Lithofacies and biostratigraphical analysis has enabled the establishment of a stratigraphic event framework for Ludfordian and Pridoli strata in south Wales and the Welsh Borderland. In SW Wales, the Golden Grove Axis acted as a structural hinge separating the shallow marine storm-influenced Cae’r mynach Seaway from a pediment surface above which Ludfordian colluvium (Abercyfor Formation) was deposited. The Axis seeded four NW-derived river-influenced delta progrades of Leintwardinian to early Pridoli age (Tilestones Formation). A NE-sourced early Pridoli wave-influenced delta deposited the Downton Castle Sandstone Formation (DCSF), coeval to the youngest Tilestones prograde, with a lateral interface existing between Mynydd Epynt and the Clun Forest area. Except for the Malverns area, the DCSF is no longer recognized south of the Neath Disturbance. Early Pridoli forced regression promoted widespread subaerial exposure north of the Neath Disturbance, with incision into tracts close to the Welsh Borderland Fault System. The basinward-shift in facies belts resulted in marine erosion and deposition of a phosphatic ravinement pebble lag. The wave-influenced Clifford’s Mesne Sandstone Formation delta subsequently seeded on the Gorsley Axis with tidally influenced Rushall Formation accumulating in a back-barrier setting. The Pwll-Mawr Formation records the easterly advance of coeval coastal deposits on the western side of the remnant Cae’r mynach Seaway. Behind migrating delta coastlines, green muds accumulated on coastal plains (Temeside Mudstone Formation) with better drained red dryland alluvium (Moor Cliffs Formation) charting expansion of Old Red Sandstone lithofacies. Mid-Pridoli incision preserves the Pont ar Llechau Formation estuarine valley fill.

In this study, we investigated the high-pressure (HP) metamorphism of the Precambrian continental crust exposed in the Zheltau terrane in South Kazakhstan (Koyandy complex) and the Chu-Kendyktas terrane in the North Tien Shan of Kyrgyzstan (Aktyuz, Kemin and Kokdzhon complexes) within the SW part of the Central Asian Orogenic Belt. HP quartz–feldspar lithologies of the Koyandy complex consist of migmatized kyanite-bearing garnet–mica paragneisses, garnet–kyanite paragneisses and their derivatives associated with eclogites. Paragneisses demonstrate prograde evolution involving mica dehydration melting and producing magnesium-rich garnet, kyanite and K-feldspar at the near-peak to retrograde stages at pressures of 15–18.5 kbar and temperatures of 800–870°C. The widespread growth of micas in these rocks reflects lower stages of retrogression at P = 10–12 kbar and T = 720–770°C. The age distributions of the cores of detrital zircon grains from the paragneisses indicate a predominance of Neoproterozoic and minor occurrence of Mesoproterozoic and Palaeoproterozoic sources of their protoliths. The ages of ∼487–485 Ma obtained from the zircon rims of the paragneisses reflect the timing of their HP metamorphic re-equilibration. These age clusters are consistent with the age estimates obtained from the rims of zircons in the eclogite-bearing garnet gneisses of the adjacent Aktyuz complex in the North Tien Shan. The P–T paths and zircon ages obtained from the high-grade quartz–feldspar gneisses of the Zheltau and Chu-Kendyktas terranes are thus interpreted to indicate involvement of the crustal material derived from the Precambrian basement (magmatic zircons aged ca. 844 Ma) and its Ediacaran–Cambrian sedimentary cover (detrital zircons with maxima at 1 Ga and 800–600 Ma) in the latest Cambrian subduction processes induced by the closure of the oceanic basins assigned to the Palaeo-Asian Ocean.

The South Altyn Orogenic Belt (SAOB) is one of the most important orogenic belts in NW China, consisting of the South Altyn Continental Block and the Apa–Mangya Ophiolitic Mélange Belt. However, its Palaeozoic tectonic evolution is still controversial. Here, we present petrological, geochemical, zircon U–Pb and Lu–Hf isotopic data for the Mangya plutons with the aim of establishing the Palaeozoic tectonic evolution. We divide the Early Palaeozoic magmatism in the Apa–Mangya Ophiolitic Mélange Belt into four episodes and propose a plate tectonic model for the formation of these rocks. During 511–494 Ma, the South Altyn Ocean (SAO) was in a spreading stage, and some shoshonite series, I-type granitic rocks were generated. From 484 to 458 Ma, the oceanic crust of the SAO subducted northward, accompanied by large-scale magmatic events resulting in the generation of vast high-K calc-alkaline series, I-type granitic rocks. During 450–433 Ma, the SAO closed, and break-off of the subducted oceanic slab occurred, with the generation of some high-K calc-alkaline series, I–S transitional type granites. The SAOB was in post-orogenic extensional environment from 419 to 404 Ma, and many A-type granites were generated.

