No continuous suture between Kudi and Oytag: new evidence from geochronology and geochemistry data

2021 ◽  
Author(s):  
Johannes Rembe ◽  
Edward R. Sobel ◽  
Jonas Kley ◽  
Renjie Zhou ◽  
Rasmus Thiede ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Second Phase ◽  
The West ◽  
Holistic View ◽  
The North ◽  
Icp Ms ◽  
Mantle Component ◽  
West Kunlun ◽  
Granitoid Intrusions ◽  
Paleozoic Rocks

<p>A lateral continuity between belts of mafic and ultramafic Paleozoic rocks found in the West Kunlun of Northern Tibet and comparable rocks, known from an outcrop in the Chinese North Pamir, has long been proposed. This led to the concept of an originally generally straight, E–W trending Oytag–Kudi suture zone. In turn, this paleogeographic model formed a key constraint for the hypothesis, that the Pamir has indented 300 km northward with respect to Tibet during the Cenozoic. We show, that the arc volcanic rocks found in the North Pamir are distinguishable from the units known from the West Kunlun.<br>The North Pamir is dominated by Paleozoic arc volcanic rocks. We present new geochemical and geochronological data to give a holistic view of an early to mid-Carboniferous arc complex. This belt was previously identified as an intraoceanic arc in the northeastern North Pamir. Our data yields evidence for a gradual lateral change towards the west into a Cordilleran-style arc in the Tajik North Pamir. Large leucocratic granitoid intrusions are hosted in part by Devonian to Carboniferous oceanic crust and the metamorphic Kurguvad basement block of Ediacaran age (maximum deposition age) in Tajikistan. LA-ICP-MS U-Pb dating of zircons, together with whole rock geochemistry derived from tonalitic to granodioritic intrusions, reveal a major Visean to Bashkirian intrusive phase between 340 and 320 Ma ago.<br>The West Kunlun experienced two major intrusive phases, connected with arc-volcanic activity — a first phase during Proto-Tethys closure in Ordovician and Silurian times and a second phase connected to the Triassic Paleo-Tethys closure. The Carboniferous arc-volcanic phase in the North Pamir clearly postdates Paleozoic arc-magmatic activity in the West Kunlun by ~100 Ma. This observation, along with geochemical evidence for a more pronounced mantle component in the Carboniferous arc-magmatic rocks of the North Pamir, disagrees with the common model of a continuous Kunlun belt from the West Kunlun into the North Pamir. Moreover, Paleozoic oceanic units younger than and west of Tarim cratonic crust challenge the idea of a continuous cratonic Tarim-Tajik continent beneath the Pamir.</p>

scholarly journals The Carboniferous Arc of the North Pamir

Lithosphere ◽  
2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Johannes Rembe ◽  
Edward R. Sobel ◽  
Jonas Kley ◽  
Renjie Zhou ◽  
Rasmus Thiede ◽  
...  
Keyword(s):  
The West ◽  
Holistic View ◽  
Volcanic Arc ◽  
The North ◽  
Magmatic Rocks ◽  
Icp Ms ◽  
Mantle Component ◽  
The Common ◽  
West Kunlun ◽  
Intrusive Phase

Abstract In this study, we investigate the age and geochemical variability of volcanic arc rocks found in the Chinese, Kyrgyz, and Tajik North Pamir in Central Asia. New geochemical and geochronological data together with compiled data from the literature give a holistic view of an early to mid-Carboniferous intraoceanic arc preserved in the northeastern Pamir. This North Pamir volcanic arc complex involves continental slivers in its western reaches and transforms into a Cordilleran-style collision zone with arc-magmatic rocks. These are hosted in part by Devonian to Carboniferous oceanic crust and the metamorphic Kurguvad basement block of Ediacaran age (maximum deposition age) in Tajikistan. We discuss whether a sliver of Carboniferous subduction-related basalts and intruded tonalites close to the Chinese town of Mazar was part of the same arc. LA-ICP-MS U-Pb dating of zircons, together with whole rock geochemistry derived from tonalitic to granodioritic intrusions, reveals a major Visean to Bashkirian intrusive phase between 340 and 320 Ma ago. This clearly postdates Paleozoic arc-magmatic activity in the West Kunlun by ~100 Ma. This observation, along with geochemical evidence for a more pronounced mantle component in the Carboniferous arc-magmatic rocks of the North Pamir, disagrees with the common model of a continuous Kunlun belt from the West Kunlun into the North Pamir. Moreover, Paleozoic oceanic units younger than and west of the Tarim cratonic crust challenge the idea of a continuous cratonic Tarim-Tajik continent beneath the Pamir.

