Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Spatial variations in T-e in the southern Appalachians, eastern United States
Autore:
Armstrong, GD; Watts, AB;
Indirizzi:
Univ Oxford, Dept Earth Sci, Oxford OX1 3PR, England Univ Oxford Oxford England OX1 3PR pt Earth Sci, Oxford OX1 3PR, England
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
fascicolo: B10, volume: 106, anno: 2001,
pagine: 22009 - 22026
SICI:
0148-0227(20011010)106:B10<22009:SVITIT>2.0.ZU;2-5
Fonte:
ISI
Lingua:
ENG
Soggetto:
EFFECTIVE ELASTIC THICKNESS; CONTINENTAL LITHOSPHERE; ISOSTATIC COMPENSATION; GRAVITY-ANOMALIES; CANADIAN SHIELD; NORTH-AMERICA; EVOLUTION; FLEXURE; MECHANISMS; TOPOGRAPHY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
54
Recensione:
Indirizzi per estratti:
Indirizzo: Armstrong, GD Univ Oxford, Dept Earth Sci, Parks Rd, Oxford OX1 3PR, England Univ Oxford Parks Rd Oxford England OX1 3PR X1 3PR, England
Citazione:
G.D. Armstrong e A.B. Watts, "Spatial variations in T-e in the southern Appalachians, eastern United States", J GEO R-SOL, 106(B10), 2001, pp. 22009-22026

Abstract

Various studies in the oceans have shown that the flexural rigidity, or equivalently effective elastic thickness (T-e), of the lithosphere is determined by the load and plate age. The results of studies in the continents have, however, been more controversial. Determinations of T-e made using spectral studies and based on the Bouguer anomaly coherence technique and surface and subsurface loading suggest that North America has a high T-e "core" (> 100 km) which is flanked by lower values. In contrast, studies based on the free air admittance suggest that T-e of North America is < 25 km, and ofthe order of the seismogenic layer thickness. It has been proposed that this discrepancy results from the fact that estimates based only on Bouguer coherence may be biased upward due to topographical erosion which introduces"noise", especially at short wavelengths. In order to address this question further, we have used a maximum entropy based coherence method to determine the wavelength relationship between gravity and topography in the southern Appalachians, a region where the Bouguer coherence, free-air admittance,and forward modeling techniques have already been applied. Our studies reveal a variable T-e structure with a mean T-e of 51 km and values which havea range 20 to 100 km. The mapped T-e fabric has a distinct NE-SW.trend which appears to follow the tectonic elements of the southern Appalachians. Inparticular, the foreland is generally associated with higher T-e values than the flanking orogenic belt. Correlations at smaller scales are difficult, however, to establish. The T-e fabric does not reflect the complex terrains that make up highly deformed regions within the orogenic belt. Our spectrally determined T-e estimates are in close agreement with ones based on forward modeling. They are a factor of 4 higher, however, than results previously based on free-air admittance. We attribute this to the fact that we have used the Bouguer coherence technique which accounts for both surface andsubsurface loading. Our results suggest that while other factors such as erosion may upwardly bias T, in some regions, buried loads satisfactorily explain the spectral estimates in the southern Appalachians, irrespective of whether they are based on Bouguer coherence or free-air admittance. There is solid geological evidence in the southern Appalachians which is readily attributable to the presence of subsurface loads. This is a strong argument,we believe, to suggest that T-e in the continents is high and can have values which range from 20 to 100 km.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/04/20 alle ore 15:15:25