Mineral Fork Formation
# Mineral Fork Formation

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:

* Antelope Island
* Big Cottonwood Canyon
* Santaquin-Provo

And also:

* Little Cottonwood Canyon

### Fossils

Abundant microfossils of planktonic alga of Bavlinella faveolata.

## 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.

