T165 Structure and Tectonic Studies, from Outcrop to Supercontinent I: In Honor of Ian Dalziel

Tuesday, 24 September 2019
8:00 AM - 12:00 PM
Room 229A, North Building

MARATHON FOLD-THRUST BELT, GEO-REPOSITORY FOR >1 GA OF SUPERCONTINENT INTERACTIONS – NEW ZIRCON U/PB DATA REFINE TIMING

Paper number: T165-10
Program: Technical Sessions
Time: 10:10 AM – 10:25 AM

Authors

Abstract

The Marathon fold-thrust belt in West Texas preserves a record of supercontinent interactions along the southern Laurentian margin – from Grenvillian orogenesis and assembly of Rodinia, to its fragmentation by rifting, to amalgamation of Pangaea. New zircon U/Pb data (LA-ICP-MS) from lower Paleozoic sedimentary rocks exposed in the Solitario dome (SW Marathon belt) refine the timing of rifting and departure of the Laurentian Cuyania terrane and of its accretion to W. Gondwana. Samples from 3 Western Ouachita-Cuyania Basin formations were analyzed:

U. Cambrian Dagger Flat Ss, quartz arenite (n = 135): Minor Granite-Rhyolite Province (1350-1301 Ma), dominantly Grenvillian (1281-1002 Ma, rare 988-809 Ma), rare Cryogenian (798-657 Ma). PROVENANCE: W. TX Grenvillian in Franklin, Carrizo, Hueco Mts.; youngest grains may be from Pump Station Hills, Hueco Mts. Granite-Rhyolite Province in Carrizo Mts. Cryogenian – 1st-phase Rodinia rift volcanics.

L. Ordovician Marathon Fm, bentonitic shale (n = 120): Minor Archean (2730-2600), Yavapai-Mazatzal (1800-1600 Ma), Granite-Rhyolite Province (1440-1300 Ma), dominantly Grenvillian (1100-1070 and minor 1250 Ma), minor Cryogenian (750 Ma). PROVENANCE: W-NW; widespread Grenvillian in W. TX (Franklin, Carrizo, Hueco Mts). Granite-Rhyolite Province in Carrizo Mts. First Archean and Yavapai-Mazatzal grains from NW. Possible Archean source – Wyoming Province grains from northernmost CO, reworked into nearby Yavapai-Mazatzal metasediments; Cryogenian – 1st-phase Rodinia rift volcanics.

M Ordovician Ft. Peña Fm, quartzose sandstone, bentonitic shale (n = 372): Common Archean (2880-2510 Ma), major Yavapai-Mazatzal (1800-1600 Ma), Granite-Rhyolite Province (1380 Ma), Grenvillian (1250-1110 Ma), significant Ordovician (470 Ma), rare Eocambrian (540-530 Ma). Yavapai-Mazatzal and Grenvillian alternate as most abundant. PROVENANCE: Archean and Yavapai-Mazatzal from NW, as for Marathon Fm. 470-Ma zircons may reflect direct input from the Famatina magmatic belt (Argentina), a result of Cuyania subduction. Ft. Peña deposition coincided with peak Famatina volcanism at 472-468 Ma; directly correlative bentonites in the Precordillera. Paleo-winds favored transport to the Western Ouachita-Cuyania Basin. Eocambrian (2nd phase) Rodinia rift volcanics.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-341338

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