Mineral Fork Formation

Mineral Fork Formation Stratigraphic range: Proterozoic
Boulder of diamictite of the Mineral Fork Formation, along the Elephant Head Trail, Antelope Island, Utah.
Type	sedimentary
Underlies	Mutual Formation (Big Cottonwood Canyon), Tintic Formation (Santaquin-Provo), or Kelly Canyon Formation (Antelope Island)[1]
Overlies	Farmington Canyon Complex (Antelope Island), Big Cottonwood Formation (other locations)[1]
Thickness	1000 to 3000 feet
Lithology
Primary	Tillite, Shale, Quartzite, Conglomerate
Location
Named for	Mineral Fork, Salt Lake County, Utah
Named by	Granger et al., 1952[2]
Region	Southern Rocky Mountains
Extent	Wasatch Mountains, Antelope Island

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.^[2]

Exposures

According to Yonkee et al. (2000), the Mineral Fork is exposed a the following locations in Utah^[1]:

• Antelope Island
• Big Cottonwood Canyon
• Santaquin-Provo

And also:

• Little Cottonwood Canyon

Fossils

Abundant microfossils of planktonic alga of Bavlinella faveolata.^[3]

Age

The presence of Bavlinella faveolata in the formation indicates a likely age of 650-750 Ma, because this fossil occurs elswhere 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.^[3]

References

1. ^ ^{a b c} 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.
2. ^ ^{a b} Granger, 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.
3. ^ ^{a b} Knoll, A.H., Blick, N., and Awramik, S.M., 1981, Stratigraphic and ecologic implications of late Precambrian microfossils from Utah: American Journal of Science, v. 281, no. 3, p. 247-263.