| Computer Code: |
GOIN |
Preferred Map Code: |
notEntered |
| Status Code: |
Full, without ratification |
| Age range: |
Stephanian Stage (CS)
— Stephanian Stage (CS) |
| Lithological Description: |
The intrusion is composed of two distinct types of granite: biotite-granite and Lithium-mica granite. Biotite granite of the Godolphin intrusion has rare megacrysts of potassium feldspar up to 20 mm long. Lithium-mica granite has a coarse, hypidiomorphic texture and is predominately composed of anhedral quartz, potassium feldspar, plagioclase and lithium mica (pale brown in colour) with accessory minerals including topaz, black tourmaline and fluorite. The biotite granite is seen as veins within the coarser lithium-mica granite; in a quarry at Tregonning Hill [SX 5998 3006] an inclusion of biotite granite is seen within lithium-mica granite. |
| Definition of Lower Boundary: |
Not known. |
| Definition of Upper Boundary: |
Not known. |
| Thickness: |
Not known. |
| Geographical Limits: |
Part of a chain of intrusions that are interconnected at depth and stretch from the Isles of Scilly to Dartmoor; the Godolphin Intrusion is part of this Cornubian Batholith. |
| Parent Unit: |
Not Applicable (-)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
Tregonning-Godolphin Granite
|
| Stratotypes: |
| Type Area |
Godolphin Hill, Cornwall. Goode and Taylor, 1988. |
| Reference(s): |
| De La Beche, H T, 1839. Report on the geology of Cornwall, Devon and west Somerset. Memoir of the Geological Survey. |
| Goode A J J, and Taylor R T. 1988. Geology of the country around Penzance. Memoir of the British Geological Survey, sheets 351 and 358. |
| Exley C S, and Stone M. 1966. The granite rocks of south-west England. 131-184 in 'Present views of some aspects of the geology of Cornwall and Devon', Royal Geological Society of Cornwall, Commemorative Volume for 1964. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