Harvest of Briars

2019 ◽  
pp. 121-158
Author(s):  
A. Wess Mitchell
Keyword(s):  
Eighteenth Century ◽  
Ottoman Empire ◽  
Cost Effective ◽  
Balkan Peninsula ◽  
The Black Sea ◽  
Second Phase ◽  
Habsburg Monarchy ◽  
The West ◽  
The North ◽  
Third Phase

This chapter examines the competition with the Ottoman Empire and Russia, from the reconquest of Hungary to Joseph II’s final Turkish war. On its southern and eastern frontiers, the Habsburg Monarchy contended with two large land empires: a decaying Ottoman Empire, and a rising Russia determined to extend its influence on the Black Sea littorals and Balkan Peninsula. In balancing these forces, Austria faced two interrelated dangers: the possibility of Russia filling Ottoman power vacuums that Austria itself could not fill, and the potential for crises here, if improperly managed, to fetter Austria’s options for handling graver threats in the west. In dealing with these challenges, Austria deployed a range of tools over the course of the eighteenth century. In the first phase (1690s–1730s), it deployed mobile field armies to alleviate Turkish pressure on the Habsburg heartland before the arrival of significant Russian influence. In the second phase (1740s–70s), Austria used appeasement and militarized borders to ensure quiet in the south while focusing on the life-or-death struggles with Frederick the Great. In the third phase (1770s–90s), it used alliances of restraint to check and keep pace with Russian expansion, and recruit its help in comanaging problems to the north. Together, these techniques provided for a slow but largely effective recessional, in which the House of Austria used cost-effective methods to manage Turkish decline and avoid collisions that would have complicated its more important western struggles.

scholarly journals Hydrogeochemistry and lead contamination of groundwater in the north part of Esfahan province, Iran

2018 ◽  
Vol 16 (4) ◽  
pp. 622-634 ◽  
Author(s):  
Kaveh Pazand ◽  
Davoud Khosravi ◽  
Mohammad Reza Ghaderi ◽  
Mohammad Reza Rezvanianzadeh
Keyword(s):  
Inductively Coupled Plasma ◽  
Arid Regions ◽  
Volcanic Rocks ◽  
Primary Source ◽  
Lead Contamination ◽  
Inductively Coupled ◽  
The North ◽  
Icp Ms ◽  
North Part ◽  
Plasma Mass Spectrometry

Abstract Geochemical and hydrogeochemical studies were conducted to assess the origin and geochemical mechanisms driving lead enrichment in groundwaters of semi-arid regions in Central Iran. In this study, 149 water samples were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Concentrations of Pb and As in about 68% and 27% of the samples, respectively, exceeded WHO guidelines. Analyzing the results of ICP-MS of parental rocks and aquifer sediments shows that unweathered volcanic rocks were the primary source for lead mobilizing to groundwaters.

Geochemistry of the Cenozoic Potassic Volcanic Rocks in the West Kunlun Mountains and Constraints on Their Sources

2010 ◽  
Vol 78 (4) ◽  
pp. 912-920
Author(s):  
ZHANG Zhaochong ◽  
XIAO Xuchang ◽  
WANG Jun ◽  
WANG Yong ◽  
LUO Zhaohua
Keyword(s):  
Volcanic Rocks ◽  
The West ◽  
Kunlun Mountains ◽  
West Kunlun

Structural and metamorphic relationships between the Mount Ida and Monashee Groups at Mara Lake, British Columbia

1982 ◽  
Vol 19 (2) ◽  
pp. 288-307 ◽  
Author(s):  
Kent C. Nielsen
Keyword(s):  
British Columbia ◽  
Large Scale ◽  
Ductile Deformation ◽  
Late Triassic ◽  
Second Phase ◽  
The West ◽  
Late Mesozoic ◽  
The North ◽  
Phase Deformation ◽  
Metamorphic Core

Mara Lake, British Columbia straddles the boundary between the Monashee Group on the east and the Mount Ida Group on the west. Correlation of units across the southern end of Mara Lake indicates lithologic continuity between parts of the groups. Both groups have experienced four phases of deformation. Phases one and two are tight and recumbent, trending to the north and to the west, respectively. Phases three and four are open to closed and upright, trending northwest and northeast, respectively. Second-phase deformation includes large-scale tectonic slides that separate areas of consistent vergence. Slide surfaces are folded by third- and fourth-phase structures and outline domal outcrop patterns. Metamorphic grade increases from north to south along the west side of Mara Lake. Calc-silicate reactions involving the formation of diopside are characteristic. From west to east increasing grade is evident in the reaction of muscovite + quartz producing sillimanite + K-feldspar + water. These prograde reactions are related to relative position in the second-phase structure. The highest grade is located near the lowest slide surface. Greenschist conditions accompanied phase-three deformation. Fourth phase is characterized by hydrothermal alteration, brittle fracturing, and local faulting. First-phase deformation appears to be pre-Late Triassic whereas second and third phases are post-Late Triassic and pre-Cretaceous. The fourth phase is part of a regional Tertiary event. The third folding event is correlated with the development of the Chase antiform and the second-phase folding is related to the pervasive east–west fabric of the Shuswap Complex. The timing of these events indicates that the metamorphic core zone of the eastern Cordillera was relatively rigid during the late Mesozoic foreland thrust development. Ductile deformation significantly preceded thrusting and developed a fabric almost at right angles to the trend of the thrust belt.

