A grey pyritic mudstone from Central Wales (Red Vein unit of the Dicellograptus anceps zone, Upper Ordovician Ashgill) has been examined in thin section by scanning electron microscopy using backscattered electrons. Using backscatter it is possible to identify individual mineral constituents of the mudstone by virtue of their atomic number (Z) contrast and differential hardness (relief). The amount of detail observable is far greater than that possible with optical microscopy. Valuable information can be obtained relating to particle form, orientation, texture and internal structure which aids in interpretation of the deformational and diagenetic history of the rock. The adoption of electron microscopical methods in the study of thin sections and polished rock chip surfaces promises to revolutionize the field of shale petrology.

Jabal Dumbeir is a nepheline syenite-carbonatite complex of Cambrian age (550 ± 87 Ma). The earliest igneous event of the complex was the intrusion of a phlogopite-sodalite nepheline syenite (ditroite) which was derived from the partial melting of the upper mantle. K, CO2 and F-rich volatiles metasomatise both the ditroite and the gneissic country rock which results in an orthoclase-rich undersaturated syenite (orthoclasite). Carbonatitic breccias and sovite dykes were subsequently emplaced carrying high levels of F, REE, Y and Th with extremely high LREE/HREE ratios (CeN/YbN = 64 ± 8). Such carbonatiticmagmas may be derived by partial melting of an LREE-enriched upper mantle. Hydrothermal emplacement of fluorite-quartz veins represent the final phase of igneous activity and these carry high levels of REE, Y, Th and U. Their emplacement was strongly controlled by a system of NNE strike-slip faults which have been reactivated in recent times.

The current situation in 1982 regarding the status and validity of the Ulakhan-Sulugur section on the Aldan River as a candidate for the global stratotype section and point for the Precambrian-Cambrian (PC-C) Boundary is reviewed with details of new work since 1973 and consequent revisions of views on controversial topics on a regional, continental and intercontinental scale of stratigraphic correlations with a short note regarding accessibility.

16 samples of Ordovician basic volcanic rocks of the South Connemara Group, which abut the southern side of the metamorphic rocks of the Connemara massif in western Ireland, have been analysed for both major and trace elements. Although subject to low grade regional metamorphism and subsequently hornfelsed by the Galway Granite (400 Ma), their immobile element contents do not appear to be significantly disturbed. These elements characterise the metabasites of the South Connemara Group as ocean floor basalts having their origins in a marginal basin. The Skird Rocks Fault, separating the South Connemara Group from high grade metamorphic rocks of the Connemara massif, is consequently regarded as the northern margin of the vestiges of the lapetus Ocean which can be traced into, and along, the Southern Uplands Fault.

Late Precambrian polymict conglomerates are described from Bellsund, western Spitsbergen, where they are intimately associated with authentic glacigenic sediments. They display normal, compound and reverse grading. Spectacular flame, injection and incipient rip-up structures are developed at the base of some beds. The conglomerates were initially deposited either as foreset debris beneath a wet-based glacier, or on the subaqueous part of a glaciomarine outwash delta, and were subsequently redeposited from mass gravity flows initiated by slumping on the unstable glacial detritus slope. An informal stratigraphic nomenclature is proposed for the Kapp Martin area to the north of Bellsund and the Kapp Lyell area to the south.

Comparison is made between the semipelitic and psammitic schists of the Morar and Glenfinnan Division in their type areas and the succession in the Fannich district of Northern Ross-shire. The tentative lithological correlation of the Morar Pelite with the Sgurr Mor Pelite is confirmed, while the Meall an t-Sithe Pelite and the semipelites of the Glenfinnan Division likewise have a similar geochemistry. In establishing these similarities, ratios involving Sr, Nb, Y, Zr and P2O5 have been found to be most useful, particularly Sr/Y. Other ratios (Ca/Y, K/Rb, K2O/(Na2O+CaO) and K/Ba) can also yield useful information regarding correlation and sedimentary history. Sr/Y decreases stratigraphically upwards in these successions and also towards the north east, suggesting a palaeogeography for the Morar Division involving increasing remoteness from the source area with time and in a northeasterly direction.

The ophiolitic complexes within the Indoburman orogenic belt form a conspicuous N-S line along the eastern margins of Manipur and Nagaland. The rock assemblages consisting of mafic-ultramafics are associated with deep sea pelagic sediments of the Disang Group (Lower Cretaceous-Eocene). The ultramafics in part, represent the oceanic crust and upper mantle material that formed the basement on which the radiolarites and other pelagic sediments were deposited. The fossil radiolaria present in the cherts suggest that the orogen took its foundation during late Jurassic-Lower Cretaceous time. The westward obduction of the flysch ophiolites in the form of large thrust sheets was possible during underthrusting of the Indian plate beneath the Burmese. The position of the ophiolitic belt defines the Indoburman suture zone.

A course of action is described for obtaining an English translation of a Russian geological text. It is suggested that the Russian ‘language barrier’ in this field is largely psychological.