Large Mafic Igneous Province (LIP) in central Alaska

This project is a collaborative with the BLM Delta River Mining District (DRMD) study to be completed in FY05. USGS is investigating the structural controls on the northern- and western-most segment of a continental-scale mafic large igneous province (LIP) - the Triassic Nikolai Greenstone).

Abstract

This project is a collaborative with the BLM Delta River Mining District (DRMD) study to be completed in FY05. USGS is investigating the structural controls on the northern- and western-most segment of a continental-scale mafic large igneous province (LIP) - the Triassic Nikolai Greenstone). New microfossil and radiometric samples may provide age control for the LIP intrusions and their host rocks. Modeling of new ground and airborne poential field and magnetotelluric geophysical data in a stratigraphic context provides a regional framework for the location of the intrusions and detailed profiles of the structural context of several of the largest exposed bodies. Intrusive rocks that are part of the Nikolai LIP system have very high potential for nickel-copper and platinum-group element deposits. These intrusions are abundant, extensive, and chemically differentiated in the central Alaska Range, unlike many other segments of the Nikolai LIP. This area is the focus of ongoing mineral exploration and accelerated land transfers between the BLM and the State of Alaska. The USGS study identifies the structures that control the primary Triassic emplacement of magmas. This project provided framework geology to more accurate assessment of the character, and possible locations of mineral concentrations.

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Products

Title	Type
Crustal structure of the AK Range orogen and Denali fault along the Richardson Highway	Publication
Gravity and magnetic character of SC AK: constraints on geologic interpretation	Publication
Metallogeny of the Nikolai large igneous province in southern AK	Publication
Geophysical investigation of the Denali Fault and AK Range orogen	Publication
Geophysical data revearl the crustal structure of the AK Range orogen	Publication
A kinematic model for the southern AK orocline based on regional fault patterns	Publication
2D inverse and 3D forward modeling of MT data to evaluate mineral potential, Amphitheatre Mtns.	Publication
Magnetotelluric data along the Tangle Lakes profile, Alaska	Publication
Principal Facts for 463 gravity stations in the vicinity of Tangle Lakes, EC Alaska	Publication
Magnetotelluric data in the Delta River mining district, near the Tangle Lakes area of SC Alaska	Publication
3D model of an ultramafic feeder system to the Nikolai Greenstone mafic large igneous province	Publication

Contacts

Schmidt, Jeanine M., 907-786-7494

Status: completed
Start Year: 2003
End Year: 2005

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Project Sites

Collaborators

BLM - Alaska State Office

Location

Clearwater Mountains
Fish Lake
Tangle Lakes

USGS Mission Area and Program

Energy and Minerals → Mineral Resources

Keywords

Solid Earth > Geochemistry > Major Elements
Solid Earth > Geochemistry > Trace Elements
Solid Earth > Geodetics/Gravity > Gravity
Solid Earth > Geomagnetism > Electrical Field
Solid Earth > Geomagnetism > Magnetic Anomalies
Solid Earth > Natural Resources > Metals
Solid Earth > Rocks/Minerals > Bedrock Lithology
Solid Earth > Rocks/Minerals > Igneous Rocks
Solid Earth > Tectonics > Faults
Solid Earth > Tectonics > Stratigraphic Sequence