The Sinian and Cambrian systems within the Yangtze stratigraphic province represent continuous deposits, and the strata above and below the Sinian–Cambrian boundary are rich in fossils. From all the relevant boundary sections, the Meishucun section in Jinning County, Yunnan Province serves as the stratotype section for the Sinian–Cambrian boundary and is the Chinese candidate for the global stratotype section and point for the Precambrian–Cambrian boundary. The present paper, with the various charts and tables, elaborates on several typical Sinian–Cambrian boundary sections and the distribution of fossils in them.

In accordance with the characteristics of biological evolution, three biotas can be recognized for the period from the Late Sinian to the Early Cambrian. The first biota appeared in the Late Sinian, characterized by the presence of the soft-bodied metazoans; the second biota occurred during the Meishucun Stage of the early Cambrian, and is characterized by the appearance and prevalence of small shelly fossils from many different phyla; and the third biota came into existence during the Qiongzhusi Stage of the Early Cambrian; it is characterized by the first appearance and prevalence of trilobites.

The Meishucun Stage of the Lower Cambrian can be divided into three fossil zones. The Sinian–Cambrian boundary is placed at the base of the first Anabarites–Circotheca–Protohertzina zone. According to isotopic dating by the Rb–Sr whole-rock isochron technique, the age of the Sinian–Cambrian boundary is inferred to be 610±10 Ma.

Cumulative curves of grain-size against frequency often show segmented shapes. These shapes have been interpreted as resulting from a combination of normally distributed populations each of which should reflect a mode of transport. The present study deals with samples in motion as bedload, pure saltation load and suspended load. All of these exhibited segmented shapes on cumulative curves. An explanation of this is that the populations are better described as log-hyperbolic distributions rather than as a mixture of log-normal distributions. The log-hyperbolic distribution when plotted on probability paper has a shape which can be misinterpreted as consisting of segments.

This petrographic and chemical study of the Hercynian granitoids of the Central Palaeozoic Massif of Morocco covers the Zaër, Ment, Oulmès, and Moulay Bouazza plutons. These plutons are formed of biotite or two-mica, quartz-rich granodiorites and monzogranites containing reddish-brown, inclusion-rich biotites as the only essential mafic mineral; zoned plagioclase; and perthitic K-feldspar. The modal contents of micas and K-feldspar are highly variable. The granitoids are generally medium to coarse grained, massive; however foliated varieties are also commonly found, particularly at the contact of the' plutons with sedimentary rocks.

The strongly peraluminous character of the granitoids is shown by high normative corundum and high molar Al2O3/(CaO + Na2O + K2O) ratio, and is reflected by the occasional presence of aluminosilicates.

The mineralogical and chemical characteristics of the granitoids are similar to those of the S-type granites, and were inherited from the crustal source of the granitic magmas which are thought to have been generated by partial equilibrium fusion of the sandy argillaceous sediments of the Massif. The heat source for the fusion might have been provided by intrusion of mantle-derived material.

The subsidence history of the Aquitaine basin has been determined from deep exploratory well data. The contribution of sediment loading to the subsidence has been evaluated and removed, including corrections for effects of compaction, water depth and changes of sea-level but not of flexural rigidity of the lithosphere. The tectonic subsidence curves obtained indicate that the basin underwent two periods of subsidence acceleration in the Trias–Early Lias and Late Jurassic–Early Cretaceous. They are interpreted in relation to the displacements of Iberia with respect to Europe as two periods of extension followed by periods of passive subsidence due to conductive cooling of the lithosphere; the formation of the ‘flysch trough’ in the southern part of the basin is then discussed.

Biplanispira Umbgrove is closely related to Pellatispira Boussac, from which it probably arose by the subdivision of the median chambers by the rapidly expanding marginal crest and the development of planispirally arranged secondary chambers on both sides of the peripheral flange. The genus appears to be polyphyletic, its species having been derived from different representatives of Pellatispira. Illustrated records of Biplanispira are confined to the region between eastern India and Eua, Tonga, and the genus appears to be restricted to the middle and upper parts of the Upper Eocene. In the Upper Eocene of the Garo Hills, eastern India, it is represented by B. hoffmeisteri (Whipple) and in the Andaman Islands by B. mirabilis (Umbgrove). This is the first record of the genus from mainland India.

Nautiloids from the shallow water Ordovician carbonates of Central and Southern Thailand can be grouped into five broad assemblages. 1. The Middle Ibexian fauna of indeterminate endocerids from Tarutao Island. 2. Hardmanoceras chrysanthimum (Kobayashi) of the Upper Ibexian age strata on Tarutao Island. 3. The Upper Ibexian Manchuroceras nakamense sp.nov. from Ron Phibum, Southern Thailand. 4. Wutinoceras sp., Chaohuceras? sp. of Lower to Middle Whiterockian age strata from Satun Province. 5. Wutinoceras sp., Armenoceras chediforme Kobayashi and Georgina sp. of Lower-Middle Whiterockian age strata from Kanchanaburi, Central Thailand. All of these genera occur in Australia and China.

