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GEOREF RECORD

Extracting ore-deposit-controlling structures from aeromagnetic, gravimetric, topographic, and regional geologic data in western Yukon and eastern Alaska

Matias G. Sanchez, Murray M. Allan, Craig J. R. Hart and James K. Mortensen
Extracting ore-deposit-controlling structures from aeromagnetic, gravimetric, topographic, and regional geologic data in western Yukon and eastern Alaska (in Interpretation and integration of gravity and magnetic data, Ran Zhang (prefacer), Rao Yalamanchili (prefacer) and Alan Aitken (prefacer))
Interpretation (Tulsa) (November 2014) 2 (4): SJ75-SJ102

Abstract

Aeromagnetic lineaments interpreted from reduced-to-pole (RTP) magnetic grids were compared with gravity, topography, and field-based geologic maps to infer regional structural controls on hydrothermal mineral occurrences in a poorly exposed portion of the North American Cordillera in western Yukon and eastern Alaska. High-frequency and variable-intensity aeromagnetic lineaments corresponding to discontinuities with an aeromagnetic domain change were interpreted as steep-dipping and either magnetite-destructive or magnetite-additive faults. These structures were interpreted to be predominantly Cretaceous in age and to have formed after the collision of the Intermontane terranes with the ancient Pacific margin of North America. To demonstrate the reliability of the aeromagnetic interpretation, we developed a multidata set stacking methodology that assigns numeric values to individual lineaments depending on whether they can be traced in residuals and first vertical derivative of RTP aeromagnetic grids, isostatic residual gravity grids, digital topography, and regional geologic maps. The sum of all numeric values was used to estimate the likelihood of the aeromagnetic lineament as a true geologic fault. Fault systems were interpreted from zones of lineaments with high spatial density. Using this procedure, 10 major northwest-trending fault systems were recognized. These were oriented subparallel to the regional Cordilleran deformation fabric, the mid-Cretaceous Dawson Range magmatic arc, and well-established crustal-scale dextral strike-slip fault systems in the area. These orogen-parallel fault systems were interpreted to play a structural role in the emplacement of known porphyry Cu-Au and epithermal Au systems of mid-Cretaceous (115-98 Ma) and Late Cretaceous (79-72 Ma) age. The procedure also identified seven northeast-trending, orogen-perpendicular fault-fracture systems that are prominent in eastern Alaska and exhibit sinistral-to-oblique extensional kinematics. These structures were interpreted to govern the emplacement of Late Cretaceous (72-67 Ma) porphyry Mo- and Ag-rich polymetallic vein and carbonate replacement systems in the region.


ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 2
Serial Issue: 4
Title: Extracting ore-deposit-controlling structures from aeromagnetic, gravimetric, topographic, and regional geologic data in western Yukon and eastern Alaska
Title: Interpretation and integration of gravity and magnetic data
Author(s): Sanchez, Matias G.Allan, Murray M.Hart, Craig J. R.Mortensen, James K.
Author(s): Zhang, Ranprefacer
Author(s): Yalamanchili, Raoprefacer
Author(s): Aitken, Alanprefacer
Affiliation: University of British Columbia, Mineral Deposit Research Unit, Vancouver, BC, Canada
Affiliation: BHP Billiton, London, United Kingdom
Pages: SJ75-SJ102
Published: 20141101
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 139
Accession Number: 2015-007671
Categories: Structural geologyApplied geophysicsEconomic geology, geology of ore deposits
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch maps
N51°00'00" - N72°00'00", W130°00'00" - E173°00'00"
N60°00'00" - N70°00'00", W141°00'00" - W125°00'00"
Secondary Affiliation: CGG GravMag Solutions, USA, United StatesUniversity of Western Australia, AUS, Australia
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 201504
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