D. Plašienka, J. Michalík, J. Soták & R. Aubrecht comment: In their recent paper, Golonka et al. (2015) described the Cretaceous and Palaeogene olistostromes and other types of mass-transport deposits occurring within the Pieniny Klippen Belt (PKB) of the Western Carpathians. After a short introduction into the olistostrome concept and an overall description of the PKB structure, the authors presented their views on the composition and evolution of the PKB with olistostromes as the leading phenomenon. Although novel in some aspects, the model they present is largely oversimplified and partly erroneous in our opinion. In the following, we shall comment on the several most disputable statements and interpretations offered in the discussed paper.

The occurrences herein described have been brought to light as a result of the work of the Road Materials Division of the Geological Survey of Canada. Those at Ste. Monique and at Husereau's Farm, near Oka, were discovered by Mr. H. Gauthier in 1916 (1), and those at Isle Cadieux, Como and Cascades Point were discovered by Mr. R. H. Picher in the same year (2). It is owing to the kindness and courtesy of Mr. William McInnes, at that time directing geologist of the Geological Survey of Canada, and of Dr. L. Reinecke, at that time chief of the Road Materials Division of the Geological Survey of Canada, that the writer has been given the opportunity of studying these rocks.

A pebble lineation has been produced as a result of the first phase deformation that formed the Chamba syncline and the associated slaty cleavage. The lineation indicates the principal direction of maximum elongation of the finite tectonic strain ellipsoid of the first phase deformation and lies nearly normal to the axial direction of the Chamba syncline. The mineral lineation and the long axes of deformed crinoid ossicles show paralelism to subparallelism with the pebble lineation. The second and third phases of deformation, which are characterized by open style folds and associated crenulation cleavage, appear to be of weak magnitude and have not modified the orientations of pebble lineation.

Chloritoid-biotite- and chloritoid-staurolite-bearing rocks occur around Blair Atholl, Perthshire. Textures suggest staurolite to be produced from chloritoid by a prograde ionic reaction involving muscovite. Chloritoid rocks are aluminous, lying above the muscovite-chlorite join, and staurolite formation involves the breakdown of chloritoid and muscovite. Their presence indicates that the chloritoid-biotite zone of Stonehaven continues as far SW as Central Perthshire, although its occurrence is severely limited by a lack of aluminium-rich rocks. The use of the chloritoid outcrop in the NE as an indication of pressure decrease to the SW is therefore queried.

The occurrence of what is probably clear secondary zircon on detrital grains of this mineral seems first to have been noticed by Butterfield (1936), in heavy residues from the Millstone Grit of Yorkshire. He showed that the outgrowths were too sharp and delicate to have withstood transport, and were, therefore, formed after the deposition of the rock. He also gave some account of their frequency and mode of occurrence in relation to the crystals to which they were attached. Smithson (1937) found similar outgrowths on zircons from the Middle Jurassic of Yorkshire, remarking that until we know of other occurrences it may be unwise to generalize, but that Butterfield's Millstone Grit zircons and his own Jurassic examples occurred in deposits which were either deltaic in origin, or closely associated with deltaic conditions.

The Tarim Basin in Northwest China hosts petroleum reservoirs of Cambrian, Ordovician, Carboniferous, Triassic, Jurassic, Cretaceous and Tertiary ages. The sedimentary thickness in the basin reaches about 15 km and with an area of 560000 km2, the basin is expected to contain giant oil and gas fields. It is therefore important to determine the ages and depositional environments of the petroleum source rocks. For prospective evaluation and exploration of petroleum, palynological investigations were carried out on 38 crude oil samples collected from 22 petroleum reservoirs in the Tarim Basin and on additionally 56 potential source rock samples from the same basin. In total, 173 species of spores and pollen referred to 80 genera, and 27 species of algae and fungi referred to 16 genera were identified from the non-marine Mesozoic sources. By correlating the palynormorph assemblages in the crude oil samples with those in the potential source rocks, the Triassic and Jurassic petroleum source rocks were identified. Furthermore, the palynofloras in the petroleum provide evidence for interpretation of the depositional environments of the petroleum source rocks. The affinity of the miospores indicates that the petroleum source rocks were formed in swamps in brackish to lacustrine depositional environments under warm and humid climatic conditions. The palynomorphs in the crude oils provide further information about passage and route of petroleum migration, which is significant for interpreting petroleum migration mechanisms. Additionally, the thermal alternation index (TAI) based on miospores indicates that the Triassic and Jurassic deposits in the Tarim Basin are mature petroleum source rocks.

