scholarly journals The Billefjorden Fault Zone north of Spitsbergen: a major terrane boundary?

2021 ◽  
Vol 40 ◽  
Author(s):  
Jean-Baptiste Koehl ◽  
Lis Allaart
Keyword(s):  
Fault Zone ◽  
Seismic Data ◽  
Short Contribution ◽  
Basement Rocks ◽  
North Eastern ◽  
Caledonian Orogeny ◽  
Tectonic Boundary ◽  
North Western

The Billefjorden Fault Zone is a major terrane boundary in the Norwegian Arctic. The fault separates basement rocks of Svalbard’s north-eastern and north-western terranes that recorded discrete Precambrian tectonothermal histories and were accreted, intensely deformed and metamorphosed during the Caledonian Orogeny. Although the fault represents a major, crustal-scale tectonic boundary, its northward extent is not well constrained. The present short contribution addresses this issue and presents new seismic mapping of structures and rock units north of Wijdefjorden, where the Billefjorden Fault Zone may continue. This study shows that there is no evidence for major faulting of the top-basement reflection, and therefore, that the Billefjorden Fault Zone may die out within Wijdefjorden–Austfjorden, step ≥ 20 km laterally, or be invisible on the presented seismic data. Seismic data also suggest that Caledonian basement rocks in Ny-Friesland (north-eastern terrane) are not significantly different from basement rocks below the Devonian Graben in Andrée Land (north-western terrane). Potential implications include the absence of a major terrane boundary in northern Spitsbergen.

scholarly journals Devonian–Mississippian collapse and core complex exhumation, and partial decoupling and partitioning of Eurekan deformation as alternatives to the Ellesmerian Orogeny in Spitsbergen

2020 ◽  
Author(s):  
Jean-Baptiste P. Koehl
Keyword(s):  
Fault Zone ◽  
Seismic Data ◽  
Lower Devonian ◽  
Hanging Wall ◽  
Sedimentary Rocks ◽  
Late Devonian ◽  
Strain Partitioning ◽  
Core Complex ◽  
Basement Rocks ◽  
Proterozoic Basement

Abstract. In the Late Devonian, Svalbard was affected by a short-lived episode of contraction called the Ellesmerian (Svalbardian) Orogeny, which resulted in top-west thrusting of Proterozoic basement rocks onto Devonian sedimentary strata along the Balliolbreen Fault, a major fault segment of the east-dipping Billefjorden Fault Zone, and juxtaposition of undeformed Mississippian–Permian strata against intensely folded Devonian rocks. The present study of field and seismic data shows that backward-dipping duplexes comprised of phyllitic coal and bedding-parallel décollements and thrusts localized along lithological transitions in thickened uppermost Devonian–Mississippian coals and coaly shales of the Billefjorden Group partially decoupled uppermost Devonian–Permian sedimentary rocks of the Billefjorden and Gipsdalen groups from Devonian rocks during Cenozoic contraction–transpression. In addition, Devonian strata probably experienced syn-depositional, post-Caledonian, extensional, detachment-related folding. Seismic data in Sassenfjorden and Reindalspasset show the presence of Cenozoic duplexes and bedding-parallel décollements within Lower–Middle Devonian, uppermost Devonian–Mississippian and uppermost Pennsylvanian–lowermost Permian sedimentary strata of the Wood Bay and/or Widje Bay and/or Grey Hoek formations, of the Billefjorden Group and of the Wördiekammen Formation respectively, which further decoupled stratigraphic units during Eurekan deformation. Bedding-parallel décollements and thrusts are possibly related to shortcut faulting, a roof décollement of a fault-bend hanging wall (or ramp) anticline, an imbricate fan, antiformal thrust stacks and/or fault-propagation folds over reactivated/overprinted basement-seated faults. Seismic data in Reindalspasset also indicate that Devonian sedimentary rocks might have deposited east of the Billefjorden Fault Zone, thus ruling out Late Devonian reverse movement along the Billefjorden Fault Zone in this area. Based on the present findings, juxtaposition of Proterozoic basement rocks against Lower Devonian sedimentary rocks along the Balliolbreen Fault in central Spitsbergen (e.g., Pyramiden–Odellfjellet) may be explained by down-east Carboniferous normal faulting with associated footwall rotation and exhumation and subsequent top-west Cenozoic thrusting along the Billefjorden Fault Zone. The uncertain relationship of the Balliolbreen Fault with uppermost Devonian–Mississippian sedimentary strata, the poorly constrained nature of the contact (unconformity or bedding-parallel décollements and thrusts?) between Lower Devonian and uppermost Devonian–Mississippian sedimentary strata, and along strike variations in cross-section geometry, offset stratigraphy, and inferred timing and kinematics along the Balliolbreen Fault suggest that this fault consists of several, discrete, unconnected (soft-linked and/or stepping) or, most probably, offset fault segments that were reactivated/overprinted with varying degree during Eurekan deformation due to strain partitioning. Finally, recent evidence for Devonian core complex exhumation and reinterpretation of presumed Ellesmerian structures and of Late Devonian amphibolite facies metamorphism suggest that Ellesmerian contraction is not necessary to explain fault geometries and (differential) deformation within Devonian–Permian sedimentary strata in Spitsbergen.

