Experiments and thermodynamic modelling on the blueschists in the Longmu Co‐Shuanghu Suture Zone, North Tibet: Estimation of the metamorphic conditions and implications for garnet stability in the subduction zone

2021 ◽  
Author(s):  
Neng Gong ◽  
Xiao‐Chao Che ◽  
Guo‐Li Yuan ◽  
Gen‐Hou Wang ◽  
Toshiaki Tsunogae ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Suture Zone ◽  
Thermodynamic Modelling

Tectono-stratigraphic evolution of the Early Proterozoic Wisconsin magmatic terranes of the Penokean Orogen

1989 ◽  
Vol 26 (10) ◽  
pp. 2145-2158 ◽  
Author(s):  
P. K. Sims ◽  
W. R. Van Schmus ◽  
K. J. Schulz ◽  
Z. E. Peterman
Keyword(s):  
Subduction Zone ◽  
Continental Margin ◽  
Volcanic Rocks ◽  
Alkali Feldspar ◽  
Suture Zone ◽  
Island Arcs ◽  
Calc Alkaline ◽  
The South ◽  
Early Proterozoic ◽  
Felsic Volcanic

The Early Proterozoic Penokean Orogen developed along the southern margin of the Archean Superior craton. The orogen consists of a northern deformed continental margin prism overlying an Archean basement and a southern assemblage of oceanic arcs, the Wisconsin magmatic terranes. The south-dipping Niagara fault (suture) zone separates the south-facing continental margin from the accreted arc terranes. The suture zone contains a dismembered ophiolite.The Wisconsin magmatic terranes consist of two terranes that are distinguished on the basis of lithology and structure. The northern Pembine–Wausau terrane contains a major succession of tholeiitic and calc-alkaline volcanic rocks deposited in the interval 1860–1889 Ma and a more restricted succession of calc-alkaline volcanic rocks deposited about 1835 – 1845 Ma. Granitoid rocks ranging in age from about 1870 to 1760 Ma intrude the volcanic rocks. The older succession was generated as island arcs and (or) closed back-arc basins above the south-dipping subduction zone (Niagara fault zone), whereas the younger one developed as island arcs above a north-dipping subduction zone, the Eau Pleine shear zone. The northward subduction followed deformation related to arc–continent collision at the Niagara suture at about 1860 Ma. The southern Marshfield terrane contains remnants of mafic to felsic volcanic rocks about 1860 Ma that were deposited on Archean gneiss basement, foliated tonalite to granite bodies ranging in age from about 1890 to 1870 Ma, and younger undated granite plutons. Following amalgamation of the two arc terranes along the Eau Pleine suture at about 1840 Ma, intraplate magmatism (1835 Ma) produced rhyolite and anorogenic alkali-feldspar granite that straddled the internal suture.

Diopsidites from a Neoproterozoic–Cambrian suture in southern India

2010 ◽  
Vol 147 (5) ◽  
pp. 777-788 ◽  
Author(s):  
M. SANTOSH ◽  
V. J. RAJESH ◽  
T. TSUNOGAE ◽  
S. ARAI
Keyword(s):  
Rare Earth ◽  
Subduction Zone ◽  
Rare Earth Element ◽  
Earth Element ◽  
Suture Zone ◽  
Dharwar Craton ◽  
Southern India ◽  
The North ◽  
Calcic Amphibole ◽  
Gondwana Supercontinent

AbstractWe report the occurrence and characteristics of diopsidite dykes and veins from the Palghat-Cauvery Suture Zone (PCSZ) marking the boundary between the Archaean Dharwar craton to the north and the Proterozoic Madurai Block to the south, which is considered as a trace of the Cambrian Gondwana suture zone in southern India. The diopsidites are composed predominantly of coarse crystals of diopside [Mg no. (100 Mg/(Mg+Fetot)) up to 89] surrounded by retrograde calcic amphibole, plagioclase and phlogopite with accessory titanite and calcite. The major, trace and rare earth element characteristics of the diopside crystals suggest their formation in a subduction zone setting. We correlate the petrogenesis of the diopsidites with the tectonics associated with the subduction and closure of the Neoproterozoic Mozambique Ocean prior to the final collisional assembly of the Gondwana supercontinent in Cambrian.

Subduction and roll-back of narrow oceanic slabs: Back-arc basin modelling of the Carpathians subduction zone

2021 ◽  
Author(s):  
István Bozsó ◽  
Ylona van Dinther ◽  
Liviu Matenco ◽  
Attila Balázs ◽  
István Kovács
Keyword(s):  
Subduction Zone ◽  
Pannonian Basin ◽  
Suture Zone ◽  
The Carpathians ◽  
Mediterranean Systems ◽  
Set Up ◽  
Sag Basin ◽  
Back Arc ◽  
Roll Back ◽  
Oceanic Domain

