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Imaging the Moho Topography Beneath the Northern Canadian Cordillera from Virtual Deep Seismic Sounding

Description: 

The Northern Canadian Cordillera (NCC) in northwestern Canada is a tectonically active orogenic belt known for its high topography, transpressional accretion, and complex tectonic history. The ongoing uplift seen in the Mackenzie Mountains (MM) in the NCC remains enigmatic because it is ~700 km from the Yakutat collision zone. Several geophysical studies, particularly receiver function (RF) analyses, have been conducted to better understand crustal dynamics responsible for the MM uplift from Moho depth and geometry information. However, these RF studies faced difficulties in imaging the Moho topography beneath some seismic stations along the Mackenzie Mountains EarthScope Project (MMEP) transect near the Cordilleran Deformation Front (CDF) due to thick sedimentary cover, poor stack quality, and sometimes aberrant RFs. Here, we use a recently developed passive teleseismic technique known as virtual deep seismic sounding to produce a new Moho depth model of the NCC using seismic data from 227 stations, including the past seismographic stations (2000 – 2014), the MMEP, and the recently deployed (since 2021) broadband seismographs in Yukon, British Columbia, and Alberta. Our preliminary results reveal a Moho depth in the range of 28 – 42 km beneath the MMEP transect line, with a mean Moho depth of 35 km. Crustal thickening with a Moho depth range: 30 – 42 km, and possibly crustal shortening, is observed beneath the northwestern region of the MM, which was previously attributable to crustal stacking of NCC and earlier Laurentian lithosphere. The Moho topography is relatively flat and uniform between the Denali Fault and the Cordilleran crust. However, there are localized crustal thickenings between Teslin and Tintina Faults, which is consistent with findings from previous studies. Crustal thinning is observed near the CDF, caused by deep hot mantle upwelling within the MM range, which later transitions to thickened Canadian craton. Generally, the crustal thickness within the Cordilleran is insufficient to support the overlying high topography in the NCC, accentuating the thermal isostatic buoyancy of the hot backarc.

Session: Earth’s Structure from the Crust to the Core [Poster]

Type: Poster

Date: 4/16/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Sherif

Student Presenter: Yes

Invited Presentation: 

Poster Number: 101

Authors