scholarly journals Comment on ‘Unveiling ductile deformation during fast exhumation of a granitic pluton in a transfer zone’ by Richard Spiess, Antonio Langone, Alfredo Caggianelli, Finlay M. Stuart, Martina Zucchi, Caterina Bianco, Andrea Brogi, & Domenico Liotta

2021 ◽  
Author(s):  
Francesco Mazzarini ◽  
Giovanni Musumeci ◽  
Samuele Papeschi
Keyword(s):  
Tectonic Setting ◽  
Horizontal Displacement ◽  
Northern Apennines ◽  
Ductile Deformation ◽  
Upper Crust ◽  
Small Section ◽  
Granitic Pluton ◽  
Thermal Peak ◽  
Ebsd Data ◽  
Transfer Zone

In their paper, Spiess et al. (2021) published structural, geochronological, and EBSD data on one of the monzogranite apophyses (Capo Bianco) of the buried Porto Azzurro Pluton (island of Elba, Northern Apennines, Italy), a pluton emplaced in the upper crust (P < 0.2 GPa; e.g. Papeschi et al., 2019). The authors publish a new U/Pb age of 6.4 ± 0.4 Ma, associated to the thermal peak, and a U-Th/He apatite age of 5.0 ± 0.6 Ma, related to a T of 60 °C. Spiess et al. (2021) use these ages to model the exhumation of the pluton controlled by the sub-horizontal Zuccale Fault, a fault with 6 km of horizontal displacement (ZF; Keller & Coward, 1996). Their structural dataset from the macro to the microscale and EBSD analyses relies on a small section (about 100 m wide) in the NE part of the Calamita Peninsula. Based on their documentation of (1) vertical dykes in the monzogranite, (2) vertical to low-angle top-to-the-E extensional faults, and (3) later NW-striking oblique faults, they interpret the Porto Azzurro Pluton as emplaced in an extensional to transcurrent tectonic setting, extrapolating their findings to the entire Eastern Elba.

Reply to Mazzarini et al. comment on ‘Unveiling ductile deformation during fast exhumation of a granitic pluton in a transfer zone’

2021 ◽  
pp. 104498
Author(s):  
Richard Spiess ◽  
Antonio Langone ◽  
Alfredo Caggianelli ◽  
Finlay M. Stuart ◽  
Martina Zucchi ◽  
...  
Keyword(s):  
Ductile Deformation ◽  
Granitic Pluton ◽  
Transfer Zone

The cooling, deformation and exhumation history of the late Miocene syn-tectonic Porto Azzurro pluton in a regional transfer zone (Elba Island, Italy)

2020 ◽  
Author(s):  
Andrea Brogi ◽  
Richard Spiess ◽  
Alfredo Caggianelli ◽  
Antonio Langone ◽  
Fin Stuart ◽  
...  
Keyword(s):  
Tectonic Setting ◽  
Northern Apennines ◽  
Contact Metamorphism ◽  
Pluton Emplacement ◽  
Vertical Permeability ◽  
Extensional Tectonic ◽  
History Of ◽  
Elba Island ◽  
Exhumation History ◽  
Transfer Zone

&lt;p&gt;In extensional tectonic settings, stretched terrains are often associated to lithosphere partial melting and widespread magmatism with plutons emplaced in the thinned crust. Emplacement of felsic magmas, at upper crustal levels, represents the final stage of the magma transfer from profound to shallow depth. In this framework, a mostly vertical permeability controls the magma uprising migration, as induced by dominant transcurrent crustal structures. Nevertheless, the interplay between extension and prolonged heat transfer favors uplift and progressive exhumation of the magmatic bodies, during their cooling.&lt;/p&gt;&lt;p&gt;In this presentation, we show an example of a felsic magmatic intrusion, the Porto Azzurro pluton (inner northern Apennines), emplaced in an extensional tectonic setting and mainly controlled by a regional transfer zone related to the opening of the Tyrrhenian Basin. This is exposed in the eastern Elba Island (Tuscan Archipelago). The hosting rocks of the Porto Azzurro pluton are mainly represented by micaschist, paragneiss and quartzite, affected by contact metamorphism and intense fluid circulation. We have analysed the structures that assisted the pluton emplacement and the ones that deformed the pluton itself during its cooling, from melt-present to brittle conditions, based on the integration among fieldwork, micro-structural, petrological and EBSD analyses. Furthermore, new U/Pb geochronological data on zircons and (U-Th)/He on apatite fission track refined the age of the pluton emplacement and its cooling, adding new data about the pluton history. Existing petrological analyses of the hosting rocks allowed us to better constrain the time-evolution of the thermal perturbation, permitting to frame the deformation and exhumation history of the Porto Azzurro monzogranite in the context of the Neogene extensional tectonics affecting the inner Northern Apennines.&lt;/p&gt;

Unveiling ductile deformation during fast exhumation of a granitic pluton in a transfer zone

