The Trans-Hudson Orogen (THO) of North America and the

Himalayan Journal of Sciences, 2008

1] The Trans-Hudson Orogen (THO) of North America and the Himalaya-Karakoram-Tibetan Orogen (HKTO) of Asia preserve a Paleoproterozoic and Cenozoic record, respectively, of continentcontinent collision that is notably similar in scale, duration and character. In THO, the tectonothermal evolution of the lower plate involves (1) early thinskinned thrusting and Barrovian metamorphism, (2) out-of-sequence thrusting and high-T metamorphism, and (3) fluid-localized reequilibration, anatexis, and leucogranite formation. The crustal evolution of the Indian lower plate in HKTO involves (1) early subduction of continental crust to ultrahigh pressure (UHP) eclogite depths, (2) regional Barrovian metamorphism, and (3) widespread high-T metamorphism, anatexis, and leucogranite formation. The shallow depths of the high-T metamorphism in HKTO are consistent with early to mid-Miocene ductile flow of an Indian lower plate midcrustal channel, from beneath the southern Tibetan Plateau to the Greater Himalaya. Melt weakening of the lower plate in THO is not observed at a similar scale probably due to the paucity of pelitic lithologies. Tectonothermal events in the upper plate of both orogens include precollisional accretion of crustal blocks, emplacement of Andean-type plutonic suites, and high-T metamorphism. Syncollisional to postcollisional events include emplacement of garnet-biotite-muscovite leucogranites, anatectic granites, and sporadic metamorphism (up to 90 Myr following the onset of collision in THO). Comparing the type and duration of tectonothermal events for THO and HKTO supports the notion of tectonic uniformitarianism for at least the later half of dated Earth history and highlights the complementary nature of the rock record in an older ''exhumed'' orogen compared to one undergoing present-day orogenesis. Citation: St-Onge, M. R., M. P. Searle, and N. Wodicka (2006), Trans-Hudson Orogen of North America and Himalaya-Karakoram-Tibetan Orogen of Asia: Structural and thermal characteristics of the lower and upper plates, Tectonics, 25, TC4006,

Tectonics, 2006

1] The Trans-Hudson Orogen (THO) of North America and the Himalaya-Karakoram-Tibetan Orogen (HKTO) of Asia preserve a Paleoproterozoic and Cenozoic record, respectively, of continentcontinent collision that is notably similar in scale, duration and character. In THO, the tectonothermal evolution of the lower plate involves (1) early thinskinned thrusting and Barrovian metamorphism, (2) out-of-sequence thrusting and high-T metamorphism, and (3) fluid-localized reequilibration, anatexis, and leucogranite formation. The crustal evolution of the Indian lower plate in HKTO involves (1) early subduction of continental crust to ultrahigh pressure (UHP) eclogite depths, (2) regional Barrovian metamorphism, and (3) widespread high-T metamorphism, anatexis, and leucogranite formation. The shallow depths of the high-T metamorphism in HKTO are consistent with early to mid-Miocene ductile flow of an Indian lower plate midcrustal channel, from beneath the southern Tibetan Plateau to the Greater Himalaya. Melt weakening of the lower plate in THO is not observed at a similar scale probably due to the paucity of pelitic lithologies. Tectonothermal events in the upper plate of both orogens include precollisional accretion of crustal blocks, emplacement of Andean-type plutonic suites, and high-T metamorphism. Syncollisional to postcollisional events include emplacement of garnet-biotite-muscovite leucogranites, anatectic granites, and sporadic metamorphism (up to 90 Myr following the onset of collision in THO). Comparing the type and duration of tectonothermal events for THO and HKTO supports the notion of tectonic uniformitarianism for at least the later half of dated Earth history and highlights the complementary nature of the rock record in an older ''exhumed'' orogen compared to one undergoing present-day orogenesis. Citation: St-Onge, M. R., M. P. Searle, and N. Wodicka (2006), Trans-Hudson Orogen of North America and Himalaya-Karakoram-Tibetan Orogen of Asia: Structural and thermal characteristics of the lower and upper plates, Tectonics, 25, TC4006,

Tectonics, 2007

Canadian Journal of Earth Sciences, 2005

A summary and comparison of geophysical data and models for the Trans-Hudson Orogen in northern Manitoba and Saskatchewan are presented. Magnetic total field and Bouguer gravity maps are used to define the along-strike extension of geological domains of the orogen exposed on the Canadian Shield, and a two-dimensional density model is produced, which accounts for the observed variations of the Bouguer gravity field across the orogen. An 800-km-long crustal section across the entire continent-continent collision zone, including the edges of the bounding cratonic blocks, is presented. It incorporates seismic reflectivity, seismic velocities, resistivity, and density models. Key results include (1) evidence for west-vergent crustal stacking and exhumation in the eastern Trans-Hudson Orogen in the form of preserved Moho topography and the presence of higher grade (higher velocity) rocks in the hanging wall of an eastdipping crustal stack; (2) definition of the eastward extent of the Archean Sask craton in the subsurface based on distinct lower crustal properties; and 400 m of present-day surface topography and 6-8 km of relief on the Moho are isostatically compensated mainly within the upper mantle by a westward increase in upper mantle temperatures by 40-155°C and (or) 16-107 km of thinning of the mantle lithosphere. Résumé : Cet article présente un résumé et une comparaison des données géophysiques et des modèles de l'orogène trans-hudsonien au Manitoba et en Saskatchewan. Les cartes de champ magnétique total et les cartes gravimétriques de

