scholarly journals The role of extensional detachment systems in thinning the crust and exhuming granulites: analogies between the offshore Le Danois High and the onshore Labourd Massif in the Biscay/Pyrenean rifts

2021 ◽  
Author(s):  
Patricia Cadenas ◽  
Rodolphe Lescoutre ◽  
Gianreto Manatschal ◽  
Gabriela Fernández-Viejo
Keyword(s):  
Cross Sections ◽  
Hanging Wall ◽  
Field Observations ◽  
Detachment Faults ◽  
The North ◽  
Brittle Ductile Transition ◽  
Crustal Thinning ◽  
Seismic Reflection Profiles ◽  
First Time

Large uncertainties remain about the architecture, timing and role of the structures responsible for high degrees of crustal thinning and the exhumation of mid-crustal granulites in the Pyrenean and Biscay rift systems. Both, Le Danois High in the North Iberian margin and the Labourd Massif in the Western Pyrenees preserve evidence of extensional detachment faults and include exhumed granulites, which are locally reworked in syn-rift sediments. In this study, we compare the crustal structure and their link to the overlying sediments at the two sites based on the interpretation of high quality 2D seismic reflection profiles offshore and field observations and published geological cross-sections onshore. New reported seismic and field observations support the interpretation that the Le Danois High and the Labourd Massif are capped by extensional detachment systems, advocating for a similar tectonic evolution of the two sites. We propose that the two detachment systems were responsible for high degrees of crustal thinning and the exhumation of the pre-rift brittle-ductile transition and associated mid-crustal granulites during Aptian to Cenomanian extension, leading to the formation of the Le Danois and Labourd crustal tapers. Tilted and uplifted during the Alpine convergence, the two basement blocks lay at present in the hanging-wall of major Alpine thrusts. Their position at overlapping, en-echelon hyperextended rift segments at the end of rifting, and the occurrence of shortcutting structures linking neighbouring rift segments, can explain the preservation of the rift-related detachment systems. This study not only proposes for the first time analogies between the offshore Le Danois High and the onshore Labourd Massif, but it also demonstrates the importance of extensional detachment systems in thinning the crust and exhuming mid-crustal granulites at the seafloor in the Biscay and Pyrenean domains during Aptian to Cenomanian extension.

Extensional detachments related to extreme crustal thinning and their fate during contractional reactivation: the Le Danois-North Mauléon offshore-onshore examples in north Iberia

2021 ◽  
Author(s):  
Patricia Cadenas ◽  
Rodolphe Lescoutre ◽  
Gianreto Manatschal
Keyword(s):  
Cross Sections ◽  
Rift System ◽  
Northern Spain ◽  
Crustal Rocks ◽  
Detachment Faults ◽  
The North ◽  
Rifted Margins ◽  
Crustal Thinning ◽  
Seismic Reflection Profiles ◽  
Detachment Faulting

<p>Extensional detachment faults accommodate high degrees of crustal thinning and exhumation, shaping largely the final architecture of magma-poor rifted margins. Great efforts have been directed to study extensional detachments based on offshore seismic surveys and onshore field analogues. However, little is known about the breakaway of these structures as well as their role and evolution during rifting and subsequent contractional reactivation. </p><p>In this work, we use the Le Danois-Labourd offshore-onshore natural laboratory (northern Spain) to explore the features characterising major Mesozoic extensional detachment faults and their fate during subsequent Alpine contractional reactivation. Both sites keep evidence of Mesozoic extensional detachment faulting and high degrees of crustal thinning, including exhumed mid-crustal granulites reworked as clasts into Apto-Albian syn-rift sediments, and show mild Alpine reactivation, corresponding at present-day to structural highs. Relying on the interpretation of high quality 2D seismic reflection profiles offshore and on field-based cross-sections onshore, we describe and compare the former rift architecture associated with these major detachment faults and the distribution of contractional structures at the two sites.</p><p> This combined study enable us to evidence strong structural similarities between the two sites and to propose that the Le Danois and the North Mauléon extensional detachment systems are major rift structures within the North Iberian rift system. We propose that they were responsible for high degrees of crustal thinning and the exhumation of mid-crustal rocks during the Late Aptian to Albian N-S directed extension. Major thrusts truncated the two extensional detachments during subsequent Alpine reactivation, leading to the uplift and tilting of the Le Danois and the Labourd rift-inherited crustal blocks. We suggest that the location of the two blocks at the termination of offset/overlapped hyperextended rift segments allowed for their preservation as mildly inverted structural highs, including rift-related structures.</p>

