Low-T thermochronology as a tool to decipher differential exhumation of crustal blocks of western Norway

Western Norway is dissected by the major, late-Caledonian Hardangerfjord shear zone (HSZ) into a northwestern and a southeastern part. To the SW, the HSZ continues through the North Sea into northern England, while its NE extension is the Lærdal-Gjende fault. It also subdivides western Norway into slightly different “thermochronological blocks” to the NW and SE that show different post-Caledonian exhumation histories on either side. Coastal western Norway underwent further structural segmentation during North Sea rifting along N-S trending faults. Overall, the distribution pattern of apatite fission-track and (U-Th)/He ages shows a strong structural control of this shear zone and fault pattern, with significant age jumps across some of these structures.

This MSc project will either fission-track- or He-date existing samples of a near-vertical - but so far undated profile - along the southern margin of the HSZ, or a suite of new samples of a selected crustal block with poor age coverage so far that was affected by combined faulting along the HSZ and along N-S faults. The main aim will be to gain a better understanding of the differential post-Caledonian exhumation history of the different fault-bounded blocks of Western Norway.

The project is integrated into the PhD project of Rebecca Jacoby that will re-evaluate the post-Caledonian exhumation history of Western Norway from a low-T thermochronological perspective in a wholistic way. The project requires training in low-T thermochronological techniques, including apatite fission-track analysis and (U-Th)/He dating.

Proposed course plan during the master's degree (60 ECTS)
Geov 341

Field-, lab- and analysis work
Sampling Hardangerfjord, mineral separation, fission-track analysis

Student

Erlend Bjelland

Supervisors

Joachim Jacobs (main supervisor)

Rebecca Jacoby, GEO-UiB