How sharp is the sharp Archean Moho? Example from eastern Superior Province

TY - JOUR

T1 - How sharp is the sharp Archean Moho? Example from eastern Superior Province

AU - Levin, Vadim

AU - VanTongeren, Jill A.

AU - Servali, Andrea

N1 - Funding Information: This work was supported by the NSF Earthscope grant EAR-1147831 and the Aresty Center for Undergraduate Research andmade possible by the open data policy of the Canadian National Data Centre for Earthquake Seismology and Nuclear Explosion Monitoring. Discussions with C. Herzberg, O. Jagoutz,W. Menke, and M. Bostock, as well as reviews by Andrew Hynes and anonymous, helped us sharpen the arguments. Figures were drawn using GMT [Wessel and Smith, 1991]. Publisher Copyright: © 2016. American Geophysical Union. All Rights Reserved.

PY - 2016/3/16

Y1 - 2016/3/16

N2 - The Superior Province of North America has not experienced major internal deformation for nearly 2.8 Gyr, preserving the Archean crust in its likely original state. We present seismological evidence for a sharp (less than 1 km) crust-mantle boundary beneath three distinct Archean terranes and for a more vertically extensive boundary at sites likely affected by the 1.2-0.9 Ga Grenville orogeny. At all sites crustal thickness is smaller than expected for the primary crust produced by melting under higher mantle potential temperature conditions of Archean time. Reduced thickness and an abrupt contrast in seismic properties at the base of the undisturbed Archean crust are consistent with density sorting and loss of the residues through gravitational instability facilitated by higher temperatures in the upper mantle at the time of formation. Similar sharpness of crust-mantle boundary in disparate Archean terranes suggests that it is a universal feature of the Archean crustal evolution.

AB - The Superior Province of North America has not experienced major internal deformation for nearly 2.8 Gyr, preserving the Archean crust in its likely original state. We present seismological evidence for a sharp (less than 1 km) crust-mantle boundary beneath three distinct Archean terranes and for a more vertically extensive boundary at sites likely affected by the 1.2-0.9 Ga Grenville orogeny. At all sites crustal thickness is smaller than expected for the primary crust produced by melting under higher mantle potential temperature conditions of Archean time. Reduced thickness and an abrupt contrast in seismic properties at the base of the undisturbed Archean crust are consistent with density sorting and loss of the residues through gravitational instability facilitated by higher temperatures in the upper mantle at the time of formation. Similar sharpness of crust-mantle boundary in disparate Archean terranes suggests that it is a universal feature of the Archean crustal evolution.

KW - Moho

KW - craton

KW - receiver function

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U2 - https://doi.org/10.1002/2016GL067729

DO - https://doi.org/10.1002/2016GL067729

M3 - Article

VL - 43

SP - 1928

EP - 1933

JO - Geophysical Research Letters

JF - Geophysical Research Letters

SN - 0094-8276

IS - 5

ER -