POSSIBLE INFLUENCE OF A MAJOR INFERRED FAULT ON THE OCCURRENCE OF SINISTRAL TOP-TO-THE NW DEFORMATION IN THE ZAGROS HINTERLAND FOLD-AND-THRUST BELT, IRAN

In the present study, fault slip data, the geometry of en-echelon vein arrays (tension gash), and pressure-solution seams (stylolites), in the northeastern margin of Fars Province were analyzed. The results of this study indicate that in the time of the development of these structures, the maximum principal (σ1) stress axes were generally horizontal and directed towards NE-SW and ENE-WSW. This general direction is compatible with the expected directions of σ1 stress axes responsible for the occurrence of the sinistral top-to-the NW ductile and brittle-ductile shear zones of the area. This compatibility suggests a long-lasting stable stress condition over a long period and different pressure/temperature conditions. This longstanding constant stress state can be interpreted as the result of the occurrence of a major strike-slip NW-SE trending fault in the NE of the Zagros Hinterland Fold-and-Thrust Belt. The dextral activities of the Main Zagros Thrust and this inferred fault, which are subparallel, might result in the sinistral topto-the NW deformation in the area between this fault, which we named it Abarkuh Fault and the Main Deep Fault. This inferred fault has been covered by Quaternary alluvium of the Abarkuh plain, but the great age difference of rock units of the Esteghlal Anticline and its northeastern rock exposures, and the significant change in topography between the Abarkuh plain and its southwestern mountains can be two consequences of the existence of this probable fault.

Nonrigid Bookshelf Kinematics of Northeastern Tibet: Constrains from Fault Slip Rates around the Qinghai Lake and Chaka-Gonghe Basins

The Elashan fault (ELSF) and Qinghainanshan fault (QHNF), two major faults developed around the Qinghai Lake and Chaka-Gonghe basins, are of great importance for investigating the deformation model of the internal northeastern Tibetan Plateau. However, their late Pleistocene slip rates remain poorly constrained. In this study, we combine high-resolution topography acquired from unmanned aerial vehicles (UAV) and geomorphological dating to calculate the slip rates of the two faults. We visited the central ELSF and western QHNF and measured displaced terraces and stream channels. We collected 10Be samples on the surface of terraces to constrain the abandonment ages. The dextral slip rate of the central segment of the Elashan fault is estimated to be 2.6±1.2 mm/yr. The uplift rates since the late Pleistocene of the Elashan and Qinghainanshan faults are 0.4±0.04 mm/yr and 0.2±0.03 mm/yr, respectively. Comparing the geological rates with the newly published global positioning system (GPS) rates, we find that the slip rates of the major strike-slip faults around the Qinghai Lake and Chaka-Gonghe basins are approximately consistent from the late Pleistocene to the present day. The overall NE shortening rates by summing up the geological slip rates on major faults between the East Kunlun and Haiyuan faults are ~3.4 mm/yr, smaller than the geodetic shortening rates (~4.9 to 6.4 mm/yr), indicating that distributed deformation plays an important role in accommodating the regional deformation. By analyzing the geometrical and kinematic characteristics of the major faults surrounding the basins, we suggest that the kinematic deformation of the internal northeastern Tibet is a nonrigid bookshelf model that consists of counterclockwise rotation (~0.8° Myr-1) and distributed thrusting.

