2005 Salt Lake City Annual Meeting (October 16–19, 2005)

Paper No. 7
Presentation Time: 8:00 AM-12:00 PM


MROFKA, David D., Department of Earth Sciences, Univ of California Riverside, Riverside, CA 92521-0423 and KENNEDY, Martin, Department of Earth Sciences, University of California, Riverside, Riverside, CA 92521, david.mrofka@email.ucr.edu

Stratigraphic relations in the late Neoproterozoic southern Kingston Peak Formation (KPF) of southeastern California show: 1) an unconformity between KP-1 and KP-2, 2) conformity between its upper 3 units, KP-2 thru KP-4, and with the overlying Noonday Dolomite, 3) thickening of units away from faults within the KPF, and 4) channels of diamictite with striated clasts thought to be of a glacial origin interbedded within gravity dominated deposits of probable tectonic origin within KP-4. Establishing the timing of the KPF and depositional relation of the overlying Noonday Dolomite is important because extensional faulting within the KPF is thought to mark rifting that led to development of the Cordilleran continental margin and conglomeratic facies within the KPF are used as evidence for Cordilleran glaciation. There are at least three interpretations of stratigraphic relationships between the KPF and the Noonday Dolomite: 1) all but the lowermost member of the KPF are conformable with one another while an angular unconformity separates the KPF from the overlying Noonday Dolomite (Wright et al., 1974), 2) the KPF and the Noonday Dolomite are conformable with localized inter-fingering between the two formations (Miller, 1983), or 3) two phases of glaciation and rifting are separated by a major unconformity within the KPF (Prave, 1999). Stratigraphic mapping within the Kingston Range and in the Alexander Hills in southern Death Valley identifies fault-related km-scale thickening of gravity dominated deposits away from uplifted horsts and inter-fingering with the lower Noonday Dolomite. The KP-3 is gradational and interbedded with the KP-4, while KP-3 and KP-2 are locally interbedded and record deposition from two distinct provenances. Thus a conformable series of sediments from KP-2 through the Noonday Dolomite argues against a second rifting cycle or major unconformity between the KPF and the Noonday Dolomite. The significance of glaciation within the KPF is difficult to assess given the strong local tectonic/gravity influence on sedimentation. However, rare striated and faceted clasts are present within thin channel fills near the top of KP-4 in the Alexander Hills and Kingston Range; thus local adiabatic glaciation related to uplifted horsts can not be ruled out during deposition of the Kingston Peak Formation.