Bennett Island stands alone in a remote part of the Arctic and information on its geology is essential to ascertain relations with other terranes in order to restore the early Palaeozoic Arctic palaeogeography. Lower Palaeozoic sedimentary rocks throughout the island were studied thoroughly for the first time. The Ordovician section (> 1.1 km thick) comprises three units: Tremadocian, lowest Floian black shale (130–140 m); Floian, lower Dapingian carbonate turbidite (> 250 m); and Dapingian, lower Darriwilian siliciclastic turbidite (> 730 m). Ordovician deposits conformably overlie Cambrian rocks deposited within the Siberian shelf, as shown earlier. Most of the Ordovician succession was formed in a deep trough that received carbonate debris from a nearby carbonate platform and silicate material from a distant landmass located to the NE (present coordinates). The Bennett Island Ordovician rocks have much in common with those of both the Central and Northern Taimyr belts. It could be tentatively suggested that both belts merged at their eastern continuation in the vicinity of De Long Islands. The whole system probably extends further eastwards. The Ordovician facies patterns and faunal assemblages in the New Siberian Islands are notably similar to those of northwestern Alaska, where the same lateral transition from turbidites to shelf limestones was reported.

A comprehensive geochronological and geochemical study was carried out on the gneissic monzogranites, porphyritic granodiorites and charnockites in the Gaozhou complex of the Yunkai massif in the southern part of the South China block to better understand the Early Palaeozoic tectonic regime of the South China block. Laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) U–Pb dating of zircons indicates an age of 453.2 ± 5.1 Ma to the formation of the gneissic monzogranites, whereas the porphyritic granodiorites and charnockites were generated at 437.0 ± 1.5 Ma and 435.2 ± 2.2 Ma, respectively. The gneissic monzogranites show geochemical features consistent with the high-K, calc-alkaline rock series and are strongly peraluminous. They have SiO2 contents ranging from 67.75 to 69.65 wt. % and relatively low CaO contents (1.66–1.94 wt. %). Their REE patterns are fractionated with enriched LREEs and negative Eu anomalies. The samples also show enrichment in LILEs (e.g. Rb and K) and Pb, and depletion in Sr, Ba and HFSEs (e.g. Nb, Ta, Ti and P). They have εNd(t) values of −8.2 to −7.7. Conversely, the porphyritic granodiorites and charnockites are characterized as medium-K, calc-alkaline rock series and weakly to strongly peraluminous. They exhibit pronounced depletions in HFSEs and positive Pb anomalies. Compared to the earlier gneissic monzogranites, these rocks have relatively lower SiO2 (65.50–69.36 wt. %), but higher CaO contents (3.34–4.05 wt. %), and have slightly lower εNd(t) values (−9.1 to −8.4). Petrography and geochemical compositions of the gneissic monzogranites indicate that they are S-type granite and likely formed by partial melting of Neoproterozoic to Early Palaeozoic immature metagreywackes; whereas The porphyritic granodiorites and charnockites are A-type granite and likely derived from low degrees of partial melting of the dry, granulitic residue depleted by prior extraction of granitic melt. The new data for the Caledonian granitoids in the Yunkai massif suggest that they were formed in a post-collisional tectonic setting. They represent the earliest post-collisional alkaline magmatism reported so far in the Yunkai massif, and thus indicate a tectonic regime switch, from compression to extension, as early as the Late Ordovician to Early Silurian (~450–435 Ma).

Chitinozoans are considered as reproductive bodies of marine invertebrates, called chitinozoophorans. These chitinozoophorans were most likely to have been small, pelagic or necto-pelagic, soft-bodied, probably wormlike animals, and judging from the size of chitinozoans, they probably measured from a few millimetres to a few centimetres in length. The chitinozoophorans most likely survived by grazing on phytoplankton. There is no evidence of a large colonization of the pelagic niche in the Cambrian, but from the Early Ordovician onward, this niche was exploited chiefly by graptolites and chitinozoophorans. Both groups inhabited nearshore and offshore habitats, but in contrast to the graptolites, the chitinozoans displayed their highest diversity at high latitude, in less distal (that is, upper and lower offshore) environments. The chitinozoan group evolved rapidly during the Ordovician and reached its maximum Ordovician diversity in the late Darriwilian. From the first occurrence of chitinozoans in early Tremadocian times, to the biodiversity crisis in latest Ordovician times, nearly 80 % of the morphological innovations took place. Until their extinction in the latest Devonian, chitinozoans survived through several biodiversity crises: in the early Late Ordovician, late Hirnantian, late Wenlock, earliest Emsian, and in the latest Frasnian (Kellwasser event). During the melting of the Hirnantian ice sheet, most Ordovician genera and species became extinct, but some genera extended beyond the boundary (e.g. Spinachitina, Belonechitina, Cyathochitina, Ancyrochitina). The Hirnantian glaciation was not directly responsible for the dramatic extinction of organic-walled microfossils, but it certainly accelerated the extinction of lineages that had already been weakened since the early to mid-Katian. The late Wenlock and earliest Emsian graptolite crises affected the chitinozoophorans to a lesser degree, and the latest Frasnian Kellwasser event did not greatly affect chitinozoophorans. The disappearance of the chitinozoan group at the end of the Famennian resulted from a combination of factors, for example, the chitinozoophorans probably no longer had the genetic potential for successful adaptations to successive drastic environmental changes (only one species is known from the latest Famennian), their usual niche was invaded by more efficient groups, and their usual food supply disappeared or was no longer sufficient. The latter factor is supported by the contemporaneous decline in phytoplankton.