Olivine-bearing lamproite magmas intruded into Permian coal seams in northeast India occur as root-like cylinder stockworks, extending for up to several kilometres up-dip along the bedding planes of their sedimentary host. Clusters of eight or more conduits are typical, linked by thin tubular cross-branches. Cylindrical geometry may arise by injection of hot, low-viscosity fluid through a slot, with the development of multiple tube-like instabilities at the interface between the moving fluid and a higher-viscosity host. This behaviour appears more complex than the models of Chouke, van Meurs & van der Pod, and Saffman & Taylor, which predict the development of a single dominant tube in porous or layered flow. Cylinder emplacement may be an essentially passive process, in which the sediment column is reduced by expulsion of heated pore fluids at the head of the moving intrusion, creating a space into which the melt can propagate. Generation of a superheated vapour envelope by non-nucleated film boiling of these fluids around the hot lamproite magma (the Leidenfrost effect) allows melt flow to be maintained in a lengthening tube thermally insulated from the surrounding coal, in a manner analogous to submarine lava tubes. Cooling of the magma through the Nukiyama temperature (the temperature at which maximum evaporation of the heated fluid occurs) may give rise to violent surface boiling and the formation of large vapour bubbles at the magma–coal interface. Implosion of these bubbles could then result in the formation of shock breccias, comparable to hyaloclastites produced by bubble or surface film collapse in the vicinity of pillow lava tubes. The operation of such a process around lamproite magma is suggested by the presence of complex breccias composed of highly fragmented coal, sandstone, and lamproite, at the termini of certain cylinders.

Surface and subsurface exposures of the cylinders reveal the presence of a carbonate–chlorite–clay halo surrounding each intrusion, resulting from the alteration of mafic mineral phases by fugitive volatiles released from the protective vapour jacket. The coal seams proximal to intrusion clusters are relatively undeformed, with no evidence of assimilation by the invading melts. The coals have experienced extensive carbonization, probably as a result of slow conductive heating from the cooling lamproite bodies, or fluids derived therefrom. Field observations indicate that these thermal effects are not merely confined to the coal–melt interface, but occur for some considerable distance away from the intrusions, producing large areas of naturally coked coal.

The Solonker and Shalazhashan belts are hotly debated tectonic units of the Central Asian Orogenic Belt (CAOB), because they may either represent a Permian or Triassic suture zone of the CAOB, or a rifting zone overprinted on an Early Palaeozoic orogen. Provenance analysis of the Upper Palaeozoic sandstones in these belts may provide useful constraints on this issue. This study collected six sandstone samples from three study areas: the Mandula area of the Solonker Belt, the Quagan Qulu area of the Shalazhashan Belt but close to the Alxa block, and the Enger Us area of the Shalazhashan Belt, for framework petrography, zircon morphology, U–Pb and Lu–Hf isotopic analyses. Framework petrography reveals that the Mandula and Enger Us area samples contain high proportions of volcanic fragments, whereas the samples from the Quagan Qulu area include not only volcanic fragments but also significant amounts of biotite and muscovite. The detrital zircons of the Mandula area and the Enger Us area yield two main age groups: (i) 260–330 Ma, with dominant εHf(t) values of –5 to +12; and (ii) 420–550 Ma, with dominant εHf(t) values of –9 to +9, suggesting that Early Palaeozoic arc-related magmatic rocks and Late Palaeozoic syn-depositional volcanic rocks are the main source rocks. The detrital zircons of the Quagan Qulu area have one main age group of 420–500 Ma and some grains of 0.9–1.1 Ga, 1.4–1.5 Ga, 1.8–1.9 Ga and ~ 2.5 Ga, which derive from the northern margin of the Alxa block. The lithological and fossil assemblages of the Upper Palaeozoic sandstones suggest shallow-marine to deep-water depositional environments and a northward-deepening transition. Based on the zircon spectra, sedimentary environment analysis and previous studies, we argue that the Solonker Belt and the Shalazhashan Belt of the CAOB are in extensional basins of a fore-arc or rifting setting.

