Keweenaw hot spot: Geophysical evidence for a 1. 1 Ga mantle plume beneath the Midcontinent Rift System

Journal Article · Tue Jul 10 00:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JB095iB07p10869· OSTI ID:5456203

Hutchinson, D R ^[1]; White, R S ^[2]; Cannon, W F; Schulz, K J ^[3]

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1. Geological Survey, Woods Hole, MA (USA)
2. Cambridge Univ. (England)
3. Geological Survey, Reston, VA (USA)

The Proterozoic Midcontinent Rift System of North America is remarkably similar to Phanerozoic rifted continental margins and flood basalt provinces. Like the younger analogues, the volcanism within this older rift can be explained by decompression melting and rapid extrusion of igneous material during lithospheric extension above a broad, asthenospheric, thermal anomaly which the authors call the Keweenaw hot spot. Great Lakes International Multidisciplinary Program on Crustal evolution seismic reflection profiles constrain end-member models of melt thickness and stretching factors, which yield an inferred mantle potential temperature of 1,500-1,570C during rifting. Combined gravity modeling and subsidence calculations are consistent with stretching factors that reached 3 or 4 before rifting ceased, and much of the lower crust beneath the rift consists of relatively high density intruded or underplated synrift igneous material. The isotopic signature of Keweenawan volcanic rocks, presented in a companion paper by Nicholson and Shirey (this issue), is consistent with the model of passive rifting above an asthenospheric mantle plume.

• OSTI ID: 5456203
• Journal Information: Journal of Geophysical Research; (United States), Vol. 95:B7; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
NORTH AMERICA
RIFT ZONES
VOLCANISM
BASALT
CONTINENTAL MARGIN
DENSITY
EXTRUSION
GEOCHEMISTRY
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGIC MODELS
IGNEOUS ROCKS
SEISMIC SURVEYS
TECTONICS
TEMPERATURE DEPENDENCE
CHEMISTRY
FABRICATION
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
MATERIALS WORKING
PHYSICAL PROPERTIES
ROCKS
SURVEYS
VOLCANIC ROCKS
580000* - Geosciences