Assessing Pleistocene climate on the Southern High Plains through geochemical and physical characteristics of paleosols archived in the Blackwater Draw Formation
type: CreativeWork
description: The Southern High Plains (SHP) is a large plateau, encompassing an area ~130,000 km2 from southeastern New Mexico to northern Texas. The SHP was largely a site of sediment aggradation since the Pecos River cut off the Rocky Mountain highlands to the west between 2 and 1.4 Ma, and forming the Blackwater Draw Formation, an eolian mantle, locally up to 27 m thick, composed of loess (wind-blown silt) deposits with loess tops forming individual paleosols. Loess-paleosol couplets represent periods of deposition followed by periods of landscape stability accompanied by pedogenesis. Here we utilize geochemical and physical properties of loess-paleosol couplets recorded in the Black Water Draw Formation are used to interpret on climatic conditions of the Pleistocene. Petrographical and geochemical evidence indicates five buried soils (buried soil 5 = oldest to buried soil 1=youngest) are present in the Type Section of the Blackwater Draw Formation. Buried soils 4 and 5 are classified as Aridisols due to low clay content and shallow horizons of calcareous nodules. Buried soils 3 through 1 are classified as Mollisols as predominantly evidenced by circumgranular, clayey peds. Physical and geochemical characteristics indicate two distinct facies are present within the type section, with buried soils 3, 4, and 5 representing a coarse, very fine to fine sand facies and buried soils 1 and 2 representing a finer, sandy mud facies. Whole-rock geochemical profiles illuminate distinct chemical weathering profiles that indicate specific pedogenic processes such as hydrolysis, salinization, and leaching. These pedogenic processes are interpreted through analysis of select ratios and trends of relatively reactive elements versus immobile elements. Degree of pedogenesis is then predominantly a function of water availability and soil temperature. These parameters are quantitatively assessed through climo-functions developed from the relationship between geochemical ratios and modern soil fo…
abstract: The Southern High Plains (SHP) is a large plateau, encompassing an area ~130,000 km2 from southeastern New Mexico to northern Texas. The SHP was largely a site of sediment aggradation since the Pecos River cut off the Rocky Mountain highlands to the west between 2 and 1.4 Ma, and forming the Blackwater Draw Formation, an eolian mantle, locally up to 27 m thick, composed of loess (wind-blown silt) deposits with loess tops forming individual paleosols. Loess-paleosol couplets represent periods of deposition followed by periods of landscape stability accompanied by pedogenesis. Here we utilize geochemical and physical properties of loess-paleosol couplets recorded in the Black Water Draw Formation are used to interpret on climatic conditions of the Pleistocene. Petrographical and geochemical evidence indicates five buried soils (buried soil 5 = oldest to buried soil 1=youngest) are present in the Type Section of the Blackwater Draw Formation. Buried soils 4 and 5 are classified as Aridisols due to low clay content and shallow horizons of calcareous nodules. Buried soils 3 through 1 are classified as Mollisols as predominantly evidenced by circumgranular, clayey peds. Physical and geochemical characteristics indicate two distinct facies are present within the type section, with buried soils 3, 4, and 5 representing a coarse, very fine to fine sand facies and buried soils 1 and 2 representing a finer, sandy mud facies. Whole-rock geochemical profiles illuminate distinct chemical weathering profiles that indicate specific pedogenic processes such as hydrolysis, salinization, and leaching. These pedogenic processes are interpreted through analysis of select ratios and trends of relatively reactive elements versus immobile elements. Degree of pedogenesis is then predominantly a function of water availability and soil temperature. These parameters are quantitatively assessed through climo-functions developed from the relationship between geochemical ratios and modern soil fo…
author: Baird, Hollee
language: eng
keywords: Paleoclimate, Pleistocene, Paleosols, Southern High Plains, Blackwater draw, Geochemistry
date published: 2015-05
date modified: 2026-07-24T05:04:51Z
provider: Texas Technology University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Texas Tech University

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2346/62278