Intrusive Events Research Articles

The 3D Crustal Structure of the Wilkes Subglacial Basin, East Antarctica, Using Variation of Information Joint Inversion of Gravity and Magnetic Data

AbstractDirect geological information in Antarctica is limited to ice free regions along the coast, high mountain ranges, or isolated nunataks. Therefore, indirect methods are required to reveal subglacial geology and heterogeneities in crustal properties, which are critical steps toward interpreting geological history. We present a 3D crustal model of density and susceptibility distribution in the Wilkes Subglacial Basin (WSB) and the Transantarctic Mountains (TAM) based on joint inversion of airborne gravity and magnetic data. The applied “variation of information” technique enforces a coupling between inferred susceptibility and density, relating these quantities to the same gravity and magnetic sources to give an enhanced inversion result. Our model reveals a large body located in the interior of the WSB interpreted as a batholithic intrusive structure, as well as a linear dense body at the margin of the Terre Adélie Craton. Density and susceptibility relationships are used to inform the interpretation of petrophysical properties and the reconstruction of the origin of those crustal bodies. The petrophysical relationship indicates that the postulated batholitic intrusion is granitic, but independent from the Granite Harbor Igneous Complex described previously in the TAM area. Emplacement of a large volume of intrusive granites can potentially elevate local geothermal heat flow significantly. Finally, we present a new conceptual tectonic model based on the inversion results, which includes development of a passive continental margin with seaward dipping basalt horizons and magmatic underplating followed by two distinct intrusive events associated with the protracted Ross Orogen.

Multi-stage magmatism and Sn-polymetallic mineralization in the Shuicheng Region, SW China

The economically important tin‑tungsten mineralization in southwestern China has attracted much interest in recent years, yet its age, tectonic setting, and genetic relationship to the host granites remain uncertain in most regions. Our focus in this study is the Shuicheng tin-polymetallic deposit, situated in the western sector of the Diantan Batholith, within the northern Tengchong Block. The granites in this area consist of two intrusive units, i.e., 1) biotite monzogranite (T1), with LA-ICP-MS zircon UPb ages ranging from 76.88 ± 0.43 Ma to 74.69 ± 0.57 Ma, whole-rock εNd(t) values ranging from −9.75 to −8.11, and zircon εHf(t) values from −12.19 to −8.85; and 2) alkali-feldspar granite (T2), with an LA-ICP-MS zircon UPb age of 52.16 ± 0.23 Ma, whole-rock εNd(t) values of −10.15 to −8.25, and zircon εHf(t) values of −9.64 to −8.06. These two intrusive events have been linked to prolonged low-angle subduction and retreat of the subducting Neo-Tethys Ocean Plate, respectively. The Shuicheng granites exhibit high concentrations of SiO2 and Al2O3, contrasted with low levels of FeOT, CaO, MgO, TiO2, and P2O5, suggesting that they are highly fractionated S-type granites. High abundances of Rb, K, U, and Hf, along with low contents of Ba, Sr, and Ti, further indicate significant fractionation and crystallization processes during magma evolution. Importantly, a transition from purely magmatic conditions to a magmatic-hydrothermal state occurred during the latter stages of magmatic evolution. This transition, associated with an amplified potential for tin mineralization, provides fresh insight into the role of magmatic processes in ore genesis, enriching our understanding of the tin‑tungsten mineralization history of the Tengchong region.

