Early Proterozoic tectonics in the north-central United States
New insights into the tectonic evolution of the buried Precambrian basement in the north-central United States have come from a compilation of drill hole data, which was recently prepared in cooperation with the respective state geological surveys. The data reveal an Early Proterozoic orogen (Central Plains; 1.64-1.75 Ga) more than 1000 km long and 500 km wide, extending east-southeast from western Nebraska through Kansas into southeast Missouri. Two diachronous (1.48 Ga and 1.35-1.4 Ga) anorogenic rhyolite-granite terranes overlap the orogen on the south. From isotopic ages, lithotypes, and magnetic anomaly data the authors interpret the Central Plains orogen to be the eastern extension of the Early Proterozoic metamorphic foldbelt in Colorado and Wyoming; it truncates the southern margin of the Superior Archean craton and its truncates the southern margin of the Superior Archean craton and its marginal Early Proterozoic orogens - the Penokean (1.83-1.9 Ga) and the Trans-Hudson (1.85-1.95 Ga). This truncation accounts for the absence of 1.8-1.95 Ga metamorphic rocks in southwestern US. The authors interpret the Trans-Hudson, Penokean, and Central Plains orogens as products of continent-arc collision. Intersecting Early Proterozoic mobile belts that partly enclose Archean cratons suggest continental growth by the accretion of successively younger primitive oceanic arcs onto rifted continental margins of subcontinent dimensions. Consolidation of this part of the North American continent was completed by approx. 1.6 Ga.
- Research Organization:
- Geological Survey, Denver, CO (USA)
- OSTI ID:
- 6070847
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
FEDERAL REGION VII
PLATE TECTONICS
GRANITES
ISOTOPE DATING
RHYOLITES
BASEMENT ROCK
CONTINENTAL CRUST
PRECAMBRIAN ERA
RIFT ZONES
AGE ESTIMATION
EARTH CRUST
GEOLOGIC AGES
GEOLOGIC STRUCTURES
IGNEOUS ROCKS
NORTH AMERICA
PLUTONIC ROCKS
ROCKS
TECTONICS
USA
VOLCANIC ROCKS
580100* - Geology & Hydrology- (-1989)
580201 - Geophysics- Seismology & Tectonics- (1980-1989)