The depth distribution of illite/smectite (I/S) compositions was investigated for a well drilled to a depth of 3462 m on Barbados Island, the only subaerial exposure of the Barbados accretionary complex. The classical pattern of increasing percentage of illite interlayers in the mixed-layer clay with increasing burial depth was not observed. Rather, the data describe an irregular, zig-zag trend with depth. This trend is probably the result of reverse faulting in the section. I/S data were also used to infer several kilometers of uplift and subsequent erosion of the section. This study shows that irregular patterns of clay diagenesis with depth can be anticipated for sequences that have undergone complicated tectonism and deformation. Combined with other geologic information, these patterns can help to determine the tectonic history of the sedimentary sequence.

The Weaklaw vent in SE Scotland (East Lothian coast), inferred to be Namurian, produced lava spatter and volcanic bombs. The latter commonly contained ultramafic xenoliths. All were metasomatised by carbonic fluids rich in incompatible elements. The lavas and xenoliths are inferred to have been basanites and lherzolites prior to metasomatism. The abundance and size of (carbonated) peridotite xenoliths at Weaklaw denotes unusual rapidity of magma ascent and high-energy eruption making Weaklaw exceptional in the British Isles. The lavas and xenoliths were altered subsequently by low-temperature (<200°C) carbo-hydrous fluids to carbonate, clay and quartz assemblages. A small irregular tuffisite ‘dyke’ that transects the ejecta is also composed dominantly of carbonates and clays. The peridotitic xenoliths are typically foliated, interpreted as originating as pre-entrainment mantle shear-planes.

Analyses of the relic spinels shows them to be compositionally similar to spinels in local unaltered lherzolites from near-by basanitic occurrences. Chromium showed neither significant loss nor gain but was concentrated in a di-octahedral smectite allied to volkonskoite. It is in the complex association of smectite with other clays, chlorite and possibly fuchsite that the diverse incompatible elements are concentrated.

We conclude that late Palaeozoic trans-tensional fault movement caused mantle shearing. Rapid ascent of basanite magma entrained large quantities of sheared lithospheric mantle. This was followed by ascent of an aggressive carbonate-/ hydroxyl-rich fluid causing pervasive metasomatism. The vent is unique in several ways: in its remarkable clay mineralogy and in displaying such high Cr-clays in a continental intra-plate setting; in being more productive in terms of its ‘cargo’ of peridotite xenoliths; in presenting an essentially un-eroded sequence of Namurian extrusives; and, not least, for giving evidence for post-eruptive, surface release of small-melt, deep-source fluids.

The Coire Dhuinnid fault zone contains emerald green chromian illite-ankerite-quartz rocks that are similar in appearance to the fuchsite(or mariposite)-carbonate-quartz parageneses that are commonplace in Archaean greenstone belts but which are rather rare in Phanerozoic rocks. The chromian illite contains 2.3 wt.% Cr2O3, low K2O (7.1–7.6 wt.%) and high H2O+ (5.7 wt.%), and it is a 1M polytype with ≤10% of an illite/smectite interstratification indicative of a formation temperature of c. 175–200°C. The host rocks contain high concentrations of Ni and Cr, and show low concentrations of Ti, Nb, Y and Zr, suggesting a former primitive mafic protolith (boninitic magma?); they are considered to be retrograde remnants of Lewisian rocks. The latter, and the associated rocks of the Moine Series, have been affected by CO2 metasomatism that was accompanied by the addition of Ca(+Sr), Fe and Mg, and by the removal of Na from, and the addition of H2O to the Moine metasediments. Radiogenic isotope studies of mineral separates and whole rock from sample no. 43 yielded ages of 483±2 Ma (Ar-Ar dating on Cr illite), 413±12 Ma (K-Ar dating on Cr illite), and 322±9 Ma (Rb-Sr dating on minerals and whole rock); the significance of this discrepant pattern is discussed.

The Sierras Pampeanas of Córdoba are the easternmost uplifted blocks caused by Andean foreland deformation, over 700 km from the Chile trench. This deformation started at c. 340 Ma through basement faults, thrusts and reactivation of normal faults of the Cretaceous rift during the opening of the Atlantic Ocean. Other older faults, major oblique lineaments, were also reactivated. Thermochronological and geothermobarometric data indicate that some topographic relief could have been Palaeozoic–Mesozoic relicts and not only produced by the Andean orogeny. Faults are partially controlled by the early Cambrian S2 metamorphic foliation, coincident with the curved fault traces at map scale. During Pliocene time, two deformation phases post-dating Miocene–Pliocene magmatism are recognized. Shallow seismicity data (c. 25 km depth) indicate that the Sierras de Córdoba accommodate Quaternary displacement. Magnetotelluric studies detect the interface between the Pampia terrane and the Río de la Plata craton. The role of the oblique lineaments in the nucleation and development of the Tertiary faulting has been little considered; they could be correlated with an old pan-Gondwanan trend. During the Cretaceous period these lineaments worked in a transtensive way, producing the uplift of high-grade rocks and segmentation of the mountain chain favouring the diachronous uplift along the ranges. Recently, both the brittle–ductile transition at c. 23 km depth and the crustal thickness have been determined by seismicity analysis. The oblique lineaments displace normally the Mohorovicic discontinuity. Main basement thrusts were probably rooted in the suture between the Pampia terrane and the Río de la Plata craton.

