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

T. White, B. Witzke, G. Ludvigson, R. Brenner

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


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
Issue number1
StatePublished - Jan 2005

All Science Journal Classification (ASJC) codes

  • Geology


Dive into the research topics of 'Distinguishing base-level change and climate signals in a Cretaceous alluvial sequence'. Together they form a unique fingerprint.

Cite this