Geology and Structure of the Río Blanco Cu-Mo Porphyry Deposit, Central Chile

Abstract The Río Blanco-Los Bronces deposit is the largest Cu-Mo porphyry deposit in the world in terms of contained Cu metal. It is the product of protracted superposed magmatic and hydrothermal activity associated with multiple intrusive and brecciation events, with simultaneous regional uplift, erosion and unroofing, and decompression. Magmatism resulted in three major mineralization-alteration stages. The premineralization stage occurred during the emplacement of the San Francisco batholith, resulting in late magmatic and early hydrothermal events. The synmineralization stage corresponds to the main hydrothermal events associated with the Río Blanco-Los Bronces porphyry and breccia complexes, which were related to three intrusion phases, widespread brecciation, and an epithermal-style advanced argillic alteration. Late-stage magmatism, followed by hydrothermal activity, was associated with the emplacement of subvolcanic rhyolite complexes and late-stage porphyry intrusions. The synmineralization intrusions are associated with high-grade breccia bodies that have well-defined alteration-zonation patterns. Compilation and analysis of the historical Río Blanco structural data sets from the different mines, tunnels, and pits have allowed the assignment of all mapped structures to four hierarchical orders based on their continuity, crosscutting relationships, and infill compositions. The larger structures (orders 0 and 1) have along-strike continuity, correlate between drifts and/or mine levels, whereas smaller structures (orders 2 and 3) were grouped according to their dimensions and distributions within the larger-order structure-defined panels. All orders 0 and 1 structures were modeled in three dimensions, while orders 2 and 3 were in two dimensions. The structures mapped at Río Blanco have an intimate relationship with the pre- to the late-stage geologic evolution of magmatism and mineralization. The regional-and to a lesser extent district-scale structural evolution was related to premineralization basin-opening and subsequent tectonic inversion, whereas at the camp scale, syn- to late mineralization intrusions and related hydrothermal features were superimposed on this inherited structural architecture.

Petrogenesis of the Marginal Sill Phase and Lower Zone in the Eastern Limb of the Bushveld Complex: Incremental development of igneous layering and syn-magmatic emplacement of peridotite intrusions and sills

Abstract The petrogenesis of the mafic-ultramafic layered rocks of the Bushveld Complex, i.e., the Rustenburg Layered Suite (RLS) remains uncertain despite more than a century of intensive research. An investigation of a 100 km strike section in the Eastern Limb has led us to propose that igneous layering in the lowermost part of the RLS developed from a succession of intrusive events. Zonal boundaries and geochemical discontinuities are explained by radical switches in the composition of parental magmas. Magmas were sourced from deep staging chambers, and we find no evidence for the existence of a large magma reservoir in the shallow crust. At the base of the RLS is the Marginal Sill Phase (MSP), a stacked sequence of noritic-gabbronoritic and pyroxenitic sills that form a continuum with the syn-Bushveld sills in the floor rocks. The MSP does not constitute the chilled carapace of a magma chamber and the postulated so-called “B1” (tholeiitic) parental magmas have little direct bearing on the overlying components of the RLS. The Lower Zone (LZ) reflects a switch to ultramafic parental magmas. Magmas were fed into isolated subchambers, each of which has a unique igneous stratigraphy. The primary component of the LZ is an adcumulate comprised of >98.5 modal % orthopyroxene (En87-83) and from which Cr-spinel is conspicuously absent. Chemical equilibrium was maintained as the orthopyroxene-saturated magmas were intruded, not as sills, but as thin magma laminae. The increments of magma laminae matched the rate of batch crystallisation, and there is no evidence of a fractionated residue having been ejected. In a later phase of magmatism, peridotite magmas were injected into the floor rocks, where they formed complexly layered peridotite intrusions with their anastomosing groups of sills. Formation of peridotite bodies such as the Aapiesdoorndraai Intrusion with distinct layers of dunite, harzburgite and olivine orthopyroxenite (Fo92-83) (+Cr-spinel) result from near-equilibrium crystallisation of the olivine- and Cr-spinel-saturated magmas. Some peridotite sills stepped up through the thermal aureole and intruded the earlier-formed MSP and LZ, crystallising as syn-magmatic sills with broadly similar compositions. Development of the trough-like subchambers with thick sequences of the MSP and LZ triggered extensive deformation and thermal metamorphism of the floor rocks. Sinking of subchambers was compensated by intervening domes and upwarps, the crests of which reveal tectonically thinned sequences of the MSP and from which the LZ is absent. This early phase of syn-Bushveld tectonism has resulted in the Lower Critical Zone (LCZ) discordantly overlying either the MSP (on the crests of domes and upwarps) or the LZ (in subchambers). Field relationships thus demonstrate that the LCZ developed entirely independently of the MSP and LZ, from a new series of intrusive events and a new lineage of parental magma.

