Ives Head Formation
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| Ives Head Formation | |
|---|---|
| Stratigraphic range: Ediacaran | |
 Ives Head, the locality after which the formation is named. | |
| Type | Formation |
| Unit of | Blackbrook Group |
| Sub-units | Morley Lane Tuffs, Lubcloud Greywackes, South Quarry Slump Breccia Members |
| Underlies | Blackbrook Reservoir Formation[2] |
| Thickness | 820 m (2,690 ft)[2] |
| Lithology | |
| Primary | Tuff |
| Other | Breccia, Greywacke, Sandstone, Dacite |
| Location | |
| Region | Leicestershire |
| Country | United Kingdom |
| Type section | |
| Named for | Ives Head |
The Ives Head Formation is a geologic formation in Leicestershire, England. It forms part of the Blackbrook Group within the Charnwood Forest succession. The unit preserves rocks of Lower Ediacaran age and is named after the locality of Ives Head.
Members
The Ives Head Formation is the lowest formation within the Blackbrook Group, being overlain by the tuffaceous Blackbrook Reservoir Formation. The dominate rocks in this formation are also tuffaceous in nature. A borehole sample taken below the formation itself, known as the "Morley Lane Borehole", noted that the formation is underlain by 541 m (1,775 ft) of tuffs, pelites and sandstone, as well as a further 294 m (965 ft) of dacite lava-rock.[2]
There can be found three members in this formation, which are as follows, in ascending stratigraphic order (lowest to highest):
- Morley Lane Tuffs Member: Coming in at 238 m (781 ft), this member is primarily composed of coarse-grained tuffs, with moderate amounts of finely laminated dust-tuffs and tuffaceous pelites.[2]
- Lubcloud Greywackes Member: Coming in at 550 m (1,800 ft), this member is dominated by medium to very fine-grained greywackes, with some layers of greywackes being tuffaceous in nature. There can also be found throughout the member moderate amounts of coarse-grained greywackes and finely laminated tuffaceous pelites.[2]
Dating
The Ives Head Formation has been dated using U–pd dating on several zircon samples collected from the base, middle, and top of the formation. Samples collected from the top and middle of the formation yielded a date range of 611+2
−4 Ma to 611±2 Ma, giving a maximum deposition age of 611 Ma. Samples from the base of the formation would yield a date range of 622 Ma to 620 Ma, with a minimum deposition age of 620 Ma used.[1]