<p>The Carpathians subduction system evolved similarly to many Mediterranean systems where extensional back-arc basins and separate large sag basins develop in the overriding plate. The evolution of such basins can be explained in the context of roll-back of narrow oceanic slabs. Their evolution is linked to extensional and sag back-arc basins, retreating orogenic systems and slab detachment. A recent example of slab detachment can be studied by the Vrancea slab beneath the SE Carpathians.<br>Significant effort has been dedicated to modelling such Mediterranean-style subduction systems, and in most cases the model was set up with a narrow oceanic domain, which has an increased difficulty to create rollback due to reduced buoyancy of the slab.<br>Our approach is to use a two-dimensional thermo-mechanical numerical model that introduces an inherited oceanic domain, which adds to the younger, narrow ocean developed in the later stages.<br>Our model can produce sustained subduction of the oceanic slab associated with roll-back and slab detachment. In most of our models a retro-arc sag basin develops, which can be interpreted as the Transylvanian Basin. This sag basin is one of the most consistent features of our model. At larger distances from the subduction zone, the extensional back-arc of the Pannonian basin can be modelled by introducing an lithospheric weakness zone, which represents a suture zone inherited from a previous orogenic evolution. Such a suture zone is compatible with the overall orogenic evolution of the Alps-Carpathians-Dinarides system. We furthermore discuss the limitations of our 2D modeling in the overall 3D settings of the Carpathians system and possibilities of future integration.</p>

scholarly journals Subducting serpentinites release reduced, not oxidized, aqueous fluids

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
F. Piccoli ◽  
J. Hermann ◽  
T. Pettke ◽  
J. A. D. Connolly ◽  
E. D. Kempf ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Oxygen Fugacity ◽  
Mantle Wedge ◽  
Thermodynamic Modelling ◽  
Arc Magmatism ◽  
Redox Processes ◽  
Arc Magmas ◽  
Reducing Conditions ◽  
Mid Ocean Ridge ◽  
Ocean Ridge

AbstractThe observation that primitive arc magmas are more oxidized than mid-ocean-ridge basalts has led to the paradigm that slab-derived fluids carry SO2 and CO2 that metasomatize and oxidize the sub-arc mantle wedge. We combine petrography and thermodynamic modelling to quantify the oxygen fugacity (fO2) and speciation of the fluids generated by serpentinite dehydration during subduction. Silicate-magnetite assemblages maintain fO2 conditions similar to the quartz-fayalite-magnetite (QFM) buffer at fore-arc conditions. Sulphides are stable under such conditions and aqueous fluids contain minor S. At sub-arc depth, dehydration occurs under more reducing conditions producing aqueous fluids carrying H2S. This finding brings into question current models in which serpentinite-derived fluids are the cause of oxidized arc magmatism and has major implications for the global volatile cycle, as well as for redox processes controlling subduction zone geodynamics.

Stratigraphy, structure and evolution of the Tibetan–Tethys zone in Zanskar and the Indus suture zone in the Ladakh Himalaya

1983 ◽  
Vol 73 (4) ◽  
pp. 205-219 ◽  
Author(s):  
M. P. Searle
Keyword(s):  
Subduction Zone ◽  
Late Cretaceous ◽  
Volcanic Rocks ◽  
Ocean Basin ◽  
Suture Zone ◽  
Island Arc ◽  
Indian Plate ◽  
Northern Margin ◽  
Ladakh Himalaya ◽  
Late Tertiary

ABSTRACTThe Tibetan–Tethys zone of the Zanskar Himalaya shows a complete Mesozoic shelf carbonate sequence overlying metamorphic basement of the Central crystalline complex and Palaeozoic sedimentary rocks. Continental rifting in the Permian produced the alkaline and basaltic Panjal volcanic rocks and by Triassic time a small ocean basin was developed in the Indus-Tsangpo zone. Stable sedimentation continued until the Middle-Late Cretaceous when a thick sequence of tholeiitic to andesitic island arc lavas (Dras arc) were erupted in the basin above a N-dipping subduction zone. The Spontang ophiolite was emplaced southwards onto the Zanskar shelf edge during latest Cretaceous or earliest Tertiary times.Following emplacement of the Spontang ophiolite, deep-sea sedimentation ended abruptly with initial collision between the Indian plate and the Dras island arc. Emplacement of the massive Ladakh (Trans-Himalayan) batholith along the southern margin of Tibet in late Cretaceous-Eocene time occurred by crustal melting as a result of northward subduction of Mesozoic oceanic crust along the Indus subduction zone. Southward-directed thrusting in both Zanskar and Indus zones accompanied ocean closure during the late Cretaceous–Eocene. Late Tertiary compression caused intense folding, overturning and a phase of northward-directed thrusting along the Indus suture zone and the northern margin of the Tibetan–Tethys zone, resulting in a large amount of crustal shortening.

Upper Cretaceous trench deposits of the Neo-Tethyan subduction zone: Jiachala Formation from Yarlung Zangbo suture zone in Tibet, China

2018 ◽  
Vol 61 (9) ◽  
pp. 1204-1220 ◽  
Author(s):  
Hanpu Fu ◽  
Xiumian Hu ◽  
Erica M. Crouch ◽  
Wei An ◽  
Jiangang Wang ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Upper Cretaceous ◽  
Suture Zone ◽  
Yarlung Zangbo Suture Zone
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