Chatterjee, S., Goswami, A., and C.R. Scotese, 2013. The longest voyage: Tectonic, magmatic, and paleoclimatic evolution of the Indian plate during its northward flight from Gondwana to Asia, Gondwana Research, 23: 238-267. , 2013

2013.01 The tectonic evolution of the Indian Plate, which started in Late Jurassic about 167 million years ago (approximately 167Ma) with the breakup of Gondwana, presents an exceptional and intricate case history against which a variety of plate tectonic events such as: continental breakup, sea-floor spreading, birth of new oceans, flood basalt volcanism, hotspot tracks, transform faults, subduction, obduction, continental collision, accretion, and mountain building can be investigated. Plate tectonic maps are presented here illustrating the repeated rifting of the Indian plate from surrounding Gondwana continents, its northward migration, and its collision first with the Kohistan-Ladakh Arc at the Indus Suture Zone, and then with Tibet at the Shyok - Tsangpo Suture. The associations between flood basalts and the recurrent separation of the Indian plate from Gondwana are assessed. The breakup of India from Gondwana and the opening of the Indian Ocean is thought to have been caused by plate tectonic forces which were localized along zones of weakness caused by mantle plumes (Bouvet, Marion, Kerguelen, and Reunion Plumes). The sequential spreading of the Southwest Indian Ridge/Davie Ridge, Southeast Indian Ridge, Central Indian Ridge, Palitana Ridge, and Carlsberg Ridge in the Indian Ocean were responsible for the fragmentation of the Indian Plate during the Late Jurassic and Cretaceous times. The Reunion and the Kerguelen Plumes left two spectacular hotspot tracks on either side of the Indian Plate. With the breakup of Gondwana, India remained isolated as an island continent, but reestablished its biotic links with Africa during the Late Cretaceous during its collision with the Kohistan-Ladakh Arc ( approximately 85Ma) along the Indus Suture. Soon after the Deccan eruption, India drifted northward as an island continent by rapid motion carrying Gondwana biota, about 20cm/year, between 67Ma to 50Ma; it slowed down dramatically to 5cm/year during its collision with Asia in early Eocene (approximately 50Ma). A northern corridor was established between India and Asia soon after the collision allowing faunal interchange. This is reflected by mixed Gondwana and Eurasian elements in the fossil record preserved in several continental Eocene formations of India. A revised India-Asia collision model suggests that the Indus Suture represents the obduction zone between India and the Kohistan-Ladakh Arc, whereas the Shyok Suture represents the collision between the Kohistan-Ladakh Arc and Tibet. Eventually, the Indus-Tsangpo Zone became the locus of the final India-Asia collision, which probably began in early Eocene ( approximately 50Ma) with the closure of Neotethys Ocean. The post-collisional tectonics for the last 50 million years is best expressed in the evolution of the Himalaya-Tibetan Orogen. The great thickness of crust beneath Tibet and Himalaya and a series of north vergent thrust zones in the Himalaya and the south-vergent subduction zones in Tibetan Plateau suggest the progressive convergence between India and Asia of about 2500km since the time of collision. In the early Eohimalayan phase ( approximately 50 to 25Ma) of Himalayan Orogeny (middle Eocene-late Oligocene), thick sediments on the leading edge of the Indian Plate were squeezed, folded, and faulted to form the Tethyan Himalaya. With continuing convergence of India, the architecture of the Himalayan - Tibetan Orogen is dominated by deformational structures developed in the Neogene Period during the Neohimalayan phase ( approximately 21Ma to present), creating a series of north-vergent thrust belt systems such as the Main Central Thrust, the Main Boundary Thrust, and the Main Frontal Thrust to accommodate crustal shortening. Neogene molassic sediment shed from the rise of the Himalaya was deposited in a nearly continuous foreland trough in the Siwalik Group containing rich vertebrate assemblages. Tomographic imaging of the India-Asia Orogen reveals that Indian lithospheric slab has been subducted subhorizontally beneath the entire Tibetan Plateau that has played a key role in the uplift of the Tibetan Plateau. The low-viscosity channel flow in response to topographic loading of Tibet provides a mechanism to explain the Himalayan-Tibetan Orogen. From the start of its voyage in Southern Hemisphere, to its final impact with the Asia, the Indian Plate has experienced changes in climatic conditions both short-term and long-term. We present a series of paleoclimatic maps illustrating the temperature and precipitation conditions based on estimates of Fast Ocean Atmospheric Model, a coupled global climate model. The uplift of the Himalaya-Tibetan Plateau above the snow line created two most important global climate phenomena-the birth of the Asian monsoon and the onset of Pleistocene glaciation. As the mountains rose, and the monsoon rains intensified, increasing erosional sediments from the Himalaya were carried down by the Ganga River in the east and the Indus River in the west, and were deposited in two great deep-sea fans, the Bengal and the Indus. Vertebrate fossils provide additional resolution for the timing of three crucial tectonic events: India-KL Arc collision during the Late Cretaceous, India-Asia collision during the early Eocene, and the rise of the Himalaya during the early Miocene.

