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Article: 2480 Ma mafic magmatism in the northern Black Hills, South Dakota: a new link connecting the Wyoming and Superior cratons (1).
- Article from:
- Canadian Journal of Earth Sciences
- Article date:
- October 1, 2006
- Author:
CopyrightCOPYRIGHT 2006 NRC Research Press. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Abstract: The Laramide Black Hills uplift of southwest South Dakota exposes a Precambrian crystalline core of ~2560-2600 Ma basement granitoids nonconformably overlain by two Paleoproterozoic intracratonic rift successions. In the northern Black Hills, a 1 km thick, layered sill (the Blue Draw metagabbro) that intrudes the older rift succession provides a key constraint on the timing of mafic magmatism and of older rift-basin sedimentation. Ion microprobe spot analyses of megacrysts of magmatic titanite from a horizon of dioritic pegmatite in the uppermost sill portion yield a [sup.207]Pb/[sup.206]Pb upper-intercept age of 2480 [+ or -] 6 Ma (all age errors [+ or ...
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