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Full-Text Articles in Physical Sciences and Mathematics
Source Of The Northeastern Idaho Batholith: Isotopic Evidence For A Paleoproterozoic Terrane In The Northwestern U.S., Paul A. Mueller, Robert Duncan Shuster, K. A. D'Arcy, A. L. Heatherington, A. P. Nutman, I. S. Williams
Source Of The Northeastern Idaho Batholith: Isotopic Evidence For A Paleoproterozoic Terrane In The Northwestern U.S., Paul A. Mueller, Robert Duncan Shuster, K. A. D'Arcy, A. L. Heatherington, A. P. Nutman, I. S. Williams
Geography and Geology Faculty Publications
The northeastern portion of the Idaho batholith (NIB) intruded Proterozoic rocks of the Belt-Purcell supergroup between SO and 90 Ma. Whole-rock Sm-Nd isotopic analyses of batholithic rocks yield depleted mantle model ages (T oM) between 1. 72 and 1.93 Ga and values of eNd between -17. 7 and - 21.2, similar to associated metamorphic rocks and within the range for Belt-Purcell sedimentary rocks. Premagmatic zircons from one sample of the NIB were analyzed individually using the SHRIMP ion microprobe and yielded a single age population at 1.74 Ga. This apparently single-aged source contrasts with the range of ages reported for …
Strontium Isotope Stratigraphy And Age Estimates For The Leisey Shell Pit Faunas, Hillsborough County, Florida, Douglas S. Jones, Paul A. Mueller, Teresa Acosta, Robert Duncan Shuster
Strontium Isotope Stratigraphy And Age Estimates For The Leisey Shell Pit Faunas, Hillsborough County, Florida, Douglas S. Jones, Paul A. Mueller, Teresa Acosta, Robert Duncan Shuster
Geography and Geology Faculty Publications
The vertebrate fauna of the Leisey Shell Pit near Tampa Bay, Florida, represents one of the more significant lrvingtonian mammalian faunas of North America. The fossil vertebrates occur in thin bone beds bounded above and below by massive shell beds containing a rich invertebrate ( chiefly molluscan) fauna. Debate has arisen concerning the precise age of the faunas at Leisey. Although generally agreed to be Pleistocene, estimates based upon vertebrate biostratigraphy suggest a somewhat older age than do estimates based upon molluscan biostratigraphy. To help resolve this controvefliy, 87Sr/86Sr ratios were determined on molluscan shells throughout the …