scholarly journals Nd isotope mapping of the Grenvillian Allochthon Boundary Thrust in Algonquin Park, Ontario

2019 ◽  
Vol 56 (2) ◽  
pp. 101-110 ◽  
Author(s):  
A.P. Dickin ◽  
J.W.D. Strong
Keyword(s):  
High Grade ◽  
Geographical Pattern ◽  
Precise Location ◽  
Nd Isotope ◽  
North Shore ◽  
The North ◽  
Digital Elevation ◽  
Elevation Data ◽  
Digital Elevation Data ◽  
Isotope Analyses

Over 50 new Nd isotope analyses are presented for high-grade orthogneisses from Algonquin Park and surrounding region to map major Grenvillian thrust boundaries. Nd model ages display a consistent geographical pattern that allows detailed mapping of the boundary between the Algonquin and Muskoka domains, here interpreted as the local trajectory of the Ottawan-age Allochthon Boundary Thrust (ABT). The ABT is underlain by a domain with Paleoproterozoic Nd model ages, interpreted as a tectonic duplex entrained onto the base of the main allochthon. The boundaries determined using Nd isotope mapping are consistent with field mapping and with remotely sensed aeromagnetic and digital elevation data. The precise location of the ABT can be observed in a road-cut on Highway 60, on the north shore of Lake of Two Rivers in the centre of Algonquin Park.

An application of Nd isotope mapping in structural geology: delineating an allochthonous Grenvillian terrane at North Bay, Ontario

2003 ◽  
Vol 140 (5) ◽  
pp. 539-548 ◽  
Author(s):  
A. P. DICKIN ◽  
R. H. MCNUTT
Keyword(s):  
Structural Geology ◽  
Amphibolite Facies ◽  
High Grade ◽  
Grenville Province ◽  
Nd Isotope ◽  
Bay Area ◽  
The North ◽  
Depleted Mantle ◽  
Different Types ◽  
Isotope Analyses

Fifty new Nd isotope analyses are presented from the North Bay area of the Grenville Province in Ontario. These data are used to map the extent of an allochthonous Grenvillian terrane which is an outlier of the Allochthonous Polycyclic Belt of the Grenville Province. Amphibolite facies orthogneisses from the allochthonous terrane have depleted mantle Nd model ages (TDM) below 1.8 Ga, whereas the gneisses of the structurally underlying parautochthon almost invariably have model ages above 1.8 Ga. The distribution of model ages is consistent with the distribution of distinct types of metabasic rock, used by other researchers as the criterion for recognizing rocks of the allochthonous and parautochthonous belts of the Grenville Province. The agreement between these different types of evidence demonstrates that Nd isotope mapping is a reliable and powerful tool for mapping terrane boundaries in high-grade metamorphic belts.

Geomorphological evidence of icefield-style glaciation in the Šumava/Bayerischer Wald mountains, Central Europe

2020 ◽  
Author(s):  
Martin Margold ◽  
David Krause
Keyword(s):  
High Resolution ◽  
Central Europe ◽  
Eastern Alps ◽  
Mountain Range ◽  
Glacial Erosion ◽  
Mountain Glaciers ◽  
The North ◽  
Digital Elevation ◽  
Elevation Data ◽  
Digital Elevation Data

<p>The Šumava/Bayerischer Wald mountains are located to the north of the eastern Alps, at the borders of present-day Austria, Bavaria and the Czech Republic. The Šumava/Bayerischer Wald belong to the Variscan mountain ranges of central Europe; these ranges hosted mountain glaciers at the times when the region of central Europe formed a broad unglaciated corridor between the glaciated Alps and the southern margin of the Fennoscandian Ice Sheet. While the region was home to some of the early studies into Pleistocene glaciations in the 19<sup>th</sup> century, there is still uncertainty both about the maximum extent of Pleistocene glaciation and its chronology. With the availability of high-resolution digital elevation data it is now possible to map the geomorphological traces of glaciation better than before.</p><p>We mapped glacial geomorphology from high-resolution digital elevation data for the entire mountain range. We newly find evidence of glacial erosion outside of the well-developed and earlier studied glacial cirques. Widespread traces of glacial erosion in the relatively low-relief, high-elevated central portion of the range indicate that the maximum Pleistocene extent of glaciation might have taken the form of an icefield. The scarcity of glacial depositional landforms beyond the well-developed glacial cirques (the moraines of which have earlier been dated to Marine Isotope Stage 2) may indicate that the icefield existed during one or more of the earlier cold stages of the Pleistocene and most of the depositional landforms formed by those glaciations have since been denudated. Quantitative geochronology would have the potential to correlate the occurrence of the inferred icefield in the Šumava/Bayerischer Wald mountains with the glaciations of the eastern Alps.</p>

scholarly journals Landslides across the USA: occurrence, susceptibility, and data limitations

