Crustal thickness variation in south-central Alaska

Crustal thickness variation in south-central Alaska,10.1130/G22615.1,Geology,Elizabeth Veenstra,Douglas H. Christensen,Geoffrey A. Abers,Aaron Ferris

Crustal thickness variation in south-central Alaska   (Citations: 7)
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Crustal thicknesses have been determined by receiver function analysis of broadband teleseismic waveforms recorded during the Broadband Experiment Across the Alaska Range (BEAAR). Typical crust beneath the northern lowlands is 26 km thick, while be- neath the mountains it is 35-45 km thick. The transition from thick to thin crust coincides with the location of the Hines Creek fault, a major tectonostratigraphic boundary. Crustal thicknesses determined by receiver functions agree with those predicted from topography assuming Airy type isostasy, suggesting that the Alaska Range is compensated by its crust- al root. North of the range, however, the crust is systematically thinner than predicted by simple Airy isostasy. A crustal density contrast of 4.6% across the Hines Creek fault, 2700 kg m3 to the north and 2830 kg m3 to the south, explains the observed difference between the crustal thicknesses predicted by simple Airy isostasy, and the crustal thick- nesses determined by receiver function analysis.
Journal: Geology , vol. 34, no. 9, 2006
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    • ...[22] Moho depths (Figures 7 and 8 and Table 1) generally agree with those by Veenstra et al. [2006], and show a thicker crust south of the Denali fault and � 10 km thinner crust north it. Individual Moho depths vary from 27 to 45 km, while the Vp/Vs ratio varies from 1.62 to 2.04 with an average of 1.78, slightly above the global average for continental crust of 1.76 [Christensen, 1996]...
    • ...However, the observed Moho cannot be reproduced with a simple, uniform thin elastic plate supporting topography, indicating a complicated and asymmetrical compensation process as discussed elsewhere [Veenstra et al., 2006]...
    • ...Isostatic balance calculations [Veenstra et al., 2006] show that the northward thinning in crustal thickness greatly exceeds that predicted by the change in elevation, requiring a lower lithospheric density north of the Denali fault...

    Giovannibattista Rossiet al. Unusual mantle Poisson's ratio, subduction, and crustal structure in c...

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