Mid-Ordovician subduction, obduction, and eduction in western Newfoundland; an eclogite problem

The narrow, short-lived Taconic-Grampian Orogen occurs along the north-western margin of the Appalachian-Caledonian Belt from, at least, Alabama to Scotland, a result of the collision of a series of early Ordovician oceanic island arcs with the rifted margin of Laurentia. The present distribution of Taconian-Grampian ophiolites is unlikely to represent a single fore-arc from Alabama to Scotland colliding at the same time with the continental margin along its whole length; more likely is that there were several Ordovician arcs with separate ophiolites. The collision suture is at the thrust base of obducted fore-arc ophiolite complexes, and obduction distance was about two hundred kilometres. Footwalls to the ophiolites are, sequentially towards the continent, continental margin rift sediments and volcanics and overlying rise sediments, continental shelf slope carbonates, and sediments of foreland flexural basins. The regionally-flat obduction thrust complex between the ophiolite and the rifted Laurentian margin is the collision suture between arc and continent. A particular problem in drawing tectonic profiles across the Taconic-Grampian Zone is several orogen-parallel major strike-slip faults, both sinistral and dextral, of unknown displacements, which may juxtapose portions of different segments. In western Newfoundland, most of the Grenville basement beneath the Fleur-de-Lys metamorphic complex (Neoproterozoic to early Ordovician meta-sediments) was eclogitised during the Taconic Orogeny and separated by a massive shear zone from the overlying Fleur-de-Lys, which was metamorphosed at the same time but in the amphibolite facies. The shear zone continued either to a distal intracontinental “subduction zone” or to the main, sub-fore-arc, subduction zone beneath which the basement slipped down to depths of up to seventy kilometres at the same time as the ophiolite sheet and its previously-subcreted metamorphic sole were being obducted above. Subsequently, the eclogitised basement was returned to contact with the amphibolite-facies cover by extensional detachment eduction, possibly enhanced by subduction channel flow, which may have been caused by slab break-off and extension during subduction polarity flip. Although the basal ophiolite obduction thrust complex and the Fleur-de-Lys-basement subduction-eduction surfaces must have been initially gently-dipping to sub-horizontal, they were folded and broken by thrusts during late Taconian, late Ordovician Salinic-Mayoian, and Acadian shortening.

Three-dimensional imaging of the Mérida Andes, Venezuela

<p>The Mérida Andes are a 100 km wide mountain chain that extends from the Colombian/Venezuelan border to the Caribbean coast. To the north and south, the Mérida Andes are bound by hydrocarbon-rich sedimentary basins. Uplift of the mountains started in the late Miocene due to oblique convergence of the Caribbean and South American tectonic plates and the north-eastwards expulsion of the North Andean Block (NAB). This tectonic interaction fostered major strike-slip fault systems, with associated high seismicity, and the partitioning of the North Andean Block into smaller tectonic units, whose interaction accelerated the uplift of the Mérida Andes since the Plio-Pleistocene.</p><p>We present the three-dimensional inversion results of broadband magnetotelluric (MT) data from 72 sites gathered along a 240 km long profile across the central part of the MA, the Maracaibo (MB), and Barinas-Apure (BAB) foreland basins. Directionality and dimensionality analyses suggested 3D structures for the MA section, with the induction vectors indicating off-profile structures, particularly at long periods. Since the distribution of sites predominantly along a single profile can have adverse effects on the outcome of the 3D inversion, we rigorously tested all model features for robustness and excluded artefacts.</p><p>One of the main findings is a deep connection (> 10km) between the most prominent faults of the MA, the Valera and Boconó fault systems, with a deep off-profile conductor to the east of our profile. We interpret this conductive structure as a detachment surface of the Trujillo Block, which is part of the NAB and whose expulsion to the NE significantly influences the present-day geodynamic evolution of western Venezuela. A conductive zone under the Maracaibo Basin correlates spatially with the location of a Bouguer low. Both geophysical anomalies may be caused by a SE tilt of the Maracaibo Triangular Block under the Mérida Andes, bound by the north-western thrust system which could reach depths of 30 km.</p>

New insights into the crustal architecture and tectonic evolution of the Eastern Gulf of Mexico.