2021 ◽  
pp. 104326
Author(s):  
Richard Spiess ◽  
Antonio Langone ◽  
Alfredo Caggianelli ◽  
Finlay M. Stuart ◽  
Martina Zucchi ◽  
...  
Keyword(s):  
Ductile Deformation ◽  
Granitic Pluton ◽  
Transfer Zone

scholarly journals Statherian (ca. 1714–1680 Ma) Extension-Related Magmatism and Deformation in the Southwestern Korean Peninsula and Its Geological Significance: Constraints from the Petrological, Structural, Geochemical and Geochronological Studies of Newly Identified Granitoids

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 557
Author(s):  
Byung-Choon Lee ◽  
Weon-Seo Kee ◽  
Uk-Hwan Byun ◽  
Sung-Won Kim
Keyword(s):  
Korean Peninsula ◽  
Tectonic Setting ◽  
Alkali Feldspar ◽  
Ductile Deformation ◽  
Southwestern Part ◽  
The North ◽  
Deformation Event ◽  
Geochemical Analyses ◽  
A Minor ◽  
T Values

In this study, petrological, structural, geochemical, and geochronological analyses of the Statherian alkali feldspar granite and porphyritic alkali feldspar granite in the southwestern part of the Korean Peninsula were conducted to examine petrogenesis of the granitoids and their tectonic setting. Zircon U-Pb dating revealed that the two granites formed around 1.71 Ga and 1.70–1.68 Ga, respectively. The results of the geochemical analyses showed that both of the granites have a high content of K2O, Nb, Ta, and Y, as well as high FeOt/MgO and Ga/Al ratios. Both granites have alkali-calcic characteristics with a ferroan composition, indicating an A-type affinity. Zircon Lu-Hf isotopic compositions yielded negative εHf(t) values (−3.5 to −10.6), indicating a derivation from ancient crustal materials. Both granite types underwent ductile deformation and exhibited a dextral sense of shear with a minor extension component. Based on field relationships and zircon U-Pb dating, it was considered that the deformation event postdated the emplacement of the alkali feldspar granite and terminated soon after the emplacement of the porphyritic alkali feldspar granite in an extensional setting. These data indicated that there were extension-related magmatic activities accompanying ductile deformation in the southwestern part of the Korean Peninsula during 1.71–1.68 Ga. The Statherian extension-related events are well correlated with those in the midwestern part of the Korean and eastern parts of the North China Craton.

scholarly journals Transient rhyolite melt extraction to produce a shallow granitic pluton

2021 ◽  
Vol 7 (21) ◽  
pp. eabf0604
Author(s):  
Allen J. Schaen ◽  
Blair Schoene ◽  
Josef Dufek ◽  
Brad S. Singer ◽  
Michael P. Eddy ◽  
...  
Keyword(s):  
Time Scales ◽  
Explosive Eruptions ◽  
Upper Crust ◽  
Saturation Model ◽  
Granitic Pluton ◽  
Melt Extraction ◽  
High Silica ◽  
Melt Segregation ◽  
Zircon Saturation

Rhyolitic melt that fuels explosive eruptions often originates in the upper crust via extraction from crystal-rich sources, implying an evolutionary link between volcanism and residual plutonism. However, the time scales over which these systems evolve are mainly understood through erupted deposits, limiting confirmation of this connection. Exhumed plutons that preserve a record of high-silica melt segregation provide a critical subvolcanic perspective on rhyolite generation, permitting comparison between time scales of long-term assembly and transient melt extraction events. Here, U-Pb zircon petrochronology and 40Ar/39Ar thermochronology constrain silicic melt segregation and residual cumulate formation in a ~7 to 6 Ma, shallow (3 to 7 km depth) Andean pluton. Thermo-petrological simulations linked to a zircon saturation model map spatiotemporal melt flux distributions. Our findings suggest that ~50 km3 of rhyolitic melt was extracted in ~130 ka, transient pluton assembly that indicates the thermal viability of advanced magma differentiation in the upper crust.

Chapter 3 Archean (>2.6 Ga) and Paleoproterozoic (2.5–1.8 Ga), pre- and syn-orogenic magmatism, sedimentation and mineralization in the Norrbotten and Överkalix lithotectonic units, Svecokarelian orogen

2020 ◽  
Vol 50 (1) ◽  
pp. 27-81 ◽  
Author(s):  
Stefan Bergman ◽  
Pär Weihed
Keyword(s):  
Variable Temperature ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Volcanic Rocks ◽  
Shear Zones ◽  
Ductile Deformation ◽  
Fe Oxide ◽  
Ductile Shear Zones ◽  
Three Stages ◽  
Felsic Volcanic

