Mineral Fork Formation
{{Short description|Geologic formation}}
{{Infobox Rockunit
| name = Mineral Fork Formation
| image = Diamictite Mineral Fork.JPG
| caption = Boulder of diamictite of the Mineral Fork Formation, along the Elephant Head Trail, Antelope Island, Utah.
| type = sedimentary
| prilithology = Tillite, Shale, Quartzite, Conglomerate
| otherlithology =
| namedfor = Mineral Fork, Salt Lake County, Utah
| namedby = Granger et al., 1952Granger, A.E., Calkins, F.C., Crittenden, M.D., Jr., and Sharp, B.J., 1952, Geology of the Wasatch Mountains east of Salt Lake City, IN Marcel, R.E., ed., Geology of the central Wasatch Mountains, Utah: Utah Geological Society, Guidebook to the geology of Utah, no. 8, p. 1-37.
| region = Southern Rocky Mountains
| unitof =
| subunits =
| overlies = Farmington Canyon Complex (Antelope Island), Big Cottonwood Formation (other locations)
| underlies = Mutual Formation (Big Cottonwood Canyon), Tintic Formation (Santaquin-Provo), or Kelly Canyon Formation (Antelope Island)
| thickness = 1000 to 3000 feet
| extent = Wasatch Mountains, Antelope Island
| age = Proterozoic
}}
The Mineral Fork Formation is a mapped Proterozoic bedrock unit in Utah.
Description
Granger et al. (1952) describe the Mineral Fork Formation as black tillite consisting of boulders, cobbles and pebbles of quartzite, limestone, or granitic rocks in a black sandy matrix, with dark-gray to black varved slate or shale, dark-gray quartzite, and occasional channel fillings of boulder conglomerate.
=Exposures=
According to Yonkee et al. (2000), the Mineral Fork is exposed at the following locations in Utah:Yonkee, W.A, Willis, G.C., and Doelling, H.H., 2000, Proterozoic and Cambrian Sedimentary and Low-grade Metasedimentary Rocks on Antelope Island, in The Geology of Antelope Island, Davis County, Utah, eds. J.K. King and G.C. Willis, Utah Geological Survey, p. 37–47.
And also:
=Fossils=
Age
The presence of Bavlinella faveolata in the formation indicates a likely age of 750–650 Ma, because this fossil occurs elsewhere where it is well-dated radiometrically. The Mineral Fork Formation is no older than 1,250 Ma and no younger than 540 Ma. Thus it is likely Neoproterozoic but possibly Mesoproterozoic.