Early Miocene calc-alkaline felsic tuffs within deep-marine turbidites in the Kyrenia Range, north Cyprus, with a possible post-collisional eruptive centre in western Anatolia

2021 ◽  
pp. 1-13
Author(s):  
Guohui Chen ◽  
Alastair H. F. Robertson
Keyword(s):  
Volcanic Rocks ◽  
Trace Element Analysis ◽  
Western Mediterranean ◽  
Early Miocene ◽  
Western Anatolia ◽  
Terrigenous Material ◽  
Element Analysis ◽  
The North ◽  
North Cyprus ◽  
Felsic Volcanic

Abstract Felsic tuff as a direct fallout deposit is known from one small area in the Kyrenia Range, north Cyprus, within deep-sea terrigenous turbidites. Nearby tuffaceous siltstones contain compositionally similar felsic volcanic rocks (c. 5–10%), mixed with terrigenous material. Sedimentary evidence indicates that the fallout tuff was variable reworked locally, whereas the tuffaceous siltstones are interpreted as turbidites mixed with terrigenous material derived from Anatolia. U–Pb dating of zircons that were extracted from a sample of relatively homogeneous tuff yielded a dominant age of 16.64 ± 0.12 Ma (Burdigalian). Zircon trace-element analysis indicates predominant derivation from within-plate-type felsic magma. Whole-rock chemical analysis of the tuffaceous sediments as a whole is compatible with a felsic arc source, similar to the post-collisional magmatism within Anatolia. Regional comparisons suggest that the nearest volcanism of similar age and composition is located c. 500 km away, within the Kırka area (Eskişehir region) of the Western Anatolia Volcanic Province. Evidence of tephra dispersal in the western Mediterranean region and climatic modelling suggests E-wards prevailing winds and therefore tephra transport over southern Anatolia and adjacent areas during early Miocene time. The north Cyprus tuffs could represent powerful Minoan (Plinian)-type eruptions in western Anatolia, coupled with SE-wards tephra transport during and soon after the onset of post-collisional magmatism.

Petrogenesis and age of the felsic volcanic rocks from the North Baikal volcanoplutonic belt, Siberian craton

Petrology ◽  
2008 ◽  
Vol 16 (5) ◽  
pp. 422-447 ◽  
Author(s):  
T. V. Donskaya ◽  
E. V. Bibikova ◽  
D. P. Gladkochub ◽  
A. M. Mazukabzov ◽  
T. B. Bayanova ◽  
...  
Keyword(s):  
Siberian Craton ◽  
Volcanic Rocks ◽  
The North ◽  
Felsic Volcanic ◽  
Volcanoplutonic Belt ◽  
Felsic Volcanic Rocks

Early Proterozoic (1.88–1.87 Ga) tholeiitic magmatism in the New Québec orogen

1993 ◽  
Vol 30 (7) ◽  
pp. 1505-1520 ◽  
Author(s):  
Thomas Skulski ◽  
Robert P. Wares ◽  
Alan D. Smith
Keyword(s):  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Passive Margin ◽  
Magma Chambers ◽  
Sedimentary Sequences ◽  
The North ◽  
Marine Sedimentation ◽  
Lithospheric Extension ◽  
Felsic Volcanic ◽  
Ocean Ridge

The New Québec orogen contains two volcano-sedimentary sequences bounded by unconformities. Each sequence records a change from continental sedimentation and alkaline volcanism to marine sedimentation and tholeiitic volcanism. The first sequence records 2.17 Ga rifting and the development, by 2.14 Ga, of a passive margin along the eastern part of the Superior craton. The second sequence developed between 1.88 and 1.87 Ga in pull-apart basins that reflect precollisional dextral transtension along the continental margin. Second-sequence magmatism comprises (i) carbonatitic and lamprophyric intrusions and mildly alkaline mafic to felsic volcanic rocks; (ii) widespread intrusion of tholeiitic gabbro sills, and submarine extrusion of plagioclase glomeroporphyritic basalts and younger aphyric basalts and picrites; and (iii) late-stage, mafic to felsic volcanism and intrusion of carbonatites. Crustal thinning allowed primitive tholeiitic magmas to equilibrate at progressively lower pressures before more buoyant derivative liquids could erupt. Early primitive melts were trapped at the base of the crust and crystallized olivine and orthopyroxene with minor crustal contamination. Derivative melts, similar to transitional mid-ocean-ridge basalts, migrated upward into mid-crustal magma chambers where they became saturated in calcic plagioclase. Subsequent tapping of these magma chambers allowed plagioclase ultraphyric magmas to intrude the sedimentary pile and erupt on the sea floor. Prolonged lithospheric extension resulted in more voluminous mantle melting and eruption of picrites and basalts in the south. Primitive magmas in the north were trapped beneath thicker crust and crystallized wehrlite cumulates. Resulting basaltic melts intruded the volcano-sedimentary pile, or erupted as aphyric basalts.