scholarly journals Impact of Timanian thrusts on the Phanerozoic tectonic history of Svalbard

2020 ◽  
Author(s):  
Jean-Baptiste Koehl
Keyword(s):  
Fault Zone ◽  
Barents Sea ◽  
Normal Faults ◽  
Strain Partitioning ◽  
Tectonic Event ◽  
Svalbard Archipelago ◽  
Basement Rocks ◽  
Caledonian Orogeny ◽  
Early Cenozoic ◽  
Northwestern Russia

<p>Despite more than a century of investigation, the relationship between basement rocks throughout the Svalbard Archipelago is still a mystery. Though these rocks display similar geochronological ages, they show significantly different metamorphic grades and structures. Thus far, Svalbard was believed to be composed of three terranes of rocks formed hundreds–thousands of kilometers apart and accreted in the mid-Paleozoic during the Caledonian and Ellesmerian orogenies.</p><p>New evidence from seismic, gravimetric, aeromagnetic, seismological, bathymetric, and field data show that these terranes might have already been juxtaposed in the late Neoproterozoic. Notably, the data show that at least three–four, crustal-scale, WNW–ESE-striking fault systems segment Spitsbergen and merge with Timanian thrusts in the northern Barents Sea and northwestern Russia. These thrusts were reactivated as and/or overprinted by sinistral-reverse oblique-slip faults and partly folded during the Caledonian Orogeny and Eurekan tectonic event, and reactivated as and/or overprinted by sinistral-normal faults during Devonian–Mississippian extensional collapse of the Caledonides, thus offsetting N–S-trending Caledonian grain and post-Caledonian basins, and explaining the juxtaposition of basement rocks with seemingly different origin.</p><p>The presence of Timanian faults explains basement heterogeneities throughout the Svalbard Archipelago, strain partitioning during the Caledonian Orogeny and Eurekan tectonic event and, thus, the western vergence of early Cenozoic folds in Devonian rocks in central–northern Spitsbergen (previously ascribed to the Late Devonian Ellesmerian Orogeny) and the arch shape of the early Cenozoic West Spitsbergen Fold-and-Thrust Belt in Brøggerhalvøya, the distribution of Mississippian rocks and Early Cretaceous intrusions along a WNW–ESE-trending axis in central Spitsbergen, the transport of Svalbard in the Cenozoic from next to Greenland to its present position (c. 400 km southwards), the strike and location of transform faults and oceanic core complexes and gas leakage along the Vestnesa Ridge west of Spitsbergen, the continental nature and NW–SE strike of basement fabrics in the Hovgård Ridge between Greenland and Svalbard, and the occurrence of recent (< 100 years old) earthquakes in Storfjorden and Heer Land in eastern Svalbard.</p><p>Further implications of this work are that the tectonic plates constituting present-day Arctic regions (Laurentia and Baltica) have retained their current geometry for the past 600 Ma, that the Timanian Orogeny extended from northwestern Russia to Svalbard, Greenland and, potentially, Arctic Canada, that the De Geer Zone does not exist, that the Billefjorden Fault Zone (Svalbard) and the Great Glen Fault (Scotland) were not part of the same fault complex, and that the Harder Fjord Fault Zone (northern Greenland) possibly initiated (or was reactivated) as a Timanian thrust.</p>

scholarly journals A Review of Recently Discovered Remains of the Pleistocene Branchiopods (Anostraca, Notostraca) from NE Siberia and Arctic Canada

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 280
Author(s):  
D. Christopher Rogers ◽  
Anton A. Zharov ◽  
Anna N. Neretina ◽  
Svetlana A. Kuzmina ◽  
Alexey A. Kotov
Keyword(s):  
Western North America ◽  
Temporary Wetlands ◽  
Indicator Organisms ◽  
Aquatic Habitats ◽  
Eastern Asia ◽  
Large Mammal ◽  
Large Branchiopods ◽  
North Eastern ◽  
North Western ◽  
Large Branchiopod

