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Geology and terrane relationships of the Tar River Area, Franklin and Granville Counties, North Carolina

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
Kenneth R. Robitaille (Creator)
Institution
The University of North Carolina Wilmington (UNCW )
Web Site: http://library.uncw.edu/
Advisor
David Blake

Abstract: Geologic mapping and geochemical analysis indicate that metaigneous rocks of the Tar River area in the eastern North Carolina Piedmont share similar lithologic and major trace element attributes that are compatible with an origin in a late Proterozoic to Cambrian, peri-Gondwanan, calc-alkaline island-arc known as the Carolina Zone. The results of structural analyses indicate that these rocks experienced a complex tectonothermal history that spans the late Proterozoic into the early Mesozoic. The metaigneous rocks are grouped into two structural domains that encompass four lithotectonic terranes on the western flank of the Alleghanian Wake-Warren anticlinorium. Western Domain I includes the Carolina terrane, which primarily contains the Gibbs Creek metatonalite pluton. This pluton hosts greenstone, amphibolite, metaultramafic, and metagranitoid enclaves that experienced a greenschist to amphibolite facies metamorphism (Me) prior to their inclusion in the pluton. Amphibolite and metagranitoid retain an Se foliation that possibly represents a pre-Taconic (De) deformation. The Gibbs Creek pluton is in contact with a small metagranodiorite pluton along its eastern edge and is crosscut by a map-scale metagabbro dike. The Ruin Creek Gneiss defines the eastern limits of Domain I and is a mylonitic granitic gneiss that may represent a deformed late Paleozoic intrusion. Domain II includes the Falls Lake, Crabtree, and Raleigh terranes. The Falls Lake terrane contains a biotite white mica schist, the Falls Lake Schist and bodies of metaultramafic rocks. The Crabtree terrane contains interlayered felsic, intermediate, and mafic gneiss known as the Middle Creek Gneiss and Middle Creek Amphibolite, and more minor blocks of metaultramafic rocks. The Raleigh terrane contains interlayered felsic, intermediate, and mafic gneiss known as the Raleigh Gneiss and the Falls Leucogneiss, and also includes more minor bodies of metaultramafic rocks. The Wilton granite pluton and two smaller foliated granitic bodies are late Paleozoic intrusions that intrude all terranes of Domain II. The metaigneous rocks experienced a Taconic greenschist facies M1 metamorphism that is related to the collision between the Carolina Zone and Laurentia and is only preserved within Domain I. An Alleghanian amphibolite facies M2 metamorphism affected the rocks within Domain II. M2 was accompanied by a D3 deformation that affected both domains during the transpressional collision between Laurentia and Gondwana and the formation of Pangea. D3 produced a northeast-striking S1 mylonite foliation, subhorizontal L1 stretch lineation, and minor F1 folds along with small ductile dextral faults and the larger terrane bounding Falls Lake and Nutbush Creek fault zones. The western portions of Domain I also preserve several D4 ductile-brittle normal faults that contain a northeast-striking S2 phyllonite foliation and L2 dip-parallel stretch lineation. D4 deformation also produced a major terrane-bounding brittle normal fault, the Jonesboro fault, which separates the Domain I graben from Domain II horst and highlights the distinct metamorphic discontinuity between rocks on either side of the fault. The formation of the Jonesboro normal fault, combined with the intrusion of Jurassic-age diabase dikes that crosscut all terranes within the Tar River area, are attributed to the initial breakup and rifting of the Pangean supercontinent.

Additional Information

Publication
Thesis
A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment of the Requirements for the Degree of Master of Science
Language: English
Date: 2009
Keywords
Geology--North Carolina--Franklin County, Geology--North Carolina--Granville County, Geology--North Carolina--Tar River Area
Subjects
Geology -- North Carolina -- Franklin County
Geology -- North Carolina -- Granville County
Geology -- North Carolina -- Tar River Area