In this paper the author describes the results of the Rb-Sr isotopic dating of black shale at the Sinian (Precambrian)–Cambrian boundary at the Meishucun section, Jinning County, Yunnan Province, China. The Sinian and Cambrian strata in eastern Yunnan are well developed, the Sinian–Cambrian boundary section in the vicinity of Meishucun Village in Jinning County being representative. These well developed strata provide excellent conditions for research on the radiometric age of the Precambrian–Cambrian boundary. An Rb-Sr isochron age of 579.7 ±8.2 Ma has been obtained on black shale from the Badaowan Member of the Early Cambrian Qiongzhusi Formation, which occurs at 20 m above the Sinian–Cambrian boundary. So an inferred age of 610±10 Ma is given for the Sinian (Precambrian)–Cambrian boundary.

The time span of the Proterozoic is taken as from 2600 to 600 Ma with subdivision boundaries at 1850 and 1050 Ma respectively, as 2600 Ma seems more appropriate for the initial Proterozoic in China, Siberia and parts of Gondwanaland, and 600 Ma is an inferred age of the Precambrian–Cambrian boundary based on recent study of the Yangtze Gorge section. The Proterozoic of China includes the Lower Proterozoic Wutaian and Hutuo-an, the Middle Proterozoic Changchengian and Jixianian and the Upper Proterozoic Qingbaikou-an and Sinian.

Based mainly on tectono-sedimentary types and associations, seven stratigraphic super-regions are recognized in the Proterozoic of China and stratigraphic successions of various representative regions are shown in two tables, one for the Sinian and another for the Pre-Sinian Proterozoic. Palaeogeographic outline of the main super-regions and chronometric limit of the principal stratigraphic units are briefly discussed. Three types of stable Sinian successions are distinguished, the Yangtze type, the Quruktagh type and the Jiaoliao type, which are correlated mainly on the basis of tillite horizons and of sabelliditids and the Ediacara type of fossils. Semi-stable and mobile types of Sinian deposits in Southeast China are also briefly mentioned.

The Proterozoic tectonic units of China and the nature of their boundaries are shown on a sketch map showing basement structures. Crustal sectors of continental nature are designated as continental tectonic domains, while broad and complicated crustal sectors of mainly transitional and partly oceanic nature may be called continental margin tectonic domains. The boundaries between these domains are usually the principal crustal consumption zones. On this basis, three continental domains, the North China, the South China and the Southern (Gondwana), and two continental margin domains, the Northern (Siberian–Mongolian) and the East China, are distinguished. Platforms, continental nuclei, massifs and uplifts are used to denote subdivisions within the tectonic domains. The development of aulacogens is an outstanding feature in the continental domains, especially in the Middle Proterozoic. Aulacogens may be classified into an intra-platform type and a platform margin type. Early Proterozoic aulacogens are usually brachy-axial and intermittent, and show conspicuous deformation at closure, much like a geosyncline. Thirteen aulacogens of different types are shown on the sketch map.

The boundary nature of continental domains is analysed in terms of island arcs and marginal seas, and also of emplacement of granite rocks in border parts. The North China Domain was basically consolidated at around 1850 Ma and has a passive northern margin stretching from Nei Mongol to Central Tianshan, but the southern margin was active and was twice subducted by the Qinling marine realm at 1700 and 1000 Ma approximately. The Yangtze Platform was not completely consolidated until 1050 Ma BP but has a core older than 1850 Ma. A broad continental margin terrain had developed in the Jiangnan region and farther to the southeast in the Middle and Late Proterozoic. At least two island arc belts with interarc basins, an inner Fanjingshan and an outer Sibao, may be discerned in the Middle Proterozoic, and a Late Proterozoic island arc zone over 1000 km in length was developed along the southern margin of the Jiangnan Uplift, represented by the Banxi Group and equivalent strata. This kind of broad complicated continental margin tract which has a long development history may be called the open type or the West Pacific type.

A major ductile shear zone in the gneissic core of the Saint-Barthélemy Massif, central Pyrenees, is characterized by an asymmetric shear strain profile defined as mylonite-dominated footwall geometry. The shear zone is part of a low angle fault system in the massif which caused thinning of a sequence of lithologic units and isograds. The shear zone is interpreted as a low angle normal fault zone of probably Cretaceous age, predating Alpine crustal shortening in the central Pyrenees.

