Geodynamic Environment of the ca. 3800 Ma Outer Arc Group, Isua (Greenland)

2021 ◽  
Vol 321 (6) ◽  
pp. 643-679
Author(s):  
Allen P. Nutman ◽  
Clark R.L. Friend ◽  
Vickie C. Bennett ◽  
Martin Van Kranendonk ◽  
Allan R. Chivas
Keyword(s):  
Geodynamic Environment

HT/LP metamorphic zoning in the eastern Voronezh Crystalline Massif: Age and parameters of metamorphism and its geodynamic environment

Petrology ◽  
2015 ◽  
Vol 23 (6) ◽  
pp. 559-575 ◽  
Author(s):  
K. A. Savko ◽  
A. V. Samsonov ◽  
E. B. Sal’nikova ◽  
A. B. Kotov ◽  
N. S. Bazikov
Keyword(s):  
Voronezh Crystalline Massif ◽  
Geodynamic Environment

Caractérisation du magmatisme Protérozoïque supérieur en Afrique de l'ouest et implications géodynamiques : des rifts intracratoniques au Panafricain?

1987 ◽  
Vol 24 (1) ◽  
pp. 96-109 ◽  
Author(s):  
P. L. Dupont ◽  
H. Lapierre ◽  
M. Gravelle ◽  
J. M. Bertrand
Keyword(s):  
Carbonate Platform ◽  
Continental Collision ◽  
Greenschist Facies ◽  
Late Proterozoic ◽  
Western Africa ◽  
The North ◽  
Pan African ◽  
Geodynamic Environment ◽  
Unstable Environment ◽  
Afrique De L'ouest

The main petrological, mineralogical, and geochemical features of the metavolcanites belonging to the Late Proterozoic tectono-sedimentary units of southern Mauritanides (Termessé and Niokolo Koba – Koulountou) and western Hoggar, Algeria (Timesselarsine), permit a reconstruction of the geodynamic environment that controlled the evolution of the Pan-African ranges of western Africa. Flows and pyroclastic beds metamorphosed under greenschist-facies conditions are interbedded within detritic and carbonate platform sediments, suggesting an unstable environment in the vicinity of a continental margin.The association of oceanic tholeiites slightly enriched in LREE and basalts more enriched in TiO2, Zr, Nb, and LREE displaying alkalic affinities suggests intracontinental rifting succeeded by expansion. The lack of ultrabasic – basic complexes (oceanic paleosutures) in southern Mauritanides and their occurrence in the Hoggar suggest that the opening was bigger in the north than in the south.The later calc-alkalic sequences of the Niokolo Koba – Koulountou units are tectonically associated with the Termessé unit. In the Timesselarsine unit, calc-alkalic acid rocks coexist with the basic lavas previously mentioned. Thus, the closure of the rift related to a continental collision appears to be later in southern Mauritanides than in the Hoggar.

Isotopic and trace element constraints on the genesis of a boninitic sequence in the Thetford Mines ophiolitic complex, Quebec, Canada

1997 ◽  
Vol 34 (9) ◽  
pp. 1258-1271 ◽  
Author(s):  
Valérie Olive ◽  
Réjean Hébert ◽  
Michel Loubet
Keyword(s):  
Trace Element ◽  
Trace Element Composition ◽  
Nd Isotope ◽  
Geodynamic Environment ◽  
The Pacific ◽  
Geochemical Study ◽  
Mid Ocean Ridge ◽  
Isochron Diagram ◽  
Component C ◽  
Ocean Ridge