In this study, we examine, identify, and discuss fossil remains of large branchiopod crustaceans collected from six sites across the Beringian region (north-eastern Asia and north-western North America). Eggs and mandibles from Anostraca and Notostraca, as well as a notostracan telson fragment and a possible notostracan second maxilla, were collected from both paleosediment samples and also from large mammal hair. The remains of large branchiopods and other species that are limited to seasonally astatic aquatic habitats (temporary wetlands) could be useful indicator organisms of paleoecological conditions. Different recent large branchiopod species have very different ecological preferences, with each species limited to specific geochemical component tolerance ranges regarding various salinity, cation, and gypsum concentrations. Our purpose is to bring the potential usefulness of these common fossil organisms to the attention of paleoecologists.

scholarly journals Nutraceutical potential of Ficus roxburghii an underutilized fruit of Sikkim Himalayas

2018 ◽  
Vol 10 (3) ◽  
pp. 876-880
Author(s):  
Yamuna Pandey ◽  
S. Upadhyay ◽  
S. Manivannan ◽  
L. Sharma ◽  
S.S. Bhatt
Keyword(s):  
Ascorbic Acid ◽  
Mineral Content ◽  
Total Phenols ◽  
Total Carotenoids ◽  
Energy Value ◽  
Phytochemical Content ◽  
Balanced Diet ◽  
Western Himalayan Region ◽  
North Eastern ◽  
North Western

Ficus roxburghii, “Elephant ear fig “or wild fig is one of very popular fruits found growing wild in the hills of North Eastern and North Western Himalayan region. The fruit of wild fig has also been used as medicine by the tribal people of Sikkim and other states of India. Keeping this in view, the present study was conducted at Laboratory of Department of Horticulture, Sikkim University, Sikkim to access the different nutraceuticals properties as nutritional constituent like protein, fat, fibre, carbohydrate and energy value, mineral content viz.Ca, K, Mg, Na, Zn, Co, Mo, Fe, Mn and phytochemical content such as total phenols, flavonoid, ascorbic acid, anthocyanin and total carotenoids of F. roxburghii. The results of present study revealed that fruit of F. roxburghii contains significant amount of nutritional, mineral and phytochemical properties viz. protein (3.00±0.06%), fat (0.13±0.04%), fibre (3.06±0.02%), carbohydrate (90.81±0.44 %), energy value (376.45±1.44), Ca (23.69 ± 1.7), Mg  (73.09 ± 2.1), K (819.64 ± 12.54), Mo (0.58 ±  0.06), Na (6.73 ± 1.2), Zn (0.34 ± 0.10). Fe (26.55 ± 2.8), Cu (4.22 ± 0.20), Mn (7.11 ± 0.11), total phenols (4.13±0.52 mg GAE/ G), total flavonoid (3.10±0.09 mg GAE/ G), ascorbic acid (3.36±0.27 mg GAE/ G), anthocyanin (1.13±0.15 mg GAE/ G) and total carotenoids (0.68±0.10 mg GAE/ G). It may be concluded that the fruit of F. roxburghiiis rich in nutraceuticals and must be incorporated in our balanced diet.

Active-middle alignment and the aoristic drift

2020 ◽  
pp. 191-212
Author(s):  
Delia Bentley
Keyword(s):  
The North ◽  
North Eastern ◽  
North Western

In the classification of Romance along a northern–southern continuum the languages which exhibit patterns of active-middle alignment (notably, the HABERE ~ ESSE alternation in the perfect) are also known to have undergone the aoristic drift. This article starts from Smith’s (2016) observation that the north-western oïl varieties have maintained the preterite, while also alternating the two auxiliaries, whereas the north-eastern oïl varieties have lost the HABERE ~ ESSE alternation and undergone the aoristic drift. It is argued that the developments which have occurred in the north-western varieties are not theoretically challenging or unique within the Romània. With respect to the generalization of habere in the north-eastern areas and, less conspicuously, throughout Gallo-Romance, it is claimed that this development was engendered by the rise of a dependent-marking system which follows undifferentiated nominative alignment. It is concluded that the modern Romània exhibits a stronghold of active-middle alignment in a group of central languages, which are essentially head marking.

