The metamorphic environment of the Sgurr Beag Slide; a major crustal displacement zone in Proterozoic, Moine rocks of Scotland

1981 ◽  
Vol 138 (6) ◽  
pp. 661-673 ◽  
Author(s):  
D. Powell ◽  
A. W. Baird ◽  
N. R. Charnley ◽  
P. J. Jordan
Keyword(s):  
Moine Rocks ◽  
Displacement Zone

Field and isotopic evidence for a c. 750 Ma tectonothermal event in Moine rocks in the Central Highland region of the Scottish Caledonides

1983 ◽  
Vol 73 (3) ◽  
pp. 119-134 ◽  
Author(s):  
M. A. J. Piasecki ◽  
O. van Breemen
Keyword(s):  
Crustal Rocks ◽  
Highland Region ◽  
Ductile Shearing ◽  
Central Highland ◽  
Isotopic Studies ◽  
Previous Hypothesis ◽  
Moine Rocks ◽  
Early Palaeozoic ◽  
Similar Vein ◽  
Tectonothermal Event

ABSTRACTEvidence is presented for a late Proterozoic, tectonothermal event which affected the rocks of the Moine assemblage in the Central Highland region of the Scottish Caledonides c. 750 Ma ago. This is about 200 Ma before the early Palaeozoic Grampian orogeny, whose effects are superimposed on the Moine rocks as well as dominating the tectonism in the Dalradian Supergroup.Field and isotopic studies are integrated in zones of ductile thrusting (sliding) which are typified by belts of tectonic schists with related swarms of quartz and muscovite-bearing pegmatite veins. Of particular significance is a ductile thrust (the Grampian slide) which separates deeper crustal rocks (the Central Highland division), interpreted as showing the imprint of the Grenville orogeny, from shallower rocks (the Grampian division) representing a supracrustal assemblage formed between the Grenville and the c. 750 Ma events.The Grampian slide is the structurally highest member of a system of related, previously unrecorded slides affecting the Central Highland division. New structural, petrographic and Rb-Sr isotopic data, obtained largely from a recently recognised inlier of the Central Highland division at Laggan, bear out that the quartz and pegmatite veins are segregations formed during ductile shearing under amphibolite facies conditions. Muscovites from these veins yield ages between 780 and 730 Ma, and a regression analysis of tectonic schists and the muscovites gives an age of 740 ± 40 Ma. These data substantiate our previous hypothesis that the deeper-seated Moine rocks were affected by a distinct orogenic event at 750 ± 30 Ma.In the Northern Highlands, similar vein swarms are related to the Sgurr Beag slide and to belts of previously unrecorded tectonic schists in the Glenfinnan division of the Moine assemblage. A new, 755 ± 8 Ma age obtained from such a tectonic schist at Kinloch Hourn, combined with previous, similar age data from lensoid pegmatites, imply that the c. 750 Ma event may have also affected the Morar and Glenfinnan divisions.

scholarly journals Working Mechanism of Pile Group with Different Pile Spacing in Dense Sand

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Yadong Chen ◽  
Fan Lu ◽  
Abdoullah Namdar ◽  
Jiangdong Cai
Keyword(s):  
Three Dimensional ◽  
Interaction Mechanism ◽  
Pile Group ◽  
Resistance Pattern ◽  
Pile Groups ◽  
Pile Spacing ◽  
Dense Sand ◽  
Energy Mechanism ◽  
Tip Resistance ◽  
Displacement Zone

Complex interaction mechanism exists between the pile group and soil. To realize the pile-soil load transmission mechanism in detail, the failure pattern of pile groups installed in dense sand considering different pile spacing was investigated by means of laboratory experimental model test and three-dimensional discrete element method. The results suggested that the narrow pile spacing was beneficial to the development of the pile tip resistance, and it enhanced the bearing performance of the pile group at the initial stage of settlement. The pile spacing changed the shaft resistance pattern with modification of the strain energy mechanism released within the subsoil. The pile group with 6b pile spacing had higher composite group efficiency. A joint fan-shaped displacement zone was formed beneath the pile tip for the pile group with 3b pile spacing; this pile foundation presented the block failure mechanism. The sand displacement beneath the cap for the pile group with 6b pile spacing mainly located on the upper part of the piles, the sand displacement around both sides of the piles presented asymmetric, and a relatively independent fan-shaped displacement zone was formed beneath the pile tip.