This paper presents recently collected swath bathymetry from the Firth of Lorn. 553 km2 of data were collected during 2012–2013 as part of the INIS Hydro (Ireland, Northern Ireland and Scotland Hydrographic Survey) programme.

The area proves to consist of bedrock-dominated seabed, divided into narrow, stratigraphically-constrained and glacially-over-deepened basins. The bedrock is composed of late Proterozoic Dalradian metasediments overlain unconformably by Old Red Sandstone (ORS) sediments and lavas of ?Silurian-age. The central region of the Firth of Lorn is dominated by a vertical cliff, up to 150 m high and extending for approximately 24 km. This feature, here termed the Insh Fault, may have originated as a Dalradian extensional fault, been reactivated as an ORS feature and now forms a fault-line scarp with resistant ORS rocks on the downthrown side, flanking the more deeply eroded metasediments exposed in the basin. Tertiary intrusives are common, in particular, swarms of Paleocene dolerite dykes exposed on the sediment-free bedrock surfaces, and can be traced for many kilometres.

Evidence for past glaciation is widespread, manifest in the extensive erosion of the bedrock platforms and the abundance of well-preserved moraines and over-deepened basins. The survey region includes the Corryvreckan Whirlpool and Great Race, beneath the tidal flows of which occur submarine dunes.

Sub-Antarctic Marion Island was the site of extensive volcanism as well as glaciation during both the Quaternary and the Holocene. Initial reconstructions suggested a link between deglaciation and the initiation of faulting which, in turn, facilitated lava eruptions during the interglacials. However, our reassessment of the faulting, volcanic rock, and palaeoglacier distribution indicate that these original interpretations were erroneous. Features thought to be due to faulting are shown to be erosional scarps and this significantly changes interpretations of former glacier distribution. Further, the loss of the former ice cap has revealed new information on former glaciers and their flow directions, thereby allowing reconstruction of palaeoglaciers. Our new reconstruction fits with information from invertebrate genetic mapping that suggest some lava outcrops were nunataks and, therefore, refuges during the Last Glacial period. The new findings of glacial landforms in areas previously covered by snow suggest there was a significant ice advance during the Little Ice Age. Although Holocene volcanic rocks overlie and mask much of the glacial evidence, it has been possible to develop a proposed new reconstruction for glaciation, which is presented together with some of the implications.

Deception Island is the largest volcano in the actively extending Bransfield Basin, a marginal basin situated behind the extinct South Shetland Islands arc. Deception Island has been well studied but its submerged flanks have not. A multibeam bathymetry survey was conducted around the island in 2005. Data from the flooded caldera show no evidence for recent localized resurgence. The gently-sloped bottom of the caldera basin is consistent with either a broad zone of resurgence on its east side associated with trap door deformation or with higher rates of sediment supply from the east side of the island. Around the island, numerous tectonic and volcanic features on the volcano's east and west flanks are nearly all aligned with the regional strike (~060°) of the Bransfield rift and there is very little evidence for the other fault populations that have been identified on the island. We infer that models that link the ongoing tectonic development of Deception Island to complex regional tectonics are less likely than models in which the dominant regional extension in Bransfield Strait is modulated by the local effects of caldera collapse and possibly a small right-lateral transfer zone offsetting the primary extension axes in the Central and Western Bransfield Basins.

The Sanggan River is an alluvial river flowing through a graben basin system of the northern Shanxi Rift Zone, North China. During Pleistocene times, the river reach in the Datong Basin was affected successively by various external variables, such as invasion by basaltic flow, along-valley faulting and climatic change. Therefore, it provides excellent constraints for differentiating tectonically driven and climate-related fluvial incision in the context of tectonic subsidence. Based on equilibrium profile analysis, K–Ar dating of basalts (0.74–0.41 Ma), studies of the river terrace and of stream action history, we present a conceptual model for differentiating fault-driven and climate-related fluvial incision by the river. The results show that fluvial incision induced by tectonic lowering of the base-level due to along-valley movement on the Sanggan River fault is equal to fault displacement. The amount of post-basalt fluvial incision of the reach upstream from the lava dam is 23 to 25 m, of which the fault-driven and climate-related incisions are 15 m and 8 to 10 m, respectively, the former predominating over the latter. The total amount of incision in the lava dam reach is 40 to 47 m, of which the fault-driven and climate-related incisions are 10 m and 30–37 m, respectively; here the latter is predominant over the former. Since 0.41 ± 0.10 Ma, the rate of fluvial incision of the lava dam reach of the river has reached 98–115 m/Ma, which is 1.5–2 times as great as those of the reaches upstream and downstream from the lava dam. The higher rate of fluvial incision can be attributed to high water levels supplied by the onset and maintenance of backwater conditions in the reach upstream from the lava dam, due to the long period of warm and humid climate in this region. Plucking, abrasion and knickpoint migration appear to be the primary erosional processes in the lava dam reach.