The Flowers River Igneous Suite of north-central Labrador comprises several discrete peralkaline granite ring intrusions and their coeval volcanic succession. The Flowers River Granite was emplaced into Mesoproterozoic-age anorthosite–mangerite–charnockite–granite (AMCG) -affinity rocks at the southernmost extent of the Nain Plutonic Suite coastal lineament batholith. New U–Pb zircon geochronology is presented to clarify the timing and relationships among the igneous associations exposed in the region. Fayalite-bearing AMCG granitoids in the region record ages of 1290 ± 3 Ma, whereas the Flowers River Granite yields an age of 1281 ± 3 Ma. Volcanism occurred in three discrete events, two of which coincided with emplacement of the AMCG and Flowers River suites, respectively. Shared geochemical affinities suggest that each generation of volcanic rocks was derived from its coeval intrusive suite. The third volcanic event occurred at 1271 ± 3 Ma, and its products bear a broad geochemical resemblance to the second phase of volcanism. The surrounding AMCG-affinity ferrodiorites and fayalite-bearing granitoids display moderately enriched major- and trace-element signatures relative to equivalent lithologies found elsewhere in the Nain Plutonic Suite. Trace-element compositions also support a relationship between the Flowers River Granite and its AMCG-affinity host rocks, most likely via delayed partial melting of residual parental material in the lower crust. Enrichment manifested only in the southernmost part of the Nain Plutonic Suite as a result of its relative proximity to multiple Palaeoproterozoic tectonic boundaries. Repeated exposure to subduction-derived metasomatic fluids created a persistent region of enrichment in the underlying lithospheric mantle that was tapped during later melt generation, producing multiple successive moderately to strongly enriched magmatic episodes.

The late Palaeozoic Yong’an–Meizhou depression belt is an important iron (Fe) and polymetallic metallogenic belt in southern China. It has undergone a transformation from Tethys to the circum-Pacific tectonic domain. The Luoyang deposit is one of the typical Fe skarn deposits in the Yong’an–Meizhou depression belt of eastern China. Garnet is a characteristic mineral in the deposit. Two generations of garnets are detected in the deposit based on their textural characteristics and trace-element contents, and are represented by Fe-enriched andradite. The first generation of garnets (Grt1) have two types of garnets (Grt1-A and Grt1-B). Type A garnets of the first generation (Grt1-A) (Adr80-88) replaced by massive diopside-magnetite assemblage exhibit distinct oscillatory zonings and display patterns of enriched light rare earth elements (LREE) to weak heavy rare earth elements (HREE), with weak negative to positive Eu anomalies, and highest U, ΣREE and Sn contents. Type B garnets of the first generation (Grt1-B) are irregular zones (Adr94-96) coexisting with magnetite, in which Grt1-A is generally dissolved, and have obviously LREE-enriched and HREE-depleted patterns, with weak negative to positive Eu anomalies, and moderate U, ΣREE and Zn contents. Garnets of the second generation (Grt2) (Adr96-99) that replaced massive magnetite together with sphalerite show unzoned patterns, with a flat REE pattern and pronounced negative Eu anomalies as well as contents of lowest U and ΣREE, and highest W. The substitution of REEs in garnets occurs as [X2+]VIII –1[REE3+]VIII +1[Si4+]IV –1[Z3+]IV +1in an Al-enriched environment. Luoyang hydrothermal fluids shifted from reducing conditions with relatively high-U and -ΣREE characteristics to oxidizing conditions with relatively low-U and -ΣREE characteristics. The reduced siderophile elements and increased fO2 in fluid during Grt1-B formation caused magnetite mineralization and reduced Zn contents during Grt2 formation, causing the deposition of sphalerite. All garnets formed from magmatic fluid and were controlled by infiltrative metasomatism in an opened system.

Hyoliths are extinct enigmatic organisms of early lophotrochozoan affinity known globally from the Palaeozoic Era and were especially diverse and abundant in the Cambrian Period. However, the commonly incomplete preservation of hyolith exoskeletons and our limited knowledge of their soft anatomy makes their ecological and biological aspects unclear. Konservat-Lagerstätte are crucial windows to unlock the mysteries of hyoliths. Here we report a new occurrence of exceptionally preserved hyolithid hyoliths from the middle Cambrian Mantou Formation (Miaolingian, Wuliuan) in Shandong Province, North China. The preserved soft organs of the new species Novakotheca weifangensis sp. nov. include a U-shaped gut and possible pharynx, oesophagus, stomach and digestive gland, which provide significant new information for the reconstruction of the digestive system of hyolithids. Two taphonomic modes of hyoliths described herein are recognized: soft tissue preservation through pyritization and three-dimensional shell preservation through phosphatization. Morphological variations due to different preservational pathways in the same species are revealed, highlighting the taphonomic bias on taxonomy. The ecological association between hyoliths and small brachiopod epibionts is a direct example of species interactions, providing insights into the ecological structures and adaptability of early animals during Cambrian time.