scholarly journals Mass bleaching of soft coral, Sarcophyton spp. in Thailand and the role of temperature and salinity stress

2009 ◽  
Vol 66 (7) ◽  
pp. 1515-1519 ◽  
Author(s):  
Suchana Chavanich ◽  
Voranop Viyakarn ◽  
Thepsuda Loyjiw ◽  
Priyapat Pattaratamrong ◽  
Anchalee Chankong
Keyword(s):  
Salinity Stress ◽  
Soft Coral ◽  
Elevated Temperatures ◽  
Gulf Of Thailand ◽  
Field Observations ◽  
Experimental Trial ◽  
First Time ◽  
Upper Gulf Of Thailand ◽  
Mass Bleaching

Abstract Chavanich, S., Viyakarn, V., Loyjiw, T., Pattaratamrong, P., and Chankong, A. 2009. Mass bleaching of soft coral, Sarcophyton spp. in Thailand and the role of temperature and salinity stress. – ICES Journal of Marine Science, 66: 1515–1519. From June to October 2006 and 2007, mass bleaching of the soft coral, Sarcophyton spp., occurred for the first time in the upper Gulf of Thailand. Approximately 90% of the populations experienced extensive bleaching, and almost 95% of colonies were affected. Field observations also revealed that fragmentation of Sarcophyton spp. set in 1 month after the onset of bleaching. Some colonies started to recover to some extent by the end of July, with 95% of the population of Sarcophyton spp. recovering by October. Both acute and chronic trials were conducted to determine whether temperature and/or salinity triggered bleaching. In the acute tests, Sarcophyton spp. at 40°C and salinity 20 psu were completely bleached, and death occurred after 57 and 204 h, respectively. However, the colonies at 40 psu could survive through the experimental trial. In the chronic tests, Sarcophyton spp. died when exposed to 34°C, whereas complete bleaching and mortality of Sarcophyton spp. occurred at salinities of 10 and 49 psu. We conclude that elevated temperatures had a greater effect on the bleaching of Sarcophyton spp. than did salinity.

scholarly journals Structural cross sections through the Corinth-Patras detachment fault-system in Northern Peloponnesus (Aegean Arc, Greece)

2001 ◽  
Vol 34 (1) ◽  
pp. 235 ◽  
Author(s):  
N. FLOTTÉ ◽  
D. SOREL
Keyword(s):  
Cross Sections ◽  
Detachment Fault ◽  
Fault System ◽  
Normal Faults ◽  
Field Observations ◽  
Structural Mapping ◽  
The North ◽  
Gulf Of Corinth ◽  
Aegean Arc

Structural mapping in northern Peloponnesus reveals the emergence of an E-W striking, more than 70km long, low angle detachment fault dipping to the north beneath the Gulf of Corinth. This paper describes four north-south structural cross-sections in northern Peloponnesus. Structural and sedimentological field observations show that in the studied area the normal faults of northern Peloponnesus branch at depth on this major low angle north-dipping brittle detachment. The southern part of the detachment and the related normal faults are now inactive. To the north, the active Helike and Aigion normal faults are connected at depth with the seismically active northern part of the detachment beneath the Gulf of Corinth.

