Middle Cretaceous greenhouse hydrologic cycle of North America
- 1Geoscience Department, University of Iowa, Iowa City, Iowa 52240, USA
- 2Iowa Geologic Survey, Iowa City, Iowa 52240, USA
- 3Earth Sciences Department, University of Southern California, Los Angeles, California 90089, USA
Abstract
We present a paleolatitudinal precipitation reconstruction for the greenhouse setting of mid-latitude North America based on the oxygen isotopic composition of sphaerosiderites found in middle Cretaceous wetland paleosols. Our reconstructed middle Cretaceous δ18O values of precipitation are ∼4‰ less than values from comparable modern low-elevation coastal settings free of monsoons. The data fit a conceptual model in which the precipitation source for the eastern margin of the Cretaceous Western Interior Seaway of North America is an 18O-enriched oceanic coastal jet. In this subtropical-tropical setting, mid- Cretaceous precipitation rates are interpreted to range from ∼2500 to ∼4100 mm/yr.
Footnotes
-
↵*Present address: Earth and Mineral Sciences Environment Institute, Pennsylvania State University, University Park, Pennsylvania 16804, USA. tswhiteessc.psu.edu.
-
- Accepted December 21, 2000.
- Received July 19, 2000.
- Revision received December 11, 2000.
- Geological Society of America
