Isotopic connections between basement rocks exposed in the St. Francois Mountains and the Arbuckle Mountains,southern mid-continent,North America |
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Authors: | C Renee Rohs W R Van Schmus |
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Institution: | (1) Northwest Missouri State University, 800 University Dr., Maryville, MO 64468, USA;(2) Department of Geology, University of Kansas, Lawrence, KS 66045-7613, USA |
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Abstract: | Two distinct crustal provinces have been identified in the southern mid-continent based on U–Pb crystallization ages. Both
contain large volumes of undeformed granite and rhyolite, with minor amounts of metamorphic rock and mafic intrusions. The
Eastern Granite-Rhyolite province is characterized by felsic rocks with crystallization ages of 1,470 ± 30 Ma and exposures
are restricted to the St. Francois Mountains in southeastern Missouri. Similarly, the Southern Granite-Rhyolite (SGR) province
is characterized by felsic units with ages of 1,370 ± 30 Ma with primary exposures in the eastern Arbuckle Mountains of southern
Oklahoma. Within the SGR province three magmatic pulses can be identified starting at 1,400, 1,370, and 1,340 Ma. Although
the crystallization ages are different, the Sm–Nd isotopic signatures are similar for the units exposed in these areas as
well as the buried basement in between. Depleted mantle model ages for rocks within the Arbuckle Mountains range from 1,530
to 1,430 Ma with ɛNd(t) values of +3.2 to +4.1 while units of the St. Francois Mountains range from 1,550 to 1,430 Ma and +4.5 to +4.7. Comparison
of Sm–Nd isotopic data also indicate similarities between the 147Sm/144Nd and 143Nd/144Nd ratios for the rock units in these areas suggesting a common source. |
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Keywords: | Precambrian St Francois Mountains Arbuckle Mountains Zircon dating Sm– Nd |
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