scholarly journals Passive imaging of collisional orogens: a review of a decade of geophysical studies in the Pyrénées

2022 ◽  
Vol 193 ◽  
pp. 1
Author(s):  
Sébastien Chevrot ◽  
Matthieu Sylvander ◽  
Antonio Villaseñor ◽  
Jordi Díaz ◽  
Laurent Stehly ◽  
...  

This contribution reviews the challenges of imaging collisional orogens, focusing on the example of the Pyrenean domain. Indeed, important progresses have been accomplished regarding our understanding of the architecture of this mountain range over the last decades, thanks to the development of innovative passive imaging techniques, relying on a more thorough exploitation of the information in seismic signals, as well as new seismic acquisitions. New tomographic images provide evidence for continental subduction of Iberian crust beneath the western and central Pyrénées, but not beneath the eastern Pyrénées. Relics of a Cretaceous hyper-extended and segmented rift are found within the North Pyrenean Zone, where the imaged crust is thinner (10–25 km). This zone of thinned crust coincides with a band of positive Bouguer anomalies that is absent in the Eastern Pyrénées. Overall, the new tomographic images provide further support to the idea that the Pyrénées result from the inversion of hyperextended segmented rift systems.

Author(s):  
Robert Fritzen ◽  
Victoria Lang ◽  
Vittorio A. Gensini

AbstractExtratropical cyclones are the primary driver of sensible weather conditions across the mid-latitudes of North America, often generating various types of precipitation, gusty non-convective winds, and severe convective storms throughout portions of the annual cycle. Given ongoing modifications of the zonal atmospheric thermal gradient due to anthropogenic forcing, analyzing the historical characteristics of these systems presents an important research question. Using the North American Regional Reanalysis, boreal cool-season (October–April) extratropical cyclones for the period 1979–2019 were identified, tracked, and classified based on their genesis location. Additionally, bomb cyclones—extratropical cyclones that recorded a latitude normalized pressure fall of 24 hPa in 24-hr—were identified and stratified for additional analysis. Cyclone lifespan across the domain exhibits a log-linear relationship, with 99% of all cyclones tracked lasting less than 8 days. On average, ≈ 270 cyclones were tracked across the analysis domain per year, with an average of ≈ 18 year−1 being classified as bomb cyclones. The average number of cyclones in the analysis domain has decreased in the last 20 years from 290 year−1 during the period 1979–1999 to 250 year−1 during the period 2000–2019. Spatially, decreasing trends in the frequency of cyclone track counts were noted across a majority of the analysis domain, with the most significant decreases found in Canada’s Northwest Territories, Colorado, and east of the Graah mountain range. No significant interannual or spatial trends were noted with bomb cyclone frequency.


2019 ◽  
pp. 23-50
Author(s):  
John Henderson

This chapter discusses the origins and spread of plague in northern Italy. Plague arrived in Italy in 1629 with French and German troops. It is no accident that the initial cases of plague identified in October of 1629 were first in Piedmont in the Val di Susa, west of Turin and near the border with France, and secondly in the Valtellina in Lombardy, subsequently travelling to Lake Como to the north of Milan. Other cities in northern Italy soon became infected and on May 6, 1630, the authorities as far south as Bologna announced the official outbreak of plague. Judging by the rapidity with which plague spread between these northern urban centres, one would have expected the epidemic to have arrived in Tuscany by early May, given that Bologna is only 65 miles north of Florence, but it was delayed by both natural and man-made factors. Tuscany is separated from Reggio-Emilia by the Apennine mountain range, which provided a physical barrier and facilitated the control of traffic coming from the north. The chapter then traces the preventive measures adopted by the health board as the plague approached Tuscany, including cordons sanitaires along frontiers, the removal of the sick to quarantine centres, and the rapid burial of the dead.