The earliest stage of magmatic activity within the Palabora carbonatite was marked by the intrusion of phosphate-bearing pyroxenite. In good exposures in the north, large-scale (2m diameter) orbicular structures are found. These consist of regularly-spaced alternating dark layers (phlogopite-rich) and light layers (diopside-plus apatite-rich) which, in hand specimen, are very similar to the ‘inch-scale’ planar layering which has been described in layered mafic instrusions. One of the purposes of this paper is to describe these unique features which are currently being destroyed by mining, as they form economic phosphate concentrations.

The resemblance of the Palabora orbicules to Liesegang rings has led to the development of a qualitative model whereby the orbicules are regarded as having been formed by concentric periodic precipitation around central cores within dynamically quiet, isolated pockets of largely liquid magma. The controlling parameters are interpreted as being the rates of growth of the constituent minerals and the rates of diffusion of the elements crucial to their growth, i.e. K+, Al3+ and (OH)- for dark layers, and Ca2+ and P5+ for light layers.

The presence of these spectacular structures with their delicate layering indicates that at the time of crystallization of the pyroxenites relatively non-turbulent conditions prevailed, and diopside, phlogopite and apatite crystallized essentially coevally. Hence, the vertical large-scale banding in the pyroxenite may also be a function of diffusion controlled processes rather than being caused by separate magma pulses.

Some 880 m of grey, green and purple argillites are estimated to be present in complexly deformed Upper Devonian successions which occur in several overlapping coastal sections. Four lithostratigraphical formations are formally defined, in order of decreasing age: the Marble Cliff Limestone; Longcarrow Cove Slate; Harbour Cove Slate; and Polzeath Slate Formations. Improved correlation and biostratigraphical control is available for the two younger formations which are studied in detail. The formations range in age from lowest Frasnian to mid Famennian. Despite the intense deformation there are no major structural breaks in the successions.

From 70 km northeast of Milford Sound (44.14° S, 168.55° E) to the coast at Milford Sound (44.53° S, 167.83° E) the trace of the Alpine Fault is nowhere more than 1.2 km from the arc with a centre at 48.81° S, 173.20° E and a radius of 628 km (5.65° latitude). Earthquake epicentres indicate that the arc defines the position of the fault just off Fiordland's outer coast and then to near the north end of Puysegur Trench at 46.9° S, 165.25° E. Along the fault vertically to a depth of 10 km the Fiordland rocks are 0.6 Mg/m3 denser than those to the northwest. Displaced post-glacial topography at and near Milford Sound shows that the dip of the fault is southeast at 75 ± 5° and that the faulting is pure dextral at a rate of at least 46 ± 5 mm/yr.

The I.U.G.S. Subcommission on Carboniferous Stratigraphy recommends that the base of the Westphalian D is best recognized using plant macrofossils. In Britain, however, South Wales is the only coalfield where the distribution of the plants is sufficiently well known for them to be used to locate this boundary. Elsewhere in Britain other criteria have been used, particularly non-marine bivalves and plant microfossils, but these must be regarded with considerable caution.

The rates of resorption of pyrope in basaltic melt and of pyrope decomposition to pyroxene + melt at pressures below the stability of garnet are used to examine the proposition (Chapman, 1976) that pyrope megacrysts in the Elie Ness neck began ascent from the mantle at 1300–1450°C. Both reactions are extremely rapid at these temperatures and yet the petrographic evidence is that neither occurred. Either the transporting magma cooled extremely rapidly during ascent (> 30000 °/h) or, more likely, was considerably cooler than previously proposed. Water was a significant constituent of the magma, and a crystallization temperature for the garnet of as little as 1000 °C is possible, based on existing phase–equilibria data.

Systematic descriptions of specimens collected from Pachchham ‘Island’, Kachchh, Western India, belonging to the genera Micromphalites Buckman and Gracilisphinctes Buckman are given. Their affinities with the different forms belonging to the above genera are discussed and described as Micromphalites aff. hourcqui Collignon and Gracilisphinctes cf. arkelli Collignon respectively. The distribution of these two genera in other regions is also briefly discussed.

The Cambrian and Precambrian sedimentary strata in the centre and west part of the Yangtze Platform are in continuous successions, in which the Tiantzushan Member and the Meisuchun Formation are exceedingly rich in shelly fossils. In Co-operation with the stratigraphic study in depth and in order to determine the isotopic age for the Precambrian–Cambrian boundary in the Yangtze Platform, a number of isotopic age determinations by different techniques have been made in the laboratories of the Yichang Institute of Geology and Mineral Resources and the Research School of Earth Sciences, Australian National University, mainly on the sequences in the Yangtze Gorges area together with those from some other areas in the Yangtze Platform. In this paper, the authors summarize all of these results and infer 610±10 Ma as an age for the Sinian–Cambrian Boundary in the Yangtze Platform if the ‘golden spike’ is considered to be placed at the bottom of the Meishucun Stage.

