Computer Code: |
LOFA |
Preferred Map Code: |
LoFa |
Status Code: |
Full |
Age range: |
Caradoc Series (O4)
— Caradoc Series (O4) |
Lithological Description: |
Vitric tuff and lapilli-tuff; massive homogeneous andesitic ignimbrite; some intercalated pyroclastic breccia. |
Definition of Lower Boundary: |
At base of homogeneous lapilli-tuff - sharp contact on thin bed of volcaniclastic sandstone at top of reworked, underlying ignimbrite or on pyroclastic breccia of Sides Farm Member. |
Definition of Upper Boundary: |
Not seen, but mapped at the change from densely welded tuff to a mixed sequence of lithic-rich tuff and parataxitic tuff of the Loweray Formation. |
Thickness: |
380m+ in type section - total thickness unproved because of eroded top. (Thickness not corrected for strutural dip or borehole deviation from the vertical). |
Geographical Limits: |
Sellafield boreholes 2 (NY00SE/28), 4 (NY00SE/29), 5 (NY00SE/30), 8A (NY00SE/38), 10A (NY00SW/38) , RCF1 (NY00SE/35), RCF2 (NY00SE/36), RCF3 (NY00SE/37), RCM1 (NY00SE/41), RCM2 (NY00SE/40) and RCM3 (NY00SE/39). |
Parent Unit: |
Fleming Hall Tuff Formation (FLH)
|
Previous Name(s): |
Longlands Farm Member [Obsolete Name and Code: Use LOFA]
(-1041)
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Alternative Name(s): |
none recorded or not applicable
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Stratotypes: |
Partial Type Section |
Sellafield borehole No 4, BGS Registered No. NY00SE/29, 411.75m - 795.90m below Rotary Table Elevation, 338.15m - 722.3m below OD. |
Reference(s): |
Akhurst, M C, Chadwick, R A, Holliday, D W, McCormac, M, McMillan, A A, Millward, D, Young, B, Ambrose, K, Auton, C A, Barclay, W J, Barnes, R P, Beddoe-Stephens, B, James, J C W, Johnson, H, Jones, N S, Glover, B W, Hawkins, M P, Kimbell, G S, MacPherson, K A T, Merritt, J W, Milodowski, A E, Riley, N J, Robins, N S, Stone, P, and Wingfield, R T R. 1997. The geology of the west Cumbria district. Memoir of the British Geological Survey, Sheets 28, 37 and 47 (England and Wales). 138pp. |
Beddoe-Stephens, B and Millward, D, 2000. Very densely welded, rheomorphic ignimbrites of homogeneous intermediate calc-alkaline composition from the English Lake District. Geological Magazine, Vol.137, 155-173. |
1:50K maps on which the lithostratigraphical unit is found, and map code used: |
E037
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