102nd Annual Meeting of the Cordilleran Section, GSA, 81st Annual Meeting of the Pacific Section, AAPG, and the Western Regional Meeting of the Alaska Section, SPE (810 May 2006)
Paper No. 24-6
Presentation Time: 3:30 PM-3:50 PM


LINDSLEY-GRIFFIN, Nancy1, GRIFFIN, John R.1, and FARMER, Jack D.2, (1) Geosciences, University of Nebraska, 214 Bessey Hall, Lincoln, NE 68588-0340, nlg@unlserve.unl.edu, (2) Dept. Geological Sciences, Arizona State Univ, Tempe, AZ 85287-1404

Certain fossils from the Yreka terrane (Yt) of northern California's Klamath Mountains are similar to fossils in Alaska's Nixon Fork and Alexander terranes, especially early Paleozoic gastropods, brachiopods, and sphinctozoan sponges described in the literature. These similarities, plus species of shelly fauna endemic to the Yt, suggest that it was partially isolated in the Ordovician and Silurian but partially connected with tectonic elements that evolved into Alaskan accreted terranes. Other faunal affinities suggest early Paleozoic links with Laurentia, Siberia, Uralian terranes, and Baltica.

Where did these terranes develop? The Yt provides a Neoproterozoic starting point. Over 250 cyclomedusoid fossils of the Ediacaran biota include Ediacaria and Beltanella sp., recovered from argillites interbedded with the upper part of the Antelope Mountain Quartzite (AMQ). These fossils exhibit closest affinities to Ediacaran cyclomedusoids from Finnmark in northern Baltica, and from NW Laurentia; work by B. Waggoner also suggests ties to Australia and Siberia. AMQ provenance is continental but probably not the Laurentian craton (Bond and Devay, 1980). AMQ detrital zircons (E.T. Wallin and colleagues) are diverse but include Archean (3.20-2.60 Ga) through Proterozoic (2.53-1.3 Ga) with most being 1.9-1.8 Ga; a partial Laurentian source is permitted but other, cryptic sources are implied. These data suggest that the AMQ was deposited on a continental shelf following the breakup of Rodinia ca. 580-560 Ma, between the microcontinents of Baltica, Australia, Siberia, and Laurentia. The AMQ was later accreted to a series of island chains that eventually became the Klamath and Alaskan terranes. Paleolatitudes published by Mankinen et al. (2002) place the Yt at 7N or 7S ca. 580-570 Ma, and 31N or S in mid-Devonian.

102nd Annual Meeting of the Cordilleran Section, GSA, 81st Annual Meeting of the Pacific Section, AAPG, and the Western Regional Meeting of the Alaska Section, SPE (810 May 2006)
General Information for this Meeting
Session No. 24
GSA: Accreted Terranes of Western North America: An Update on Current Research on the Construction of the Cordillera I
Anchorage Hilton Hotel: Aleutian
1:20 PM-5:00 PM, Tuesday, 9 May 2006

Geological Society of America Abstracts with Programs, Vol. 38, No. 5, p. 36

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