The Jueluotage area, which is located in the southern branch of the Eastern Tianshan and northeast of the Tarim Basin, represents a vital locality for investigating intracontinental reactivation induced by the tectonic events at the Eurasian plate margin. This study applies zircon and apatite (U–Th)/He and apatite fission-track thermochronology to the Jueluotage area in the Eastern Tianshan. Our data and thermal history modelling show that the Jueluotage area experienced Triassic–Early Jurassic (˜240–180 Ma) cooling, reflecting the closure of the North Tianshan Ocean and subsequent far-field effects of collision/accretion of the Qiangtang Block and Kunlun terrane. Following this period of fast cooling, a differential exhumation process occurred between the various tectonic belts in the Jueluotage area. The Aqishan–Yamansu belt was exposed at the surface during the Triassic–Early Jurassic cooling phase and experienced subsequent burial, which continued until Early Cretaceous time when a pulse of exhumation occurred. However, the major fault zones (Kanggurtag ductile shear zone and Aqikkuduk Fault) and Central Tianshan arc have remained tectonically stable since Early Jurassic time. No Cenozoic rapid cooling was recorded by the low-temperature thermochronology results in this study, indicating that much of the Jueluotage area was exhumed to the upper crust in the late Mesozoic period.

We present a δ13Ccarb chemostratigraphy for the Late Ordovician Hirnantian Stage based on 208 whole-rock samples from six outcrops in the Oslo–Asker district, southern Norway. Our data include the Norwegian type section for the Hirnantian Stage and Ordovician–Silurian boundary at Hovedøya Island. The most complete record of the Hirnantian Isotope Carbon Excursion (HICE) is identified in a coastal exposure at Konglungø locality where the preserved part of the anomaly spans a c. 24 m thick, mixed carbonate–siliciclastic succession belonging to the upper Husbergøya, Langåra and Langøyene formations and where δ13Ccarb peak values reach c. +6 ‰. Almost the entire HICE occurs above beds containing the Hirnantia Fauna, suggesting a latest Hirnantian age for the peak of the excursion. The temporal development of the HICE in southern Norway is associated with substantial shallowing of depositional environments. Sedimentary facies and erosional unconformities suggest four inferably fourth-order glacio-eustatically controlled sea-level lowstands with successively increased exposure and erosion to the succession. The youngest erosional unconformity is related to the development of incised valleys and resulted in cut-out of at least the falling limb of the HICE throughout most of the Oslo–Asker district. The fill of the valleys contains the falling limb of the HICE, and the postglacial transgression therefore can be assigned to the latest part of the Hirnantian Age. We address the recent findings of the chitinozoan Belonechitina gamachiana in the study area and its relationship to the first occurrence of Hirnantia Fauna in the studied sections, challenging identification of the base of the Hirnantian Stage.

Study of constraints of stock emplacement and geometry on associated skarn orebodies is significant for the understanding of the epithermal deposit system. We have chosen the typical Tongguanshan skarn ore deposit (eastern China) as our target area. The Tongguanshan stock was emplaced at the NE–SW-striking Tongguanshan anticline and is characterized by macroscopically homogeneous quartz–monzodiorite. The magnetic parameters show that the stock is dominated by oblate magnetic ellipsoids and a high degree of anisotropy (> 1.1), and this value is higher at the stock margin. The strike of magnetic foliation at the stock margin is parallel to the stock boundary with sub-horizontal magnetic lineations. A vertical NE–SW-striking magnetic foliation, which is parallel to the regional structures, is revealed inside the stock. The three-dimensional geometric modelling shows that the stock has a tongue-like geometry and the contact surface in both eastern and western sides dips to the NW, but the western side is steeper. Nevertheless, the orebodies are almost developed at the eastern side. Accordingly, we propose that the Tongguanshan stock was constructed by multiple magma pulses, initiated at the SW part of the stock, and ascended along inherited NE–SW extended fractures in the Tongguanshan anticline. The successive magma pulses either accreted by a unilateral E-wards trend or by bilateral magma accretion, which resulted in a deformation difference in the contact zone and caused uneven orebody development. Our study also shows that the strike, dip angle and curvature situation of contact surface, which affects the water–rock reaction process and distribution of the dilation zone, are important ore-controlling factors.

Enrichment of the heavy rare earth elements (HREE) in carbonatites is rare as carbonatite petrogenesis favours the light (L)REE. We describe HREE enrichment in fenitized phonolite breccia, focusing on small satellite occurrences 1–2 km from the Songwe Hill carbonatite, Malawi. Within the breccia groundmass, a HREE-bearing mineral assemblage comprises xenotime, zircon, anatase/rutile and minor huttonite/thorite, as well as fluorite and apatite.

A genetic link between HREE mineralization and carbonatite emplacement is indicated by the presence of Sr-bearing carbonate veins, carbonatite xenoliths and extensive fenitization. We propose that the HREE are retained in hydrothermal fluids which are residually derived from a carbonatite after precipitation of LREE minerals. Brecciation provides a focusing conduit for such fluids, enabling HREE transport and xenotime precipitation in the fenite. Continued fluid–rock interaction leads to dissolution of HREE-bearing minerals and further precipitation of xenotime and huttonite/thorite.

