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.

scholarly journals Great Salt Lake–Effect Precipitation: Observed Frequency, Characteristics, and Associated Environmental Factors

2012 ◽  
Vol 27 (4) ◽  
pp. 954-971 ◽  
Author(s):  
Trevor I. Alcott ◽  
W. James Steenburgh ◽  
Neil F. Laird
Keyword(s):  
Environmental Factors ◽  
Temperature Difference ◽  
Large Scale ◽  
Salt Lake ◽  
Great Salt Lake ◽  
Threshold Value ◽  
Substantial Improvement ◽  
Lake Area ◽  
Lake Effect ◽  
The Difference

Abstract This climatology examines the environmental factors controlling the frequency, occurrence, and morphology of Great Salt Lake–effect (GSLE) precipitation events using cool season (16 September–15 May) Weather Surveillance Radar-1988 Doppler (WSR-88D) imagery, radiosonde soundings, and MesoWest surface observations from 1997/98 to 2009/10. During this period, the frequency of GSLE events features considerable interannual variability that is more strongly correlated to large-scale circulation changes than lake-area variations. Events are most frequent in fall and spring, with a minimum in January when the climatological lake surface temperature is lowest. Although forecasters commonly use a 16°C lake–700-hPa temperature difference (ΔT) as a threshold for GSLE occurrence, GSLE was found to occur in winter when ΔT was only 12.4°C. Conversely, GSLE is associated with much higher values of ΔT in the fall and spring. Therefore, a seasonally varying threshold based on a quadratic fit to the monthly minimum ΔT values during GSLE events is more appropriate than a single threshold value. A probabilistic forecast method based on the difference between ΔT and this seasonally varying threshold, 850–700-hPa relative humidity, and 700-hPa wind direction offers substantial improvement over existing methods, although forecast skill is diminished by temperature and moisture errors in operational models. An important consideration for forecasting because of their higher precipitation rates, banded features—with a horizontal aspect ratio of 6:1 or greater—dominate only 20% of the time that GSLE is occurring, while widespread, nonbanded precipitation is much more common. Banded periods are associated with stronger low-level winds and a larger lake–land temperature difference.

scholarly journals External Groundwater Alleviates the Degradation of Closed Lakes in Semi-Arid Regions of China

2019 ◽  
Vol 12 (1) ◽  
pp. 45 ◽  
Author(s):  
Jiaqi Chen ◽  
Jiming Lv ◽  
Ning Li ◽  
Qingwei Wang ◽  
Jian Wang
Keyword(s):  
Time Series ◽  
Large Scale ◽  
Isotopic Signature ◽  
Water Infiltration ◽  
Agricultural Irrigation ◽  
Lake Area ◽  
Daihai Lake ◽  
Huangqihai Lake ◽  
The Impact ◽  
Semi Arid

There are a large number of lakes with beaded distribution in the semi-arid areas of the Inner Mongolian Plateau, and some of them have degraded or even disappeared during the past three decades. We studied the reasons of the disappearance of these lakes by determining the way of replenishment of these lakes and the impact of the natural-social environment of the basin, with the aim of saving these gradually disappearing lakes. Based on remote sensing image and hydrological analysis, this paper studied the recharge of Daihai Lake and Huangqihai Lake. The deep learning method was used to establish the time-series of lake evolution. The same method was combined with the innovative woodland and farmland extraction method to set up the time-series of ground classification composition in the basins. Using relevant survey data, combined with soil water infiltration test, water chemical, and isotopic signature analysis of various water bodies, we found that the Daihai Lake area is the largest in dry season and the smallest in rainy season and the other lake is not satisfied with this phenomenon. In addition, we calculated the specific recharge and consumption of the study basin. These experiments indicated that the exogenous groundwater is recharged directly through the faults at the bottom of Daihai Lake, while the exogenous groundwater is recharged in Huangqihai Lake through rivers indirectly. Large-scale exploitation of groundwater for agricultural irrigation and industrial production is the main cause of lake degradation. Reducing the extraction of groundwater for agricultural irrigation is an important measure to restore lake ecology.