Contractional salt tectonics and role of pre-existing diapiric structures in the Southern Pyrenean foreland fold–thrust belt (Montsec and Serres Marginals)

2021 ◽  
pp. jgs2020-085 ◽  
Author(s):  
Laura Burrel ◽  
Antonio Teixell
Keyword(s):  
Cross Sections ◽  
Foreland Basin ◽  
Salt Tectonics ◽  
Structural Development ◽  
Field Observations ◽  
Content Type ◽  
Growth Strata ◽  
Structural Style ◽  
Supplementary Material

Triassic Keuper evaporites have long been recognized as the main detachment level for thrusting in the Pyrenean fold–thrust belts. The deformed Late Cretaceous–Eocene foreland basin of the Southern Pyrenees has structures and stratal geometries that can be interpreted as related to salt tectonics (e.g. unconformities, rapid thickness variations, long-lived growth fans and overturned flaps), although they have been overprinted by shortening and thrusting. Based on field observations and published maps, we build new structural cross-sections reinterpreting two classic transects of the Southern Pyrenees (Noguera Ribagorçana and Noguera Pallaresa river transects). The sequential restoration of the sections explores the variations in structural style, addressing the role of halokinesis in the tectonic and sedimentary development. In the Serres Marginals area, we propose that salt pillows and diapirs started developing locally during the Mesozoic pre-orogenic episode, evolving into a system of salt ridges and intervening synclines filled with early synorogenic sediments. Rapid amplification of folds recorded by widespread latest Cretaceous–Paleocene growth strata is taken as marking the onset of contractional folding in the area. During Pyrenean compression, folding mechanisms transitioned from dominantly halokinetic to a combination of buckling and differential sedimentary loading. Squeezing of salt diapirs and thrust welding occurred as salt ridges were unroofed. We provide new field observations that lead to a reinterpretation of the regional structural development and contribute to the debate about the role of salt tectonics in the Pyrenees.Supplementary material: Table S1, giving the thickness of the main stratigraphic units, is available at https://doi.org/10.6084/m9.figshare.c.5287737

scholarly journals Secondary convective rings in an intense asymmetric cyclone of the Bay or Bengal

MAUSAM ◽  
2021 ◽  
Vol 48 (2) ◽  
pp. 273-282
Author(s):  
AKHILESH GUPTA ◽  
U. C. MOHANTY
Keyword(s):  
Indian Ocean ◽  
East Coast ◽  
Structural Characteristics ◽  
North Indian Ocean ◽  
Wall Structure ◽  
Sea Level Pressure ◽  
Cyclonic Storm ◽  
The North ◽  
First Time

ABSTRACT. The severe cyclonic storm with a core of hurricane winds of 4-11 May 1990, which crossed the Indian east coast near Machilipatnarn (Andhra Pradesh), was one of the most intense cyclones in recent years over the Bay of Bengal region of the north Indian Ocean. The storm reported the minimum sea level pressure of 912 hPa, the lowest observed value for any cyclone in the region. The storm exhibited certain interesting structural characteristics. The most striking  feature observed was the formation of secondary convective rings wrapped around the primary eyewall. These features were observed for nearly two days by four cyclone detection radars (CDR) located on the east coast of India. The paper presents an analysis of these features. We find that the double eye-wall structure of the storm has undergone a repetitive cycle characterized by the contraction of the outer eyewall and the weakening of the inner eyewall during the life of the cyclone. These interesting characteristics are observed for the first time in the north Indian Ocean for any cyclone. Some of the related aspects of double eyewall features, such as, the possible role of double eyewall structure on the recurvature or turning of the storm and the effect of land obstacle in the development of a secondary eyewall are discussed.        

scholarly journals Study of Oil in the North of Russia by the Geological Committee at the End of the 19th Century – the Beginning of the 20th Century

2021 ◽  
Vol 937 (4) ◽  
pp. 042082
Author(s):  
T P Filippova
Keyword(s):  
Field Studies ◽  
The Arctic ◽  
Russian Science ◽  
The North ◽  
New Information ◽  
Wide Range ◽  
Northern Territories ◽  
The 19Th Century ◽  
First Time

