T113 Along-Strike Variations in Mountain Belts: Why Are They Important and What Causes Them?

Monday, 26 September 2016
8:00 AM - 12:00 PM
Mile High Ballroom 2B

THE CENTRAL AND SOUTHERN APPALACHIAN BLUE RIDGE PROVINCE: ALONG-STRIKE VARIATION AT THE APPALACHIAN OROGEN’S THICK- TO THIN-SKINNED DEFORMATION FRONT

Paper number: T113-11
Program: Technical Sessions
Time: 10:30 AM – 10:45 AM

Authors

Abstract

The Blue Ridge province forms a major structural element in the central and southern Appalachian Orogen. The Blue Ridge province extends more than 1,000 km from southern Pennsylvania to Alabama, tracing a wide swath across multiple salients and recesses. The Blue Ridge is distinctive because it: 1) exposes Mesoproterozoic basement, 2) includes the Ediacaran/Cambrian rifted margin that formed along Laurentia’s southeastern edge, and 3) bounds the thin-skinned Appalachian foreland fold-and-thrust belt. However, the structural style of the Blue Ridge changes significantly from the central to the southern Appalachians.

Northward from central Virginia, the province is a broad basement-cored anticlinorium which formed during NW-directed contractional deformation and greenschist facies metamorphism that occurred ~370 and 330 Ma (Acadian to Neoacadian). Later, as the Appalachian foreland fold-and-thrust belt developed between ~300 and 280 Ma (Alleghanian), the northern Blue Ridge was a relatively cool and strong massif that was thrust, out-of-sequence onto Paleozoic strata in the foreland.

The southern Blue Ridge, to the south of Roanoke Virginia, records a more complex Paleozoic history that includes structural elements from an Ordovician accretionary wedge complex, multiple magmatic pulses, high grade metamorphic events, and significant transpressional faulting. Exposed Mesoproterozoic inliers include high-grade gneiss domes as well as faulted-bounded windows through duplexed in-sequence Alleghanian thrust sheets. The contrasting style of deformation across the Appalachian Blue Ridge province reflects both a tectonic inheritance from the pre-Appalachian rift structures and associated strata as well as differences in the Paleozoic thermal history along the Laurentian margin during subduction and collisional tectonism.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-287590

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