The BGS Lexicon of Named Rock Units — Result Details

Ron Volcanics Member

Computer Code: ROVL Preferred Map Code: notEntered
Status Code: Full, pending ratification
Age range: Bathonian Age (JN) — Callovian Age (JC)
Lithological Description: Variegated (purple-grey, greenish grey, red-brown, yellow-brown), porphyritic, alkali basalt, locally amygdaloidal, lava flows interbedded with tuffaceous volcaniclastics and cut by igneous intrusions. Individual flows sometimes exhibit evidence of an unweathered lower part passing upward into a more weathered and altered top, suggesting subaerial eruption. Basalt flows show overall low gamma-ray values and high velocity responses. However, interbedded units (either potassium-rich intrusive ingneous rocks or interbedded argillaceous sediments) show much higher values (Fall et al., 1982).
Definition of Lower Boundary: The base is defined by a down-section change from basalt lava flows and tuffs to coal-bearing sediments (Pentland Formation), Triassic red beds or Zechstein evaporites. Wireline log responses are variable and the boundary cannot be picked out with certainty.
Definition of Upper Boundary: The top is defined by a down-section change from coal-bearing sediments (Pentland Formation), marine mudstones (Heather or Kimmeridge Clay formations) and marine sandstones (Fulmar Formation) to volcanic rocks. Wireline log responses are variable and the boundary cannot be picked out with certainty.
Thickness: Up to 1945 m.
Geographical Limits: The Ron Volcanic Member is confined to a small part of the Central Graben in Quadrant 29.
Parent Unit: Pentland Formation (PNTL)
Previous Name(s): Rattray Formation (-5144)
Alternative Name(s): none recorded or not applicable
Type Section  North Sea well 29/14b-3 between the depths 3121 and 3714 m below KB (Richards et al., 1993). 
Reference Section  North Sea well 29/14a-4 between the depths 2328.5 and 2638.5 m (depths given by Richards et al., 1993 in their text are incorrect, but see wireline log on page 93). 
Fall, H G, Gibb, F G F and Kanaris-Sotiriou, R. 1982. Jurassic volcanic rocks of the northern North Sea. Journal of the Geological Society, London, 139, 277-292. 
Smith, K and Ritchie, D. 1993. Jurassic volcanic centres in the Central North Sea. In: Parker, J R (ed.) Petroleum geology of Northwest Europe: Proceedings of the 4th conference, 519-531. [Geological Society, London] 
Richards, P C, Lott, G K, Johnson, H, Knox, R W O'B. and Riding, J B. 1993. 3. Jurassic of the Central and Northern North Sea. In: Knox, R W O'B and Cordey, W G (eds.). Lithostratigraphic nomenclature of the UK North Sea. [British Geological Survey, Nottingham] viii + 219 pp. 
Deegan, C E and Scull, B J. 1977. A standard lithostratigraphic nomenclature for the Central and Northern North Sea. Report of the Institute of Geological Sciences, 77/25; NPD Bulletin No.1. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable