Stratal architecture and evolution of a slope mass-transport complex, Isaac Formation, Neoproterozoic Windermere Supergroup, southern Canadian Cordillera, British Columbia, Canada

2018 ◽  
Vol 477 (1) ◽  
pp. 265-276 ◽  
Author(s):  
Lilian Navarro ◽  
R. William C. Arnott
Keyword(s):  
Mass Transport ◽  
Close Association ◽  
Sediment Supply ◽  
Slope Instability ◽  
Coarse Grained ◽  
Canadian Cordillera ◽  
Stratigraphic Position ◽  
Lateral Extent ◽  
Stratal Architecture ◽  
Transport Complex

AbstractDetailed sedimentological and stratigraphic analyses of a c. 1500 m thick, siliciclastic-dominated slope succession in the Neoproterozoic Isaac Formation at the Castle Creek study area (southern Canadian Cordillera) reveals the occurrence of four well-preserved mass-transport complexes (MTCs) composed principally of slide/slump and debris-flow deposits. The stratigraphically lowest of these complexes is about 60 m thick and crops out for >2.5 km laterally, consisting of slide and debrite. The slide has an irregular erosive base with ramp-and-flat geometry. This is overlain locally by boulder-sized blocks of slightly to moderately deformed strata, bounded by shear surfaces. The slide is overlain by a debrite that pinches and swells laterally, consisting of matrix-supported conglomerate with common metre-scale clasts of mudstone and coarse-grained sandstone embedded in a mudstone-rich matrix with dispersed, pebble quartz grains. Based on its stratigraphic position at the base of the slope, vertical stacking of slide-debrite, lithological distribution, considerable thickness and lateral extent, this MTC is interpreted to be associated with a major episode of continental slope instability and submarine mass-wasting. The close association between the MTC and underlying/overlying mixed carbonate-siliciclastic strata suggests that sea level most likely exerted a key control on sediment supply, which ultimately led to the emplacement of this MTC.

scholarly journals Late Cenozoic shelf delta development and Mass Transport Deposits in the Dutch offshore area – results of 3D seismic interpretation

2012 ◽  
Vol 91 (4) ◽  
pp. 591-608 ◽  
Author(s):  
A. Benvenuti ◽  
H. Kombrink ◽  
J.H. ten Veen ◽  
D.K. Munsterman ◽  
F. Bardi ◽  
...  
Keyword(s):  
Mass Transport ◽  
Sea Level ◽  
North Sea ◽  
Sediment Supply ◽  
Slope Instability ◽  
Shear Surface ◽  
Southern North Sea ◽  
Basal Shear ◽  
Mass Transport Deposits ◽  
High Sediment

AbstractIn this study, seismic stratigraphic criteria have been used to characterise the evolution of the Southern North Sea (SNS) shelf-delta system that progressively filled the Southern North Sea basin during Plio-Pleistocene times. Based on the prograding and down-stepping architecture of the shelf-delta sequence it is inferred that deposition occurred during a time of high sediment supply and overall sea-level lowering. During this time the delta slopes failed several times, creating at least 30 internally coherent Mass Transport Deposits (MTDs) mainly grouped in common areas, affecting the same clinoform set and partially sharing the basal shear surface (groups of MTDs). The most important features of the studied MTDs are 1) the dominance of brittle deformation; 2) the small amount of material removal from the headwall domain (lack of completely depleted areas above the basal shear surface); and 3) the lack of an emergent toe domain above the un-failed sediment located basinward, although proper confining geometries for the MTD are not detected. Therefore, the studied MTDs can neither be classified as frontally confined nor as frontally emergent but they are a new intermediate type of submarine landslides which has not been described before. These characteristics suggest that the mass movement ceased relatively soon after initiation of failure. Incisions on top of the MTDs suggest the presence of erosive flows. These flows were probably generated due to a concentration of the drainage in the negative morphology the failure event left behind in the upper sector of the slope. The stronger progradational character of the reflections on top of MTDs confirms a concentration of drainage after the erosional phase too.The interplay between high sediment supply and constant or even decreasing accommodation space (caused by constant or decreasing sea-level) is supposed to be the main precondition for slope instability for most of the MTDs in this study area. Slope failures themselves can also be considered a preconditioning factor by the creation of local very high sedimentation rates (see groups of MTDs). Salt-induced seismicity and storm waves' effect superimposed on high frequency sea level fall are considered the most important triggering factors.

Badakhshanite-(Y), Y2Mn4Al(Si2B7BeO24), a new mineral species of the perettiite group from a granite miarolic pegmatite in Eastern Pamir, the Gorno Badakhshan Autonomous Oblast, Tajikistan

2020 ◽  
Vol 58 (3) ◽  
pp. 381-394
Author(s):  
Leonid A. Pautov ◽  
Mirak A. Mirakov ◽  
Fernando Cámara ◽  
Elena Sokolova ◽  
Frank C. Hawthorne ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Close Association ◽  
Coarse Grained ◽  
New Mineral ◽  
Orthorhombic Space Group ◽  
Calculated Density ◽  
Conchoidal Fracture ◽  
New Mineral Species ◽  
Mohs Hardness ◽  
Cation Sites

