TIMING OF NEOPROTEROZOIC-E. PALEOZOIC RIFTING, DRIFTING, TERRANE TRANSFER AND VOLCANISM, S. LAURENTIA  (DEVILS RIVER UPLIFT, MARATHON BASIN, SOLITARIO)

Dickerson, Patricia W.

Paper No. 20-2

Presentation Time: 8:25 AM

TIMING OF NEOPROTEROZOIC-E. PALEOZOIC RIFTING, DRIFTING, TERRANE TRANSFER AND VOLCANISM, S. LAURENTIA (DEVILS RIVER UPLIFT, MARATHON BASIN, SOLITARIO)

DICKERSON, Patricia W., American Geological Institute and Jackson School of Geosciences, University of Texas at Austin, Geological Sciences, C1160, 2305 Speedway, Austin, TX 78712, STOCKLI, Daniel F., Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX 78712, HALL, Blaine R., Texas Parks and Wildlife Department, Interpretive Ranger (retired), PO Box 1262, Fort Davis, TX 79734, STOCKLI, Lisa D., Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78712, HANSON, Richard E., Department of Geological Sciences, Texas Christian University, Fort Worth, TX 76129, FANNING, C. Mark, Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia and RODRIGUEZ, Edna, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX 78705

Integrated zircon U/Pb data (SHRIMP & LA ICP MS), whole-rock geochemical and isotopic data from W. Texas outcrops and cores shed light on evolution of S. Laurentia. Devils River Uplift, Marathon fold-thrust belt, and the Solitario – structural elements spanning ~400 km -- preserve evidence of Rodinia rifting, foundering of Iapetus, the separation of Cuyania from Laurentia and its accretion to Gondwana, accompanied by subduction volcanism.

RODINIA RIFTING (Cryogenian & Eocambrian)

Marathon Basin: First surface samples of Rodinia rift lavas. Cryogenian (706 Ma) basalt and trachyandesite boulders; intraplate rift geochemistry. Felsic tuff boulder (750-700 Ma) also yielded Eocambrian (580-520 Ma) zircons. Solitario: No lavas but rare Cryogenian detrital grains (798-657 Ma) in U. Cambrian- L. Ordovician sediments. Devils River Uplift: Laurentian rift block, Llano Grenvillian basement (1230 Ma), driven back onto the margin during Ouachita collision. Cryogenian (676 Ma) dominant in L€ metaigneous rocks; some Eocambrian (600-500 Ma) present as well.

IAPETUS OPENING, DRIFT PHASE (U. Cambrian-Mid-Ordovician)

Marathon Basin: Iapetus deepening, tectonic instability – extensive olistostromes (tens of meters) in L-MO sediments. Solitario: Headward erosion of drainages and NW-ward shift in provenance. In U€, mainly W. Texas Grenvillian (1281-1002, rare 988-809 Ma), with Granite-Rhyolite Province (1440-1300 Ma) and minor Cryogenian (798-657 Ma). In LO, first Yavapai-Mazatzal and Archean from NW; Wyoming Province Archean reworked into Yavapai-Mazatzal sediments; more abundant in MO. Rare Eocambrian (540-530 Ma). Devils River Uplift: L-M€ – Cryogenian (700-780 Ma) and Eocambrian (500-600 Ma) common in metaigneous and metasedimentary rocks. U€ – Llano Grenvillian dominant (1275-1094 Ma); common Granite-Rhyolite (1500-1300 Ma); no Cryogenian.

TERRANE TRANSFER & SUBDUCTION VOLCANISM (Mid-Ordovician)

In the L-MO the W. Ouachita Basin, Cuyania and W. Gondwana were in proximity at ~26°S. Cuyania was colliding with W. Gondwana at 470 Ma, fueling Famatina subduction volcanism. During peak arc activity (472-468 Ma) ash accumulated in the W. Ouachita-Cuyania Basin. U/Pb ages of magmatic zircons in the Ft. Peña Fm (Solitario, 488-469 Ma) and in Cuyania bentonites are within the same close range.

Session No. 20

T16. The Role of Geochronology in Constraining the Development of Earth’s Lithosphere: Focus on the U.S. South-Central Region, Mexico, and Beyond

Tuesday, 10 March 2020: 8:00 AM-12:00 PM

Meeting Room 202CD (Fort Worth Convention Center)

Geological Society of America Abstracts with Programs. Vol. 52, No. 1
doi: 10.1130/abs/2020SC-343824

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South-Central Section - 54th Annual Meeting - 2020

TIMING OF NEOPROTEROZOIC-E. PALEOZOIC RIFTING, DRIFTING, TERRANE TRANSFER AND VOLCANISM, S. LAURENTIA (DEVILS RIVER UPLIFT, MARATHON BASIN, SOLITARIO)