scholarly journals Narrow belt of debris around the Sco-Cen star HD141011

2021 ◽  
Author(s):  
M. Bonnefoy ◽  
J. Milli ◽  
F. Menard ◽  
P. Delorme ◽  
A. Chomez ◽  
...  
Keyword(s):  
Narrow Belt

scholarly journals Glaciotectonic Structures in Central Sweden and their Significance for Glacial Theory

2007 ◽  
Vol 42 (3) ◽  
pp. 315-323 ◽  
Author(s):  
James S. Aber ◽  
Jan Lundqvist
Keyword(s):  
Regional Distribution ◽  
Ice Sheet ◽  
Outer Zone ◽  
Intermediate Zone ◽  
Pressure Gradients ◽  
Last Glaciation ◽  
Narrow Belt ◽  
Sheet Deformation

ABSTRACT Various glaciotectonic structures and landforms created by ice pushing are common in drift and interstadial sediments in a narrow belt of central Sweden. Described examples from the Lake Storsjôn vicinity demonstrate that glaciotectonic deformation took place while the area was deeply covered by the last Fennoscandian Ice Sheet. Deformation was controlled by pressure gradients related to position of the ice divide and ice movement away from the divide. As the position of the divide shifted during the last glaciation, so did the orientation of glaciotectonic structures. The regional distribution of glaciotectonic features in Fennoscandia falls into three zones: (1) inner zone of widespread, small- to moderate-sized features in older drift, (2) intermediate zone of small, isolated features in drift of the last glaciation, and (3) outer zone with all manner of large and small features in drift and soft bedrock. These zones are the cumulative results of multiple glaciations and reflect the overall distribution of deformable sediment and bedrock within the continental substratum.

scholarly journals Ice shelf internal reflection horizons reveal ice provenance, dynamics, surface accumulation and oceanic melt

2021 ◽  
Author(s):  
Inka Koch ◽  
Reinhard Drews ◽  
Daniela Jansen ◽  
Steven Franke ◽  
Vjeran Visnjevic ◽  
...  
Keyword(s):  
Shear Zones ◽  
Ultra Wideband ◽  
Internal Layers ◽  
Ice Shelf ◽  
Ice Streams ◽  
Catchment Scale ◽  
Ice Dynamics ◽  
Ice Shelves ◽  
Wideband Radar ◽  
Narrow Belt

<p>Ice shelves are widely known to slow the transfer of Antarctic grounded ice to the ocean, especially if their flow is decelerated by local pinning points. Their longevity is influenced by variations in ice dynamics, surface accumulation and oceanic conditions in the ice shelf cavity. This is reflected in the ice shelf structure, which can be characterized by the shape of internal radar reflection horizons.</p><p>We aim to map the internal ice shelf stratigraphy of ice shelves, starting with the narrow belt of ice-shelves in the Dronning Maud Land area. The final goal will be to evaluate these as a spatiotemporal archive of ice provenance and ice dynamics. The bulk of the data presented here were collected with AWI’s airborne multi frequency ultra-wideband radar and we combine these new observations with airborne and ground-based radar surveys from previous years. We present a consistent set of internal radar isochrones on a catchment scale for the Roi Baudoin area including the Ragnhild ice streams, the grounding-zone, the iceshelf and multiple ice rises.  Using pattern matching technique we can link isochrones across different ice rises in the area, and hence provide first observational constraints on how ice rises jointly react to changes in atmospheric and oceanographic forcings. We also find a number of interesting features including dynamically induced dips in shear zones, truncating layers at the ice-shelf base, and the development of a meteoric ice layer distinguishing advected from newly accumulated ice in the iceshelf. The time series provided by radar observations over the last 10 years also offers the potential to map temporal changes. We use ice-flow modelling to provide age constraints for some internal layers and delineate portions within the shelf as a function of their advection history, hence marking areas of differing rheologies within the shelf. Taken together, this case study on a catchment scale is a primer to unravel the information stored in the isochronal stratigraphy of coastal Antarctica and contributes to international efforts (e.g., SCAR AntArchitecture)  of mapping stratigraphy on ice sheet scales.</p>

scholarly journals Conodonts from the Ordovician of East Greenland

1982 ◽  
Vol 108 ◽  
pp. 14-14
Author(s):  
M.P Smith
Keyword(s):  
East Greenland ◽  
Narrow Belt