The Mont Ham Massif (part of the Thetford Mines ophiolite, south Quebec) represents a magmatic sequence made up of tholeiitic and boninitic derived products. A geochemical study confirms the multicomponent mixing models that have been classically advanced for the source of boninites, with slab-derived components added to the main refractory harzburgitic peridotite. An isochron diagram of the boninitic rocks is interpreted as a mixing trend between two components: (i) a light rare earth element (LREE) enriched component (A), interpreted as slab-derived fluid–melts equilibrated with sedimentary materials (εNd = −3, 147Sm/144Nd = 0.140), and (ii) a LREE-depleted component (B) (0.21 < 147Sm/144Nd < 0.23), interpreted as slab-derived fluid–melt equilibrated with recycled Iapetus oceanic crust and equated to the Nd-isotope characteristics of the Iapetus mantle (εNd = 9). A multicomponent source is also necessary to explain the Nd-isotope and trace element composition of the tholeiites, which are explained by the melting of a more fertile, lherzolitic mantle and (or) mid-ocean ridge basalt source (component C), characterized by a large-ion lithophile element depleted pattern and an Iapetus mantle Nd isotopic composition (εNd = 9), mixed in adequate proportions with the two previously infered slab-derived components (A and B). The genesis of the boninites of Mont Ham is not significantly different from those of boninites located in the Pacific. An intraoceanic subduction zone appears to be an appropriate geodynamic environment for the Mont Ham ophiolitic sequence.

scholarly journals THE CHARACTERISTICS OF THE GEODYNAMIC ENVIRONMENT AND ELEMENTS OF STRUCTURAL-MATERIAL COMPLEXES OF THE CENTRAL CAUCASUS AT A DEEP INCISION HEALTHSCOPE PROFILE

2018 ◽  
Author(s):  
В.Б. Заалишвили ◽  
Х.О. Чотчаев ◽  
А.Г. Шемпелев
Keyword(s):  
Structural Material ◽  
Practical Interest ◽  
Ophiolite Complex ◽  
The Caucasus ◽  
Deep Incision ◽  
Geodynamic Environment ◽  
Consolidated Crust ◽  
Central Caucasus ◽  
Full Vector

В статье рассматривается возможность выделения наследственных признаков геодинамической обстановки и элементов структурно-вещественных комплексов, участвующих в геологическом развитии  Кавказа, на глубинных геоэлектрических и сейсмологических разрезах для создания геолого-геофизической моделей земной коры вдоль региональных профилей. Современные структурно-тектонические и структурно-вещественные комплексы восточной части Центрального Кавказа интерполируются с основными структурами консолидированной коры и низов коры. Обосновывается научный и практический интерес корреляционной увязки глубинных коровых и мантийных структур с месторождениями твердых полезных ископаемых и углеводородов, роль границы Мохоровичича в локализации месторождений. Субширотная структура реликтового рубца (геосутуры), уверенно выделяемая по минимумам напряженности полного вектора магнитного поля по структурно-вещественным элементам (олистостромы, офиолиты, микститы) представляется убедительным наследственным признаком субдукции. Реликтовый рубец представляется выполненным тектонизированным терригенным материалом, содержащим разного размера глыбы и блоки вулканогенно-осадочных пород и ремобилизованные олистостромы пород офиолитового комплекса, что является формационным признаком геодинамической обстановки, фиксируемой в развитии структуры Кавказа. The article deals with the possibility of identifying hereditary features of the geodynamic situation and elements of structural and material complexes involved in the geological development of the Caucasus, in deep geoelectric and seismological sections to create geological and geophysical models of the earth's crust along the regional profiles. Modern structural-tectonic and structural-material complexes of the Eastern part of the Central Caucasus are interpolated with the main structures of the consolidated crust and the lower crust. The scientific and practical interest of correlation linking of deep crustal and mantle structures with deposits of solid minerals and hydrocarbons, the role of the boundary of Mokhorovichych in the localization of deposits is substantiated. Latitudinal structure of the relic scar (geostructure), confidently allocated to the minimum of the tension of magnetic field full vector on structural-material elements (olistostromes, ophiolites, mixtite) persuasive inherited character of subduction. Relict scar is represented by tectonized terrigenous material containing different size blocks and blocks of volcanogenic-sedimentary rocks and remobilized olistostromes of rocks of the ophiolite complex, which is a formative sign of geodynamic situation, recorded in the development of the structure of the Caucasus.

