The evolving paleobathymetry of the circum-Antarctic Southern Ocean since 34 Ma – A key to understanding past cryosphere-ocean developments

The Southern Ocean is a key player in the climate, ocean and atmospheric system. As the only direct connection between all three major oceans since the opening of the Southern Ocean gateways, the development of the Southern Ocean and its relationship with the Antarctic cryosphere has influenced the climate of the entire planet. Although the depths of the ocean floor have been recognized as an important factor in climate and paleoclimate models, appropriate paleobathymetric models including a detailed analysis of the sediment cover are not available. Here, we utilize more than 40 years of seismic reflection data acquisition along the margins of Antarctica and its conjugate margins, along with multiple drilling campaigns by the International Ocean Discovery Program (IODP) and its predecessor programs. We combine and update the seismic stratigraphy across the regions of the Southern Ocean and calculate ocean-wide paleobathymetry grids via a backstripping method. We present a suite of high-resolution paleobathymetric grids from the Eocene-Oligocene Boundary to modern times. The grids reveal the development of the Southern Ocean from isolated basins to an interconnected ocean affected by the onset and vigor of an Antarctic Circumpolar Current, as well as the glacial sedimentation and erosion of the Antarctic continent. The ocean-wide comparison through time exposes patterns of ice sheet development such as switching of glacial outlets and the change from wet-based to dry-based ice sheets. Ocean currents and bottom-water production interact with the sedimentation along the continental shelf and slope and profit from the opening of the ocean gateways

Tectonic evolution of the Eastern Moroccan Meseta: from Late Devonian fore‐arc sedimentation to Early Carboniferous collision of an Avalonian promontory

This study was founded by the Ministerio de Economia y Competitividad (MINECO) of Spain through the project PANGEATOR (CGL2015-71692-P) and the Doctoral scholarship BES-2016-078168. GeoHistory Facility instruments were funded via an Australian Geophysical Observing System grant provided to AuScope Pty Ltd. by the AQ44 Australian Education Investment Fund program. The NPII multicollector was obtained via funding from the Australian Research Council LIEF program (LE150100013). The authors want to express their gratitude to Dr. Manuel Francisco Pereira (University of Evora, Portugal) and Dr. Michel Villeneuve (Centre Europeen de Recherche et d'Enseignement des Geosciences de l'Environnement, France) for their constructive reviews that helped to improve the quality of the original manuscript. Special thanks to Brad McDonald (Curtin University, Australia) for technical assistance regarding LA-ICPMS and Hf analyses, Profs. Abdelfatah Tahiri (University Mohammed V of Rabat, Morocco) and Hassan El Hadi (University Hassan II of Casablanca, Morocco) for their support during field work, Prof. Yvette Kuiper (Colorado School of Mines, USA) for her precious hints about the interpretation of Hf data, and Dr. Lorenzo Valetti for proofreading the manuscript. Supporting information can be obtained in Mendeley Data: https://doi.org/10.17632/b8fdbykmbx.1 (https://data.mendeley.com/datasets/b8fdbykmbx/draft?a=eaae2da0-8e224056-861b-4824984f1c10).The deformed Paleozoic succession of the Eastern Moroccan Meseta crops out in relativelysmall and isolated inliers surrounded by Mesozoic and Cenozoic rocks. Two of the largest inliers(Mekkam and Debdou) are characterized by a monotonous succession of slates and greywackes affected bypolyphasic folding that occurred at low‐to very low grade metamorphic conditions. New U‐Pb ages ondetrital zircon grains from the Debdou‐Mekkam metasediments constrain the maximal depositional age asLate Devonian, interpreted to be close to the true sedimentation age. Furthermore, theεHfvalues of theDevonian detrital zircons, together with the presence of a series of scattered zircon grains with ages betweenc. 0.9 and c. 1.9 Ga, suggest provenance from a subduction‐related magmatic arc located on the Avalonianmargin. The Debdou‐Mekkam massif is characterized by an Early Carboniferousfirst deformationalevent (D1), which gave way to a pervasive cleavage (S1) associated with plurikilometric‐scale, tight toisoclinal, overturned to recumbent folds. Later events (Dc) occurred at Late Carboniferous time andgenerated variably developed crenulation cleavages (Sc) associated with variously oriented metric‐tokilometric‐scale folds, which complicate the pattern of both D1 intersection lineations (L1) and axial traces.The restoration of this pronounced curved pattern yields originally SW‐NE‐oriented D1 fold axes withregional SE‐vergence. This important Early Carboniferous shortening and SE‐directed tectonic transport canbe explained by closure of the Rheic Ocean and thefirst phases of the collision between the northern passivemargin of Gondwana and an Avalonian promontory.Ministerio de Economia y Competitividad (MINECO) of Spain CGL2015-71692-P BES-2016-078168Australian Geophysical Observing SystemAustralian Education Investment Fund program AQ44Australian Research Council LE15010001

Mantle Flow and Deforming Continents: From India-Asia Convergence to Pacific Subduction