The Cambro-Ordovician of East Greenland outcrops in a narrow belt between Canning Land (71°36') and C. H. Ostenfeld Nunatak (72°22'N). The uppermost three units, namely the Cape Weber, Narwhale Sound and Heim Bjerge Formations of the 4000 m thick sequence, have been sampled for conodonts.

The Croatian Renaissance

Slavic Review ◽  
1962 ◽  
Vol 21 (1) ◽  
pp. 65-88
Author(s):  
Ante Kadic
Keyword(s):  
Creative Writing ◽  
Eastern Shore ◽  
Cultural Importance ◽  
Narrow Belt ◽  
Venetian Republic

It was along the eastern shore of the Adriatic, in Dalmatian coastal towns and on neighboring islands, in the narrow belt of territory that had escaped Turkish conquest, that the Croatian Renaissance developed. The literature of this period is considered the beginning of Croatian creative writing and the foundation of the Croatian revival, known also as the Illyrian movement, that occurred three centuries later. Why did this Slavic literature develop in this small territory, which had been taken away from the Hungaro-Croatian kingdom and annexed to the Venetian Republic (1409-20) and whose high administrative, military, and often ecclesiastical officials were imported from Venice? A brief survey of what took place during several centuries on this Dalmatian coastland—rocky and barren, but surprisingly rich in events of political and cultural importance—may provide some explanation.

Vegetation East of the Rocky Mountains 18,000 Years Ago

1981 ◽  
Vol 15 (2) ◽  
pp. 113-125 ◽  
Author(s):  
H.E. Wright
Keyword(s):  
United States ◽  
Boreal Forest ◽  
New England ◽  
Jack Pine ◽  
Atlantic Coastal Plain ◽  
Reference Level ◽  
Eastern United States ◽  
Southern Limit ◽  
Southern Georgia ◽  
Narrow Belt

AbstractThe various lobes and segments of the southern periphery of the Laurentide ice sheet reached their maximum extension at different times between 21,000 and 14,000 yr ago, but the CLIMAP date of 18,000 yr ago is taken as a reference level to review the distribution of major vegetational formations in central and eastern United States. Tundra was apparently confined to a narrow belt peripheral to the ice margin only in the Minnesota area and from northern Pennsylvania to New England, with extensions down the crest of the Appalachian Highlands at least as far as Maryland. Some areas south of the Great Lakes may later have been marked by treeless vegetation briefly as the ice retreated. The boreal forest to the south in the central United States was dominated by spruce; the jack pine that had prevailed during previous times was apparently eliminated by the time the ice reached its maximum. In the Appalachian Highlands and the Atlantic Coastal Plain, however, jack pine occurred along with spruce, which decreased in importance southward. The southern limit of the boreal forest in the Southeast was perhaps somewhere in southern Georgia and Alabama. Oak and other temperate deciduous trees were minor components of the boreal coniferous forests especially in the southern Appalacchians, but there is no evidence yet in the southeastern states for a relic mixed mesophytic forest 18,000 yr ago similar to the rich modern deciduous forests of the region, except possibly in the Lower Mississippi Valley. The climate in much of the Southeast was apparently dry as well as cool at that time; in Florida oak/pine scrub and prairie-like openings prevailed, and all but the deepest lakes dried up.