Abstract The article draws attention to the study of the historical experience of Russian science in the development of the Arctic and northern territories of Russia. Based on a wide range of archival and published sources, the role of the Geological Committee in the scientific study of the Ukhta oil-bearing region is analyzed. The chronological framework of the study covers the period of the organization’s activity from 1882 to 1929. The field studies carried out by the Geological Committee which started during this period in the Ukhta region are considered in detail. As a result of this activity, this territory was comprehensively studied for the first time, including a detailed geological survey, the search for oil deposits, and an assessment of its industrial potential. It has been determined that as a result of the surveys of the Geological Committee, new information about the features of the geological and orographic structure of the region was obtained and the oil-bearing potential was proved. It has been concluded that the research of the scientists of the committee laid a fundamental basis for the study of the Ukhta oil-bearing region and predetermined its further development history and great significance for the state.

scholarly journals National and cultural activities of the Tatar diaspora in the North Western China in the first half of the XX century: theater and string orchestra

2020 ◽  
pp. 60-64
Author(s):  
G.N. Khisamieva
Keyword(s):  
Local Population ◽  
Northwest China ◽  
Western China ◽  
String Orchestra ◽  
The North ◽  
Cultural Life ◽  
The People ◽  
History Of ◽  
First Time

The relevance of the study lies in the fact that the national and cultural life of the Tatar diaspora in the Northwest China has not been the subject of the research. The research interest is also caused by the fact that the history of the formation and development of the Tatar diaspora, every day, spiritual, educational and cultural life has not been studied at all and is of particular interest to researchers. The scientific novelty of the work lies in the fact that the article examines the process of formation of Tatar theaters and string orchestras in the cities of Kuldzha and Chuguchak for the first time, where the bulk of Tatar emigrants lived. Particular attention was paid to the role of Tatar theaters in the life of indigenous and visiting peoples of the XUAR of the PRC. The purpose of the work is to study and systematize the national and cultural life of the Tatars of Xinjiang. As a result of the study, it can be concluded that the creation of theaters and string orchestras has contributed to the rallying of the Tatars, as well as the preservation of the native language, literature, traditions, culture and identity of the people, which is also a very important factor in preserving identity among the local population of Xinjiang.

Rift evolution and structural style in the Orphan Basin: results from regional structural restorations and crustal area balancing 

2021 ◽  
Author(s):  
Adam J. Cawood ◽  
David A. Ferrill ◽  
Alan P. Morris ◽  
David Norris ◽  
David McCallum ◽  
...  
Keyword(s):  
Cross Sections ◽  
Seismic Data ◽  
Large Scale ◽  
Structural Evolution ◽  
Strike Slip ◽  
Detachment Faults ◽  
The North ◽  
Structural Style ◽  
Complex Structural ◽  
Structural Configurations

