scholarly journals Geodynamic setting and models of the emplacement of ophiolitic allochthons in the structure of accreted island arcs of the pacific north-western framing

2019 ◽  
pp. 5-11
Author(s):  
V. D. Chekhovich ◽  
A. N. Sukhov
Keyword(s):  
Geodynamic Setting ◽  
Island Arcs ◽  
The Pacific ◽  
North Western

Little-known arctic species Montacuta spitzbergensis (Bivalvia: Montacutidae) from the north-western Pacific with notes on Montacuta substriata and Tellimya ferruginosa

2008 ◽  
Vol 88 (2) ◽  
pp. 347-356 ◽  
Author(s):  
Gennady M. Kamenev
Keyword(s):  
Sea Of Okhotsk ◽  
First Record ◽  
Western Pacific ◽  
The Arctic ◽  
Arctic Species ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean ◽  
North Western ◽  
North Western Pacific

An expanded description of a little-known arctic species Montacuta spitzbergensis from the Sea of Okhotsk with new data on its morphology, ecology and geographical distribution is given. This is the first record of M. spitzbergensis from the north-western Pacific. It differs from other species of Montacuta in its large (to 8.4 mm), elongate–ovate, thick shell with wide, slightly curved hinge plate, wide, short, and shallow resilifer, and weakly developed external ligament. This species occurs in the Arctic Ocean (Spitsbergen, Barents, Kara, Laptev and Chukchi Seas) and the Pacific Ocean (Sea of Okhotsk) at depths from 9 to 232 m at a bottom temperature from −1.62°C to +2.50°C. The hinge structure of the type species of the genera Montacuta and Tellimya is also discussed.

Different Types of Island-Arcs in the Pacific

1945 ◽  
Vol 106 (5/6) ◽  
pp. 198 ◽  
Author(s):  
J. H. F. Umbgrove
Keyword(s):  
Island Arcs ◽  
The Pacific ◽  
Different Types

Calicium sequoiae, a new lichen species from north-western California, USA

2008 ◽  
Vol 40 (3) ◽  
pp. 185-194 ◽  
Author(s):  
Cameron B. WILLIAMS ◽  
Leif TIBELL
Keyword(s):  
Phylogenetic Analysis ◽  
New Species ◽  
Pacific Northwest ◽  
Its Region ◽  
Sequoia Sempervirens ◽  
Old Growth ◽  
The Pacific ◽  
Secondary Substance ◽  
North Western ◽  
A New Species

Abstract:We describe Calicium sequoiae as a new species of lichenized Ascomycota from north-western California, USA. The species is distinguished morphologically from other known members of Calicium by its stalks that react I+ blue, mature ascospores that are ornamented with spiral ridges, and apothecia that produce prominent white pruina. It is also the only Calicium known to produce thamnolic acid as a major secondary substance. Sequences from the ITS-region showed C. sequoiae to be unique among calicioid Physciaceae, and phylogenetic analysis positioned it close to C. adspersum, C. chlorosporum, C. lenticulare, Cyphelium notarisii, and C. tigillare. Thus far, Calicium sequoiae has been collected only from old-growth redwood (Sequoia sempervirens) forests, where it occurred on thick, fibrous bark of large redwood trees. A key to the 12 species of Calicium known from the Pacific Northwest is provided.

scholarly journals Особенности спектров ЯМР -=SUP=-63,65-=/SUP=-Cu в локальном поле образцов полупроводникового минерала CuFeS-=SUB=-2-=/SUB=- из сульфидных месторождений океана

2018 ◽  
Vol 52 (8) ◽  
pp. 836
Author(s):  
В.Л. Матухин ◽  
А.И. Погорельцев ◽  
А.Н. Гавриленко ◽  
С.О. Гарькавый ◽  
Е.В. Шмидт ◽  
...  
Keyword(s):  
Room Temperature ◽  
Global Ocean ◽  
Island Arcs ◽  
Nmr Spectrum ◽  
Nmr Method ◽  
The Pacific ◽  
Different Types ◽  
Asymmetric Shape ◽  
The Pacific Ocean ◽  
Polymetallic Sulfides

AbstractThe results of studying natural samples of CuFeS_2 chalcopyrite mineral from hydrothermal ore manifestations of island arcs of the Pacific Ocean by ^63Cu nuclear magnetic resonance (^63Cu NMR) in a local field at room temperature are presented. The asymmetric shape of the detected resonance lines in the ^63Cu NMR spectrum indicates the presence of at least two overlapping lines. The presence of two overlapping central components can be a consequence of the occurrence of regions with different types of structural distortion near the resonant nuclei. These results show that the pulsed ^63Cu NMR method can be an effective method for studying the physical properties of deep-sea polymetallic sulfides of the global ocean.

