Robin Buckley

In the Expedition Fiord region (c.a. 79o24’N/90o50’W) of Axel Heiberg Island exposed evaporite diapir structures with associated perennial springs are present. These diapers are rooted in a shallow allochthonous evaporite canopy that lies beneath this region. This study presents apatite (U-Th-Sm)/He thermochronologic data from the Expedition Fiord region for comparison with existing data from the eastern Sverdrup Basin. The apatite (U-Th-Sm)/He cooling ages of the regional data reflect exhumation cooling during the Eurekan Orogeny (ca.45-65 Ma). In the vicinity of Expedition Fiord (U-Th-Sm)/He ages are considerably younger (ca. 32-41 Ma) indicating the rocks now at the surface cooled through He-retention temperatures (ca. 75 + 15oC) ~10 Ma later than rocks to the east in the Geodetic Hills region (ca. 48-61 Ma) as well as regional rocks. Data from this study are compatible with the thermal history previously suggested by apatite fission track-length modeling. Another result of this study is the identification of a significantly younger cooling age (13.9 + 1.4 Ma) at the western edge of the study area in an island in Expedition Fiord.

A possible explanation for these data and anomalously young cooling ages is later exhumation of the rocks in the region of the canopy due to activity of the salt structure itself. If is also proposed that the effect may be due to the thermal effect of individual diapers but the preferred hypothesis to explain the anomalously young data is a thermal effect that delayed cooking of the rocks in this specific area caused by the underlying salt canopy and heat advection by fluids.

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Pages: 46
Supervisor: Marcos Zentilli