Glacial and syntectonic sedimentation: The upper Proterozoic Kingston Peak Formation, southern Panamint Range, eastern California
A sedimentological-stratigraphic study of the upper Proterozoic Kingston Peak Formation in the southern Panamint Range shows that it was deposited under glacial conditions with contemporaneous volcanism and tectonic activity. Evidence for glaciation rests primarily upon (1) the homogeneity, thickness, and lateral extent of two diamictite units; (2) the facies association of the diamictite; and (3) presence of striated stones and dropstones within the formation elsewhere in the Death Valley area. In the Panamint Range, pillowed basalt interbedded with diamictite demonstrates synchronous subaqueous volcanism. Lower Kingston Peak units rest on a variable substrate and locally overlap faults, indicating tectonism prior to deposition. Tectonism during Kingston Peak deposition is inferred from abrupt thickness changes and buried faults. Sedimentation was chiefly on a submerged continental platform and locally terrestrial, during a period of incipient rifting. Two ice advances are recorded with associated sea-level fluctuations. The formation thickens northward from 40 to about 1,200 m over ∼40 km. Initial sediments were fine grained and in basins a few kilometres across; nearby islands provided coarse debris. Overlying sandstone and conglomerate indicate regression. Predominantly massive diamictite, as much as 450 m thick and interpreted as lodgment till or glacioma-rine sediment, records the first ice advance. A northward increase in diamictite thickness, decrease in clast size, and facies change from diamictite to argillite and graywacke suggest a southern source. Overlying laminated limestone marks a transgression. Succeeding interbedded sandy limestone, thick-bedded graywacke, and parallel-laminated siltstone and sandstone double in thickness over a few kilometres, demonstrating local subsidence and renewed terrigenous input. Trough, cross-laminated, arkosic sandstone and conglomerate overlain by predominantly massive diamictite, as much as 190 m thick with a locally erosive base, represent glaciofluvial deposits and lodgment till and record the second ice advance.