Monday, June 07, 2010
Jurassic river flowed from Appalachians to Colorado Plateau
A new study published by UA geologist Bill Dickenson and colleagues in Geology finds that detrital zircons in Michigan were "deposited by northern tributaries of a transcontinental Jurassic paleoriver system that transported detritus from headwaters in Atlantic rift highlands of the Appalachian region to floodplains and deltas in the present northern Rocky Mountains region. Previous detrital zircon studies have indicated that sedimented lowlands in that paleogeographic position were deflated by paleowinds to feed eolian sand southward (in present coordinates) into the Colorado Plateau ergs (sand seas)." [right, Navajo Sandstone. Credit, NPS]
The idea of an ancient river system comparable to the Amazon flowing west across the continent is catching the popular media. The story is being widely disseminated.
Ref: William R. Dickinson, George E. Gehrels, and John E. Marzolf, Detrital zircons from fluvial Jurassic strata of the Michigan basin: Implications for the transcontinental Jurassic paleoriver hypothesis, Geology, doi: 10.1130/G30509.1 v. 38 no. 6 p. 499-502
at 12:34 PM