Floodplains and paleosols of Pakistan Neogene and Wyoming Paleogene deposits: a comparative study

Anna K. Behrensmeyer, Brian J. Willis, Jay Quade

Research output: Contribution to journalArticle

63 Citations (Scopus)

Abstract

Comparative study of fossil-bearing fluvi' deposits in the Eocene Willwood Formation of northern Wyoming and the Miocene Chinji Formation of northern Pakistan indicate how tectonic and climatic processes operating at different scales controlled physical and chemical features of floodplain environments and affected preservation of the paleontological record. The architecture of Willwood Fm. floodplain deposits represents a combination of avulsion-belt sediment packages and overbank sediments that formed alluvial ridges. The architecture of the Chinji Fm. floodplain deposits was controlled by widely distributed crevasse-splay deposition and floodplain topography. Similarities in individual paleosol-bounded overbank sequences from the two formations indicates that the internal structure of such deposits can be independent of channel belt proximity to areas of aggradation. Chinji Fm. paleosols have little vertical zonation and show no consistent pattern of lateral change in relation to major channels, while overbank paleosols in the Willwood Fm, exhibit considerable soil horizon development and a pattern of increasing maturity from alluvial ridge to distal floodplain. The "pedofacies model" of Bown and Kraus (1987) based on such lateral trends in the Willwood paleosols is not applicable to the Chinji Fm. Plant and animal fossils are abundant in the Willwood overbank deposits, with vertebrate remains concentrated in paleosol A horizons. Plant remains are rare in the Chinji Fm. and vertebrate fossils occur primarily in channel fills rather than in paleosols. These differences relate to contrasting patterns of floodplain deposition and to levels of oxidation that controlled penecontemporaneous recycling of organic material, particularly in paleosols. Different large-scale climatic and tectonic controls on temperature and rainfall, water table fluctuations, and soil biota are proposed to account for the differences in organic preservation. Large and small-scale environmental processes also affected spatial and temporal resolution of the organic record, resulting in important differences in the paleoecological and evolutionary information that can be reconstructed from the two sequences.

Original languageEnglish (US)
Pages (from-to)37-60
Number of pages24
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume115
Issue number1-4
DOIs
StatePublished - 1995

Fingerprint

paleosol
floodplains
Paleogene
Pakistan
Neogene
floodplain
comparative study
fossils
tectonics
fossil
vertebrates
vertebrate
sediments
overbank sediment
A horizons
avulsion
soil horizons
soil biota
crevasse
aggradation

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Earth-Surface Processes
  • Oceanography
  • Palaeontology

Cite this

Floodplains and paleosols of Pakistan Neogene and Wyoming Paleogene deposits : a comparative study. / Behrensmeyer, Anna K.; Willis, Brian J.; Quade, Jay.

In: Palaeogeography, Palaeoclimatology, Palaeoecology, Vol. 115, No. 1-4, 1995, p. 37-60.

Research output: Contribution to journalArticle

@article{7b8ed5b283c74c7ca1c879329872a5f6,
title = "Floodplains and paleosols of Pakistan Neogene and Wyoming Paleogene deposits: a comparative study",
abstract = "Comparative study of fossil-bearing fluvi' deposits in the Eocene Willwood Formation of northern Wyoming and the Miocene Chinji Formation of northern Pakistan indicate how tectonic and climatic processes operating at different scales controlled physical and chemical features of floodplain environments and affected preservation of the paleontological record. The architecture of Willwood Fm. floodplain deposits represents a combination of avulsion-belt sediment packages and overbank sediments that formed alluvial ridges. The architecture of the Chinji Fm. floodplain deposits was controlled by widely distributed crevasse-splay deposition and floodplain topography. Similarities in individual paleosol-bounded overbank sequences from the two formations indicates that the internal structure of such deposits can be independent of channel belt proximity to areas of aggradation. Chinji Fm. paleosols have little vertical zonation and show no consistent pattern of lateral change in relation to major channels, while overbank paleosols in the Willwood Fm, exhibit considerable soil horizon development and a pattern of increasing maturity from alluvial ridge to distal floodplain. The {"}pedofacies model{"} of Bown and Kraus (1987) based on such lateral trends in the Willwood paleosols is not applicable to the Chinji Fm. Plant and animal fossils are abundant in the Willwood overbank deposits, with vertebrate remains concentrated in paleosol A horizons. Plant remains are rare in the Chinji Fm. and vertebrate fossils occur primarily in channel fills rather than in paleosols. These differences relate to contrasting patterns of floodplain deposition and to levels of oxidation that controlled penecontemporaneous recycling of organic material, particularly in paleosols. Different large-scale climatic and tectonic controls on temperature and rainfall, water table fluctuations, and soil biota are proposed to account for the differences in organic preservation. Large and small-scale environmental processes also affected spatial and temporal resolution of the organic record, resulting in important differences in the paleoecological and evolutionary information that can be reconstructed from the two sequences.",
author = "Behrensmeyer, {Anna K.} and Willis, {Brian J.} and Jay Quade",
year = "1995",
doi = "10.1016/0031-0182(94)00106-I",
language = "English (US)",
volume = "115",
pages = "37--60",
journal = "Palaeogeography, Palaeoclimatology, Palaeoecology",
issn = "0031-0182",
publisher = "Elsevier",
number = "1-4",

}

TY - JOUR

T1 - Floodplains and paleosols of Pakistan Neogene and Wyoming Paleogene deposits

T2 - a comparative study

AU - Behrensmeyer, Anna K.