The continuation of the Mull Dyke Swarm into the Southern North Sea

We present new geophysical observations of the Mull Dyke Swarm in the Southern North Sea. Two- and three-dimensional seismic reflection and aeromagnetic data were used to map the dykes. The three main dyke groups recognized onshore (Cleveland, Blyth and Hawick–Acklington) are found to extend to varying distances into the North Sea, crossing a number of major crustal-scale fault zones and domain boundaries, with almost no reorientation. The Blyth Dyke Group extends furthest, for a distance of 672 km from the source on Mull. The seismic data show extensive development of pit chain craters above the upper tips of these dykes, which can be approximately dated to the late Paleocene from the ages of crater fills. Volumetric estimates are made of the intrusive volumes associated with each group, ranging from 90 to 202 km 3 . These three main axes of intrusion probably formed in different intrusive events within a c. 1 myr period, from 59 to 58 Ma, during magnetic chron C26R.

TWO STAGES OF MINERALIZATION IN THE SOUTHERN TIEN SHAN Au-W METALLOGENIC BELT: ISOTOPIC U-Pb DATING (LA-ICP-MS METHOD) OF ZIRCON FROM INTRUSIVE ROCKS AT THE JILAU W-Au DEPOSIT (TAJIKISTAN)

The paper presents new isotopic U–Pb zircon data (LA–ICP–MS method) on the intrusive rocks from the Chinorsai massif, which is spatially and probably genetically related to the large Jilau tungsten-gold deposit. This deposit, together with the other large Au deposits (Muruntau, Zarmitan, Kumtor, etc.) is part of the largest Au (Au–W) metallogenic belt of Tien Shan. The deposit is represented by small zones of scheelite-bearing skarn and later (overprinting) large stockwork of veins and veinlets with scheelite-gold mineralization that occurs within and near the intrusion. The concordant isotopic zircon U-Pb data (301.0 ± 2.6 Ma; MSWD = 2.6) are older than the isotopic zircon U–Pb data previously reported (about 288 Ma). This indicates a substantial extent of the magma emplacement and crystallization process that probably corresponded to several intrusive events or phases, which is a prerequisite for the formation of associated intrusive-related Au deposits. Also, the isotopic age determined highlights the earlier formation of gold-polymetallic-tungsten deposits as compared to Mo–W and Sn-W deposits in the region, which are related to the later Early Permian intrusions. In addition, zircon xenocrysts with much older age (from ca. 970 Ma to ca. 2200 Ma) have been identified; they probably represent the age of the orogenic basement including that of the basement terranes of the Tarim and Karakum cratons.

Temporal clustering of fissural eruption across multiple segments within the Ethiopian Rift

Magmatic continental rifts show evidence that discrete rift segments experience episodic intrusive and eruptive events, more commonly termed rifting episodes. However, whether multiple rifting episodes across adjacent rift segments are clustered in time is not well understood. To address this issue, we conduct new radiocarbon dating that constrains the timing of the most recent rifting episode at the Boset magmatic segment of the northern Ethiopian rift, and combine this with historical dating of similar rifting events in the adjacent magmatic segments. New radiocarbon dates of multiple charcoal samples from the base of the most recent fissural lava at the Boset Volcanic Complex indicate that it likely occurred between 1812 and 1919 CE. These dates are similar to those from historical accounts of fissural eruption from the neighbouring Kone (∼1810 CE), and Fantale (∼1770 to 1808 CE) magmatic segments. We conduct new analysis of major and trace element compositions from these historical fissural lavas, as well as from a fresh-looking lava flow from Beru cone near to Kone volcano. The results of the geochemistry from these flows of all three magmatic segments show compositions that vary in the basalt and trachybasalt fields, with sufficient variation to rule out them having erupted from a single dike intrusion episode. This, combined with the scatter in dates from the radiocarbon analysis and historical accounts, along with the location of each eruption in a discrete and spatially offset magmatic segment, favours an interpretation of each magmatic segment experiencing separate rifting episodes but with these being clustered in time. Mechanisms to explain the clustering of rifting episodes are more speculative but could include stress transfer from dike intrusion and deep crustal hydraulic connection in the plumbing system of multiple segments.