The taxonomy of the Middle Jurassic ammonite genus Spiroceras Quenstedt, 1856, is critically assessed. It is found that the genus was originally proposed conditionally without any included species, and the type species is Spiroceras bifurcatum Hyatt, 1900, by subsequent monotypy. A neotype is now designated for that species, because Hyatt's figured holotype is lost.

Measurements of the size and shape of the grey reduction spots and of the variation of iron content across the spot–host rock interface have been made on samples from the Enville Group. The red coloration due to Fe3+ is thought to reside mainly in the matrix material cementing the mineral grains of the rock. The reduction to Fe2+ is ascribed to carbonaceous particles included in the sediment. To account for the sharp boundary of the spots it is suggested that the outward movement of the boundary is due to concentration dependent inward diffusion of oxygen which converts the carbonaceous material to carbonate.

Three theories have been proposed for the origin of Carboniferous basins in Britain: megashear; tension from Rheic Ocean subduction; tension from rifting of the North Atlantic. The first two hypotheses are rejected because they do not explain the Carboniferous volcanism, Stephanian dyke swarm, Boreal marine transgressions during the late Carboniferous and Permian, Carboniferous sedimentary basin histories, basin types or basin orientations.

Carboniferous volcanics were rift-related due to crustal thinning, which also resulted in the formation of sedimentary basins in the British Isles and a marine transgression of Tethyan faunas. Newly formed Carboniferous fracture lines and basin orientations showed that tension varied between east–west and northwest–southeast. Crustal fracturing in the latest Dinantian, possibly due to collision of microcontinents in the closing Rheic and Phoibic oceans with North America, led to the synchronous initiation of rift basins in East Greenland, elevation of source areas for the Millstone Grit of the British Isles, and formation of transform fault zones near Svalbard and North Spain. The narrow, rapidly subsiding, quickly changing ‘fosse’ basins which formed in these transcurrent fault zones contrast with the coeval stable, slower subsiding rift-parallel ‘saucer’ basins of the British Isles. Variations of subsidence rates in all these basins allow interpretations of crustal stress history. Brittle fracturing in the Westphalian C formed the first oceanic crust, but free oceanic spreading from Spain to southwest of the Faeroes only occurred after Stephanian dyke intrusion and crustal thinning at the Faeroes. The Norwegian Sea underwent continental crustal thinning. Ocean spreading and crustal thinning ceased in latest Stephanian times.

Boreal marine transgressions advanced down the newly thinned Norwegian Sea, firstly along its northern part and then reaching the North Sea basins and Germany in the Rotliegendes and Zechstein. Synsedimetary ore deposits formed during early tensional fracturing of the crust; thick coal sequences formed in rift-parallel basins during clastic source decay of elevated rift margins; oil source rocks formed along narrow oceanic or continental rifts from the Westphalian C onwards.

Assemblages with muscovite + quartz show a regular increase in grade from the Chlorite Zone at the base of the Lycian Nappe Complex to the Garnet Zone within the structurally underlying Menderes Massif. Biotite enters before garnet, which precedes oligoclase. Garnet-bearing assemblages in pelites are compared with those in re-equilibrated quartzofeldspathic gneisses, where garnet is unusually calcic (in one case approaching Gross50 Alm50). Local retrograde effects are noted but no evidence is found for a polymetamorphic record in the mineral compositions. Garnet zoning, with Mn decreasing outwards, is interpreted as growth zoning; Ca decreases outwards in pelite garnets but shows the reverse effect in the gneisses. Chloritoid is common but rarely coexists with biotite, and garnet + chlorite + paragonite is found rather than chloritoid + albite. Garnet-biotite geothermometry, corrected for the effect of Ca in garnets with up to 29 mole % grossular, indicates temperatures of 530±5O°C near the garnet isograd. As in other areas, an attempt at muscovite-paragonite geothermometry gives an anomalous result. Metamorphic pressure isconsidered in the light of (i) Mn/Fe partition between garnet and biotite, (ii) Ca content of garnet coexisting with plagioclase + muscovite + biotite, (iii) Na in actinolite coexisting with albite + chlorite + magnetite, and (iv) celadonite content of muscovite which, however, shows variation due to disequilibrium within a specimen and does not provide an accurate geobarometer. Comparisons with published studies indicate a strong similarity to the Barrovian Dalradian of Scotland and lead to a tentative pressure estimate of approximately 5 kbar.