Rb–Sr whole-rock isochron ages from shale horizons in the Late Pre-Cambrian tillite succession in Varangerfjord, Northern Norway, are presented. Although data from the Stappogiedde Formation, which overlies the tillite horizons, give a Caledonian, metamorphic age of 530±50 m.y., ages obtained from shales occurring between and below the tillites are believed to represent the approximate times of deposition of the sediments. An age of 810±90 m.y. for the Tanafjord Group enables this group to be correlated with the Upper Torridonian and the age of 668±23 m.y. for the Nyborg Formation, which is taken as the age of the Varanger Ice Age, allows a tentative correlation to be made with the Egan and Marinoan Glaciation in Australia.

A small fauna of mammals, which includes Elephas antiquus, has been obtained from the Stretton Sand. This, the oldest member of the Pleistocene succession north of Moreton-in-Marsh, has previously been interpreted as glacial outwash from a Severn Valley source and usually ascribed to an early phase of the Wolstonian Glaciation. It is now ascribed to the Hoxnian interglacial, with its rare erratics of presumed Welsh provenance derived from erosion of an earlier Anglian glaciation.

The distribution of Fe and Mg between coexisting garnet and biotite from andalusite-staurolite zone rocks of the Mt Lofty Ranges is briefly discussed. The average value of the corresponding distribution coefficient, and those of some related parameters, are compared with the values proposed by a number of authors as being characteristic of certain metamorphic grades. From these comparisons it is concluded that despite their occurrence in a terrain in which fibrolite commonly occurs, the rocks have probably only experienced P-T conditions corresponding to those of the andalusite phase field, and that fibrolite has formed under similar conditions.

Explanations (Burton, 1970; Ridd, 1971) of the westerly origin of the sediments now forming the rocks of northwest Malaya, by deriving them from an India which once lay contiguously against Malaya are unacceptable because of the complexity of the movement of Gondwanic India and the known history of the Indian Ocean. The effects of the movement of India into Asia were such that the Tibetan part of the orogen which continues south through Yunnan into Malaya was distorted. Before the arrival of India the Tibetan massif also may have lain still further away from the rest of Asia and moved towards the Siberian Platform by sea-floor spreading in the Tethys, so that its erosion could have provided material now forming part of Malaya. The Tibetan–Yunnan–Malay orogen has a complex and probably sutured form.

Values of quartile deviations (QDa) and medians (Mdmm) have been calculated from over 400 grain-size distributions of modern and ancient turbidites. Each QDa–Md pair is plotted on double-log paper to establish any distinctive trends. The QDa–Md analysis of modern turbidites reveals a steep gradient trend derived from the grain-size distributions of submarine canyon and delta fan sediments, and a shallow gradient trend derived from the grain-size distributions of samples from oceanic bottoms and nepheloid water layers. The QDa–Md analysis of ancient turbidites reveals two trends, but these do not coincide with their modern counterparts. The steeper gradient trend is related to distal and proximal turbidites, while the shallow trend is related to fluxoturbidites. The disparity between the ancient and modern QDa–Md analyses is caused by textural modifications of turbidites by diagenetic disintegration of unstable minerals. The alteration products are incorporated subsequently in the matrix. The diagenetic effects on the positions of the QDa–Md plots are demonstrated theoretically by computing the textural alteration of six modern turbidites by assuming that they will lose 20%, and then 40%, of their sand-sized particles to the matrix. By working in reverse the QDa–Md plots of ancient turbidites can be ‘restored’ to their diagenetically unaltered positions. Their restored positions correspond to the QDa–Md trends of modern turbidites.

Episodic hydrothermal mineralization has previously been recognized in the northern section of the Pennine orefield. Igneous rocks from the southern section (the Derbyshire orefield) have yielded isotopic ages, some of which are thought to represent ages of hydrothermal metasomatism (deuteric or subsequent). In order to ascertain whether epicyclic hydrothermal events gave rise to the Derbyshire mineral deposits, samples of highly altered doleritic lava and pumice tuff were collected adjacent to areas of mineralization. Clay-mineral concentrates from 34 samples were dated by the potassium–argon method. The conclusions drawn from these analyses support a hypothesis of repeated hydrothermal alteration of the clay minerals, reflecting at least two episodes of mineralization, one about 270 m.y., the other about 235 m.y. The geo-chronological significance of these and other results is considered.

Although the structures and textures of spilites and keratophyres are comparable to those of fresh lavas, recent work has established that they did not acquire their present mineralogy at the time of extrusion. Furthermore, the compositions of many analyzed samples of spilites and keratophyres are shown to lie outside a ‘spectrum’ of compositions of all comparable fresh igneous rocks. A later metamorphism has therefore been responsible for their formation and has commonly been accompanied by metasomatism. This possibility of later metasomatism must be appreciated before conclusions are drawn that are based upon analysis of rocks of a spilitic or keratophyric mineralogy. This applies to age-dating and to analytically based petrographic and petrogenetic conclusions.

The paper comprises descriptions of a new genus and species of multiramous dichograptid from the Bendigonian (Be 4) and a new species of Tetragraptus from the Lancefieldian (La 2).

The cumulates and crescumulates in the Crescumulate Zone of the Rognsund gabbro are described. The olivine and olivine-clinopyroxene crescumulates contain large dendritic crystals of olivine due to rapid upward growth from cumulus nucleii on the temporary floor of the magma chamber. Crescumulate growth was accompanied by the bottom accumulation of primocrysts, some of which were enlarged by the normal adcumulus process. The crescumulates are thought to have originated when cumulus crystals sank from a labile environment near the roof of the body into a metastable environment on the floor.

Potassium–argon dates from hornblende-bearing pyroxene granulites in a large xenolith near the margin of the charnockitic Ernabella Adamellite, central Australia, are interpreted in the light of oxygen isotype studies of associated mineral phases which give a detailed thermal history of the Adamellite and associated rocks.