The formation of mountain belts or rift zones is commonly attributed to interactions between plates along their boundaries, but the widely distributed deformation of Asia from Himalaya to the Japan Sea and other back-arc basins is difficult to reconcile with this notion. Through comparison of the tectonic and kinematic records of the last 50 Ma with seismic tomography and anisotropy models, we show that the closure of the former Tethys Ocean and the extensional deformation of East Asia can be best explained if the asthenospheric mantle transporting India northward, forming the Himalaya and the Tibetan Plateau, reaches East Asia where it overrides the westward flowing Pacific mantle and contributes to subduction dynamics, distributing extensional deformation over a 3,000-km wide region. This deep asthenospheric flow partly controls the compressional stresses transmitted through the continent-continent collision, driving crustal thickening below the Himalayas and Tibet and the propagation of strike-slip faults across Asian lithosphere further north and east, as well as with the lithospheric and crustal flow powered by slab retreat east of the collision zone below East and SE Asia. The main shortening direction in the deforming continent between the collision zone and the Pacific subduction zones may in this case be a proxy for the direction of flow in the asthenosphere underneath, which may become a useful tool for studying mantle flow in the distant past. Our model of the India-Asia collision emphasizes the role of asthenospheric flow underneath continents and may offer alternative ways of understanding tectonic processes

Сучасний стан і проблеми управління залізничним транспортом України

Проаналізовано стан і тенденції розвитку залізничного транспорту. Розглянуті основні завдання державного регулювання галузі.Проанализировано состояние и тенденции развития железнодорожного транспорта. Рассмотренны основные задания государственного регулирования отрасли.The condition and trends of railway transport has been anilized. The main tasks of state regulation of railway transport has been considereted

Geomagnetism, Paleomagnetism and Electromagnetism Perspectives on Integrated, Coordinated, Open, Networked (ICON) Science

This article is composed of three independent commentaries about the state of Integrated, Coordinated, Open, Networked (ICON) principles (Goldman et al., 2021, https://doi.org/10.1002/essoar.10508554.1) in the Geomagnetism, Paleomagnetism, and Electromagnetism (GPE) section and discussion on the opportunities and challenges of adopting them. Each commentary focuses on a different topic: Global collaboration, reproducibility, data sharing and infrastructure; Inclusive equitable, and accessible science: Involvement, challenges, and support of early career, BIPOC, women, LGBTQIA+, and/or disabled researchers; Community engagement, citizen science, education, and stakeholder involvement. Data sharing practices and open repository use still varies strongly between GPE communities. Some have a long tradition of data sharing; others are only starting it. Globally, GPE leadership is strongly dominated by white males and diversity may increase through the creation of Science Equality Commissions. Improved global stakeholder involvement can increase research impacts and help fight inequalities. In all investigated topics we see promising beginnings but also recognize obstacles that include a lack of funding, a lack of understanding of diversity, and prioritizing short-term gain over long-term benefit. Nonetheless, we are hopeful that our community will embrace ICON science

High-K volcanism in the Afyon region, western Turkey: from Si-oversaturated to Si-undersaturated volcanism

Volcanic rocks of the Afyon province (eastern part of western Anatolia) make up a multistage potassic and ultrapotassic alkaline series dated from 14 to 12 Ma. The early-stage Si-oversaturated volcanic rocks around the Afyon city and further southward are trachyandesitic volcanic activity (14.23 ± 0.09 Ma). Late-stage Si-undersaturated volcanism in the southernmost part of the Afyon volcanic province took place in three episodes inferred from their stratigraphic relationships and ages. Melilite– leucitites (11.50 ± 0.03 Ma), spotted rachyandesites, tephryphonolites and lamproites (11.91 ± 0.13 Ma) formed in the first episode; trachyandesites in the second episode and finally phonotephrites, phonolite, basaltic trachyandesites and nosean-bearing trachyandesites during the last episode. The parameter Q [normative q-(ne + lc + kls + ol)] of western Anatolia volcanism clearly decreased southward with time becoming zero in the time interval 10–15 Ma. The magmatism experienced a sudden change in the extent of Si saturation after 14 Ma, during late-stage volcanic activity of Afyon volcanic province at around 12 Ma, though there was some coexistence of Si-oversaturated and Si-undersaturated magmas during the whole life of Afyon volcanic province

Tsunami hazards in the Catalan Coast, a low-intensity seismic activity area

The final publication is available at Springer via http://dx.doi.org/10.1007/s11069-017-2918-zThe potential impacts of tsunamis along the Catalan Coast (NW Mediterranean) are analysed using numerical modelling. The region is characterized by moderate to low seismic activity and by moderate- to low-magnitude earthquakes. However, the occurrence of historical strong earthquakes and the location of several active offshore faults in front of the coast suggest that the possibility of an earthquake-triggered tsunami is not negligible although of low probability. Up to five faults have been identified to generate tsunamis, being the highest associated possible seismic magnitudes of up to 7.6. Coastal flooding and port agitation are characterized using the Worst-case Credible Tsunami Scenario Analysis approach. The results show a multiple fault source contribution to tsunami hazard. The shelf dimensions and the existence of submerged canyons control the tsunami propagation. In wide shelves, waves travelling offshore may become trapped by refraction causing the wave energy to reach the coastline at some distance from the origin. The free surface water elevation increases at the head of the canyons due to the sharp depth gradients. The effects of potential tsunamis would be very harmful in low-lying coastal stretches, such as deltas, with a high population concentration, assets and infrastructures. The Ebro delta appears to be the most exposed coast, and about the 20% of the delta surface is prone to flooding due to its extremely low-lying nature. The activity at Barcelona port will be severely affected by inflow backflow current at the entrance of up to 2 m/s.Peer ReviewedPostprint (author's final draft