--> Paleozoic Sediment Dispersal Patterns of the Midland Basin, U.S.A.

AAPG Southwest Section Annual Convention

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Paleozoic Sediment Dispersal Patterns of the Midland Basin, U.S.A.

Abstract

The Midland Basin in west Texas is the largest subbasin of the Permian Basin. The sediment dispersal patterns in the basin are not well constrained. Here we report detrital zircon U-Pb ages and Lu-Hf isotopic data collected from the Midland Basin to understand sediment dispersal patterns on the southern margin of Laurentia before and during the Laurentia-Gondwana collision. The ages from one Cambrian fluvial-marginal marine sandstone and one Pennsylvanian deltaic-fluvial sandstone samples span from Archean to early Paleozoic time. The Cambrian sandstone have 86.0% grains of Mesoproterozoic age and 14.0% of Grenvillian age, with εHft values between +5-+20, overlapping with the values of the Granite-Rhyolite and Grenville provinces. The high abundance of the Mesoproterozoic population suggests that the grains were dispersed by a local river draining the midcontinent granite-rhyolite province located in the Transcontinental Arch to north- northeast of the basin. The Pennsylvanian sandstone contain 32.8% grains of Archean-Early Mesoproterozoic age, 39.7% of Grenvillian age, and 25.3% of Neoproterozoic-Paleozoic age, and the εHft values are between -24-+12, indicating a different dispersal pattern during the Pennsylvanian compared to the Cambrian. The high abundance of Grenvillian grains in the Pennsylvania is a result of direct transport from the Appalachians by a transcontinental river or sediment recycling from the Mississippian-Pennsylvanian sedimentary rocks incorporated in the Ouachita orogenic front. The sample also has a distinct age peak at ~650-550 Ma, and these grains were most likely transport by local rivers draining a peri-Gondwana terrane in the Ouachita orogen.