A granophyre from Coire Uaigneich, Isle of Skye, containing quartz paramorphs after tridymite (Plate XIII)

1953 ◽  
Vol 30 (223) ◽  
pp. 263-276 ◽  
Author(s):  
L. R. Wager ◽  
D. S. Weedon ◽  
E. A. Vincent
Keyword(s):  
Final Stage ◽  
Second Generation ◽  
Textural Features ◽  
The West ◽  
Plate Xiii ◽  
Igneous Intrusions ◽  
Igneous Province ◽  
Narrow Belt ◽  
Isle Of Skye

The narrow belt of granophyre lying to the west of Blaven in the Isle of Skye showed so admirably the effects of chilling that a series of specimens was collected by one of us (L.R.W.) and found to contain, in the chilled marginal rock, phenoerysts of tridymite, now inverted to quartz. In the Thulean Tertiary igneous province former tridymite is known from certain acid lavas, for example, the Tardree rhyolite (von Lasaulx, 1877) and certain Icelandic liparites (Hawkes, 1916), and from metamorphosed arkoses adjacent to basic igneous intrusions (Harker, 1908, 1932), but it has not previously been noted in the intrusive acid rocks. In addition to phenocrysts of tridymite inverted to quartz, there is present in the groundmass of the unchilled granophyre a second generation of inverted tridymite crystals, surrounded by a final stage of quartz and felspar which has crystallized with normal microgranitic textures. Some of the textural features resemble those of the normal Skye granophyres, while others resemble certain metamorphosed arkoses.

Elba manganese ores and their origin, South-eastern Desert, U.A.R.

1971 ◽  
Vol 38 (294) ◽  
pp. 235-244 ◽  
Author(s):  
E. Z. Basta ◽  
W. S. Saleeb
Keyword(s):  
Low Temperature ◽  
Surface Oxidation ◽  
Eastern Desert ◽  
Oxidation Zone ◽  
Manganese Ores ◽  
South Eastern ◽  
Narrow Belt ◽  
Ore Types ◽  
Mineralogical Evidence ◽  
Very Low Temperature

SummaryThe manganese ores of Elba, South-eastern Desert, occur as numerous veins located within a narrow belt trending N.W.-S.E. Three ore-types were distinguished: hard crystalline ore consisting mainly of pyrolusite or ramsdellite or both, banded colloform ore consisting mainly of psilomelane, and in places cryptomelane, and soft nodular ore consisting of todorokite with minor amounts of psilomelane (or cryptomelane), nsutite, and pyrolusite. Black calcite and baryte occur in some of the veins and increase with depth.Based on the field and mineralogical evidence the origin of the ore is discussed. It is suggested that the ore is a very low-temperature epithermal fissure deposit of black calcite type that occurs near the surface (oxidation zone) in brecciated zones along faults.

Geology and geochronology of Helikian magmatism, western Labrador

1981 ◽  
Vol 18 (7) ◽  
pp. 1211-1227 ◽  
Author(s):  
Christopher Brooks ◽  
Richard J. Wardle ◽  
Toby Rivers
Keyword(s):  
Volcanic Rocks ◽  
High Grade ◽  
Regional Mapping ◽  
Grenville Province ◽  
Felsic Volcanism ◽  
High Grade Metamorphism ◽  
Narrow Belt ◽  
Intrusive Suite ◽  
Magmatic History ◽  
Magma Series

The Shabogamo intrusive suite, a predominantly gabbroic magma series intrusive into a variety of Archean, Aphebian, and Helikian units in the Churchill and Grenville Provinces of western Labrador, is reliably dated at circa 1375 Ma using both the Rb/Sr and Sm/Nd methods on whole rocks and mineral separates. The suite is thus synchronous with Elsonian magmatism in Labrador, which is characterized by the intrusion of large volumes of gabbroic, anorthositic, and associated magma, and so invites petrogenetic correlations on a regional scale.Gabbros of the Shabogamo intrusive suite are emplaced into volcanics and volcaniclastics of the Blueberry Lake group, which are provisionally dated at 1540 ± 40 Ma. The volcanic rocks are therefore of similar age to, and probably correlative with, the upper Petscapiskau Group and Bruce River Group felsic volcanics, which occur further east in a narrow belt within the Grenville Foreland zone. The linear disposition of centres of felsic volcanism in the Grenville Foreland zone about 1500 Ma ago is suggestive of the development of a major ensialic rift at least 300 km in length at that time. A twofold magmatic history during the Helikian of this part of Labrador is now emerging from the field mapping and geochronological studies. Early extrusive felsic volcanism about 1500 Ma ago confined to a linear belt immediately north of the Grenville Province was followed by voluminous mafic magmatism (with emplacement of gabbroic, anorthositic, and associated rocks) occurring over a wide area both within and outside of the present location of the Grenville Province.Rb/Sr dating of Aphebian quartzofeldspathic schists from within the Grenville Province near Wabush – Labrador City shows that the high-grade metamorphism and development of a penetrative schistosity were Grenvillian features formed about 1000 Ma ago. This result effectively precludes the possibility of a Hudsonian metamorphic imprint, a feasible interpretation that was raised during regional mapping of the area.

