Bedding in Scottish (Fifeshire) Tuff-pipes and its relevance to maars and calderas

Along the coast between Lower Largo and St. Monance, in Fife, Scotland, Carboniferous sediments are piecerd by 13 exceptionally well-exposed basaltic tuff-pipes. The pyroclastic rocks, which are bedded in either centroclinal or collapsed form, were originally formed subaerially. They are separated by ring faults from the surrounding sediments which are turned down against the pipe margins. The tuffs in the pipes have undergone cauldron subsidence of at least 500 m. Clastic and magmatic minor intrusions, particularly at the margins of the pipes, accompanied the subsidence. As comparable amounts of subsidence are recorded in many basaltic tuffpipes (some with, others without ring fractures) in other parts of the world, it is suggested that subsidence may have contributed to the formation of maars. Comparison is made between cauldron-subsidence features in tuff-pipes and those of calderas.