SW U. S. diabase province: A 1. 1-Ga intrusion event of middle Grenville and middle Keweenawan age

Conference · Mon Feb 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:6003333

Conway, C M; Elston, D P ^[1]; Wrucke, C T ^[2]

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1. Geological Survey, Flagstaff, AZ (United States)
2. Geological Survey, Menlo Park, CA (United States)

Diabase in the southwestern US intrudes Middle Proterozoic stratified rocks as sills and Early and Middle Proterozoic crystalline rocks as subhorizontal sheets and subvertical dikes. It is discontinuous in a broad belt extending from western Texas to southeastern California. The best known intrusions are sills in Middle Proterozoic strata in Death Valley, Grand Canyon, and central Arizona. Sparse to rare dikes in some of these strata trend mostly north but range from north-northeast to west-northwest. Diabase dikes widespread in crystalline rocks in western Arizona and adjacent parts of southeastern California strike from north to west-northwest, but are predominantly northwesterly. Dikes and sheets are also present in crystalline rocks in the southern Pinaleno Mountains, southeastern Arizona, where dikes strike west-northwest. The northwest trend of the diabase province and prevalent northwesterly trend of dikes in crystalline rocks suggest that intrusion was controlled by an approximately horizontal least compressive stress field roughly parallel to the Grenville Front. Radiometric ages of Arizona and California diabase indicate emplacement at [approximately]1,100 Ma. Paleomagnetic poles from diabase sills and enclosing stratified rocks in Arizona correlate with poles reported from middle and early-late Keweenawan rocks of Lake Superior. Emplacement of the diabase coincides with: (1) the middle Keweenawan eruptive and intrusive episode of the Midcontinent Rift System; (2) a major episode of (middle) Grenville thrusting and deformation documented in the Van Horn area; and (3) a time of abrupt reversal in North American apparent polar wander. These interrelated manifestations presumably arose in response to a major episode of plate interaction and collision between North American and a plate that encroached from the southeast.

• OSTI ID: 6003333
• Report Number(s): CONF-9303212--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:1
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
ARIZONA
BASALT
CALIFORNIA
DEVELOPED COUNTRIES
DIABASES
DIKES
GEOLOGIC AGES
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
IGNEOUS ROCKS
ISOTOPE DATING
NEW MEXICO
NORTH AMERICA
PLATE TECTONICS
PRECAMBRIAN ERA
ROCKS
TECTONICS
TEXAS
USA
VOLCANIC ROCKS