Structure and development of transition zones between the continents and oceans

1968 ◽  
Vol 5 (4) ◽  
pp. 1011-1026 ◽  
Author(s):  
V. V. Beloussov ◽  
I. P. Kosminskaya
Keyword(s):  
Mechanical Properties ◽  
Deep Structure ◽  
Island Arcs ◽  
Transition Zones ◽  
Marginal Seas ◽  
The Pacific ◽  
Marginal Part ◽  
The Difference ◽  
Marginal Zones ◽  
Cretaceous Period

A set of geological-geophysical data provides a good basis for the recognition of two basic types of marginal zones: Atlantic and Pacific. The analysis of the tectonics and deep structure of the crust allows us to characterize their development in time, proceeding from a basic, well-grounded conception that beginning with the Cretaceous Period processes of crustal subsidence were dominant in the marginal zones of both types. In connection with the different structure of margins on the continental side and their correspondingly different mechanical properties, i.e., strength and monolithic quality, it is evident that the effects of crustal subsidence in different zones should have different manifestations.The Atlantic type of margins is characterized on the continental side by the platform regime, and the development of the marginal zones was here accompanied by the subsidence of the marginal part of the pre-Mesozoic foundation with an increase of its tilt towards the ocean. The M boundary in this zone is observed to have a steep rise of the scarp type, approximately 15 km for every 100 km. The inhomogeneity of the foundation structure and the possible irregularity of the processes of its subsidence in certain areas resulted in the formation of small plateaus detached from the shelf. The zones of the Atlantic type were evidently unconnected with considerable reduction of land, and they are mainly located within the boundaries of the pre-Mesozoic shelf.The margins of the Pacific type are characterized by another mechanical regime, which develops on the background of largely differing geosynclinal structures of continents. Sinking of large blocks is here followed by their disintegration into smaller blocks, as well as by volcanism with which the formation of island arcs of the second type and of the accompanying troughs is associated, etc. Starting with the Neogene in the zones of this type, the areas of the ocean expanded and in place of land vast marginal seas were formed with a thinned continental and suboceanic crust.The connection between the primary mechanical properties of the earth's crust of the marginal zones and the character of structures which evolved as the result of its subsidence is only one side of the phenomena causing the difference in the types of margins. As the subsidences of the crust are succeeded by its regeneration under the influence of the processes in the mantle, it might also be supposed that in the Atlantic zones with platform conditions these phenomena developed more regularly, while in the Pacific zones in the conditions of the geosynclinal state of the interior the same process had a more complicated and diverse development.

scholarly journals SUBDUCTION EROSION AT PACIFIC-TYPE CONVERGENT MARGINS

2021 ◽  
Vol 40 (6) ◽  
pp. 3-19
Author(s):  
I.Yu. Safonova ◽  
◽  
А.I. Khanchuk ◽  
Keyword(s):  
Continental Crust ◽  
Driving Forces ◽  
Accretionary Prism ◽  
Convergent Margins ◽  
Island Arcs ◽  
The Pacific ◽  
Tectonic Erosion ◽  
Definition Of ◽  
Orogenic Belts ◽  
Oceanic Slab

The paper presents a review of processes of subduction or tectonic erosion at the Pacific-type convergent margins (PTCM) including definition of “tectonic erosion”, its triggers, driving forces and consequences. We review examples of tectonic erosion at the Circum-Pacific PTCMs and at the fossil PTCMs of the Paleo-Asian Ocean (PAO) currently hosted by the Central-Asian Orogenic Belt (CAOB). Recent geological and stratigraphic studies have shown two types of PTCMs: accreting and eroding. Accreting PTCMs consist of older deposits of accretionary and frontal prisms and grow oceanward, i.e. the trench retreats. Eroding PTCMs are characterized by the destruction of the prism, approaching arc and trench and typically form during shallow-angle and fast subduction of an oceanic slab with oceanic floor topographic highs. The mechanism of tectonic erosion includes destruction of oceanic slab, island arcs, accretionary prism, fore-arc and related prism. Tectonic erosion is a common phenomenon at many Circum-Pacific PTCMs, e.g., in South America, Tonga and Nankai troughs, Alaska. Accretion and subduction of oceanic rises contributes greatly to the processes of formation, transformation and destruction of continental crust at PTCM. The episodes of tectonic erosion can be also reconstructed for an ancient ocean, for example, for the PAO, which evolution and suturing formed the CAOB. Many CAOB foldbelts (Altai, Tienshan, eastern Kazakhstan, Transbaikalia, Mongolia) carry signs of disap-pearance of big volumes of continental crust (arcs). Studying processes responsible not only for the formation of continental crust, but also for the disappearance of big volumes of crustal mate-rial is important for correct evaluation of the nature of intra-continental orogenic belts, e.g., CAOB, and development of reliable tectonic models.

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