<p>The Orphan Basin on the eastern edge of the Newfoundland continental margin formed as a Mesozoic rift basin prior to continental breakup associated with the opening of the North Atlantic. Few exploration wells exist in the basin, and until recently regional interpretations have been based on sparse seismic data coverage - because of this the structural evolution of the Orphan Basin has historically not been well understood. Key uncertainties include the timing and amount of rift-related extension, dominant extension directions, and the structural styles that accommodated progressive rift development in the basin.     </p><p>Interpretation of newly acquired modern broadband seismic data and structural restoration of three regional, WNW-ESE oriented cross-sections across the Orphan Basin and Flemish Cap provide new insights into rift evolution and structural style in the area. Our results show that major extension in the basin occurred between 167 Ma and 135 Ma, with most extension occurring prior to 151 Ma. We show that extension after 135 Ma largely occurred east of Flemish Cap due to a shift in the locus of rifting from the Orphan Basin to east of Flemish Cap. We find no evidence for discrete rifting events in the Orphan Basin, as has been suggested by other authors.  Kinematic restoration and associated heave measurements for the Orphan Basin show that extension was both widespread and relatively evenly distributed across the basin from Middle-Late Jurassic to Early Cretaceous.</p><p>We provide evidence for more widespread deposition of Jurassic strata throughout the Orphan Basin than previously interpreted, and show that Jurassic deposition was controlled by the occurrence and displacement of crustal-scale extensional detachment faults.  Structure in the three regional cross sections is dominated by large-scale, shallowly dipping extensional detachment faults. These faults mainly dip to the northwest and control the geometry and position of extensional basins – grabens and half-grabens – which occur at a range of scales. Stacked detachment surfaces, hyperextension, and attenuation of the crust are observed in central and eastern parts of the Orphan Basin. Zones of extreme crustal attenuation (to ca. 3.7 km) are interpreted to be coincident with large-displacement (up to 60 km) low-angle detachments. Results from crustal area balancing suggest that up to 41% of extension is not recognized through structural seismic interpretation, which we attribute to subseismic-scale ductile and brittle deformation, and uncertainties in the identification of detachment surfaces or complex structural configurations (e.g., overprinting of early extensional deformation).</p><p>Rifting style in the central, northern, and eastern parts of the Orphan Basin is dominated by low-angle detachment faulting with maximum extension perpendicular to the incipient rift axis. In contrast, structural geometries in the southwestern part of the basin are suggestive of transtensional deformation, and interplay of normal and strike-slip faulting.  Results from map-based interpretation show that strike-slip faults within this transtensional zone are associated with displacement transfer between half-grabens of opposing polarity, rather than regional strike-slip displacement.  These structures are interpreted as contemporaneous and kinematically linked to displacement along low-angle detachment surfaces elsewhere, and are not attributed to distinct episodes of oblique extension.       </p>

The Role of Public Opinion in the “Jackson Era” in the USA

2019 ◽  
Author(s):  
Татьяна Алентьева ◽  
Tat'yana Alent'eva
Keyword(s):  
Public Opinion ◽  
Presidential Election ◽  
Political History ◽  
The State ◽  
Political Life ◽  
The South ◽  
The North ◽  
The Usa ◽  
First Time

The monograph first explores American public opinion as the most important factor in social and political life in the "Jackson era." Of particular value is the study of the struggle of opinions within the bipartisan system, both in the South and in the North. Against the background of a broad canvas of socio-economic and political history, the first analysis of the state and development of public opinion in the USA is given, successively from the presidential election of 1824 to the defeat of the Democrats in the presidential election of 1840, when their opponents, the Whigs, came to power for the first time.

scholarly journals Orchidaceae Juss. in Flora of Chechnya and Their Protection

2019 ◽  
Author(s):  
E L Tasueva ◽  
R S Magomadova ◽  
A S Abdurzakova ◽  
A M Umaeva ◽  
Z I Shakhgirieva ◽  
...  
Keyword(s):  
Vegetation Cover ◽  
Family Members ◽  
Common Species ◽  
Raw Material ◽  
North Caucasus ◽  
The North ◽  
The Family ◽  
Protected Plants ◽  
First Time

For the first time, perennial materials on the Orchidacaeae Juss. family of Chechnya are summarizedб consisting of 15 families and 29 species. The largest genus in the family – Orchis L. is represented by 8 species. The article presents information that all members of the family are protected plants listed in the Red Book of Chechnya, Ingushetia, Dagestan, and the Stavropol Territory. Some species are not included in the list of plants to be protected, including those species that have underground tuberoids and can serve as a source of salep (for instance, Platanthera bifolia, P. chlorantha, Herminium monorchis, Traunsteinera sphaerica, Dactylorhisa incarnata, D. salina, D. urvilleana). In this connection, data on the resources of family members and the potential possibilities of their use as a medicinal raw material are of interest. We have carried out resource studies of the most common species of Orchis tridentata Scop, within the North Caucasus. The obtained data allow us to expand our understanding of the species role of Orchidaceae Juss family. Пoлyчeнныe дaнныe пoзBoляют pacшиpить пpeдcтaBлeниe o poли BидoB ceмeйcтBa Orchidaceae Juss. of the North Caucasus flora in the composition of vegetation cover.

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