<p>The Gulf of Mexico is an intraplate oceanic basin where rifting started in the Late Triassic, leading to drifting by Middle Jurassic and ensuing oceanic accretion, which ceased by the Early Cretaceous. Its tectonic evolution encompasses multiple rifting phases dominated by orthogonal extension, major strike-slip structures, transtensional basins, variable magmatism, and salt deposition. This complex tectonic history is captured in the rifted margins of the Gulf of Mexico, especially along the eastern part of the basin; where considerable debate remains regarding the crustal configuration and tectonic evolution.</p><p>This study presents new insights into the crustal types and an updated tectonic framework for the Florida margin. An integrated analysis of seismic, gravity, and magnetic data allows us to characterise the continental crust, which shows wide zones of hyperextension that we relate to pull-apart basins, magmatic underplating, seaward dipping reflection (SDR) packages, and a narrow zone of exhumed mantle. In addition, we identified NW-SE trending sinistral strike-slip faults altering the typical crustal configuration expected in a rifted margin.</p><p>Our results suggest the need for a new plate model of the Florida margin at the Eastern Gulf of Mexico that invokes the polyphase rifting, accounts for the Yucatan’s block counter-clockwise rotation, explains the increase in magma supply, and captures the influence of strike-slip faults on the crustal boundaries and the magmatic budget.    </p>

Seismic event stratigraphy of tectonic Lake Towuti, Sulawesi, Indonesia: a 15 kyrs record of seismo-turbidites

<p>Located at the triple junction of the Pacific, Eurasian and Sunda plates, the island of Sulawesi in Indonesia is one of the most tectonically active places on Earth. This is highlighted by the recurrence of devastating earthquakes such as the 2018 Mw 7.5 earthquake that destroyed the city of Palu and caused several thousand deaths in central Sulawesi. The majority of large magnitude earthquakes on Sulawesi are related to stress release along major strike-slip faults such as the Palu-Koro fault and its southern extensions the Matano and Lawanopo faults. To date, information on the frequency and magnitude of major events on these faults is limited to instrumental records, whereas information from historical sources and natural archives is completely lacking. Considering the increase in population density and its extension into distant areas, it is important to better quantify the seismic hazard. Therefore, a systemic catalogue of past earthquakes is essential for the understanding of tectonic dynamics of the area.</p><p>            Lake Towuti, situated in Eastern Sulawesi, is a key site to study the paleoseismology on the island. The lake lies close to the Matano strike-slip fault and is hence an ideal archive for past earthquakes that have occurred in the surrounding area. Moreover, its morphology allows a temporally continuous sedimentary succession. The large and deep central basins of the lake preserve the deposits linked to seismic activity. We combine high-resolution Chirp seismic data with sedimentary analyses of sediment piston cores to assess the recurrence of major earthquakes (Mw > 6) in the area, which are expressed by earthquake-triggered Mass Wasting Deposits (MWD). Five major seismic-stratigraphic units are identified in the upper 200 milliseconds TWT and show different depositional mechanisms. MWD’s and associated seismoturbidites can be easily distinguished in seismic data and are well preserved in the cored sedimentary successions in the topmost Unit 1.1. Chronologically Unit 1.1 covers the last 15 kyrs and enables the establishment of an event chronostratigraphy for Lake Towuti’s recent past. The most recent MWD likely corresponds to an AD 1924 Mw 6.5 earthquake, which was recorded to the south of Lake Towuti. In addition, 11 seismoturbidites have been observed in the Late Glacial to Holocene (~15 kyrs) sediment succession. These results tentatively suggest an average recurrence of major events every 1300 to 1400 years.</p>

From moderate earthquakes to continuous aseismic slip, a variety of ways to release strain along the Chaman fault (Pakistan, Afghanistan).

