THE SHAPE AND THICKNESS OF AN ARCHAEAN GREENSTONE BELT BY GRAVITY METHODS

Autor:	W. H. Gross, M. A. Chinnery, F. S. Grant
Rok vydání:	1965
Předmět:	Precambrian Gravity (chemistry) Shield Archean Geochemistry General Earth and Planetary Sciences Greenstone belt Billion years Geology
Zdroj:	Canadian Journal of Earth Sciences. 2:418-424
ISSN:	1480-3313 0008-4077
DOI:	10.1139/e65-036
Popis:	The Red Lake greenstone belt is Archaean in age (older than 2.5 billion years) and is located in the Superior province of the Canadian Precambrian Shield. It is a fairly typical greenstone belt, being composed of a complex assemblage of lavas, sediments, and intrusives. The belt is completely surrounded, and therefore is isolated from other greenstone belts, by granitic batholiths and acid paragneiss. Generally speaking, greenstones are more dense than the surrounding granitic rocks and they therefore give positive gravity effects, the amplitudes of which give some indication of their shape and overall thickness.At Red Lake, the greenstone belt is approximately 35 mi long by 18 mi wide. Gravity readings taken across the width of the belt indicate that the greenstones taper sharply in depth to a maximum thickness of approximately 25 000 ft. These results appear to confirm, as most geologists feel intuitively, that greenstone belts are basin-shaped and are underlain by granitic batholiths and gneiss.
Databáze:	OpenAIRE
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