Neotectonism along the Atlantic passive continental margin: A review

Gardner, Thomas W.

doi:10.1016/0169-555x(89)90007-x

Cited by 16 publications

(12 citation statements)

References 111 publications

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“…Contemporary deformation of the middle Atlantic margin does exist in the form of a broad, flexural warp, centred across the Fall Zone, between the upwarped central Appalachians and subsided Salisbury Embayment (Pazzaglia & Gardner, 1994). Smaller tectonic fe atures, such as high-angle reverse fa ults, are superposed on this warp (Mixon & Newell, 1977;Mixon & Powars, 1984;Newell, 1985;Prowell , 1988;Gardner, 1989). It is important to point out that 258 these fa ults are small, with the known maximum total displacement on the order of tens to maybe 100 m since the Late Cretaceous.…”

Section: Settingmentioning

confidence: 98%

“…The faults that have been described are typically reactivated rift and pre-rift struc tures with less than 100 m of post-rift offset. Long-term rates of offset for known fa ult systems all fa ll below l m Myr -1 (Gardner, 1989). So we are left with interpreting our tectonic model results in terms of various epeirogenic processes.…”

Section: Tectonic and Epeirogenic Influences On Topographymentioning

confidence: 98%

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Macrogeomorphic evolution of the post‐Triassic Appalachian mountains determined by deconvolution of the offshore basin sedimentary record

1996

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A perplexing macrogeomorphic problem is the persistence of topography in mountain ranges that were initially formed by orogenic events hundreds of millions of years old. In this paper, we deconvolve the post‐Triassic macrogeomorphic history of a portion of one of these ranges, the central and northern Appalachians, using a well‐documented offshore isopach sedimentary record of the US Atlantic margin. Topography is an important signature of tectonic, eustatic and/or geomorphic processes that produces changes in the erodible thickness of the crust (ETC). We define ETC as the total thickness of crust that would have to be consumed by erosion to reduce the mean elevation of a landscape to sea level. We use the term ‘source flux’, designated by ν˙, to describe the rate of change in ETC attributed to deep‐seated geological processes such as crustal thickening, crustal extension, magmatic intrusions or dynamic flow in the mantle. In a mountain belt, the rate of change of mean elevation with respect to a base level, designated by ż′, can be represented as ż′ = c(ν˙ − kd z′ −; ėc ) −& hairsp;l˙, where kd is a proportionality constant relating the mean mechanical erosion rate to mean elevation, ėc is the mean chemcial erosion rate, c is a compensation ratio (held constant for Airy isostasy at 0.21) and l˙ is the rate of eustatic sea‐level change. This equation describes the sum of constructive source terms, two destructive erosion terms and a eustatic sea‐level term. We use this simple linear equation to develop a landscape evolution model based on the concept of a unit response function. The unit response function is analogous to a unit hydrograph which describes the relationship between input (rainfall) and output (discharge) in a hydrological system. In our case, we solve for the general relationship between the source flux into the mountain belt and the erosional flux out of the belt. Offshore sediment volumes are used to determine the erosional flux. Drainage basin area is treated as either a constant (pinned drainage divide) or as increasing through time (migrating drainage divide). We use a third‐order polynomial fit to a global sea‐level curve to account for long‐term eustatically driven changes in ETC and in drainage basin area. Chemical erosion is treated as a constant fixed at 5 m Myr−1. We consider two end‐member models. The first is a ‘tectonic’ model in which the source flux is allowed to vary while kd is assumed to be constant over geological time and equal to its mean Pleistocene value of about 0.07 Myr−1. The second is an ‘erodibility’ model in which kd is allowed to vary, reflecting changes in climatic, climatic variables and rock‐type erodibility, while the source flux is held constant at zero. The ‘tectonic’ model reveals four important increases in the source flux, ranging from 200 to 2000 m Myr−1 that occur over short (<10 Myr) time spans, followed by a protracted period (>25 Myr) where ν˙ drops below zero to values of −1000 to −6000 m Myr−1. The ‘erodibility’ model produces a topography that decays i...

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Section: Settingmentioning

confidence: 98%

Section: Tectonic and Epeirogenic Influences On Topographymentioning

confidence: 98%

Macrogeomorphic evolution of the post‐Triassic Appalachian mountains determined by deconvolution of the offshore basin sedimentary record

1996

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“…Rejuvenation may have taken place in the Cenozoic, due to convergence along the passive margin, although at strain rates much slower than occur at active plate boundaries. Minor active faulting along the Fall Zone of the central and southern United States has occurred since the middle Tertiary (Mixon & Newell, 1977; Prowell, 1988; Gardner, 1989; Marple & Talwani, 2000), and the region currently exhibits minor seismicity (Bollinger, 1973). Although this deformation has not been shown to have produced the modern topography, it does indicate a state of tectonic compression that could be driving uplift (Pazzaglia & Brandon, 1996).…”

Section: Introductionmentioning

confidence: 99%

Origin of the Blue Ridge escarpment along the passive margin of Eastern North America

et al. 2003

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The Blue Ridge escarpment is a rugged landform situated within the ancient Appalachian orogen. While similar in some respects to the great escarpments along other passive margins, which have evolved by erosion following rifting, its youthful topographic expression has inspired proposals of Cenozoic tectonic rejuvenation in eastern North America.To better understand the post-orogenic and post-rift geomorphic evolution of passive margins, we have examined the origin of this landform using low-temperature thermochronometry and manipulation of topographic indices. Apatite (UT h)/He and ¢ssion-track analyses along transects across the escarpment reveal a younging trend towards the coast.This pattern is consistent with other great escarpments and ¢ts with an interpretation of having evolved by prolonged erosion, without the requirement of tectonic rejuvenation. Measured ages are also comparable speci¢cally to those measured along other great escarpments that are as much as 100 Myr younger.This suggests that erosional mechanisms that maintain rugged escarpments in the early post-rift stages may remain active on ancient passive margins for prolonged periods.The precise erosional evolution of the escarpment is less clear, however, and several end-member models can explain the data. Our preferred model, which ¢ts with all data, involves a signi¢cant degree of erosional escarpment retreat in the Cenozoic. Although this suggests that early onset of topographic stability is not required of passive margin evolution, more data are required to better constrain the details of the escarpment's development.

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“…Prowell (1988) suggested that this reverse faulting is a result of long-term compression since late Cretaceous time in the southeastern United States, perhaps because of intraplate stresses related to the continued opening of the Atlantic Ocean. Other sources of neotectonic stresses in the southeastern United States include lithospheric flexure cause by offshore sediment loading and isostatic responses to the erosion of detritus from the continent (Gardner, 1989). Thomas (1977) has suggested that the pre-collisional Iapetan passive margin may have been the major controlling factor influencing the formation of structures along the entire AppalachianOuachita mountain belt.…”

Section: Reactivation Of Faults and Basement Controlsmentioning

confidence: 99%

Contrasts in Tectonic style of the Central and Southern Appalachians, United States: Insights from seismic reflection data

Peavy

Çoruh

Costain

et al. 2004

Journal of Geodynamics

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Neotectonism along the Atlantic passive continental margin: A review

Cited by 16 publications

References 111 publications

Macrogeomorphic evolution of the post‐Triassic Appalachian mountains determined by deconvolution of the offshore basin sedimentary record

Macrogeomorphic evolution of the post‐Triassic Appalachian mountains determined by deconvolution of the offshore basin sedimentary record

Origin of the Blue Ridge escarpment along the passive margin of Eastern North America

Contrasts in Tectonic style of the Central and Southern Appalachians, United States: Insights from seismic reflection data

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