Geochemistry and origin of felsites and associated A-type granites at Wadi Atalla area, Central Eastern Desert, Egypt: Implication for genesis of Neoproterozoic post-collisional highly silicic melts

Alkaline volcanics (felsites) and A-type granites are spatially and temporally associated in the Wadi Atalla area, Central Eastern Desert, Egypt. These rocks represent final Neoproterozoic magmatic activity in the Northern Nubian Shield. Wadi Atalla felsites form NW-trending elongate mass consisting of silicic volcanics, which is intruded by A-type granites of Um Had and Um Effein plutons. Field relations indicate that both felsites and A-type granites were emplaced in a series of magmatic pulses. Felsites include tuffaceous, porphyritic and hypabyssal varieties, while A-type granites comprise syenogranite and alkali feldspar granite. Geochemically, they are highly silicic rocks and display a narrow range of SiO2. They have high-K alkaline nature with metaluminous to peraluminous character and were erupted in a post-collisional tectonic setting. Mineral chemistry of biotite supports the alkaline and A-type characters of the studied rocks. Atalla felsites and associated A-type granites show light REE enrichment relative to heavy REE [(La/Lu)n = 2.67–5.72] with pronounced negative Eu anomalies (Eu/Eu* = 0.15–0.52). Compositional similarities between Atalla felsites and A-type granites in the studied area suggest that the intrusive and extrusive events are broadly related. The systematic variation of major- and trace-element contents of the felsites and A-type granites indicates derivation from similar sources through partial melting of juvenile crustal rocks, followed by extensive fractional crystallization. The main fractionated phases are feldspars, with minor role of fractionation of amphibole, biotite, apatite and FeTi oxides. Multiple saturation calculations indicate water-saturated storage and final equilibration conditions for the felsites ranging from 788 °C at 90 MPa to 740 °C at 255 MPa. The parental magmas of the felsites and A-type granites were linked to lithospheric delamination and upwelling of asthenospheric mantle material. This process led to generation of mantle melts that supplied heat to melt the juvenile crust of the Arabian-Nubian Shield (ANS), along with crustal uplift recorded by intersecting strike-slip faults and shear zones. Atalla felsites represent a distinctive post-collisional alkaline volcanic phase in the Nubian Shield that has been emplaced in an extensional tectonic regime, during a phase of fracturing and crustal uplift, which followed the end of the Pan-African orogeny. This volcanic phase is younger than the Dokhan volcanics in the Eastern Desert and older than the typical Katherina volcanics in southern Sinai.

The complex construction of a glaciovolcanic ridge with insights from the 2021 Fagradalsfjall Eruption (Iceland)

Glaciovolcanic landforms provide global-scale records of paleoenvironmental conditions and yield insights into subglacial eruption processes. Models for the formation of glaciovolcanic ridges, or tindars, are relatively simple, proposing a monogenetic eruption and a fairly uniform stratigraphy with or without a single transition from effusive pillow lavas to explosive fragmental deposits. Others have suggested that tindars are more complicated. To build a more robust model for tindar formation, we conducted a field and geochemical study of Undirhlíðar ridge on the Reykjanes Peninsula in southwestern Iceland. We show that the ridge was built through a complex sequence of eruptive and intrusive events under dynamically changing ice conditions. Quarry walls expose a continuous cross-section of the ridge, revealing multiple pillow and fragmental units. Pillow lava orientations record the emplacement of discrete pillow-dominated lobes and the migration of volcanic activity between eruptive vents. Volatile contents in glassy pillow rinds show repeated pulses of pillow lava emplacement under glaciostatic conditions, with periods of fragmentation caused by depressurization. Variations in major elements, incompatible trace element ratios, and Pb-isotopes demonstrate that the eruption was fed from separate crustal melt reservoirs containing melts from a compositionally heterogeneous mantle source. A shift in mantle source signature of pillow lavas suggests that the primary ridge-building phase was triggered by the injection of magma into the crust. Within the growing edifice, magma was transported through dykes and irregularly shaped intrusions, which are up to 20% by area of exposed stratigraphy sequences. The model for tindar construction should consider the significant role of intrusions in the growth of the ridge, a detail that would be difficult to identify in natural erosional exposures. The 2021–22 eruptions from the adjacent Fagradalsfjall vents allow us to draw parallels between fissure-fed eruptions in subaerial and ice-confined environments and test hypotheses about the composition of the mantle underlying the Reykjanes Peninsula. Both Fagradalsfjall and Undirhlíðar ridge eruptions may have occurred over similar spatial and temporal scales, been triggered by mixing events, erupted lavas with varying mantle source signatures, and focused volcanic activity along migrating vents. Differences in composition between the two locations are not related to systematic lateral variations in the underlying mantle. Rather, the Undirhlíðar ridge and Fagradalsfjall eruptions capture complex interactions among the crustal magma plumbing system, mantle source heterogeneity, and melting conditions for a moment in time.

