Studies of the chemistry of Lower Carboniferous igneous rocks in the Midland Valley of Scotland throw light on the nature and magmatic evolution of transitional basaltic suites. Major oxide and trace element chemistry of least altered lavas of the Campsie Fells reveals a lower group of basalts, basaltic hawaiites and hawaiites, and an upper, more variable group, ranging from basalt to trachyte. Chemical composition of associated vent intrusions confirms their association with the lower group of flows. The magmatically evolved condition of the erupted material indicates high-pressure fractionation of clinopyroxene at depth followed by fractional crystallisation of olivine, plagioclase and Ti-Fe ores at lower pressures. In the case of the upper lavas, further differentiation appears to have taken place in a shallow magma chamber under a central volcano.

The observed chemical variations in the Campsie Fells and other areas of Lower Carboniferousvolcanic activity can be attributed to a number of different factors during the evolution of the magmas. Detailed studies of the cumulative phases of the lavas may throw further light on the various stages involved.

The Indus-Tsangpo suture and its adjoining tectonic zones are well displayed in the Ladakh Himalayas where four tectonic zones have been distinguished, viz. the Zanskar, Indus suture, Shyok suture and Karakoram zones. The Zanskar zone is made up of Precambrian basement of the Zanskar crystalline complex and overlying Phanerozic sediments including Upper Palaeozoic volcanic rocks of the Zanskar Supergroup; they form the northern margin of the Indian plate. The Indus suture zone consists of a remnant of tectonised oceanic lithosphere represented by the Shergol melange and the Nidar complex with a former volcanic arc indicated by the volcanogenic Dras and Khardung formations and the Ladakh plutonic complex. The Shyok suture zone does not represent a tectonic repetition of the Indus suture; it is interpreted as a relic of a back-arc basin. The Karakoram plutonic complex appears to be genetically related to the Ladakh plutonic complex; both were generated from the subducting Indian oceanic plate. It is proposed that the boundary between the Indian and Eurasian plates does not lie along the Indus and Shyok sutures, but is located further N at the junction of Central Pamir (Alpine-Himalayan) and North Pamir (Hercynian).

A new fossil elasmobranch from the Lower Carboniferous Oil Shale groups (Viséan) of the Edinburgh area shows a mosaic of characters typical of at least two groups of early sharks. Its most distinctive feature is the small bicuspid teeth of “Diplodus” type. This, together with the long dorsal fin and the structure of the single, shallowly inserted dorsal spine, form a suite of characters previously considered unique to late Palaeozoic xenacanth sharks. Other features, such as the large equilobate tail and the structure of the pectoral fins, may have been retained from an ancestor of a more typical Palaeozoic elasmobranch appearance found in anacanthous and ctenacanth sharks. It is suggested that the xenacanths evolved from an ancestor within the anacanth-ctenacanth assemblage early in Carboniferous times and became adapted to a freshwater environment. This ancestor probably possessed a complex dermal skeleton including growing scales with both thickened and thin concave bases.

The fauna of the fish-bearing nodules amongst which this shark has been found is interpretedas being lagoonal in origin. The shark was probably a medium sized (c. 0·75–2·0 m lng)predator inhabiting the surface waters of the lagoon.

The massive pyrite-pyrrhotite-chalcopyrite-sphalerite deposit of Outokumpu, comprising the Keretti and Vuonos orebodies, is a deformed and metamorphosed strata-bound mass associated with mineralised stockworks. Mobilisation of much of the ore followed formation of large recumbent isoclinal folds that are the major structures of the surrounding rocks and associated with the modification of originally flat saucer-shaped ore lenses into elongate ruler-shaped masses. Further modification of shape took place at the mobilisation stage with much of the pyrrhotitic ore, particularly, now occupying the thickest parts of the orebodies in the form of breccia or microbreccia. In many parts gross original characters still exist and the pyritic and pyrrhotitic constituents of the ore have survived as separate entities while locally the pyritic ore retains pre-deformational characteristics and consistent stratigraphic position within a thin horizon.

Both ore and country rocks show evidence of extensive polyphase deformation with the effects of six fold phases shown in the ore. Mineral assemblages in the country rocks indicate a middle amphibolite facies peak of metamorphism. The serpentinite-black schist-carbonate-quartzite rock assemblage, with which the ore is associated, was tectonically incorporated within the regionally extensive mica schist by even earlier subhorizontal thrusting. This is related to the movement of a thrust nappe with the interdigitation of an ocean-floor ophiolite assemblage and flysch deposited during ocean closure associated with Svecokarelian tectonism.

The original formation of the Keretti and Vuonos sulphide masses took place in a marine exhalative environment with a pyritic layer overlying a pyrrhotitic layer in each of the two c. 4 km diameter irregularly oval-shaped depressions whose centres were c. 8 km apart. The mineralised stockwork below each mass represents the upper parts of the conduit for metalbearing fluids in a convective system.