Geology Reports⌕ Search

Geology topics

W. C. Prinz

Publications and source records attributed to W. C. Prinz.

6 recordsLinked to original sources
USGS1977

Geology and Rb-Sr age of Precambrian W Puritan Quartz Monzonite, northern Michigan

The Puritan Quartz Monzonite, in the western part of the Upper Peninsula of Michigan, composes a batholith at least 50 kilometres long and as much as 20 km wide on the south side of the Gogebic iron range. It is associated with subaqueous metavolcanic rocks assigned to the Precambrian W Ramsey Formation and with a complex gneissic unit of the same age. The quartz monzonite has a Rb-Sr isochron age of 2,710±140 million years and an initial 87 Sr/ 86 Sr of 0.7015±0.0017. The scatter of data points in excess of analytical error is interpreted as indicating that minor cataclasis and retrograde metamorphism produced slight open-system behavior in Precambrian X (circa 1,800 m.y.) time. The Puritan Quartz Monzonite and associated volcanic rocks are equated with similar Precambrian W greenstone-granite complexes in northern Minnesota, and clearly are a part of the Precambrian W greenstone terrane, as defined previously for the Lake Superior region.

Michigan, Wisconsin↗
USGS1976

Geochronology of the Arabian Shield, western Saudi Arabia: K-Ar results

An orogenic event, correlated with the Pan-African event in eastern Africa, affected the Arabian Peninsula between 510 and 610 m.y. ago and is well-recorded geochronologically. The event probably included two thermal pulses or maxima, the first occurring between 560 and 610 m.y. ago and the second between 510 and 540 m.y. ago. The earlier pulse, the more severe one, included the majority of the igneous activity and metamorphism. During the last part of the 510- to 610-m.y. period, left-lateral strike-slip faulting occurred along a set of northwest-trending en echelon fracture zones, whose composite displacement may be as large as 240 km. At least one and probably more orogenic events affected the Arabian Peninsula before the Pan-African event, but only minimum ages can be assigned to these, because thermal effects of the 510- to 610-m.y. event have reset K-Ar ages. Major diorite-granite batholiths, however, formed before 760 m.y. ago.

Arabian Shield↗