Effects of COVID-19 onWell-Being and Customer Loyalty: A Life Event Perspective

COVID-19 has altered mental and behavioural patterns with profound and long-lasting effects on individuals and economies. Following life event literature, this paper investigates the impact of COVID-19 on individuals’ wellbeing and customer loyalty considering underlying mechanisms. Theoretical and empirical insights from a qualitative study indicate that COVID-19 is perceived as an intrusive nonnormative life event. A quantitative study reveals that stress induced by COVID-19 is negatively related to seeking for new possibilities (i.e., developing and following new interests, hobbies, or activities) and positively with resistance to change (i.e., preferring routines over doing new things) and coping behaviour. Coping, driven by stress, associates positively with seeking for new possibilities but is not related to resistance to change. While the latter drives customer loyalty, new possibilities enhance well-being. This research offers insights into COVID-19’s conceptualization as a life event and its effects on consumers. It derives implications for marketing research, management and public policy.

Convolutional neural network-based high-precision and speed detection system on CIDDS-001

The growing interconnection of complex infrastructures gives very advanced communication functionalities, which gives a massive increase in connected devices and an associated flow volume. Cloud computing is constantly threatened by sophisticated attacks, which poses challenges for a security system. The Cloud will obsolete existing detection procedures against cyber-attacks where they would not be adapted accordingly. Intrusion detection is a classification problem wherein various machine learning and data mining techniques are applied to classify the network data into normal and attack traffic. Therefore, the proposal of new rapid and effective detection approaches is an absolute necessity. In this work, a proposed framework is a network anomaly detection system based on Deep Learning. The analysis carried out was based on the hyper-parameters of the layers of our model. This proposed model is a combination of two techniques; namely, a reduction of dimensions based on the approach of the main components and the second is based on a dense supervised neural network based on convolution neural network (CNN) for a multi-classification of normal and intrusive events from a recent data-set Coburg Network Intrusion Detection data-set (CIDDS-001). The experiments carried out show that the very precise choice of hyper-parameters gives better results. By running the proposed CNN model, it is capable of detecting attacks with an accuracy of 99.13% and an execution time of 12 s.

Emplacement age of the Markagunt gravity slide in southwestern Utah, USA

AbstractThe Markagunt gravity slide (MGS) is a large‐volume landslide in southwestern Utah that originated within the Oligocene‐Miocene Marysvale volcanic field. Gravity slides are single emplacement events with long runout distances and are now recognized as a new class of volcanic hazard. Accumulation of volcanic material on a structurally weak substrate along with voluminous shallow intrusive events led to collapse. Here, 40Ar/39Ar data for landslide‐generated pseudotachylyte, the landslide‐capping Haycock Mountain Tuff and the deformed Osiris Tuff are combined with a Bayesian age model to determine an emplacement age of 23.05 + 0.22/−0.20 Ma for the MGS. The results suggest a lag time of <200 kyr between the caldera‐forming eruption of the Osiris Tuff, additional buildup of the unstable volcanic pile and subsequent mass movement.

The Heroic Savior, the Jungle Guide and the Beacon Amidst a Fog of Uncertainty: Agency of Fathers in Prolonged Postdivorce Conflicts and Their Positioning of Children

ABSTRACT This qualitative study aims to explore how fathers in prolonged post-divorce conflict construct their parenting agency and position their child in relation to their view of conflict-related threats. Eight divorced fathers were interviewed, with experience of, on average, seven years of high conflict after separation. A reflective thematic design supplemented with positioning theory was used to analyze the fathers’ responses. Drawing on positioning theory, the fathers’ agency emerged in the analyses from three dominant storylines or world manifestations of post-divorce dangers. Fathers either acted as (1) heroic saviors in a polluted realm storyline where they positioned their children as victims that need to be saved from the dangers of impurity, (2) jungle guides in the wild nature storyline where they positioned their children as trainees of survival skills to deal with intrusive events and ever present post-divorce dangers, or (3) beacons in a foggy moor storyline where they re-positioned their own behavior to follow a self-clarifying routine so that their children would experience life in a less ambivalent, foggy and insecure manner. We argue that researchers and therapists would benefit from knowledge that captures the moral underpinnings of fathers’ agency.