2020 ◽  
Vol 18 ◽  
pp. 1-19
Author(s):  
Adrià Ramos ◽  
Berta Lopez-Mir ◽  
Elisabeth P. Wilson ◽  
Pablo Granado ◽  
Josep Anton Muñoz

The Llert syncline is located in the South-central Pyrenees, between the eastern termination of the EW-trending Cotiella Basin and the north-western limb of the NS-trending Turbón-Serrado fold system. The Cotiella Basin is an inverted upper Coniacian-lower Santonian salt-floored post-rift extensional basin developed along the northern Iberian rift system. The Turbón-Serrado fold system consists of upper Santonian – Maastrichtian contractional salt-cored anticlines developed along an inverted transfer zone of the Pyrenean rift system. Based on field research, this paper presents a 3D reconstruction of the Llert syncline in order to further constrain the transition between these oblique salt-related structures. Our results suggest that the evolution of the Llert syncline was mainly controlled by tectonic shortening related to the tectonic inversion of the Cotiella Basin synchronously to the growth of the Turbón-Serrado detachment anticline, and by the pre-compressional structural framework of the Pyrenean rift system. Our contribution provides new insight into the geometric and kinematic relationships of structures developed during the inversion of passive margins involving salt.


2017 ◽  
Vol 9 (10) ◽  
pp. 10850
Author(s):  
Arockianathan Samson ◽  
Balasundaram Ramakrishnan ◽  
Palanisamy Santhoshkumar ◽  
Sivaraj Karthick

A total of 45 sightings of 57 individual Shaheen Falcons were recorded from 2014–2016 from different locations in the Nilgiris mountain range, and eight nests were located on separate rocky cliffs.  Most of the nests (n= 6) were situated at elevations ranging from 1500–2500 m and 45% of the nests were located on the north facing exposures.


2019 ◽  
Vol 11 (3) ◽  
pp. 56 ◽  
Author(s):  
Ramón A. Delanoy ◽  
Misael Díaz-Asencio ◽  
Rafael Méndez-Tejeda

The Bay of Samaná, formed by tectonism and sedimentation, is delimited to the north by the peninsula of the same name, to the south by the north slope of the Eastern Mountain Range and Los Haitises National Park, to the east by the Atlantic Ocean, and to the west by the ancient Gran Estero, today the Lower Yuna. There follows a process of continuous degradation by the existing tectonic forces and the sediment contributions by the Yuna, Yabón, and La Yeguada rivers to the south as well as by the landslides of the mountainous area of the Samaná Peninsula, during periods of storms and hurricanes. The coastal area of Samaná Bay has altered by 2.17 km2 at the mouth of the Yuna River from 2003–2015. The high turbidity level has affected coral reefs and marine species.  The  mangroves  are  lost  faster  than  they  are  regenerated  by  the  coastline’s change. Variations in the elemental compositions of calcium and iron show the terrigenous influence on the dynamics of the bay during Extreme Weather Events (EWP) in the river basins that flow into it. Abrupt changes in the rainfall regime produced an equal change in the estuary sedimentation regime, according to the 210Pb. In the 2007–2016 period, a column of sediment that reached 38 cm and a 12 cm to 8.4 km column were deposited 4 km southeast of the municipality of Sánchez and east of the mouth of the Yuna River. The Sedimentary Accumulation Rate is very high, and the content of heavy metals exceeds the threshold values of Table SQuirt.


