technical Sessions
Time: 5:10 PM – 5:25 PM

Authors

Abstract

The Paleocene Nacimiento Formation of the San Juan Basin, New Mexico, preserves deposits of fluvial systems draining the emerging Southern Rocky Mountain Laramide highlands as well as well-developed paleosols throughout the outcrop area and the ~450 m-thick section. Most paleosols in the middle Nacimiento Formation display vertic properties, suggesting strong seasonality of moisture, but current paleoclimate estimates from the area are unable to suggest a seasonality of precipitation. When considered in basin stratigraphic context, these vertic paleosols are potentially explained as the products of pedogenesis in a seasonally or episodically flooded floodplain. Here we present the first basin-scale section of Nacimiento Formation paleosols and interpretations of the potential fluvial discharge, climate, and pedogenic explanations for the observed drying-upwards trend.

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

doi: 10.1130/abs/2016AM-284994

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