The Rauer Group, in Prydz Bay, contains reworked Archaean-Proterozoic crust in high-strain zones that formed during a pervasive high-temperature ductile deformation event related to intracratonic mechanisms. The effects of this event extend southwards from Prydz Bay into the southern Prince Charles Mountains. The associated structural evolution involved development of ductile and brittle structures that formed during an approximately north–south directed transpressional deformation event that is confined to high-grade (>800°C) shear zones in the Rauer Group. Minerals from the Rauer Group, yield 40Ar/39Ar cooling ages ranging from 560 to 460 Ma. Thermal histories derived from hornblende, biotite and feldspar suggest that the onset of rapid cooling began sometime prior to 510 Ma with cooling rates of c. 42 to 33°C myr-1 from c. 510 Ma to c. 500 Ma. Whereas, 40Ar/39Ar data obtained from plagioclase and K–feldspar suggest a slower cooling from c. 500 Ma to c. 460 Ma with cooling rates from 5 to 2°C myr-1. These results demonstrate that the early Palaeozoic cooling history and comparable palaeostress regimes are regionally extensive, which has important implications for the tectonothermal and stress-field variability across Gondwana. The elevated thermal conditions would induce lithospheric weakening and promote the early Palaeozoic intraplate orogeny observed in eastern Antarctica with the development of a large intracratonic shear system.

Well-preserved eclogites were found for the first time in Antarctica, at the Lanterman Range, northern Victoria Land. They are part of a mafic–ultramafic belt that lies between the Wilson Terrane, representing part of the palaeo-Pacific margin of Gondwana, and the Bowers Terrane, a Cambro-Ordovician volcanic are and related sediments, accreted to the margin during the Ross Orogeny. The eclogites formed at temperatures in the range 750–850°C and pressures above 15 kbar and subsequently experienced a decompressional path to low pressure amphibolite facies conditions. The formation and exhumation of eclogites and the attainment of the metamorphic peak in adjacent rock units is consistent with a plate convergent setting model at the palaeo-Pacific margin of Gondwana.

Sensitive High Resolution Ion MicroProbe (SHRIMP) U–Pb zircon dating of pegmatites from Mount Kirkby, northern Prince Charles Mountains, east Antarctica indicates felsic intrusive activity at 991 ± 22 Ma and 910 ± 18 Ma. Pegmatite emplacement occurred during prolonged high-grade early Neoproterozoic tectonism. These ages correlate well with previously published U–Pb zircon ages obtained from felsic intrusive bodies elsewhere within the northern Prince Charles Mountains. Early Palaeozoic activity at Mount Kirkby is restricted to the emplacement of minor planar pegmatites at 517 ± 12 Ma, which provide a maximum age for local development of discrete extensional mylonites. No conclusive evidence of tectonic or metamorphic events at c. 800 Ma and c. 500 Ma, which have been recently postulated for the region, can be identified from the presently available U–Pb zircon data.

An excavation in the mid-Ordovician (Caradoc) Bardahessiagh Formation at Pomeroy, Co. Tyrone, Northern Ireland in 1992 has yielded a rich fauna of invertebrates, including several specimens of the scleractiniamorph coral Kilbuchophyllia. The material is assigned to the species K. clarksoni, previously described from penecontemporaneous levels in the Kirkcolm Formation of the Northern Belt of the Southern Uplands. The diagnosis of K. clarksoni is extended to include specimens of significantly greater size than the Southern Uplands material. All the material is mouldic but includes composite moulds, which in comparison with the preservation of other faunal elements, strongly suggests an original aragonitic composition for the kilbuchophyllid skeleton. Furthermore, details of insertion of higher cycles of septa visible on one particularly well preserved specimen confirm the process of septal substitution in these corals. Septal substitution is otherwise unique to post-Palaeozoic scleractinian corals and indicates the presence of paired mesenteries in the kilbuchophyllid polyp. The significance of this for the evolution of these corals and related anemones is discussed. The discovery of kilbuchophyllid corals at Pomeroy supports the view that post-Caradoc sinistral strike-slip movement on the Southern Uplands Fault was unlikely to have exceeded 200 km.