Hornblende lineations in Trout Lake area, Lac la Ronge map sheet, Saskatchewan

1970 ◽  
Vol 7 (3) ◽  
pp. 884-899 ◽  
Author(s):  
W. M. Schwerdtner
Keyword(s):  
Large Scale ◽  
Finite Extension ◽  
Local Strain ◽  
Lake Area ◽  
Entire Area ◽  
Trout Lake ◽  
Strain Pattern ◽  
Strain Ellipsoid ◽  
Major Branch ◽  
Narrow Belt

Most rocks exposed in the Trout Lake Area are migmatitic gneisses severely deformed during the Hudsonian orogeny (± 1700 m.y. ago). Hornblende-bearing layers or lenses, mostly well lineated, are found throughout the entire area. The attitude(s) of the hornblende lineation (aligned prismatic grains) can be measured in every outcrop.Within cylindrical buckling folds and boudinage structures, involving hornblende-bearing rocks, the orientation of hornblende lineations is related to local directions of megascopic finite strain parallel to layering, for the main period of tectonic flow. Because the local strain ellipsoid is commonly oblique to layering, the strain ellipse parallel to layering is generally a non-principal section. The direction of its longest diameter is called M, regardless of whether it is a direction of extension, shortening or no longitudinal strain.Throughout all medium-scale folds and boudinage structures investigated, hornblende lineations are parallel to M. This relationship is considered as general, and hornblende lineations are employed as indicators of M within large-scale folds. (Other structural elements are used in distinguishing between finite extension and shortening parallel to M.) Finally, the strain pattern of the Trout Lake Area (west half) is analyzed by means of a contour map for the lineation plunge (non-statistical "plunge isogonic map" after D. Elliot 1965).The areal pattern of M contains a diagonal belt across which the plunge values tend to change "discontinuously." Because this narrow belt coincides roughly with a major branch of the Birch Rapids – Wepusko Bay fault zone, the angular "discontinuity" in the lineation map can be attributed to "late" rotational faulting.

Book Review of “On Strong Motion Seismology” (in Japanese) written and edited by Hiroaki Yamanaka, published by University of Tokyo Press

2006 ◽  
Vol 1 (3) ◽  
pp. 449-451
Author(s):  
Editorial Office
Keyword(s):  
Ground Motion ◽  
Strong Motion ◽  
Earthquake Ground Motion ◽  
Large Fires ◽  
Hyogo Prefecture ◽  
Narrow Belt ◽  
Oil Tanks ◽  
Second Period ◽  
Collapsed Building

This book is a work for general readers, straight-forwardly treating the theme of "strong earthquake ground motion" directly causing disaster and explaining how to cope. Eartquake ground motion is generally said to cause earthquake disasters and the degree of ground motion is determined both by the magnitude of the earthquake and the distance from its epicenter. In reality, however, things are not so simple. In the 2003 Tokachi Offshore Earthquake, for example, shaking at a relatively long 10-second period resonated at the characteristic frequency of oil tanks, triggering sloshing and causing large fires. In the 1995 Southern Hyogo Prefecture Earthquake (the Great Hanshin-Awaji Earthquake Disaster), for another example, a long narrow belt of disaster confirmed where damage to collapsed building was especially significant because only ground within this belt quaked more intensely than elsewhere.

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