A Privacy-Preserving-Based Secure Framework Using Blockchain-Enabled Deep-Learning in Cooperative Intelligent Transport System

Cooperative Intelligent Transport System (C-ITS) is a promising technology that aims to improve the traditional transport management systems. In C-ITS infrastructure Autonomous Vehicles (AVs) communicate wirelessly with other AVs, Road Side Units (RSUs) and Traffic Command Centres (TCCs) using an open channel Internet. However, the use of the Internet brings inherent vulnerabilities related to privacy (e.g., adversary performing inference and data poisoning attacks), and security (e.g., AVs can be compromised using advanced hacking techniques) issues and prevents the faster realization of C-ITS applications. To address these challenges, this paper presents a privacy-preserving-based secure framework to provide both privacy and security in C-ITS infrastructure. The proposed framework provides two level of security and privacy using blockchain and deep learning modules. First, a blockchain module is designed to securely transmit the C-ITS data between AVs–RSUs-TCCs, and a smart contract-based enhanced Proof of Work (ePoW) technique is designed to verify data integrity and mitigate data poisoning attacks. Second, a deep-learning module is designed that includes Long-Short Term Memory-AutoEncoder (LSTM-AE) technique for encoding C-ITS data into a new format to prevent inference attacks. The encoded data is used by the proposed Attention-based Recurrent Neural Network (A-RNN), for intrusive events recognition in C-ITS infrastructure. The proposed A-RNN is trained using Truncated Backpropagation Through Time (BPTT) algorithm. The framework is further validated and tested using two publicly available ToN-IoT and CICIDS-2017 datasets. The proposed framework is compared with peer privacy-preserving intrusion detection techniques, and the result shows the effectiveness of the proposed framework over several state-of-the-art techniques in both blockchain and non-blockchain systems.

Data-Driven Dynamic Simulations of Gold Extraction Which Incorporate Head Grade Distribution Statistics

The Alhué mining district, Chile, is an example of a high-grade Au-Ag-Zn(-Pb) deposit with mineralized veins that contain variable amounts of copper sulfides, which are detrimental to the cyanidation process. Similar deposits can be found in the central zone of Chile, with polymetallic veins (Au, Ag, Cu, Pb, and Zn) that are related to subvolcanic intrusive events, the development of collapse calderas, and extensive hydrothermal alteration, such as Bronces de Petorca, the Chancón mining district and Cerro Cantillana; areas of the world with similar formations include the western United States and the Henan Province in central China, for example. Mineralogical variation can be managed within the metallurgical process by alternating its operational modes. The decision to switch between modes is governed by current and forecasted stockpile levels feeding into the process, according to a discrete rate simulation (DRS) framework that has now been developed to incorporate head grade data for gold. Customized simulations that incorporate probability distribution models using head grade have now been developed, following a statistical analysis based on data from the Alhué district. This study applies data-driven simulation modeling to represent standardized operational modes and their impact on the operational performance of gold extraction.

Detrital zircon ages from Archaean conglomerates in the Singhbhum Craton, eastern India: implications on economic Au-U potential