Structural Properties of the San Jacinto Fault Zone at Blackburn Saddle from Seismic Data of a Dense Linear Array

2018 ◽  
Vol 176 (3) ◽  
pp. 1169-1191 ◽  
Author(s):  
Pieter-Ewald Share ◽  
Amir A. Allam ◽  
Yehuda Ben-Zion ◽  
Fan-Chi Lin ◽  
Frank L. Vernon
Keyword(s):  
Structural Properties ◽  
Fault Zone ◽  
Seismic Data ◽  
Linear Array ◽  
San Jacinto Fault ◽  
San Jacinto Fault Zone

Rediscovery of the Tasmanian Grasshopper Schayera-Baiulus (Orthoptera, Acrididae) in the Field

1991 ◽  
Vol 39 (6) ◽  
pp. 655 ◽  
Author(s):  
KHL Key
Keyword(s):  
Wide Distribution ◽  
Habitat Requirements ◽  
The North ◽  
North Eastern ◽  
North Western

Two nymphs of the rare Tasmanian grasshopper Schayera baiulus (Erichson), a male and a female, have been discovered in the north-eastern and north-western corners of Tasmania respectively, thus confirming its Tasmanian provenance and suggesting a former wide distribution across the north of the island. The nymphs are described and figured. The female was reared to maturity and the adult genitalia described. The very different environments at the two capture localities are documented. The problems involved in defining the habitat requirements and securing the survival of the species are discussed.

The genus Microhyla (Anura: Microhylidae) in Pakistan: species status and origins

Zootaxa ◽  
2020 ◽  
Vol 4845 (2) ◽  
pp. 293-296
Author(s):  
DANIEL JABLONSKI ◽  
MUAZZAM ALI KHAN ◽  
RAFAQAT MASROOR
Keyword(s):  
Evolutionary History ◽  
Genetic Data ◽  
Western India ◽  
Indus River ◽  
Species Status ◽  
Short Contribution ◽  
Jammu And Kashmir ◽  
The North ◽  
North Eastern ◽  
North Eastern Part

The territory of Pakistan has been influenced by biota from different geographic directions, and is divided zoogeographically into the Palearctic and Oriental regions (Khan 2006; Masroor 2012). This makes Pakistan one of the important territories in Eurasia in the understanding of past biodiversity dynamics. Well-known examples of Oriental elements among its amphibian fauna are observed in all four families of toads and frogs currently known from Pakistan: Bufonidae, Microhylidae, Megophryidae, and Dicroglossidae. In this short contribution, we focused on the species status and the origins of the genus Microhyla (Microhylidae), known from the north-eastern part (Punjab, Islamabad, and Azad Jammu and Kashmir; Masroor 2012) of the country. However, Sarkar (1984), also reported Microhyla from Bhuj in Gujarat, India, very close to the southern Pakistani province of Sindh. This genus has not yet been reported from the Palearctic region of the country and all currently known localities are from the Oriental parts of Pakistan (i.e. eastward of the Indus River). The genus is represented in the country by M. ornata (Duméril & Bibron, 1841), originally reported as Oxyglossus lima (Khan 1968). However, in view of the overall distribution and diversity of the genus based on genetic data (Garg et al. 2018, 2019; Gorin et al. 2020), it appears that populations from Pakistan could possibly have a different evolutionary history and be different taxon (see the currently scattered range of the genus between northern and western India and Pakistan; Fig. 1). Therefore, we tested this assumption using mitochondrial (mt) and nuclear (n) DNA data. 

Outcrops and well logs as a practicum for calibrating the accuracy of traveltime tomograms

2015 ◽  
Vol 3 (3) ◽  
pp. SY27-SY40 ◽  
Author(s):  
Sherif M. Hanafy ◽  
Ann Mattson ◽  
Ronald L. Bruhn ◽  
Shengdong Liu ◽  
Gerard T. Schuster
Keyword(s):  
High Resolution ◽  
Fault Zone ◽  
Great Basin ◽  
Seismic Tomography ◽  
Seismic Data ◽  
Hanging Wall ◽  
Normal Fault ◽  
Well Logs ◽  
Drill Core ◽  
Sufficient Detail

We have developed two case studies demonstrating the use of high-resolution seismic tomography and reflection imaging in the field of paleoseismology. The first study, of the Washington fault in southern Utah, USA, evaluated the subsurface deposits in the hanging wall of the normal fault. The second study, of the Mercur fault in the eastern Great Basin of Utah, USA, helped to establish borehole locations for sampling subsurface colluvial deposits buried deeper than those previously trenched along the fault zone. We evaluated the seismic data interpretations by comparison with data obtained by trenching and logging deposits across the Washington fault, and by drill-core sampling and video logging of boreholes penetrating imaged deposits along the Mercur fault. The seismic tomograms provided critical information on colluvial wedges and faults but lacked sufficient detail to resolve individual paleoearthquakes.

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