The detailed examination of rocks recently collected from a traverse and from isolated points within this intrusion has led to the conclusion that it is a large, layered intrusion showing rhythmic and cryptic variation, and comparable in many respects with the Great Dyke of Southern Rhodesia.

The Strathy Complex of the Scottish Caledonides is a bimodal association of amphibolites and siliceous grey gneisses that structurally underlies adjacent metasediments of the Moine Supergroup. Both rock units record a common polyphase Caledonian tectonometamorphic history. New elemental and radiogenic isotope data indicate that both end-members of the Strathy suite were derived from a depleted mantle source, that they are cogenetic and that they may have been related by crystal fractionation. δ18O values and their correlations with major and trace elements suggest that the protoliths were hydrothermally altered at temperatures below 200 °C. Tectonomagmatic discrimination based on relatively immobile elements and isotope systems, plus comparison with geochemically similar bimodal supracrustal associations elsewhere, strongly support the conclusion that the igneous protoliths of the Strathy Complex formed in an oceanic destructive margin setting. If TDM model ages of c. 1000 Ma approximate protolith crystallization, the Strathy Complex may have formed as juvenile crust in the peri-Rodinian ocean broadly contemporaneous with the Grenville orogenic cycle.

The material which is described in this note was collected by members of the Geological Staff of the Anglo-Persian Oil Company, Ltd.

The Vagastie Bridge granite, central Sutherland, belongs to a regional suite of igneous intrusions within Moine psammites adjacent to the base of the east Sutherland migmatite complex. An isotopic date of 405 ± 11 Ma, obtained using U–Pb determinations on zircon and sphene taken from the granite, has previously been interpreted as an intrusion age. However, a reassessment of the field relationships demonstrates that intrusion was syn-tectonic with respect to the later stages of ductile Caledonian deformation affecting the Moine rocks. It is suggested that the granite suite magmas originated at depth and that they were channelled into the still active Caledonian ductile thrust zone (the Naver Thrust) which forms the tectonic base of the Naver Nappe. On regional grounds, the interpretation of the c. 405 Ma date as an intrusion age is untenable, which implies that the isotope systematics of the Vagastie Bridge granite require re-investigation.

During late Pliocene times, extrabasinally derived acidic volcanic ashes were deposited as distal pyroclastic fallout in upland interfluvial–lacustrine settings in the northwestern part of the Siwalik basin. These ash beds occur as a bentonitized tuff band and tuffaceous mudstones in the Jammu region of India. We located and described 12 outcrops of this conspicuous, geographically widespread bentonitized tuff band and tuffaceous mudstone association at the same stratigraphic level, coincident with the Gauss–Matuyama boundary at 2.48 Ma. This bentonitized tuff band and tuffaceous mudstone association represents a stratigraphic marker horizon in the diachronous and sporadic vertebrate fauna-yielding Siwalik strata. The claystone, siltstone, and sandstone units and embedded bentonitized tuff band and tuffaceous mudstone beds represent a coarsening-upward sequence reflecting deposition in lacustrine proximal and distal bottomsets, pro-delta foresets, and mouth-bar facies capped by fluvial topsets. This study reports a chain of four contemporaneous, palaeo-lake basins at this stratigraphic level, which ranged in length from 2 to 7 km.