scholarly journals Spirulina Culture in Bangladesh XI: Selection of a Culture Medium, Suitable for Culturing a Local Strain of Spirulina

1970 ◽  
Vol 41 (3) ◽  
pp. 227-234
Author(s):  
R Khatun ◽  
P Noor ◽  
N Akhter ◽  
MAA Jahan ◽  
M Hossain ◽  
...  
Keyword(s):  
Spirulina Platensis ◽  
Climatic Condition ◽  
Large Scale ◽  
Culture Medium ◽  
Culture Media ◽  
Local Strain ◽  
Condition Effect ◽  
Selection Of

Large scale Spirulina culture is possible in Bangladesh inspite of unpredictable climatic condition. Effect of different culture media on the growth of a local strain of Spirulina (Spirulina platensis) was studied. Bangladesh medium (Bd1) was found to be more favourable for the growth of the alga. All together three culture media were included in this study. Bangladesh J. Sci. Ind. Res. 41(3-4), 227-234, 2006

Large-scale inversion of ZTEM data

Geophysics ◽  
2012 ◽  
Vol 77 (4) ◽  
pp. WB37-WB45 ◽  
Author(s):  
Elliot Holtham ◽  
Douglas W. Oldenburg
Keyword(s):  
Large Scale ◽  
Computational Cost ◽  
Natural Source ◽  
Reference Station ◽  
Coarse Mesh ◽  
Data Set ◽  
Entire Area ◽  
Electromagnetic Methods ◽  
True Model ◽  
Coarse Model

A Z-Axis Tipper Electromagnetic Technique (ZTEM) survey is an airborne natural source electromagnetic survey that relates the vertical magnetic field to the horizontal magnetic fields measured at a reference station on the ground. For large airborne surveys, the high number of cells required to discretize the entire area at a reasonable resolution can make the computational cost of inverting the data set all at once prohibitively expensive. We present an iterative methodology that can be used to invert large natural source surveys by using a combination of coarse and fine meshes as well as a domain decomposition that allows the full model area to be split into smaller subproblems, which can be run in parallel. For this procedure, the entire data set is first inverted on a coarse mesh. The recovered coarse model and computed fields are used as starting models and source terms in the subsequent tiled inversions. After each round of tiled inversions, the tiles are merged together to form an update model, which is then forward modeled to determine if the model achieves the target misfit. Following this procedure, we first invert the data computed from a large synthetic model of the Noranda mining camp. The inverted models from this example are consistent among our different tiling choices. The recovered models show excellent large-scale agreement with the true model and they also recover several of the mineralized zones that were not apparent from the initial coarse inversion. Finally, we invert a [Formula: see text] block of the 2010 ZTEM survey collected over the porphyry Pebble Deposit in Alaska. The inverted ZTEM results are consistent with the results obtained using other electromagnetic methods.

Benue Trough and Benue Chain

1982 ◽  
Vol 119 (2) ◽  
pp. 155-168 ◽  
Author(s):  
J. Benkhelil
Keyword(s):  
South America ◽  
Large Scale ◽  
Fracture Zones ◽  
Tectonic Event ◽  
Benue Trough ◽  
Cameroon Volcanic Line ◽  
Strain Pattern ◽  
Igneous Activity ◽  
The Difference ◽  
A Chain

SummaryIt is suggested that the Benue Trough may have been initiated by the extension of the equatorial oceanic fracture zones onto the continent during the early stages of the separation of Africa and South America. A transcurrent movement along deep-seated faults of the basement is responsible for the structure of the trough. After a period of extension characterized by the sedimentary infilling of the trough and igneous activity, the trough is turned into a chain through a short phase of compression. A discrete pattern of ‘en echelon’ folds and the strain pattern deduced from the analysis of large scale and microfracturing correspond to a N–S to N160° E direction of compression coupled to a sinistral transcurrent movement along a NE–SW direction. The difference in age of the folding phase in the northern and southern parts of the chain indicates a diachronous nature for this tectonic event in relation to the wrench regime. The Tertiary evolution of the trough marked by a tensional regime resulting in an E–W extension is to be related to the Cameroon Volcanic Line.

