Find publications, data and maps managed by the
Yukon Geological Survey

YGS Publication Details


Reference Number
YEG2001_15
Title
Paleomagnetism and geobarometry of the Granite Mountain batholith, Yukon: Minimal geotectonic motion of the Yukon-Tanana Terrane relative to North America
Reference Type
Indian & Northern Affairs Canada/Department of Indian & Northern Development: Exploration & Geological Services Division
Document Type
Annual Report Paper


General Information

Abstract: Paleomagnetic and geobarometric results are reported here for the Early Jurassic Granite Mountain batholith, an ~600 km² granodiorite intrusion in the Yukon-Tanana Terrane. Paleomagnetic analyses of 331 specimens from 24 sites yield magnetite-borne characteristic remanent magnetization (ChRM) directions. Eight northerly and westerly sites display a mean direction A (D=337, I=69°; a 95 =7.6°, k=54). Another 11 sites appear to be lightning-struck, or exhibit unstable remanence, and 3 sites in a fault-bounded block to the southeast carry an anomalous northeast upwards ChRM direction B. Two sites in a Cretaceous andesite porphyry dyke and its contact zone give a westerly, steep-down ChRM direction, C. Aluminum-in-hornblende geobarometry at 10 sites defines emplacement depths of ~16 km in the north and west, and ~19 km in the southeast. The batholith has probably not been significantly tilted since its emplacement, but it may be subdivided into two separate intrusive phases or structural blocks that have experienced differential uplift. Ambient temperatures at 16-19 km were too high for magnetite to record an enduring remanence, so the observed ChRMs likely record uplift of the batholith through ~15 km depth, at 180-170 Ma. Both A and C ChRM directions are similar to those expected for Early Jurassic and Late Cretaceous reference poles, respectively, suggesting that the Yukon-Tanana Terrane is not far-traveled with respect to cratonic North America since Early Jurassic time.
Authors: McCausland, P.J.A., Symons, D.T.A., Hart, C.J.R., and Blackburn, W.H.
Keywords: Regional Geology, remnant magnetism
NTS Mapsheet(s): 115I
Citation: McCausland, P.J.A., Symons, D.T.A., Hart, C.J.R., and Blackburn, W.H., 2002. Paleomagnetism and geobarometry of the Granite Mountain batholith, Yukon: Minimal geotectonic motion of the Yukon-Tanana Terrane relative to North America. In: Yukon Exploration and Geology 2001, Emond, D.S., Weston, L.W., and Lewis, L.L. (eds.), Exploration and Geological Sciences Division, Yukon Region, Indian and Northern Affairs Canada, p. 163-177.

Downloads

Name Comment
Report File is .38 MB Download PDF

Location Map

NTS Mapsheet(s): 115I

Related Occurrences

Name Number Type Status

Related Publications

Number Relationship Authors Title
YEG2001 Contained By Emond, D.S., Weston, L.W., and Lewis, L.L. (eds.) Yukon Exploration and Geology 2001