AU - Willis, Brian J.

AU - Quade, Jay

PY - 1995

Y1 - 1995

N2 - Comparative study of fossil-bearing fluvi' deposits in the Eocene Willwood Formation of northern Wyoming and the Miocene Chinji Formation of northern Pakistan indicate how tectonic and climatic processes operating at different scales controlled physical and chemical features of floodplain environments and affected preservation of the paleontological record. The architecture of Willwood Fm. floodplain deposits represents a combination of avulsion-belt sediment packages and overbank sediments that formed alluvial ridges. The architecture of the Chinji Fm. floodplain deposits was controlled by widely distributed crevasse-splay deposition and floodplain topography. Similarities in individual paleosol-bounded overbank sequences from the two formations indicates that the internal structure of such deposits can be independent of channel belt proximity to areas of aggradation. Chinji Fm. paleosols have little vertical zonation and show no consistent pattern of lateral change in relation to major channels, while overbank paleosols in the Willwood Fm, exhibit considerable soil horizon development and a pattern of increasing maturity from alluvial ridge to distal floodplain. The "pedofacies model" of Bown and Kraus (1987) based on such lateral trends in the Willwood paleosols is not applicable to the Chinji Fm. Plant and animal fossils are abundant in the Willwood overbank deposits, with vertebrate remains concentrated in paleosol A horizons. Plant remains are rare in the Chinji Fm. and vertebrate fossils occur primarily in channel fills rather than in paleosols. These differences relate to contrasting patterns of floodplain deposition and to levels of oxidation that controlled penecontemporaneous recycling of organic material, particularly in paleosols. Different large-scale climatic and tectonic controls on temperature and rainfall, water table fluctuations, and soil biota are proposed to account for the differences in organic preservation. Large and small-scale environmental processes also affected spatial and temporal resolution of the organic record, resulting in important differences in the paleoecological and evolutionary information that can be reconstructed from the two sequences.

AB - Comparative study of fossil-bearing fluvi' deposits in the Eocene Willwood Formation of northern Wyoming and the Miocene Chinji Formation of northern Pakistan indicate how tectonic and climatic processes operating at different scales controlled physical and chemical features of floodplain environments and affected preservation of the paleontological record. The architecture of Willwood Fm. floodplain deposits represents a combination of avulsion-belt sediment packages and overbank sediments that formed alluvial ridges. The architecture of the Chinji Fm. floodplain deposits was controlled by widely distributed crevasse-splay deposition and floodplain topography. Similarities in individual paleosol-bounded overbank sequences from the two formations indicates that the internal structure of such deposits can be independent of channel belt proximity to areas of aggradation. Chinji Fm. paleosols have little vertical zonation and show no consistent pattern of lateral change in relation to major channels, while overbank paleosols in the Willwood Fm, exhibit considerable soil horizon development and a pattern of increasing maturity from alluvial ridge to distal floodplain. The "pedofacies model" of Bown and Kraus (1987) based on such lateral trends in the Willwood paleosols is not applicable to the Chinji Fm. Plant and animal fossils are abundant in the Willwood overbank deposits, with vertebrate remains concentrated in paleosol A horizons. Plant remains are rare in the Chinji Fm. and vertebrate fossils occur primarily in channel fills rather than in paleosols. These differences relate to contrasting patterns of floodplain deposition and to levels of oxidation that controlled penecontemporaneous recycling of organic material, particularly in paleosols. Different large-scale climatic and tectonic controls on temperature and rainfall, water table fluctuations, and soil biota are proposed to account for the differences in organic preservation. Large and small-scale environmental processes also affected spatial and temporal resolution of the organic record, resulting in important differences in the paleoecological and evolutionary information that can be reconstructed from the two sequences.

UR - http://www.scopus.com/inward/record.url?scp=0029527133&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0029527133&partnerID=8YFLogxK

U2 - 10.1016/0031-0182(94)00106-I

DO - 10.1016/0031-0182(94)00106-I

M3 - Article

AN - SCOPUS:0029527133

VL - 115

SP - 37

EP - 60

JO - Palaeogeography, Palaeoclimatology, Palaeoecology

JF - Palaeogeography, Palaeoclimatology, Palaeoecology

SN - 0031-0182

IS - 1-4

ER -