New U–Pb age and Hf isotope data obtained on detrital zircon grains from Au- and U-bearing Archaean quartz-pebble conglomerates in the Singhbhum Craton, eastern India, specifically the Upper Iron Ore Group in the Badampahar Greenstone Belt and the Phuljhari Formation below the Dhanjori Group provide insights into the zircon provenance and maximum age of sediment deposition. The most concordant, least disturbed 207Pb/206Pb ages cover the entire range of known magmatic and higher grade metamorphic events in the craton from 3.48 to 3.06 Ga and show a broad maximum between 3.38 and 3.18 Ga. This overlap is also mimicked by Lu–Hf isotope analyses, which returned a wide range in εHf(t) values from + 6 to − 5, in agreement with the range known from zircon grains in igneous and metamorphic rocks in the Singhbhum Craton. A smaller but distinct age peak centred at 3.06 Ga corresponds to the age of the last major magmatic intrusive event, the emplacement of the Mayurbhanj Granite and associated gabbro, picrite and anorthosite. Thus, these intrusive rocks must form a basement rather than being intrusive into the studied conglomerates as previously interpreted. The corresponding detrital zircon grains all have a subchondritic Hf isotopic composition. The youngest reliable zircon ages of 3.03 Ga in the case of the basal Upper Iron Ore Group in the east of the craton and 3.00 Ga for the Phuljhari Formation set an upper limit on the age of conglomerate sedimentation. Previously published detrital zircon age data from similarly Au-bearing conglomerates in the Mahagiri Quartzite in the Upper Iron Ore Group in the south of the craton gave a somewhat younger maximum age of sedimentation of 2.91 Ga. There, the lower limit on sedimentation is given by an intrusive relationship with a c. 2.8 Ga granite. The time window thus defined for conglomerate deposition on the Singhbhum Craton is almost identical to the age span established for the, in places, Au- and U-rich conglomerates in the Kaapvaal Craton of South Africa: the 2.98–2.78 Ga Dominion Group and Witwatersrand Supergroup in South Africa. Since the recognition of first major concentration of gold on Earth’s surface by microbial activity having taken place at around 2.9 Ga, independent of the nature of the hinterland, the above similarity in age substantially increases the potential for discovering Witwatersrand-type gold and/or uranium deposits on the Singhbhum Craton. Further age constraints are needed there, however, to distinguish between supposedly less fertile (with respect to Au) > 2.9 Ga and more fertile < 2.9 Ga successions.

Internal igneous growth, doming and rapid erosion of a mature ocean island: the Miocene evolution of Maio (Cabo Verde)

Maio Island (Cabo Verde Archipelago) is composed of uplifted Early Mesozoic MORB-type pillow lavas and deep-sea sediments, unconformably overlain and intruded by Miocene igneous rocks. Combined structural analyses and 40Ar–39Ar dating were used to constrain the Miocene evolution of Maio. Structures and ages of uplifted Mesozoic sequences and crosscutting Miocene dykes showed that numerous intrusive events were associated with the intense growth of an igneous core complex in the middle to upper crust, causing semi-circular doming and partial disruption of the Mesozoic strata. Two nosean nephelinite dykes cut the Valanginian Batalha Formation and yielded phlogopite 40Ar–39Ar ages of 10.405 ± 0.033 Ma and 10.570 ± 0.053 Ma (2σ errors). A nosean nephelinite dyke that cuts the overlying Valanginian to Early Aptian Morro Formation yielded an age of 9.273 ± 0.020 Ma. Combined with existing K–Ar and 40Ar–39Ar ages, this confirmed a main period of island growth between ~ 16 and 8.7 Ma. We re-interpreted extensive polymict conglomerates, which occur below the Late Miocene Monte Penoso Formation, as landslide deposits. A nephelinite lava clast yielded a phlogopite 40Ar–39Ar age of 8.666 ± 0.0274 Ma, which represents a maximum age for these landslides and thus confined a period of large-scale flank collapses and erosion to between 8.7 and 6.7 Ma. Flank collapses and further mass wasting during this period may have rejuvenated the igneous activity, i.e., resulting in the formation of the Tortonian/Messinian Monte Penoso and Malhada Pedra Formations, due to decompression-induced melting at upper mantle depths. Such interaction between flank collapses and rejuvenated volcanism may be a key to better understand ocean island evolution worldwide.

Out of the blue: on the suddenness of perceived chance events

People commonly use terms like ‘random’, ‘by chance’, or ‘accidentally’ when they describe occurrences that sidestep the normal course of events, with no apparent causal link to ongoing activities. Such intrusive events are typically perceived as happening all of a sudden. This was demonstrated in seven experiments (N = 1299) by asking people to identify statements they believed belonged to stories about chance events, and by comparing chance vs. non-chance events from their own life and from the lives of others. Suddenness also appeared to be more strongly associated with beginnings than with endings of an episode. Thus, statements about sudden beginnings of a career or a relationship were more readily believed to happen ‘by chance’ than ‘not by chance’. But life-changing events did not become more accidental simply by being placed in the beginning of a ‘life chapter’. These studies highlight a central but neglected feature of perceived randomness.