scholarly journals Provenance of Zhou Dynasty bronze vessels unearthed from Zongyang County, Anhui Province, China: determined by lead isotopes and trace elements

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Yanjie Wang ◽  
Guofeng Wei ◽  
Qiang Li ◽  
Xiaoping Zheng ◽  
Danchun Wang
Keyword(s):  
Lead Isotopes ◽  
Isotope Analysis ◽  
Trace Element Analysis ◽  
Element Analysis ◽  
The North ◽  
Material Sources ◽  
Zhou Dynasty ◽  
Bronze Vessels ◽  
Spring And Autumn Period ◽  
North Bank

AbstractThirteen Zhou Dynasty bronze vessels and two slags from Zongyang County along the north bank of the Yangtze River in Anhui were analyzed by LA-MC-ICP-MS and EDXRF. The results of lead isotope analysis showed that there were two kinds of lead materials in the Zongyang bronzes. Vessels in Class I, thought to have originated from the Wannan region were primarily used during the Western Zhou and the following Spring and Autumn period; while those in Class II, possibly from the local mines in Zongyang County, were mainly present during the Warring States period. Such a shift in the ore material sources is also revealed by the trace element analysis of the Zongyang bronzes. With reference to the relevant historical documents, we suggest that the transformation of the bronze material sources might have been associated with the changes of the political situation during the Zhou Dynasty.

Chapter 4 Paleoproterozoic (2.0–1.8 Ga) syn-orogenic sedimentation, magmatism and mineralization in the Bothnia–Skellefteå lithotectonic unit, Svecokarelian orogen

2020 ◽  
Vol 50 (1) ◽  
pp. 83-130 ◽  
Author(s):  
Pietari Skyttä ◽  
Pär Weihed ◽  
Karin Högdahl ◽  
Stefan Bergman ◽  
Michael B. Stephens
Keyword(s):  
Volcanic Rocks ◽  
Shear Zones ◽  
Low Grade ◽  
Lower Grade ◽  
Magmatic Arc ◽  
The North ◽  
Magmatic Rocks ◽  
Structural Style ◽  
Volcanogenic Massive Sulphide ◽  
Felsic Volcanic

AbstractThe Bothnia–Skellefteå lithotectonic unit is dominated by turbiditic wacke and argillite (Bothnian basin), deposited at 1.96 (or older)–1.86 Ga, metamorphosed generally under high-grade conditions and intruded by successive plutonic suites at 1.95–1.93, 1.90–1.88, 1.87–1.85 and 1.81–1.76 Ga. In the northern part, low-grade and low-strain, 1.90–1.86 Ga predominantly magmatic rocks (the Skellefte–Arvidsjaur magmatic province) are enclosed by the basinal components. Subduction-related processes in intra-arc basin and magmatic arc settings, respectively, are inferred. Changes in the metamorphic grade and the relative timing of deformation and structural style across the magmatic province are linked to major shear zones trending roughly north–south and, close to the southern margin, WNW–ESE. Zones trending WNW–ESE and ENE–WSW dominate southwards. Slip along the north–south zones in an extensional setting initiated synchronously with magmatic activity at 1.90–1.88 Ga. Tectonic inversion steered by accretion to a craton to the east, involving crustal shortening, ductile strain and crustal melting, occurred at 1.88–1.85 Ga. Deformation along shear zones under lower-grade conditions continued at c. 1.8 Ga. Felsic volcanic rocks (1.90–1.88 Ga) host exhalative and replacement-type volcanogenic massive sulphide deposits (the metallogenic Skellefte district). Other deposits include orogenic Au, particularly along the ‘gold line’ SW of this district, porphyry Cu–Au–Mo, and magmatic Ni–Cu along the ‘nickel line’ SE of the ‘gold line’.

scholarly journals Petrogenesis and geochronology of the Arkasani Granophyre and felsic Dalma volcanic rocks: implications for the evolution of the Proterozoic North Singhbhum Mobile Belt, east India

2014 ◽  
Vol 152 (3) ◽  
pp. 492-503 ◽  
Author(s):  
H.N. BHATTACHARYA ◽  
D.R. NELSON ◽  
E.R. THERN ◽  
W. ALTERMANN
Keyword(s):  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Tectonic Activity ◽  
Mobile Belt ◽  
Northern Margin ◽  
The North ◽  
Ne India ◽  
New Findings ◽  
Minimum Age ◽  
Felsic Volcanic

