Detrital zircons indicate no drainage link between southern California rivers and the Colorado Plateau from mid-Cretaceous through Pliocene
Raymond V. Ingersoll et al., Dept. of Earth and Space Sciences, University of California, Los Angeles, 595 Charles Young Dr. East, Los Angeles, California 90095-1567, USA. Posted online 25 Jan. 2013; http://dx.doi.org/10.1130/G33807.1.
Upper Cretaceous to Pliocene (two million to 100 million year old) sandstone in coastal southern California contains almost no detrital zircon with the distinctive age signature of Colorado Plateau strata. These results presented by Raymond V. Ingersoll and colleagues conflict with the hypothesis that a major river draining the Colorado Plateau (and cutting an ancestral Grand Canyon) flowed to coastal California during the Paleogene (23 to 65 million years ago). Their results are consistent with the hypothesis that Grand Canyon was cut during the latest Miocene to present (0 to 6 million years ago) by the integrated Colorado River draining into the Gulf of California.
Fractionation of Nb and Ta by biotite and phengite: Implications for the "missing Nb paradox"
Aleksandr S. Stepanov (corresponding) and Jrg Hermann, Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia. Posted online 25 Jan. 2013; http://dx.doi.org/10.1130/G33781.1.
The subchondritic niobium/tantalum in both the continental crust and the depleted mantle remains enigmatic and is called the "missing Nb paradox." Aleksandr Stepanov and Jrg Hermann present partitioning data between biotite and granitic melt for experimental and natural sampl
|Contact: Kea Giles|
Geological Society of America