scholarly journals Long-Term Lake Area Change and Its Relationship with Climate in the Endorheic Basins of the Tibetan Plateau

2021 ◽  
Vol 13 (24) ◽  
pp. 5125
Author(s):  
Junxiao Wang ◽  
Mengyao Li ◽  
Liuming Wang ◽  
Jiangfeng She ◽  
Liping Zhu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Large Scale ◽  
Driving Forces ◽  
Atlantic Multidecadal Oscillation ◽  
The Tibetan Plateau ◽  
Lake Area ◽  
Climate Variables ◽  
Landsat Images ◽  
Area Change ◽  
Local Climate

Lakes are sensitive indicators of climate change in the Tibetan Plateau (TP), which have shown high temporal and spatial variability in recent decades. The driving forces for the change are still not entirely clear. This study examined the area change of the lakes greater than 1 km2 in the endorheic basins of the Tibetan Plateau (EBTP) using Landsat images from 1990 to 2019, and analysed the relationships between lake area and local and large-scale climate variables at different geographic scales. The results show that lake area in the EBTP has increased significantly from 1990 to 2019 at a rate of 432.52 km2·year−1. In the past 30 years, lake area changes in the EBTP have mainly been affected by local climate variables such as precipitation and temperature. At a large scale, Indian Summer Monsoon (ISM) has correlations with lake area in western sub-regions in the Inner Basin (IB). While Atlantic Multidecadal Oscillation (AMO) has a significant connection with lake area, the North Atlantic Oscillation (NAO) does not. We also found that abnormal drought (rainfall) brought by the El Niño/La Niña events are significantly correlated with the lake area change in most sub-regions in the IB.

The equine forelimb suspensory ligament exhibits a heterogeneous strain pattern under tensile load

2015 ◽  
Vol 28 (05) ◽  
pp. 306-311 ◽  
Author(s):  
M. Lavagnino ◽  
J. Madison ◽  
M. R. Williams ◽  
S. P. Arnoczky
Keyword(s):  
Repeated Measures ◽  
Tensile Load ◽  
Local Strain ◽  
Proximal Region ◽  
Materials Testing ◽  
Recurrence Rates ◽  
Injury Rates ◽  
Suspensory Ligament ◽  
Strain Pattern ◽  
Regional Strain

SummaryObjectives: To determine if regional variations in strain patterns occur within the suspensory ligament under tensile load. Local increases in strain may put certain regions of the suspensory ligament at risk and may explain the poor healing and high recurrence rates associated with suspensory branch injuries.Methods: The suspensory ligament and its bone attachments were isolated from each of 10 adult equine cadaveric forelimbs and radiodense reference beads were inserted throughout the length of the ligament. Specimens were attached to a custom fixture secured to a materials testing system. Radio-graphs were acquired at 50, 445, 1112, and 2224 N of applied tensile load. Changes in distances between the beads in each region of the suspensory ligament were measured and the regional strain was calculated. Significant differences were determined using a repeated-measures analysis of variance.Results: The suspensory ligament exhibited significant differences in regional strain (p <0.001). The distal branches of the suspensory ligament had significantly greater strains than the proximal (p = 0.025) and mid-body (p = 0.002) regions. The mid-body of the suspensory ligament also exhibited local strain variation, with the distal mid-body having significantly higher strains than the proximal mid-body (p = 0.038).Clinical significance: The equine suspensory ligament demonstrates a heterogeneous strain pattern during tensile loading, with the distal regions exhibiting significantly more strain than the proximal region. The nonhomogenous strain pattern could explain the regional difference in injury and re-injury rates.