AbstractThe North Singhbhum Mobile Belt (NSMB) is a 200 km long, curved Proterozoic fold–thrust belt that skirts the northern margin of the Archean Singhbhum Craton of NE India. The Singhbhum Shear Zone (SSZ) developed between the Dhanjori and Chaibasa formations near the southern margin of the NSMB and represents an important Cu-U-P metallotect. A SHRIMP U–Pb zircon date of 1861±6 Ma, obtained for the syn- to post-kinematic Arkasani Granophyre that has intruded the SSZ, provides a minimum age for the prolonged tectonic activity and mineralization along the SSZ and for the time of closure of the Chaibasa and Dhanjori sub-basins. The Dalma Volcanic Belt, a submarine rift-related bimodal mafic-felsic volcanic suite, forms the spine of the NSMB. A SHRIMP U–Pb zircon igneous crystallization date of 1631±6 Ma was obtained for an unfoliated felsic volcanic rock from the base of the Dalma volcanic sequence. These new findings suggest that the different sub-basins in the NSMB evolved diachronously under contrasting tectonic environments and were juxtaposed during a later orogenic movement.

U–Pb zircon ages from the Lynn Lake and Rusty Lake metavolcanic belts, Manitoba: two ages of Proterozoic magmatism

1987 ◽  
Vol 24 (5) ◽  
pp. 1053-1063 ◽  
Author(s):  
D. A. Baldwin ◽  
E. C. Syme ◽  
H. V. Zwanzig ◽  
T. M. Gordon ◽  
P. A. Hunt ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Island Arc ◽  
Quartz Diorite ◽  
The North ◽  
Volcanic Sequence ◽  
Metavolcanic Rocks ◽  
Lynn Lake ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

Two ages of magmatism have been determined from zircon in felsic flows and plutons in the Churchill Province of Manitoba. A rhyolite flow from the Lynn Lake metavolcanic belt has a U–Pb age of [Formula: see text], and a rhyolite flow from the adjacent Rusty Lake metavolcanic belt has an age of [Formula: see text]. Tonalite and quartz diorite from two composite plutons emplaced into the volcanic rocks at Lynn Lake have ages of [Formula: see text] and [Formula: see text], indistinguishable from the age of the Rusty Lake belt rhyolite. The arcuate domain of metavolcanic rocks that includes the Rusty Lake belt in the southeast, the Lynn Lake belt in the north, and the La Ronge belt (Saskatchewan) in the southwest has previously been considered a single structural sub-province with similar ages throughout. Our results and published U–Pb ages from Saskatchewan indicate that an older magmatism is represented by volcanic rocks in the Lynn Lake belt; a younger magmatism, by volcanic rocks in the Rusty Lake and La Ronge belts and plutons in the Lynn Lake belt. At Lynn Lake the older magmatism (1910 Ma) produced mafic, intermediate, and felsic volcanic rocks and synvolcanic plutons. The volcanic rocks are geochemically similar to Cenozoic island-arc magmatic sequences. These rocks were isoclinally folded and subsequently intruded by the 1876 Ma plutons. The younger, dominantly subaerial, volcanism (1878 Ma) at Rusty Lake was predominantly felsic, and the coeval plutons were granitoid. The distribution of ages and the 8 km thickness of the younger volcanic sequence suggest that the older rock served as basement during the younger magmatism.

scholarly journals Half a million years of magmatic history recorded in a K-feldspar megacryst of the Tuolumne Intrusive Complex, California, USA

Geology ◽  
2020 ◽  
Vol 48 (4) ◽  
pp. 400-404 ◽  
Author(s):  
Melissa Chambers ◽  
Valbone Memeti ◽  
Michael P. Eddy ◽  
Blair Schoene
Keyword(s):  
Volcanic Rocks ◽  
Trace Element Analysis ◽  
Ionization Mass ◽  
Intrusive Complex ◽  
Magmatic System ◽  
Element Analysis ◽  
Age Progression ◽  
Growth Environment ◽  
The Core ◽  
Magmatic History

