Distinguishing base-level change and climate signals in a Cretaceous alluvial sequence

Timothy Stapler White, B. Witzke, G. Ludvigson, R. Brenner

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

We present the results of oxygen isotope and electron-microprobe analyses of sphaerosiderites obtained from Cretaceous paleosols in Iowa. The sphaerosiderite δ18O values record Cretaceous meteoric groundwater chemistry and an overall waning of brackish groundwater inundation during alluvial-plain aggradation and soil genesis. We focus on horizons that precipitated from freshwater, in which δ18O values ranging from -3.30‰ to -6.8‰ relative to the Peedee belemnite standard are interpreted to record variations in the Cretaceous atmospheric hydrologic cycle. During relative sea-level highstands, moisture was derived from the Cretaceous Western Interior Seaway, whereas during lowstands, when the seaway narrowed and occasionally withdrew from the Midcontinent, the dominance of hemispheric-scale atmospheric moisture transport initiated in the tropical Tethys Ocean led to decreased precipitation rates. These processes did not operate like a switch, but rather as a continuum of competing moisture sources and mechanisms of transport between the nearby epicontinental sea and the distant tropics. The sphaerosiderite data demonstrate (1) temporal variation in the intensity of hemispheric-scale atmospheric moisture transport and (2) long-term amplification of the global hydrologic cycle marked by extreme 18O depletion at the Albian-Cenomanian boundary.

Original languageEnglish (US)
Pages (from-to)13-16
Number of pages4
JournalGeology
Volume33
Issue number1
DOIs
StatePublished - Jan 1 2005

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climate signal
Cretaceous
atmospheric moisture
moisture
belemnite
groundwater
inland sea
lowstand
aggradation
alluvial plain
highstand
Tethys
paleosol
electron probe analysis
oxygen isotope
amplification
temporal variation
sea level
ocean
soil

All Science Journal Classification (ASJC) codes

  • Geology

Cite this

White, Timothy Stapler ; Witzke, B. ; Ludvigson, G. ; Brenner, R. / Distinguishing base-level change and climate signals in a Cretaceous alluvial sequence. In: Geology. 2005 ; Vol. 33, No. 1. pp. 13-16.
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Distinguishing base-level change and climate signals in a Cretaceous alluvial sequence. / White, Timothy Stapler; Witzke, B.; Ludvigson, G.; Brenner, R.

In: Geology, Vol. 33, No. 1, 01.01.2005, p. 13-16.

Research output: Contribution to journalArticle

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