2019 ◽  
Vol 12 ◽  
pp. 33-53
Author(s):  
Jan Pacholski

From travel accounts to guidebooks: The beginnings of guidebooks to the Giant Mountains Karkonosze for travellers in the late 18th and early 19th centuryIn the history of European tourism the Giant Mountains Karkonosze occupy a unique place thanks to the Chapel of St. Lawrence, funded by Count Christoph Leopold Schaffgotsch and located on the summit of Śnieżka. Its construction in the Habsburg dominions in the turbulent period of the Counter-Reformation was meant to finally put an end to the Silesian-Bohemian border dispute and become a visible sign of Catholic rule over the highest mountain range of the two neighbouring countries. The construction of the chapel also marked the beginning of tourism in the highest range of the Sudetes; initially, its nature was religious and focused on pilgrimages to the summit of Śnieżka, featuring, in addition to local inhabitants, also sanatorium visitors to Cieplice Warmbrunn, which was owned by the Schaffgotschs.After the three Silesian Wars, as a result of which the lands to the north of the mountains were separated from the Habsburgs’ Kingdom of Bohemia, the situation in the region changed radically. The Counter-Reformation pressure ceased and the Lutherans began to grow in importance, supported as they were by the decidedly pro-Protestant Prussian state, governed by its tolerant monarch.The period was also marked by an unprecedented growth in the literature on the Giant Mountains — there were poems Tralles, nature studies Volkmar and travel accounts GutsMuths, Troschel and others written about the highest range of the Sudetes. A special role among these writings was played by works aimed at introducing the public from the capital Berlin to the new province of the Kingdom of Prussia, especially to the mountains, so exotic from the point of view of the “groves and sands” of Brandenburg. These publications were written primarily by Lutheran clergymen, which was not without significance to the nature of the works. This was also a time when the first guidebooks to the Giant Mountains were written, with many of their authors also coming from the same milieu.What emerges from this image is a kind of confessionalisation of tourism in the highest mountains of Silesia and Bohemia: on the one hand there are mass Catholic pilgrimages and on the other — a new type of individual tourists who, with a book in hand, traverse mountain paths in a decidedly more independent fashion.


2018 ◽  
Vol 22 (1) ◽  
pp. 29-45
Author(s):  
Fabio Silva

This paper applies a combined landscape and skyscape archaeology methodology to the study of megalithic passage graves in the North-west of the Iberian Peninsula, in an attempt to glimpse the cosmology of these Neolithic Iberians. The reconstructed narrative is found to be supported also by a toponym for a local mountain range and associated folklore, providing an interesting methodology that might be applied in future Celtic studies. The paper uses this data to comment on the ‘Celticization from the West’ hypothesis that posits Celticism originated in the European Atlantic façade during the Bronze Age. If this is the case, then the Megalithic phenomenon that was widespread along the Atlantic façade would have immediately preceded the first Celts.


1913 ◽  
Vol 19 ◽  
pp. 133-173 ◽  
Author(s):  
C. A. Scutt

The area over which the Tsakonian dialect is spoken lies on the east coast of the Peloponnese between the Parnon range and the sea. Its northern boundary is roughly the torrent which, rising on Parnon above Kastánitsa, flows into the sea near Ayios Andréas, its southern the torrent which, also rising on Parnon, passes through Lenídhi to the sea. A mountain range stretches along the coast from end to end of the district, reaching its highest point (1114 metres) in Mt. Sevetíla above the village of Korakovúni. Between Tyrós and Pramateftí, the seaward slopes of this range are gentle and well covered with soil. Behind these coast hills there stretches a long highland plain, known as the Palaiókhora, which, in the north, is fairly well covered with soil, but gradually rises towards the south into a region of stony grazing land, and terminates abruptly in the heights above Lenídhi. The high hill of Oríonda rises out of the Palaiókhora to the west and forms a natural centre-point of the whole district. Behind it stretching up to the bare rock of Parnon, is rough hilly country, cut here and there by ravines and offering but rare patches of cultivable land.


2020 ◽  
Vol 26 (1) ◽  
pp. 9-14
Author(s):  
R. Mark Bailey

ABSTRACT Naturally occurring asbestos (NOA) is being discovered in a widening array of geologic environments. The complex geology of the state of California is an excellent example of the variety of geologic environments and rock types that contain NOA. Notably, the majority of California rocks were emplaced during a continental collision of eastward-subducting oceanic and island arc terranes (Pacific and Farallon plates) with the westward continental margin of the North American plate between 65 and 150 MY BP. This collision and accompanying accretion of oceanic and island arc material from the Pacific plate onto the North American plate, as well as the thermal events caused by emplacement of the large volcanic belt that became today's Sierra Nevada mountain range, are the principal processes that produced the rocks where the majority of NOA-bearing units have been identified.


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