scholarly journals Geologie et pétrographie des roches sédimentaires et volcaniques kétilidiennes (Protérozoique inférieur) de la baignoire d'Arsuk, Groenland méridional

1974 ◽  
Vol 110 ◽  
pp. 1-157
Author(s):  
J Muller
Keyword(s):  
Volcanic Rocks ◽  
Mobile Belt ◽  
Second Phase ◽  
Early Proterozoic ◽  
The North ◽  
Western Border ◽  
Intense Deformation ◽  
Basic Rocks ◽  
North Western ◽  
Middle Proterozoic

The Arsuk ø area is situated along the north-western border of the Early Proterozoic (> 1750 m.y.) mobile belt of South Greenland. Around Arsuk ø reactivated Archaean (> 2500 m.y.) basement is represented by gneiss, amphibolites and migmatites belonging to several lithological series. In the Arsuk basin Early Proterozoic (Ketilidian) supracrustals consist of a group of sedimentary rocks which is overlain by a group of volcanic rocks. The sedimentary Ikerasârssuk Group, with a thickness between 1000 and 1500 m, consists of semi-pelites and pelites with several zones of pyrite-bearing graphite schists and dolomitic limestones. There are also numerous sills of basic rocks which have the same age as the overlying group of volcanic rocks. In some localities the basal member of the group consists of feldspathic quartzites. The volcanic Arsuk Group, the upper part of which is eroded away, has a measured thickness of 4200 m. It consists of pillow lavas, basic massive lavas, volcanic breccias, lapillis and tuffites. There are also some ultrabasic rocks and thin horizons of pyrite-bearing graphite schists with chert. These supracrustal rocks underwent intense deformation at the close of the Early Proterozoic. Three phases can be recognised. The first phase produced N-S to NNE-SSW recumbent folds and the regional schistosity. Refolding during the second phase resulted in folds with E-W to ESE-trending axial planes and a strain slip cleavage. The last phase produced N-S trending structures. The grade of metamorphism during the first phase of deformation corresponds to greenschist facies. In the supracrustals close to the basement recrystallisation in amphibolite facies took place between the first and third phases of folding. This shows the existence of a gradient towards still higher grade metamorphic conditions in the underlying Archaean basement undergoing thorough reconstitution at the end of the Early Proterozoic. As a result of the deformation the stratigraphical unconformity between the Early Proterozoic (Ketilidian) supracrustals and the Archaean basement has been destroyed. During the Gardar period (Middle Proterozoic: > 950 m.y.) and again during the Mesozoic faulting and dyking occurred.

The early Paleozoic tectonic evolution of the West Kunlun mountains: New Constraint from the North Küda Pluton

2001 ◽  
Vol 20 (1) ◽  
pp. 12-19
Author(s):  
Chao Yuan ◽  
Hui Zhou ◽  
Min Sun ◽  
Jiliang Li ◽  
Quanli Hou
Keyword(s):  
Tectonic Evolution ◽  
Early Paleozoic ◽  
The West ◽  
The North ◽  
Kunlun Mountains ◽  
West Kunlun

scholarly journals XII.—On the Carboniferous Volcanic Rocks of the Basin of the Firth of Forth—their Structure in the Field and under the Microscope

1880 ◽  
Vol 29 (1) ◽  
pp. 437-518 ◽  
Author(s):  
Geikie
Keyword(s):  
North Sea ◽  
Geographical Area ◽  
Volcanic Rocks ◽  
The South ◽  
The West ◽  
Red Sandstone ◽  
Lower Silurian ◽  
The North ◽  
The North Sea ◽  
Firth Of Forth

