| Computer Code: |
WHKD |
Preferred Map Code: |
notEntered |
| Status Code: |
Index Level |
| Age range: |
Asturian Substage (CAS)
— Asturian Substage (CAS) |
| Lithological Description: |
Hydrothermal alteration, followed by oxidation and reddening beneath the sub-Triassic unconformity, have extensively altered the dolerite and many of its original textures have been destroyed, The rare examples of fresh rock show it to be an ophitic-textured olivine-dolerite. In thin sections, olivine is completely serpentinised or chloritised, and the ophitic augite altered to chlorite. Plagioclase laths are strongly zoned, and partially sericitised. Cross-cutting mineral veins include quartz, chert, hematite, goethite, siderite, calcite, baryte and chlorite. |
| Definition of Lower Boundary: |
none recorded or not applicable
|
| Definition of Upper Boundary: |
none recorded or not applicable
|
| Thickness: |
It reaches a maximum thickness of 24.7 m in the Whitwick No. 6 Shaft [SK 4313 1450] but is generally much thinner elsewhere, due to splitting. For example, in places there are up to 9 separate sills, from 0.2 to 12.0 m thick, with an aggregate thickness of 26.3 m. |
| Geographical Limits: |
The Whitwick Dolerite is intruded as a number of sills at horizons above the Excelsior seam in the Pennine Middle Coal Measures of the Leicestershire Coalfield (Sheet 155, Coalville). It is terminated to the east against the Thringstone Fault. |
| Parent Unit: |
Not Entered (?)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
Whitwick No. 6 Shaft |
| Reference(s): |
| none recorded or not applicable |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