scholarly journals Seismogenic sources and related active faults in the gulf of Corinth; a combined approach

2018 ◽  
Vol 40 (3) ◽  
pp. 1267
Author(s):  
M. Segou ◽  
S. Lozios
Keyword(s):  
Active Faults ◽  
Fault Zones ◽  
Interesting Case ◽  
Point Of View ◽  
Combined Approach ◽  
Corinth Gulf ◽  
Seismogenic Sources ◽  
Gulf Of Corinth ◽  
Geodynamic Environment ◽  
Earthquake Potential

The neotectonic graben of Corinth gulf forms an interesting case study from the geodynamical and seismological point of view, since specific characteristics met on the fault zones around the gulf and the adjacent seismological data pose several questions related with the overall modern activity across a number of neotectonic faults. Indexing active fault zones with structural, seismological and sedimentological criteria leads to thorough understanding of the evolution and modern activity and provide researchers useful tools in order to evaluate the degree of present day activity of the broader area. The combined approach proposed here, with joint use of both, seismogenic sources and structural evidence, contributes to the re-evaluation of the earthquake potential by assessing the role of active features in the already complex geodynamic environment of the Corinthian gulf

Repeated S–I–A-type granite trilogy in the Lachlan Orogen and geochemical contrasts with A-type granites in Nigeria: implications for petrogenesis and tectonic discrimination

2019 ◽  
Vol 491 (1) ◽  
pp. 53-76 ◽  
Author(s):  
William J. Collins ◽  
Hui-Qing Huang ◽  
Peter Bowden ◽  
A. I. S. Kemp
Keyword(s):  
Precambrian Basement ◽  
Crustal Component ◽  
Tectonic Processes ◽  
Geodynamic Environment ◽  
Lachlan Orogen ◽  
Type Granite ◽  
Arc Setting ◽  
Back Arc

AbstractThe classical S–I–A-type granites from the Lachlan Orogen, SE Australia, formed as a tectonic end-member of the accretionary orogenic spectrum, the Paleozoic Tasmanides. The sequence of S- to I- to A-type granite is repeated at least three times. All the granites are syn-extensional, formed in a dominantly back-arc setting behind a single, stepwise-retreating arc system between 530 and 230 Ma. Peralkaline granites are rare. Systematic S–I–A progressions indicate the progressive dilution of an old crustal component as magmatism evolved from arc (S-type) to proximal back-arc (I-type) to distal back-arc (A-type) magmatism. The alkaline and peralkaline A-type Younger granites of Nigeria were generally hotter and drier than the Lachlan A-type granites and were emplaced into an anhydrous Precambrian basement during intermittent intracontinental rifting. This geodynamic environment contrasts with the distal back-arc setting of the Lachlan A-type granites, where magmatism migrated rapidly across the orogen. Tectonic discrimination diagrams are inappropriate for the Lachlan granites, placing them in the wrong settings. Only the peralkaline Narraburra suite of the Lachlan Orogen fits the genuine ‘within-plate’ setting of the Nigerian A-type granites. Such discrimination diagrams require re-evaluation in the light of an improved modern understanding of tectonic processes, particularly the role of extensional tectonism and its geodynamic drivers.

Geochemistry of the Eocene magmatic rocks from the Lesser Caucasus area (Armenia): evidence of a subduction geodynamic environment

2016 ◽  
Vol 428 (1) ◽  
pp. 73-98 ◽  
Author(s):  
L. Sahakyan ◽  
D. Bosch ◽  
M. Sosson ◽  
A. Avagyan ◽  
Gh. Galoyan ◽  
...  
Keyword(s):  
Magmatic Rocks ◽  
Geodynamic Environment ◽  
Lesser Caucasus
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