Minibasin mobility and obstruction on salt-detached slopes: implications for canopy dynamics and sediment routing

2020 ◽  
Author(s):  
Naiara Fernandez ◽  
Oliver Duffy ◽  
Frank Peel ◽  
Michael Hudec ◽  
Gillian Apps ◽  
...  
Keyword(s):  
Large Scale ◽  
Early Stage ◽  
Regional Scale ◽  
Local Strain ◽  
Seismic Attribute ◽  
Structural Domains ◽  
Hydrocarbon Reservoir ◽  
Sediment Routing ◽  
Attribute Analysis ◽  
The Individual

&lt;p&gt;In salt-detached gravity-gliding/spreading systems the detachment geometry is a key control on the downslope mobility of the supra-canopy (supra-salt) sequence. As supra-canopy minibasins translate downslope, they also subside into salt. If the base of salt has high relief, minibasins may weld and stop from further free translation downslope. The degree of minibasin obstruction controls both the kinematics of the individual basins, and the more regional pattern of supra-canopy strain.&amp;#160;Here, we use regional 3D seismic data to examine a salt-stock canopy in the northern Gulf of Mexico slope, in an area where supra-canopy minibasins subsided vertically and translated downslope above a complex base-of-salt with high relief.&lt;/p&gt;&lt;p&gt;At a regional scale, we distinguish two structural domains in the study area: a highly obstructed or locked domain and a highly mobile domain. Large-scale translation of the supra-canopy sequence is recorded in the mobile domain by two different structures (a far-travelled minibasin and a ramp syncline basin). Although identifying the deformation area between the two regional domains is challenging due to its diffusive nature, characterizing domains according to base-of-salt geometry and supra-canopy minibasin configuration is helpful in identifying structural domains that may share similar subsidence and downslope translation histories.&lt;/p&gt;&lt;p&gt;At minibasin scale, minibasins that become obstructed modify the local strain field, typically developing a zone of shortening immediately updip of it and an extensional breakaway zone immediately downdip. Seismic attribute analysis performed in a cluster of minibasins in the study area illustrates a long-lived sediment transport system affected by the complex strain patterns associated with minibasin obstruction. At an early stage, a submarine channel system is captured and subsequently rerouted in response to the updip shortening associated with minibasin obstruction. At a later stage, a mass-transport complex (MTC) is steered by the topographic barrier created by the downdip extensional breakaway associated with minibasin obstruction.&lt;/p&gt;&lt;p&gt;Our work illustrates how salt-tectonic processes related to minibasin obstruction can affect the canopy dynamics at both regional and minibasin scale. Furthermore, we show that minibasin obstruction processes can modify the seafloor and subsequently control deepwater sediment dispersal, which, ultimately can affect hydrocarbon reservoir distribution on salt-influenced slopes&lt;/p&gt;

scholarly journals The ascension and intrusion processes of salt water into aquifers along the tectonic discontinuities in the Żarnowieckie Lake area

2018 ◽  
Vol 54 ◽  
pp. 00006
Author(s):  
Mateusz Damrat ◽  
Rafał Warumzer
Keyword(s):  
Large Scale ◽  
Salt Water ◽  
Lake Area ◽  
Geological Structures ◽  
Neotectonic Activity ◽  
Fault Network

In this article, the authors want to pay attention to the intensity of the phenomenon of ascension of salt water from the Permo-Mesozoic formation in the geological structures of the Dębki - Żarnowiec trough. This is a unique area in Poland. The sediments (up to 320 m in thickness) of the deep Pleistocene trough, cross the Tertiary, Cretaceous and Jurassic deposits, and reach the Triassic layers in the deepest place. An additional aspect is the unquestionable presence of older structures and tectonic loosening, which conditioned the formation of such a large erosion structure. Younger tectonic (neotectonic) activity, both large-scale and resulting from isostatic movements, certainly uses the existing fault network, which in combination with the deeper layer of relatively well-permeable Pleistocene sediments is a system extremely conducive to ascension brines.

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