The NW part of the Himalayan Orogen (Kohistan, Ladakh and Karakoram, in Pakistan and India) has been investigated to reconstruct the successive stages of convergence of two continents (India and Asia) over the past 110 Ma, from oceanic to post-collisional settings. The intra-oceanic stages of the convergence have been reconstructed from study of the preserved Tethyan Arc series of the Kohistan-Ladakh Terrane. Geochemical and lithological data indicate continuation of the Kohistan intra-oceanic arc in the west into an Andean arc on the Tibetan continental margin in the east. Adakitic and Nb-Ta-Ti rich lavas appear to be present, interlayered with basalts to andesites in the intra-oceanic arc series. Along with major, trace and isotopic (Sr, Nd and Pb) data of basalt to andesite lavas, adakitic magmatism suggests complex interactions between crustal melts and mantle. In the tectonic context of the Neo-Tethys Ocean at 110 Ma, the Kohistan-Ladakh Arc system may have formed following the subduction of the Neo-Tethys mid-oceanic ridge, similar to a model which has been proposed for the initiation of Oman ophiolite obduction. This ocean-ridge subduction could be triggered by the initiation of fast northward drift of India in the Middle Cretaceous period. The post-collisional evolution comprises two stages: 1. A phase of crustal thickening by SW nappe stacking in a NE-SW shortening context, associated with Barrovian-type metamorphism (650°C, 10 kbar) between 60 and 37 Ma. 2. A phase of ongoing north-south shortening, characterised by tectonic partitioning between: a. An E-W band of domes that crosscuts the former structures, in a N-S shortening and vertical extrusion context, linked to HT granulite facies metamorphism (800°C, 6 kbar) and magmatism showing mantle affinities, formed during the last 20 Ma. This granulite grade metamorphism could be linked to advective heat input from the asthenosphere due to detachment of the Indian slab by 20 Ma. b. The Karakoram strike-slip fault, which accommodates the lateral extrusion of Tibet. Granulites exhumed within the fault zone suggest that it could be a lithospheric-scale fault, with a total dextral offset of approximately 300 km deduced from correlation between the Lhasa and Karakoram blocks.

Sociologie et sociétés, 2016

Partant de la définition de l’authentique écrivain prolétarien donnée par Henry Poulaille dans les années 1930, cet article s’interroge sur la pérennité et la validité d’une telle conception aujourd’hui. Il est demandé à l’auteur ouvrier de raconter, de témoigner — et cette demande sociale, parfois explicitée, est tout d’abord replacée dans « l’ère du témoin » ou du « storytelling ». Or, il s’avère d’une part que la plupart des récits ouvriers publiés au tournant du xxie siècle privilégient d’autres configurations que l’agencement narratif, qu’ils mêlent discours et récit, choisissant d’autres formes que le récit (le journal, le fragment, le portrait par exemple). La lisibilité et la diffusion éditoriale de ces récits exigent d’autre part l’intervention de passeurs : sociologues, journalistes, enseignants, hommes et femmes de l’ombre éditoriale, sans lesquels ils restent lettre morte, ce qui invalide l’idée d’une production spontanée ou totalement originale.

El Universal, 2024

Los abusos que cometen las grandes compañías de tecnología -big techs- son recurrentes. En Estados Unidos, tanto presidentes demócratas -como Biden-, o republicanos -como Trump-, han amagado aplicarles leyes antimonopolio para contener los excesos de los gigantes tecnológicos. A pesar de frecuentes advertencias y amagos, las grandes firmas tecnológicas no parecen dispuestas a rectificar. La administración del presidente Biden ha decidido proceder con autoridad frente a TikTok, exigiendo a ByteDance, propietario de TikTok, el corporativo dueño de TikTok, concretar la venta de la referida red sociodigital en menos de un año, o será prohibida en Estados Unidos.

יונתן מאיר - פתקאותיו של רפי וייזר ושחזור ארכיונים אבודים ------- https://youtu.be/VA47nxUhIpU?t=5225

M. Alram and R. Gyselen, Sylloge Nummorum Sasanidarum Paris Berlin Wien, vol. 1, Ardashir I. - Shapur I., ÖAW, phil.-hist. Kl., Denkschriften 317, Vienna: Verl. der ÖAW, 2003, pp. 46-69., 2003

Paleography of coins of Ardashir and Shapur I