Methodology for determining displacement zone parameters in mining diamond deposits in Yakutia using systems with cemented backfill

2020 ◽  
pp. 91-96
Author(s):  
I. B. Bokiy ◽  
◽  
V. V. Pul ◽  
O. V. Zoteev ◽  
A. S. Fedyanin ◽  
...  
Keyword(s):  
Cemented Backfill ◽  
Zone Parameters ◽  
Displacement Zone

Identification of displacement zone in extraction of coal reserves from pit wall by highwall mining systems in the Talda deposit in Kuzbass

2020 ◽  
pp. 21-24
Author(s):  
A. I. Bykadorov ◽  
◽  
D. N. Degtyarev ◽  
S. A. Smirnov ◽  
O. Yu. Pechenegov ◽  
...  
Keyword(s):  
Highwall Mining ◽  
Coal Reserves ◽  
Displacement Zone

Moine─Dalradian relationships and their palaeotectonic significance

1984 ◽  
Vol 395 (1809) ◽  
pp. 185-202 ◽  
Keyword(s):  
Thick Layer ◽  
High Heat ◽  
Source Rocks ◽  
Mineral Deposits ◽  
Common Source ◽  
Calc Alkaline ◽  
Isotopic Data ◽  
Moine Rocks ◽  
Southeastern Margin ◽  
Southern Highland

Regional geochemical and lithogeochemical data, when reviewed in relation to the development of the Caledonian orogen in Scotland, indicate that the Moine-Dalradian boundary coincides with a long-lived crustal discontinuity. It is suggested that this boundary follows the original southeastern margin of an old continental slab in which the Lewisian basement was overlain by a thick layer of ‘Old Moine’ metasediments affected by pre-Caledonian (750 Ma or over) deformation and metamorphism. Early Caledonian ‘Young Moine’ sediments on this slab resemble the underlying metasediments in lithofacies but are somewhat poorer in Zr and Y. To the southeast of the boundary, a thick Dalradian succession accumulated in a marine ensialic basin on a thinned basement of granulites and gneisses. In the Dalradian, elements of basic-ultrabasic association are high, especially in the upper Argyll and Southern Highland Groups where they are associated with products of basic volcanicity. Stratabound Ba, Pb and Zn mineral deposits occur widely not far below the volcanic horizon, and magmatism and mineralization are attributed to the opening of a palaeo-oceanic rift within the Dalradian basin. The geochemistry of the Torridonian, Old Moine and Young Moine detrital sediments suggests derivation from a common source dominated by intermediate-acid calc-alkaline rocks. Low to moderate large-ion litho-phile (l. i. l.) element levels suggest variable degrees of depletion caused by deep metamorphism of the source rocks. Isotopic data show that the sourceland was Archaean and early Proterozoic, and suggest that it may have resembled the Ketilidian and pre-Ketilidian of southern Greenland. The geochemical influence of this ancient western sourceland can be recognized throughout the Dalradian succession, constraining models that involve the availability of young island arc or exotic tectonic materials during the filling of the Dalradian basin. The mechanical strength, relatively low density and high heat production of the Old Moine rocks enhanced the contrast between the crustal slab incorporating a thick Moine layer and the main Dalradian basin beneath which this layer is absent. Tectonic and metamorphic develop­ments differed in the adjacent regions during orogeny, and deep discon­tinuities at the Moine-Dalradian boundary acted as conduits for Late Caledonian appinitic and metalliferous granites rising from sub-crustal sources.

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