Results of in situ U–Pb dating of calcite spherulites, cone-in-cone (CIC) calcite and calcite fibres from a calcareous concretion of the upper Ediacaran of Finnmark, Arctic Norway, are reported. Calcite spherulites from the innermost layers of the concretion yielded a lower intercept age of 563 ± 70 Ma, which, although imprecise, is within uncertainty of the age of sedimentation based on fossil assemblages. Non-deformed CIC calcite from the bottom part of the concretion yielded an age of 475 ± 25 Ma, which is interpreted as the age of CIC calcite formation during a period of fluid overpressure induced during burial of the sediments. Deformed CIC calcite from the top part of the concretion yielded an age of 418 ± 23 Ma, which overlaps with a known Caledonian tectono-metamorphic event, and indicates a potential post-depositional overprint at this time. Calcite fibres that grew in small fissures along spherulite rims, which are interpreted as a recrystallization feature during deformation and formation of a cleavage, gave an imprecise age of 486 ± 161 Ma. Our results show that U–Pb dating of calcite can provide age constraints for ancient carbonates and syn- to post-depositional processes that operated during burial and metamorphic overprinting.

Limestone megaclasts up to hundreds of metres in size are present within the Gwna Group mélange, North Wales, UK. The mélange has been interpreted as part of a Peri-Gondwanan fore-arc accretionary complex although the age of deposition remains contentious, proposals ranging from Neoproterozoic to Early Ordovician. This paper uses strontium isotope chemostratigraphy to establish the age of the limestone blocks and thus provide a maximum age constraint on mélange formation. Results show that, although the carbonates are locally dolomitized, primary 87Sr/86Sr ratios can be identified and indicate deposition sometime between the late Tonian and earliest Cryogenian. This age is older than that suggested by stromatolites within the limestone and indicates that the limestone did not form as cap carbonate deposits.

Twenty-one sandstone samples belonging to the intermediate part of Gorgoglione Flysch (GF) dated Middle-Miocene, cropping out in the Southern Apennines (Italy), have been studied to highlight the detritus provenance. Petrographic and chemical composition indicates that the successions consist of feldspatho-quartzose and litho-feldspatho-quartzose arenites interbedded with pelitic and calciclastic layers and reveals a provenance from a basement formed by low- to medium-grade metamorphic rocks with abundant granitoids covered by sedimentary rocks in which a volcanic component was also present. In the Mediterranean area, basements with these characteristics are widespread both in western and southwestern domains. The supply provenance of Gorgoglione Flysch has been better detailed utilizing U–Pb detrital zircon ages recording the geological history of the source rocks. Fifty-eight crystals from six samples of coarse- and fine-grained sandstones have been analysed using the U–Pb isotopic systematic (LA-ICP-MS). They produce 70 concordant zircon ages forming three defined clusters at 672 ± 28 Ma, 458 ± 9 Ma and 297 ± 8 Ma, and four zircon ages corresponding to 24 ± 1 Ma. An evaluation of the entire collected data suggests that the provenance area is better identified in northwestern sectors of the Mediterranean area in which the Sardinia–Corsica (pro-part) block plays a fundamental role.

Herpetopora Lang is considered to be a junior synonym of Pyripora d'Orbigny, from which Rhammatopora Lang is distinguished by possessing apertural spines. A new species of Pyripora is described from the Albian of Texas.

The coarse ferruginous sands at the base of the Cretaceous series, in the countries of Bedford and Cambridge, have of late years attracted considerable notice, not only as sources of iron ore, but also of phosphatic matter. To these deposits the attention of geologists has been directed, and among other valuable papers, may be mentioned some by Messrs. Seeley and Walker,1 who have treated of their general physical characters, and also of their interesting fossil contents. It may be useful to some of the readers of the Geological Magazine, who are interested in tracing out the range of this deposit, and the peculiar conditions under which it was accumulated in some parts of the area, to point out briefly its characters and contents in the adjoining county of Buckingham; i.e., around Aylesbury: more especially so, as these sands have been considered to be partly equivalent in time, or the marine conditions of the Wealden and Purbeck strata.

Limb-bones.—Since the humerus is known in Hylœsaurus (?), Omosaurus, and Stegosaurus, it is quite easy to compare the humerus of our new species with that of the other genera mentioned. Whether the shaft is hollow as in Omosaurus or solid as in Stegosaurus, cannot be ascertained without breaking the specimen; the outline of the new humerus is, however, that of Omosaurus, not that of Stegosaurus.