Separation Fear: An Integral Feature of the Complex Trauma Syndrome in War-Refugees

Feelings of uncertainty after traumatic event (i.e., forcefully leaving living place) is a common cause of severe fear (anxiety) which may contribute to development of complex trauma syndrome. Traumatic injuries of such depleted individual&amp;rsquo;s sense of aliveness might be quite catastrophic causing a perception that one&amp;rsquo;s identity, togetherness and wholeness is lost forever. In such situation, the individual&amp;rsquo;s response may lead to a cascade of the events which may result in severe symptoms of the hyperarousal, dissociation, depersonalisation, detachment, recollection of the intrusive events, and avoidance of reminder.&#x0D; Separation fear (anxiety) among war-refugees is a broader condition than it is defined as the anxiety disorder in which dominant features are excessive and inappropriate anxiety of the separation from primary attachment figure(s). In war-refugees, the clinical manifestations are realistic worries about harmful things which may happen to the attachment figure(s) who are left behind &amp;ndash; condition of persistent fears for loved ones of being killed, tortured, and possible lost forever.

The Karavansalija Mineralized Center at the Rogozna Mountains in SW Serbia: Magma Evolution and Time Relationship of Intrusive Events and Skarn Au ± Cu–Pb–Zn Mineralization

The Karavansalija Mineralized Center (KMC) with its Au–Cu skarn mineralization associated with the Rogozna Mountains magmatic suite in southwestern Serbia belongs to the Oligocene Serbo-Macedonian magmatic and metallogenic belt (SMM-MB). Samples from intrusive and volcanic rocks at the KMC show typical arc signatures of subduction-derived magmas through enrichment in large-ion lithophile elements (LILE) and depletion of high–field strength elements (HFSE). The magmas developed a high-K (calc-alkaline) fractionation trend and evolved toward shoshonitic compositions. Whole-rock trace element data suggest plagioclase-absent, high-pressure amphibole ± garnet fractionation that generates adakite-like hydrous magmas during evolution in lower crustal magma chambers. Zircon LA–ICP–MS and high-precision CA–ID–TIMS dating together with zircon trace elements and Hf isotope measurements were carried out in order to couple the geochronologic and geochemical evolution of the KMC. The results suggest that magmatism starts around 29.34 Ma with granitic to rhyodacitic subvolcanic intrusions followed by a more evolved magmatic intrusion that was emplaced into Cretaceous limestone, generating a widespread skarn alteration at ca. 28.96 Ma. After a period of quiescence of about 1.2 My, either another magma body evolved or the same upper crustal magma chamber was recharged and also likely partly reactivated older plutonic rocks as indicated by xenocrysts. The REE ratios shift from apatite, titanite ± amphibole-dominated fractionation of the older magmatic event to crystallization of allanite, efficiently depleting the LREE and Th/U in the younger upper crustal magma. After a lamproite-like melt was injected, the increased heat and fluid pressure led to the expulsion of a quartz-monzonite porphyritic stock at ca. 27.72 Ma, strongly interacting with the skarns and established a fertile hydrothermal system. Soon after a non-mineralized second pulse of some porphyry dykes cut the previous phenocryst-rich “crowded” porphyries and skarns at ca. 27.60 Ma, thus bracketing the maximum timespan of ore mineralization to about 112 ± 45 Ka. Increased contribution of a lamproite-like melt is inferred from the presence of phlogopite micro-phenocrysts, phlogopitization of biotite, and diopside clusters in the latest porphyry dykes. There is a trend of increased crustal assimilation from the oldest volcanic phase to the emplacement of the youngest porphyry dykes recorded by ɛ-Hf of the zircons. Oligocene occurrences of significant base metal mineralization within Serbia, northern Macedonia, and Greece, e.g., Crnac, Rudnik, Veliki Majdan, Stratoniu, or the Cu–Au porphyry at Buchim (northern Macedonia), are all associated with trachy-andesitic (quartz latitic) porphyry dykes, which originated through post-collisional tectonic settings or upper plate extension involving reworking of crustal arc-derived rocks and partial melting of the mantle wedge. This study demonstrates that on the basis of field relationships and the application of high-precision CA-ID-TIMS zircon age data, pulses of porphyry dykes of a 10ka age range can be distinguished, and the timing of mineralization can be parenthized.