At a maximum Y content of 3100 µg g−1, HREE concentrations in the presented example are not sufficient to constitute ore, but the similar composition and texture of these rocks to other cases of carbonatite-related HREE enrichment suggests that all form via a common mechanism linked to fenitization. Precipitation of HREE minerals only occurs where a pre-existing structure provides a focusing conduit for fenitizing fluids, reducing fluid – country-rock interaction. Enrichment of HREE and Th in fenite breccia serves as an indicator of fluid expulsion from a carbonatite, and may indicate the presence of LREE mineralization within the source carbonatite body at depth.

The Harihada–Chegendalai ophiolitic mélange, which is located between the Bainaimiao arc and the North China Craton, holds significant clues regarding the tectonic setting of the southern margin of the Central Asian Orogenic Belt. The ophiolitic mélange is mainly composed of gabbroic and serpentinized ultramafic rocks. Here, zircon U–Pb dating, in situ zircon Hf isotopic, whole-rock geochemical and in situ mineral chemical data from the ophiolitic mélange are reported. The zircons in the gabbroic rocks yielded concordia U–Pb ages of 450–448 Ma and exhibited slightly positive ϵHf(t) values (0.87–4.34). The geochemical characteristics of the gabbroic rocks indicate that they were generated from a mantle wedge metasomatized by subduction-derived melts from sediments with continental crust contamination, in a fore-arc tectonic setting. These rocks also experienced the accumulation of plagioclase. The geochemical characteristics of the ultramafic rocks and their Cr-spinels indicate that they may constitute part of residual mantle that has experienced a high degree of partial melting and has interacted with fluids/melts released from the subducted slab in the same fore-arc tectonic setting. The ophiolitic mélange may therefore have formed in this fore-arc tectonic setting, resulting from the northward subduction of the South Bainaimiao Ocean beneath the Bainaimiao arc during Late Ordovician time, prior to the collision between the Bainaimiao arc and the North China Craton during the Silurian to Carboniferous periods.

Several orogenic belts exhibit regional-scale anticlines characterized by prominent faults in their crestal/forelimb zone. These faults are also a common feature in the Neogene fold-and-thrust belt of the Apennines, where they have been contrastingly interpreted as younger-on-older thrust faults, large-scale strike-slip faults, and pre- or syn-thrusting normal faults. In this study, we analysed a NW–SE-trending fault (Montagna dei Fiori Fault) that affects the hinge-zone/forelimb of the Montagna dei Fiori Anticline. This fold is the outermost exposed contractional structure within the Pliocene–Quaternary antiformal stack of the outer Central Apennines. The integration of stratigraphic and structural data collected during a field geological survey enabled us to reconstruct a multiphase reactivation and deformation along the Montagna dei Fiori Fault. From the novel field data, a different interpretation for the evolution of the Montagna dei Fiori Fault is proposed. The fault originated as a Late Cretaceous – middle Miocene, NE-dipping, Dinaric up-thrust and was later reactivated, displaced and rotated during Pliocene Apennine thrusting and related folding, until assuming a present-day SW-dipping attitude with an apparent normal fault character. This newly proposed Dinaric origin of the Montagna dei Fiori structure is compared with an analogous subsurface example of a Palaeogene–Quaternary structure imaged by seismic reflection profile in the Adriatic foreland. The outcome of this combined field and subsurface investigation provides new elements to unravel the complex evolution of the Apennine thrust belt that developed at the expense of a previously deformed foreland, ahead of the advancing Dinaric chain.

Zircon U–Pb and Lu–Hf isotope microanalysis was conducted in (meta)-igneous units of Ammouliani island to characterize crust-forming and reworking events in the Serbo-Macedonian massif. Zircon grains from an orthogneiss of the Vertiskos unit yielded a U–Pb crystallization age for the igneous precursor at 458.8 ± 11 Ma with dominantly subchondritic ϵHf values indicating reworking of Neoproterozoic basement. A weighted mean ϵHf value of 0.7 ± 2.4 from oscillatory zoned zircon grains of the Ouranoupoli granodiorite indicates juvenile crustal input at 52.1 ± 0.6 Ma. The U–Pb–Hf zircon archive records discrete stages in the crustal evolution of the Serbo-Macedonian massif.

A new enantiornithine bird is described on the basis of a well preserved partial skeleton from the Upper Cretaceous Qiupa Formation of Henan Province (central China). It provides new evidence about the osteology of Late Cretaceous enantiornithines, which are mainly known from isolated bones; in contrast, Early Cretaceous forms are often represented by complete skeletons. While the postcranial skeleton shows the usual distinctive characters of enantiornithines, the skull displays several features, including confluence of the antorbital fenestra and the orbit and loss of the postorbital, evolved convergently with modern birds. Although some enantiornithines retained primitive cranial morphologies into the latest Cretaceous Period, at least one lineage evolved cranial modifications that parallel those in modern birds.