T69 Geologic Maps and Their Derivatives (Posters)

Sunday, 25 September 2016
9:00 AM - 5:30 PM
Exhibit Hall E/F

GEOLOGY OF THE KESSLER CREEK QUADRANGLE, WEST-CENTRAL IDAHO: EDMAP PROGRESS REPORT

Paper number: T69-5
Program: Technical Sessions
Time: 9:00 AM – 5:30 PM

Authors

Abstract

The Kessler Creek 7.5’ quadrangle in west-central Idaho [116°30’00’’–116°22’30’’x45°30’00’’–45°22’30’’] hosts accreted island-arc volcanogenic, carbonate, and siliciclastic rocks along the eastern margin of the Wallowa terrane/Blue Mtns. province. In the northwest, the Seven Devils Group [Hunsaker Creek Fm.] is intruded by ca. 226 Ma biotite-hornblende granodiorite [U-Pb zircon; Kauffman et al. 2014] of the Cold Spring pluton. In the east, Miocene flood basalts [Columbia River Basalt Gp.] overlie and are locally juxtaposed with undated marine metasedimentary units tentatively assigned to the Late Triassic Martin Bridge and Lucile Slate Formations. Mafic to intermediate composition volcanic flows [basaltic-andesite] and volcaniclastic rocks [epiclastic conglomerate + breccia] exposed in the southeast correlate with the Middle to Late Triassic Wild Sheep Creek Formation [Seven Devils Gp.]. Consistent with quadrangles to the north [Kirkwood Creek] and south [Heavens Gate], pre-Cenozoic units in the Kessler Creek quadrangle record widespread penetrative deformation and metamorphism largely in the greenschist facies. Mesoscopic structures include a northerly-striking, subhorizontal to vertical synmetamorphic foliation [S1: defined by chlorite mats, flattened lithic clasts, slaty cleavage] which commonly contains a down-dip to steeply plunging mineral or volcanic clast stretching lineation [L1]. Linear-planar tectonite fabrics are [1] folded by at least two generations of postmetamorphic macroscopic structures, [2] cut by shallow to moderately inclined, northerly-striking intraformational dip-slip faults, and [3] carried by the east- to southeast-dipping regional-scale Heavens Gate fault. At this latitude, the Heavens Gate fault marks the western limit of high strain ductile deformation related to Jura-Cretaceous suturing of the Wallowa terrane with western Laurentia. This project is funded by the EDMAP component of the USGS National Cooperative Geologic Mapping Program.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-281280

© Copyright 2016 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.