Relative timing of CAMP, rifting, continental breakup, and basin inversion: Tectonic significance

Schlische, Roy W.; Withjack, Martha Oliver; Olsen, Paul E.

doi:10.1029/136gm03

Cited by 62 publications

(83 citation statements)

References 92 publications

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“…In the Southern Appalachians, the Blue Ridge province is of particular interest because it lies northwest of the zone most directly affected by Triassic-Jurassic extension (Klitgord et al, 1988). The closest Triassic rift basin lies 250 km to the southeast, and the 200 Ma mafi c dike swarms that cut northwestward across rocks of the Carolina terrane and Inner Piedmont decrease abruptly near the Brevard fault zone (Hames et al, 2000;Schlische et al, 2003), with very few dikes extending into the Blue Ridge (King, 1961). Extension may have been followed by shortening as early as 200 Ma, at the onset of seafl oor spreading (Schlische et al, 2003); thrust faults mapped in the coastal plain suggest that the dominant horizontal stress has been compressional since at least the Cretaceous (Prowell, 1988;Manspeizer et al, 1989).…”

Section: Geologic Settingmentioning

confidence: 98%

Isostatic compensation for a portion of the Southern Appalachians: Evidence from a reconnaissance study using wide-angle, three-component seismic soundings

Hawman

Khalifa

Baker

2011

Geological Society of America Bulletin

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Wide-angle refl ections generated by fi ve controlled blasts and over 110 timed quarry blasts in the Southern Appalachians were used to test models for isostatic compensation of topog raphy. The profi les cross the Appa lachian gravity gradient and gravity low and sample the highest elevations within the orogen. Migration of P, SV, and SH refl ections suggests that crustal thickness varies from 35 to 39 km within the coastal plain and 37-39 km within the Carolina terrane. It increases northwestward from 40 to 45 km across the Inner Piedmont, and then thickens to 50-52 km along the southeastern fl ank of the Blue Ridge Mountains. Crustal thickness within the Blue Ridge Mountains ranges from 47 to 56 km. Receiver functions for broadband stations GOGA and MYNC show a similar pattern in crustal thickness. Assuming Airy compensation, the correlation between elevation and Moho depth suggests a range of 50-150 kg/m 3 for the density contrast between the crustal root and mantle. The greatest Moho depths are associated not with the tallest peaks, but rather with the broadest portions of the mountain chain. This observation is consistent with regional bending of the lithosphere. However, the planar basement surface suggests that the root either predates Alleghanian thrusting, and therefore is unrelated to the present topography, or formed in response to some other mechanism. Bounds on curvature of the basement surface suggest a lower bound of 30-40 km for the effective elastic thickness of the lithosphere. This is consistent with previous estimates for the southern Appalachians based on analysis of gravity data.

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Section: Geologic Settingmentioning

confidence: 98%

Isostatic compensation for a portion of the Southern Appalachians: Evidence from a reconnaissance study using wide-angle, three-component seismic soundings

Hawman

Khalifa

Baker

2011

Geological Society of America Bulletin

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“…Precambrian and Paleozoic rocks are intruded by large dolerite sills of Early Jurassic age (Bertrand and Villeneuve, 1989). These sills are part of the Central Atlantic Magmatic Province (CAMP) that comprises mafic volcanics documented on the Atlantic margins of North America, West Africa and Northern South America, and dated at 198-203 Ma (Schlische et al, 2003).…”

Section: Morphotectonic Settingmentioning

confidence: 99%

Planation, bauxites and epeirogeny: One or two paleosurfaces on the West African margin?

et al. 2006

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“…After rifting, many of the rift basins in the southern and central segments of the Eastern North American rift system were inverted (i.e. underwent shortening), which significantly modified the geometries of the original rift-related structures (Withjack et al 1998;Schlische 2003;Schlische et al 2003;Withjack and Schlische 2005; and references therein). (Withjack and Schlische 2005 and references therein).…”

Section: Introductionmentioning

confidence: 98%

Extensional development of the Fundy rift basin, southeastern Canada

Withjack¹,

Schlische²,

Baum³

2009

Geological Journal

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The Fundy rift basin of Nova Scotia and New Brunswick, Canada, is part of the Eastern North American rift system that formed during the breakup of Pangaea. Integrated seismic-reflection, field, digital-elevation and aeromagnetic data indicate that the Fundy rift basin underwent two phases of deformation: syn-rift extension followed by post-rift basin inversion. Inversion significantly modified the geometries of the basin and its rift-related structures. In this paper, we remove the effects of inversion to examine the basin's extensional development. The basin consists of three structural subbasins: the Fundy and Chignecto subbasins are bounded by low-angle, NE-striking faults; the Minas subbasin is bounded by E-to ENE-striking faults that are steeply dipping at the surface and gently dipping at depth. Together, these linked faults form the border-fault system of the Fundy rift basin. Most major faults within the border-fault system originated as Palaeozoic contractional structures. All syn-rift units imaged on seismic profiles thicken towards the border-fault system, reflecting extensional movement from Middle Triassic (and possibly Permian) through Early Jurassic time. Intra-rift unconformities, observed on seismic profiles and in the field, indicate that uplift and erosion occurred, at least locally, during rifting. Based on seismic data alone, the displacement direction of the hanging wall of the border-fault system of the Fundy rift basin ranged from SW to SE during rifting. Field data (i.e. NEstriking igneous dykes, sediment-filled fissures and normal faults) indicate NW-SE extension during Early Jurassic time, supporting a SE-displacement direction. With a SE-displacement direction, the NE-striking border-fault zones of the Fundy and Chignecto subbasins had predominantly normal dip slip during rifting, whereas the E-striking border-fault zone of the Minas subbasin had oblique slip with left-lateral and normal components. Sequential restorations of seismic-reflection profiles (coupled with projections from onshore geology) show that the Fundy rift basin underwent 10-20 km of extension, most of which was accommodated by the border-fault system, and was considerably wider and deeper prior to basin inversion. Post-rift deformation tilted the eastern side of the basin to the northwest/north, producing significant uplift and erosion.

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Relative timing of CAMP, rifting, continental breakup, and basin inversion: Tectonic significance

Cited by 62 publications

References 92 publications

Isostatic compensation for a portion of the Southern Appalachians: Evidence from a reconnaissance study using wide-angle, three-component seismic soundings

Isostatic compensation for a portion of the Southern Appalachians: Evidence from a reconnaissance study using wide-angle, three-component seismic soundings

Planation, bauxites and epeirogeny: One or two paleosurfaces on the West African margin?

Extensional development of the Fundy rift basin, southeastern Canada

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