Goler Formation
Goler Formation
Paleocene
A succession of interbedded sandstone, conglomerate, and shale up to 4,300 m thick (Dibblee, 1952; Cox, 1982), cropping out in the southeastern map area, in the El Paso Mountains north of the Garlock fault. Cox (1982) divided the formation into four members, across which clast composition varies. In the lower three members (nos. 1-3), clast lithologies are predominantly granitic and metasedimentary. In the upper member (no. 4), clast lithologies consist of mostly silicic volcanic rock types and quartzite (Cox, 1982).
The bulk of the strata are interpreted to have been deposited by fluvial systems operating within alluvial fans and distal alluvial plain environments, by braided rivers within a structural basin also hosting minor lacustrine environments. However, an interval of siltstone, sandstone, and conglomerate is present within the upper member, which bears marine fossils and records a period of marine transgression (Cox, 1982, 1987).
The upper two members host a very significant trove of Paleocene mammalian and other fossils, which are the only significant Paleocene terrestrial (nonmarine) fossils found in North America west of Utah (Lofgren and others, 2020, and references therein).
The upper two members host fossils of latest Torrejonian to middle Tiffanian age (Albright and others, 2009; Lofgren and others, 2020). These fossil ages coupled with magnetostratigraphy indicate an age of ~62 to 57 Ma for the upper two members (Albright and others, 2009). The lower two members are not fossil-bearing, and the maximum age of the formation is poorly constrained. The formation unconformably overlies granitic and metamorphic basement (map units Gep and EPS).
Detrital zircon age spectra and inferred sediment provenance reported by Stone (2021) changes across the lower to upper members and suggests that the lower members may differ significantly from the upper members in both age and provenance. May be partly correlative with the Witnet Formation (map unit wit; Cox, 1982). Coarse fluvial gravels in the lowest member host placer gold which has been exploited historically (Dibblee and Gay, 1952).
Chemical composition and clay mineralogy of numerous paleosol horizons present in the upper two members indicate globally warm temperatures and locally high seasonal precipitation and resultant wet and dry cycles, transitioning to more arid climate in the uppermost member (no. 4; Torres and Gaines, 2013).