ABSTRACT Badakhshanite-(Y), ideally Y2Mn4Al(Si2B7BeO24), is a tetrahedral sheet-structure mineral found in the Dorozhny (Road) miarolitic granitic pegmatite within the Kukurt pegmatite field 45 km E of Murghab, Eastern Pamir, Gorno-Badakhshan Autonomous Oblast, Tajikistan. Badakhshanite-(Y) occurs in medium- to coarse-grained non-graphic albite-microcline-quartz pegmatites in close association with smoky quartz, Sc-bearing spessartine, Sc-bearing tusionite, and schorl. It often grows together with Sc-bearing tusionite and occurs as single columnar crystals ranging from 50 to 400 μm in length, as inclusions in spessartine and tourmaline, and rarely as crystals in blebs along boundaries between garnet, tourmaline, and quartz. Badakhshanite-(Y) is yellow brown and has a white streak and a vitreous luster. It is brittle, with a conchoidal fracture, Mohs hardness of 6.5–7, and calculated density of 4.41 g/cm. In thin section it is transparent and pale yellow, non-pleochroic, biaxial (–), with α = 1.805(2), βcalc = 1.827, γ = 1.835(3) (λ = 590 nm); 2V (meas.) = –60(10)°. Dispersion is weak, r > v. Extinction is straight, elongation is negative. FTIR spectra show the absence of (OH) and H2O groups. Chemical analysis by electron microprobe using WDS (6 points), SIMS, and ICP-OES for B and Be gave SiO2 11.96, ThO2 0.12, Sm2O3 0.17, Gd2O3 0.30, Tb2O3 0.10, Dy2O3 0.73, Ho2O3 0.19, Er2O3 1.34, Tm2O3 0.54, Yb2O3 8.82, Lu2O3 2.32, Y2O3 16.60, Sc2O3 1.57, Al2O3 3.06, B2O3 22.06, FeO 0.94, MnO 23.33, CaO 0.58, BeO 2.84, total 97.57 wt.%.The empirical formula based on 24 O apfu is (Y1.21REE0.78Th0.01)Σ2(Mn3.47Y0.34Ca0.11Fe2+0.08)Σ4(Al0.63Sc0.24Fe2+0.06□0.07)Σ1[(Si2.10B6.69Be1.20)Σ9.99O24], where REE = (Yb0.47Lu0.12Dy0.04Er0.07Tm0.03 Ho0.01Gd0.02Sm0.01Tb0.01)Σ0.78. Badakhshanite-(Y) is orthorhombic, space group Pnma, a 12.852(1), b 4.5848(5), c 12.8539(8) Å, V 757.38(7) Å3, Z = 2. The crystal structure was refined to R1 = 4.31% based on 1431 unique [F > 4σF] reflections. In the crystal structure of badakhshanite-(Y), a layer of tetrahedra parallel to (010) is composed of four different tetrahedrally coordinated sites: Si, B(1), B(2), and T (<Si–O> = 1.623 Å, <B(1)–O> = 1.485 Å, <B(2)–O> = 1.479 Å, <T–O> = 1.557 Å), which form four-, five-, and eight-membered rings, having the composition (Si2B7BeO24). Between the sheets of tetrahedra, there are three cation sites: M(1), M(2), and M(3) (<M(1)–O> = 2.346 Å, <M(2)–O> = 2.356 Å, <M(3)–O> = 2.016 Å) occupied by Y(REE), Mn2+(Y, Ca, Fe2+), and Al(Sc), respectively. The M(1,2) sites ideally give Y2Mn4apfu; the M(3) site ideally gives Al apfu. Badakhshanite-(Y) is an Al- and Be-analogue of perettiite-(Y).

scholarly journals The geometry and stratigraphic position of the Maassluis Formation (western Netherlands and southeastern North Sea)

2004 ◽  
Vol 83 (2) ◽  
pp. 93-99 ◽  
Author(s):  
H.S.M. Jansen ◽  
J. Huizer ◽  
J.W.A. Dijkmans ◽  
C. Mesdag ◽  
J.E. van Hinte
Keyword(s):  
Coarse Grained ◽  
Early Pleistocene ◽  
The West ◽  
Depositional History ◽  
Offshore Area ◽  
Coastal Marine ◽  
Subtidal Environment ◽  
Stratigraphic Position ◽  
History Of ◽  
River Deposits

AbstractThe geometry and depositional history of the Maassluis Formation is described from an East-West oriented transect located in the west-central Netherlands and P- and Q-blocks in the Dutch offshore area. The Late Pliocene to Early Pleistocene Maassluis Formation was deposited under near coastal marine conditions. Two distinct facies are distinguished: (1) medium grained sands with a blocky GR/SP-log pattern that were deposited under intertidal and aeolian conditions and (2) medium to coarse grained sands deposited in a subtidal environment showing a clear coarsening upward trend. The lower part of the Maassluis Formation is laterally equivalent to the shallow marine Oosterhout Formation and gets progressively younger towards the West. The upper part is lateral equivalent to estuarine and mudflat deposits (Balk Member, c.q. Peize Formation) in the central part of The Netherlands and to river deposits (Peize Formation) further to the East.

The Gondola Slide: A mass transport complex controlled by margin topography (South-Western Adriatic Margin, Mediterranean Sea)

2015 ◽  
Vol 366 ◽  
pp. 97-113 ◽  
Author(s):  
Giacomo Dalla Valle ◽  
Fabiano Gamberi ◽  
Federica Foglini ◽  
Fabio Trincardi
Keyword(s):  
Mass Transport ◽  
Mediterranean Sea ◽  
Transport Complex
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