The geographical area embraced in the present memoir forms a well-marked basin traversed along its centre by the estuary of the Forth. It is bounded on the north by the chain of the Ochil Hills, on the south by the range of the Pentland and Lammermuir uplands. Towards the west it joins along a low watershed the basin of the Clyde, while eastwards it dips under the waters of the North Sea. Within this defined space the Carboniferous rocks occupy what may be described as one great synclinal trough, varied by innumerable smaller synclines and anticlines. Save where cut out by powerful dislocations, their lower members rise up along the margins of the basin, while their highest portions cover a smaller area in the centre. The older formations forming the northern and southern boundaries of the area belong chiefly to the Lower Old Red Sandstone, in the Lammermuir district to the Lower Silurian. The Carboniferous rocks everywhere rest upon them unconformably.

scholarly journals Improved Concept Map-Based Teaching to Promote a Holistic Earth System View

Geosciences ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 8
Author(s):  
Clara Vasconcelos ◽  
Fabio Ferreira ◽  
Ana Rolo ◽  
Beatriz Moreira ◽  
Mariana Melo
Keyword(s):  
Concept Map ◽  
Biogeochemical Cycles ◽  
Second Phase ◽  
Earth System ◽  
Holistic View ◽  
The North ◽  
The Earth ◽  
8Th Grade ◽  
Conceptual Maps ◽  
Old Portuguese

Like some other countries, seldom being sometimes addressed in classes, the Earth system approach is not emphasized enough in Portugal, nor is the interconnection between the geosphere, hydrosphere, atmosphere, and biosphere. To evaluate the Earth system holistic view of a group of 8th grade (13–15 years old) Portuguese students from a public school of the north of Portugal, an improved conceptual map-based to approach Earth system was investigated. After learning about concept mapping, students were asked to collaborate in the production of four conceptual maps regarding each one of the geochemical and biogeochemical cycles, further combining these maps in a common one. Through teamwork-based task, each group was asked to establish relations between the cycles, integrated into each one of the four Earth subsystems. The final combined maps demonstrated that, in the first phase, students had some difficulties in completing the pre-designed improved maps, being more evident in the rock cycle. Contrarily, the food chain cycle revealed fewer mistakes and more appropriate terms were added. In the second phase, the students exhibited difficulties in relating the cycles to the four subsystems and the remaining cycles, drawing many arrows without any kind of connecting words. Nevertheless, in general, students have realized how to build an improved concept map but do not possess a holistic view of the Earth system.

A geodynamic model for some structures within and adjacent to the Okanagan Valley, southern British Columbia

1981 ◽  
Vol 18 (10) ◽  
pp. 1581-1598 ◽  
Author(s):  
John V. Ross
Keyword(s):  
Volcanic Rocks ◽  
High Heat ◽  
Early Jurassic ◽  
Late Triassic ◽  
Second Phase ◽  
The North ◽  
Open Structures ◽  
International Boundary ◽  
Radiometric Ages ◽  
Okanagan Valley

Detailed and reconnaissance mapping of areas along the east and west sides of the Okanagan Valley, from the International Boundary in the south to Kamloops in the north, has revealed a similarity in structural sequence and geometry in rocks ranging in age from Pennsylvanian (Harper Ranch, Anarchist, Kobau, Old Tom, and Shoemaker Groups) through Late Triassic – Early Jurassic (Nicola, Sicamous, and Slocan Groups).Earliest recognizable folds, F1, have northerly trending axes, are isoclinal in form, and are disrupted on all scales by a strongly penetrative second phase of deformation, F2. This second phase is characterized by northerly and southerly verging isoclinal folds having east–west axes that are very nearly parallel with a well-developed stretching lineation, L2. Mylonitic lamination is developed parallel with these F2 axial surfaces. A third phase of folding, F3, comprising more unright open structures having a consistent southerly vergence, deforms the earlier F1 and F3 structures. Later phases of deformation, F4 and F5, almost coeval, have produced the present foliation configuration outlining basins and domes and associated northerly trending normal faults.Progressive metamorphism accompanied F1, F2, and F3 deformations and peaked during F2. F4 and F5 are associated with a thermal event resulting in resetting of most radiometric ages within the region.F1 deformation is probably Permo-Triassic in age and associated with lower greenschist metamorphism, whereas F2 and F3, associated with a much higher metamorphism up to amphibolite facies, affect all the sedimentary rocks within the region and apparently terminated by about 178 Ma (K–Ar on hornblende), Triassic – Early Jurassic. The latest movements, F4 and F5, involve volcanic rocks whose age of crystallization is set radiometrically at about Eocene.A plate model involving easterly obduction during the Permo-Triassic, followed by easterly dipping subduction with associated dextral transform movement during the Late Triassic – Early Jurassic, is proposed to explain the observed geometry. A mantle diapir below the region is rationalized to explain the localized high heat flow during Eocene time.

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