Landslides ◽  
2020 ◽  
Vol 17 (10) ◽  
pp. 2271-2285 ◽  
Author(s):  
Benjamin B. Mirus ◽  
Eric S. Jones ◽  
Rex L. Baum ◽  
Jonathan W. Godt ◽  
Stephen Slaughter ◽  
...  
Keyword(s):  
The United States ◽  
National Scale ◽  
Landslide Occurrence ◽  
Process Understanding ◽  
Digital Elevation ◽  
Data Limitations ◽  
Elevation Data ◽  
The Usa ◽  
Digital Elevation Data ◽  
Landslide Mapping

Abstract Detailed information about landslide occurrence is the foundation for advancing process understanding, susceptibility mapping, and risk reduction. Despite the recent revolution in digital elevation data and remote sensing technologies, landslide mapping remains resource intensive. Consequently, a modern, comprehensive map of landslide occurrence across the United States (USA) has not been compiled. As a first step toward this goal, we present a national-scale compilation of existing, publicly available landslide inventories. This geodatabase can be downloaded in its entirety or viewed through an online, searchable map, with parsimonious attributes and direct links to the contributing sources with additional details. The mapped spatial pattern and concentration of landslides are consistent with prior characterization of susceptibility within the conterminous USA, with some notable exceptions on the West Coast. Although the database is evolving and known to be incomplete in many regions, it confirms that landslides do occur across the country, thus highlighting the importance of our national-scale assessment. The map illustrates regions where high-quality mapping has occurred and, in contrast, where additional resources could improve confidence in landslide characterization. For example, borders between states and other jurisdictions are quite apparent, indicating the variation in approaches to data collection by different agencies and disparity between the resources dedicated to landslide characterization. Further investigations are needed to better assess susceptibility and to determine whether regions with high relief and steep topography, but without mapped landslides, require further landslide inventory mapping. Overall, this map provides a new resource for accessing information about known landslides across the USA.

scholarly journals Environmental classification of administrative units of the Ukrainian Carpathians

2014 ◽  
pp. 245-253
Author(s):  
Ivan Kruhlov
Keyword(s):  
Cluster Analysis ◽  
Standard Deviation ◽  
Satellite Images ◽  
Environmental Classification ◽  
Digital Elevation ◽  
Elevation Data ◽  
Digital Elevation Data ◽  
Administrative Units ◽  
Elevation Model

Boundaries of 43 administrative units (raions and oblast towns) were digitized and manually rectified using official schemes and satellite images. SRTM digital elevation data were used to calculate mean relative elevation and its standard deviation for each unit, as well as to delineate altitudinal bioclimatic belts and their portions within the units. These parameters were used to classify the units via agglomerative cluster analysis into nine environmental classes. Key words: cluster analysis, digital elevation model, geoecosystem, geo-spatial analysis.

scholarly journals Retrieval of similar topographic areas.

2016 ◽  
Vol 47 (1) ◽  
pp. 275
Author(s):  
E. Kokinou ◽  
C. Panagiotakis ◽  
Th. Kinigopoulos
Keyword(s):  
Image Processing ◽  
High Efficiency ◽  
Automatic Extraction ◽  
Local Minima ◽  
Initial Model ◽  
Area Of Interest ◽  
Digital Elevation ◽  
Elevation Data ◽  
Digital Elevation Data ◽  
Step Number

Image processing and understanding and further pattern recognition comprises a precious tool for the automatic extraction of information using digital topography. The aim of this work is the retrieval of areas with similar topography using digital elevation data. It can be applied to geomorphology, forestry, regional and urban planning, and many other applications for analyzing and managing natural resources. In specifics, the user selects the area of interest, navigating overhead a high resolution elevation image and determines two (3) parameters (step, number of local minima and display scale). Furthermore the regions with similar relief to the initial model are determined. Experimental results show high efficiency of the proposed scheme.

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