AbstractTwo lithotectonic units (the Norrbotten and Överkalix units) occur inside the Paleoproterozoic (2.0–1.8 Ga) Svecokarelian orogen in northernmost Sweden. Archean (2.8–2.6 Ga and possibly older) basement, affected by a relict Neoarchean tectonometamorphic event, and early Paleoproterozoic (2.5–2.0 Ga) cover rocks constitute the pre-orogenic components in the orogen that are unique in Sweden. Siliciclastic sedimentary rocks, predominantly felsic volcanic rocks, and both spatially and temporally linked intrusive rock suites, deposited and emplaced at 1.9–1.8 Ga, form the syn-orogenic component. These magmatic suites evolved from magnesian and calc-alkaline to alkali–calcic compositions to ferroan and alkali–calcic varieties in a subduction-related tectonic setting. Apatite–Fe oxide, including the world's two largest underground Fe ore mines (Kiruna and Malmberget), skarn-related Fe oxide, base metal sulphide, and epigenetic Cu–Au and Au deposits occur in the Norrbotten lithotectonic unit. Low- to medium-pressure and variable temperature metamorphic conditions and polyphase Svecokarelian ductile deformation prevailed. The general northwesterly or north-northeasterly structural grain is controlled by ductile shear zones. The Paleotectonic evolution after the Neoarchean involved three stages: (1) intracratonic rifting prior to 2.0 Ga; (2) tectonic juxtaposition of the lithotectonic units during crustal shortening prior to 1.89 Ga; and (3) accretionary tectonic evolution along an active continental margin at 1.9–1.8 Ga.

scholarly journals Age, origin and tectonic setting of Dulaankhan granitic pluton in northern Mongolia

2019 ◽  
pp. 22-34
Author(s):  
Baatar Gendenjamts ◽  
Baatar Munkhtsengel ◽  
Dashdorjgochoo Odgerel ◽  
Dorjgochoo Sanchir ◽  
Bayaraa Ganbat
Keyword(s):  
Tectonic Setting ◽  
Small Body ◽  
Early Jurassic ◽  
Geochemical Data ◽  
Quartz Syenite ◽  
Granitic Pluton ◽  
Eu Anomaly ◽  
High K ◽  
Northern Mongolia ◽  
Type Granite

Dulaankhan granitic pluton, which is situated in northern Mongolia, the southern portion of the Mongolian-Transbaikalian belt (MTB), is petrographically composed of fine to medium-grained peralkaline granite and is intruded by a small body of quartz syenite. Geochemical data show the Dulaankhan granite and the intruding quartz syenite are both slightly peraluminous and high-K calc-alkaline, and are enriched in LREEs relative to the HREEs, with negative Eu anomaly, and in large ion lithophile elements (LILEs; such as K, Cs and Rb) with respect to high field strength elements (HFSEs; e.g., Nb, Ta and Ti). In terms of relations of Nb, Zr and Y to Ga/Al, however, the Dulaankhan granite and quartz syenite show geochemical features of A-type granites and can be classified into the A2-sub type granite, implying that the pluton formed in an post-collision extensional environment. LA-ICPMS zircon U-Pb dating results suggest that the Dulaankhan granite crystallized at 198±1 Ma, whereas the intruding quartz syenite at 180±1 Ma, consistent with our field observation that the quartz syenite intrudes the granite, attesting that the two granitic bodies were emplaced at different times although both of them formed during the Early Jurassic period. According to these new data, as well as regional ones, we propose that the Dulaankhan granitic pluton was likely generated in the post-collision setting related to the orogenesis of the Mongol-Okhotsk belt that seems to occur prior to Early Jurassic in the northern Mongolian segment.

scholarly journals A GLACIAÇÃO STURTIANA (~750 MA), A ESTRUTURA DO RIFTE MACAÚBAS-SANTO ONOFRE E A ESTRATIGRAFIA DO GRUPO MACAÚBAS, FAIXA ARAÇUAÍ

2013 ◽  
Author(s):  
Alexandre Uhlein ◽  
Roland R. Trompette ◽  
Marcos Egydio-Silva ◽  
Alan Vauchez
Keyword(s):  
Tectonic Setting ◽  
Normal Faults ◽  
Sedimentary Sequence ◽  
Mafic Dike ◽  
Ice Caps ◽  
Sediment Gravity Flows ◽  
Gravity Flows ◽  
Rodinia Supercontinent ◽  
Eastern Edge ◽  
Transfer Zone

This paper is a contribution to the knowledge of the Sturtian glaciation (~800-750 Ma) and the gravitationalsedimentation of the Macaúbas and Santo Onofre Groups. The primary goal of this paper is: (1) todescribe glaciogenic deposits on the eastern edge of the São Francisco craton; (2) to present stratigraphic,sedimentologic and the tectonic setting of the Macaúbas-Santo Onofre rift. An extensional phase is markedby the intrusion of mafic dike swarms at 1100 – 900 Ma and alkaline rocks (750-670 Ma). The Sturtianglacial event (800-750 Ma), with formation of ice-caps in Rodinia supercontinent, is well exposed in theJequitaí area. Glaciomarine facies developed on the border of the craton grade laterally into debris-flowand turbidites. The Neoproterozoic Macaúbas – Santo Onofre rift evolved into a wide embayment limitedby normal faults and a transfer zone. The sedimentary sequence consists of the diamictites, conglomerates,sandstones,, graywackes, pelites deposited by sediment gravity flows. The Neoproterozoic Macaúbas Grouprepresents rift to drift sedimentation related to the break-up of Rodinia. Macaúbas- Santo Onofre rift isregarded as intracontinental with a limited oceanization located at southern of the basin.

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