<p>Surface fault slip can be continuously monitored at fine spatial resolution from space using InSAR. Based on 5 years of observations (2014-2019), we describe and interpret the InSAR time series of deformation around the Chaman fault, a major strike-slip fault along the boundary between the Indian and Eurasian plates. Aseismic slip was observed on two >100 km long segments, reaching a maximum of 1 cm/yr. In between, a fault segment delimited by a restraining and releasing bend in the fault trace hosted three M<sub>b</sub> 4.2, M<sub>w</sub> 5.1 and M<sub>w</sub> 5.6 earthquakes in our observation period. These earthquakes were followed by significant postseismic slip with characteristic duration between 1.5 to 3 years. Postseismic to coseismic surface slip ratios reach at least 0.6-1.2. In addition, aseismic slip was observed in close spatio-temporal relationship with those earthquakes. Finally, we argue that we detect numerous micro-slip events of M<sub>w</sub><3, although with large uncertainty. We provide an extensive description of the various modes of slip along this plate boundary fault and discuss the mechanical implications of such entangled behavior.<span> </span></p>

The level playing field of Hungarian social partners before and during the COVID-19 pandemic : Case studies from the automotive industry

For numerous reasons, social dialogue in Hungary generally does not fulfil its role on the national, sectoral, or workplace level. Social dialogue as a democratic process is dysfunctional, since its institutions and mechanisms are not implemented democratically, and no real dialogue or actual debate take place. Instead, these mechanisms work in a top-down manner – the illiberal state and its central governing bodies expect certain solutions and answers, leaving no scope for transparent democratic dialogue with the relevant social partners. Against this background, in 2019 major strike activity was witnessed in the automotive sector. However, in 2020, after the COVID-19 pandemic, the Hungarian government deployed its full power by adopting the ‘Authorization Act,’ which allowed the government to introduce significant restrictions, practically without any time limits, any debate in parliament, or guarantee of swift and effective constitutional review. Our research paper investigates these recent developments in social dialogue using a case study, with the aim of understanding the forces underlying the collective action organized in the automotive sector. Our research demonstrates that, due to the lack of institutional guarantees, social dialogue is very fragile in Hungary, and the landslide victory in 2019 was a mere reflection of labour shortages. Our mixed methodology – which combines legal and sociological approaches – is suitable for examining this complex issue; interviews conducted with representatives of labour and employers provide deep insight into motives and action in a circumvented level playing field.

PARTICIPATION OF DANYLO SHUMUK IN THE NORILSK UPRISING

The Norilsk uprising was a major strike by Gulag inmates in Gorlag, a special camp mostly for political prisoners, in the summer of 1953, shortly after Joseph Stalin’s death. About 70% of inmates were Ukrainians, many of whom had been sentenced for 25 years to the so-called «Bandera Standard». It was the first major revolt within the Gulag system in 1953-1954. Between May 26 and August 4, 1953, the inmates of the Gorlag-Main camp went on strike, which lasted 69 days. This was the longest uprising in the history of the Gulag. The preconditions for the uprising can be seen as the following: the arrival of waves of prisoners to the Gorlag, who had participated in the uprisings of 1952, the death of Stalin on March 5, 1953 and the fact that the amnesty that followed his death only applied to (non-political) criminals and convicts with short prison terms, the percentage of which was very low in Gorlag. All categories of inmates took part in the uprising, with the leading roles played by former military men and participants of national liberation movements of western Ukraine, Georgia and the Baltics. Norilsk uprising combined various forms of protest – hunger strike, resignation, riot, armed uprising. One of the leaders of the uprising was Danylo Shumuk, a former employee of one of the UPA’s political divisions. The article describes the participation of a Ukrainian political prisoner, a participant in the national liberation movement in Volyn during World War II, Danylo Shumuk in the organization of the Norilsk Uprising of Political Prisoners (June-August 1953). The process of creating a conspiratorial formation by an activist – a «Selfhelp organization», the goals, composition, methods of activity of its members, the relationship between them are shown. On the basis of domestic and foreign sources, the forms of protest of prisoners and their demands were analyzed. The main results of the struggle of political prisoners and their future fate are highlighted. It is evidence-based the Ukrainian central role in Norilsk uprising, which was one of the strongest in the history of the Gulag, and resulted its reformation.