Abstract K-feldspars reach megacrystic size (>3 cm) relative to their groundmass in many granitoid plutons and some volcanic rocks. However, the nature of the growth environment and the time scales for megacrystic growth remain poorly constrained. Chemical abrasion–isotope dilution–thermal ionization mass spectrometry with trace-element analysis (CA-ID-TIMS-TEA) U-Pb geochronology was carried out on zircon inclusions from the core and rim of one K-feldspar megacryst sampled from the interior of the Tuolumne Intrusive Complex (TIC), California, USA. Combined with new zircon ages from the groundmass, these data can test if K-feldspar megacrysts are igneous and capable of recycling and transport in the magmatic system or whether they formed by textural coarsening in low-melt-fraction or subsolidus conditions. The zircon ages reveal that the megacryst core is 0.5 m.y. older than the rim, which itself is older than the groundmass. Core ages match zircon dates from the TIC’s porphyritic Half Dome unit, and rim and groundmass ages overlap with the younger Cathedral Peak unit. Trace elements of the zircons from the megacryst core and rim are similar and less evolved than the groundmass zircons. The core-to-rim age progression of zircon inclusions is inconsistent with subsolidus K-feldspar coarsening, but instead indicates that megacrysts in the TIC grew in an igneous environment over at least 0.5 m.y., and that growth likely occurred spanning two or more intrusive episodes. This supports models of an increasingly maturing magmatic system, where crystal recycling from older into younger magma batches is common.

Defect structure and luminescence behaviour of agate — results of electron paramagnetic resonance (EPR) and cathodoluminescence (CL) studies

1999 ◽  
Vol 63 (2) ◽  
pp. 149-163 ◽  
Author(s):  
J. Götze ◽  
M. Plötze ◽  
H. Fuchs ◽  
D. Habermann
Keyword(s):  
Emission Band ◽  
Defect Density ◽  
Volcanic Rocks ◽  
Trace Element Analysis ◽  
Yellow Emission ◽  
Supersaturated Solution ◽  
High Concentration ◽  
Element Analysis ◽  
Blue Band ◽  
Paramagnetic Resonance

AbstractSamples of agate and quartz incrustations from different parent volcanic rocks of certain world-wide localities were investigated by EPR, CL and trace element analysis. In all agate samples the following paramagnetic centres were detected:, E′1, [AlO4]0 [FeO4/M+]0 and [GeO4/M+]0. Centres of the type [TiO4/Li+]0 and [TiO4/H+]0, which were detected in quartz of the parent volcanics, are absent in agate. Generally, the abundance of centres (silicon vacancy) and E′1 centres (oxygen vacancy) in agate is remarkably higher than in quartz. The high defect density in agates points to rapid growth of silica from a strongly supersaturated solution probably with a noncrystalline precursor.CL microscopy reveals internal structures and zoning in agates and quartz incrustations which clearly differ from those discernible by conventional polarizing microscopy. The CL spectra of agates differ from those of quartz from crystalline rocks. At least three broad emission bands were detected in the CL spectra: a blue band of low intensity, a yellow band at about 580 nm, and an intense red band at 650 nm. The CL emission at 650 nm shows some relations to the hydroxyl or alkali content and the abundance of centres and E′1 centres. The emission intensity increases during electron bombardement due to the conversion of different precursors (e.g. ≡Si-O-H, ≡Si-O-Na groups) into hole centres. Another conspicuous feature in the CL spectra of agates is the existence of a yellow emission band centred at around 580 nm. The predominance of the yellow CL emission band and the high concentration of E′1 centres are typical for agates of acidic volcanics and are indicative of a close relationship between the two.

Textural and Mineralogical Analysis of Volcanic Rocks by µ-XRF Mapping

2016 ◽  
Vol 22 (3) ◽  
pp. 690-697 ◽  
Author(s):  
Luigi Germinario ◽  
Roberto Cossio ◽  
Lara Maritan ◽  
Alessandro Borghi ◽  
Claudio Mazzoli
Keyword(s):  
Image Analysis ◽  
Volcanic Rocks ◽  
Trace Element Analysis ◽  
Cost Effective ◽  
Spot Size ◽  
Quantitative Information ◽  
Element Analysis ◽  
X Ray ◽  
Ne Italy ◽  
Elemental Maps

AbstractIn this study, µ-XRF was applied as a novel surface technique for quick acquisition of elemental X-ray maps of rocks, image analysis of which provides quantitative information on texture and rock-forming minerals. Bench-top µ-XRF is cost-effective, fast, and non-destructive, can be applied to both large (up to a few tens of cm) and fragile samples, and yields major and trace element analysis with good sensitivity. Here, X-ray mapping was performed with a resolution of 103.5 µm and spot size of 30 µm over sample areas of about 5×4 cm of Euganean trachyte, a volcanic porphyritic rock from the Euganean Hills (NE Italy) traditionally used in cultural heritage. The relative abundance of phenocrysts and groundmass, as well as the size and shape of the various mineral phases, were obtained from image analysis of the elemental maps. The quantified petrographic features allowed identification of various extraction sites, revealing an objective method for archaeometric provenance studies exploiting µ-XRF imaging.

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