Warren C. Day
John N. Alienikoff
Richard W. Saltus
Larry P. Gough
Warren C. Day
J. Michael O’Neill
2007
The Black Mountain tectonic zone in the YukonTanana terrane of east-central Alaska is a belt of diverse
northeast-trending geologic features that can been traced
across Black Mountain in the southeast corner of the Big Delta
1°×3° degree quadrangle. Geologic mapping in the larger
scale B1 quadrangle of the Big Delta quadrangle, in which
Black Mountain is the principal physiographic feature, has
revealed a continuous zone of normal and left-lateral strikeslip high-angle faults and shear zones, some of which have
late Tertiary to Quaternary displacement histories. The tectonic
zone includes complexly intruded wall rocks and intermingled
apophyses of the contiguous mid-Cretaceous Goodpaster and
Mount Harper granodioritic plutons, mafic to intermediate
composite dike swarms, precious metal mineralization, early
Tertiary volcanic activity and Quaternary fault scarps. These
structures define a zone as much as 6 to 13 kilometers (km)
wide and more than 40 km long that can be traced diagonally across the B1 quadrangle into the adjacent Eagle 1°×3°
quadrangle to the east. Recurrent activity along the tectonic
zone, from at least mid-Cretaceous to Quaternary, suggests
the presence of a buried, fundamental tectonic feature beneath
the zone that has influenced the tectonic development of
this part of the Yukon-Tanana terrane. The tectonic zone,
centered on Black Mountain, lies directly above a profound
northeast-trending aeromagnetic anomaly between the Denali
and Tintina fault systems. The anomaly separates moderate
to strongly magnetic terrane on the northwest from a huge,
weakly magnetic terrane on the southeast. The tectonic zone is
parallel to the similarly oriented left-lateral, strike-slip Shaw
Creek fault zone 85 km to the west.
application/pdf
10.3133/sir20075289D
en
U.S. Geological Survey
The Black Mountain tectonic zone--a reactivated northeast-trending crustal shear zone in the Yukon-Tanana Upland of east-central Alaska: Chapter D in <i>Recent U.S. Geological Survey studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada--results of a 5-year project</i>
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