Genetic significance of zircon in orthogneisses from Sierra Nevada (Betic Cordillera, Spain)

2017 ◽  
Vol 81 (1) ◽  
pp. 77-101 ◽  
Author(s):  
M. D. Ruiz-Cruz ◽  
C. Sanz de Galdeano
Keyword(s):  
Sierra Nevada ◽  
Inductively Coupled Plasma ◽  
Morphological Changes ◽  
Betic Cordillera ◽  
Geodynamic Setting ◽  
Magmatic Zircon ◽  
Common Source ◽  
Inductively Coupled ◽  
Model Based ◽  
Complete Study

AbstractZircon from two types of orthogneisses (inheritance-rich and inheritance-poor) from Sierra Nevada (Betic Cordillera, Spain) was investigated by integrating U–Pb geochronology, cathodoluminescence and back-scattered SEM imaging, laser-ablation inductively coupled plasma mass spectrometry analyses and Raman spectroscopy to examine the conditions of magmatic zircon growth and the variable extent and mechanisms of the Alpine modifications. Zircon from inheritance-rich gneiss consists of two main domains: inherited (Neoproterozoic-to-Early Paleozoic and Devonian) cores and magmatic overgrowths, which provided 206Pb/238U concordant ages of 286 ± 3 Ma. In inheritance-poor gneiss, zircons consist of magmatic cores and very altered rims defining a discordia with an upper intercept with the Concordia at 287 + 21 –22 Ma and a lower intercept at 20.8 + 48.6 –20.8 Ma. Magmatic domains of zircon from inheritance-rich gneiss have lower rare-earth element (REE) contents than magmatic domains from inheritance-poor gneiss, reflecting the less evolved nature of the melt. Altered domains in zircon from inheritance-poor gneisss how greater U concentrations, lower REE concentrations and lower Th/U ratios relative to the cores, interpreted as representing Pb loss from the U-rich magmatic domains during the Alpine event. Morphological changes within single grains and between populations reflects the evolution during magmatic cooling. We show that, whereas classic methods allow two different interpretations for the geodynamic setting of the two types of gneisses, a complete study of composition, morphology and structure of zircon can help to decide that a model based on a common source for the granitic melt better fits the zircon characteristics than a model based on melts generated in two different geotectonic settings.

A Palaeoarchean–Mesoarchean micro-continent entrained in the Jiao-Liao-Ji Belt at the southeastern North China Craton: evidence from the zircon record in the Bengbu area

2019 ◽  
Vol 156 (9) ◽  
pp. 1565-1586 ◽  
Author(s):  
Chaohui Liu ◽  
Guochun Zhao ◽  
Fulai Liu ◽  
Jia Cai
Keyword(s):  
Trace Element ◽  
North China Craton ◽  
Inductively Coupled Plasma ◽  
North China ◽  
Detrital Zircons ◽  
Magmatic Zircon ◽  
Inductively Coupled ◽  
Multi Stage ◽  
Plasma Mass Spectrometry ◽  
Trace Element Contents

AbstractThe Bengbu area in the southeastern North China Craton (NCC) consists predominantly of Archean–Palaeoproterozoic (gneissic) granitoids with minor supracrustal rocks (the Fengyang and Wuhe groups). This study presents new zircon laser ablation – inductively coupled plasma – mass spectrometry U–Pb and Lu–Hf isotopic data and trace-element contents for these granitoids, which improve understanding the Archean–Palaeoproterozoic crustal evolution of the NCC. Magmatic zircon U–Pb data reveal that zircons in the (gneissic) granitoids were generated by multi-stage events at 2.93, 2.73, 2.53–2.52 and 2.18–2.13 Ga. Metamorphic zircon U–Pb data obtained from these rocks show two distinct metamorphic ages of 2.49–2.52 and 1.84 Ga, suggesting that the Bengbu area experienced a regional metamorphic event at the end of the Neoarchean Era and encountered reworking by a tectonothermal event associated with the formation of the Palaeoproterozoic Jiao-Liao-Ji Belt. Trace-element compositions of magmatic zircons reveal the highest Ti concentrations (8.08±3.38 ppm) and growth temperatures (718±44 °C) for the zircons aged 2.13–2.17 Ga and an increase in zircon U/Yb ratios from 2.93 Ga (0.34±0.12) through 2.73 Ga (0.96±0.42) to 2.53 Ga (1.05±0.46), but an evident decrease at 2.17–2.13 Ga (0.61±0.40 ppm). Similar Palaeoarchean xenocrystic and detrital zircons with negativeɛHf(t) values, late Mesoarchean magmatic zircons with juvenile Hf isotopic features, early Neoarchean magmatic zircons with model ages of 2.9–3.0 Ga, and two regional metamorphic events at 2.52–2.48 and 1.88–1.80 Ga in the Bengbu and Jiaobei areas indicate a Palaeoarchean–Mesoarchean micro-continent entrained in the Jiao-Liao-Ji Belt at the southeastern NCC.

Model-based analysis of the silica glass film etch mechanism in CF4/O2 inductively coupled plasma

2007 ◽  
Vol 19 (10) ◽  
pp. 957-964 ◽  
Author(s):  
Mansu Kim ◽  
Nam-Ki Min ◽  
Alexander Efremov ◽  
Hyun Woo Lee ◽  
Chi-Sun Park ◽  
...  
Keyword(s):  
Silica Glass ◽  
Inductively Coupled Plasma ◽  
Glass Film ◽  
Inductively Coupled ◽  
Model Based ◽  
Model Based Analysis

Tectonic significance of the Variscan suture between Brunovistulia and the Bohemian Massif

2020 ◽  
pp. jgs2020-176
Author(s):  
S. Collett ◽  
P. Štípská ◽  
K. Schulmann ◽  
J. Míková ◽  
A. Kröner
Keyword(s):  
Bohemian Massif ◽  
Inductively Coupled Plasma ◽  
Sensu Stricto ◽  
Geochemical Data ◽  
Magmatic Zircon ◽  
Analytical Methodology ◽  
Content Type ◽  
Inductively Coupled ◽  
Single Zircon ◽  
Supplementary Material

The Velké Vrbno Dome crops-out at the boundary between the Brunovistulian Terrane and the internal parts of the Bohemian Massif. Here, eclogite boudins occur within an Ediacaran volcano-sedimentary sequence. Strong Nb depletion (Nb/Nb* = 0.19 – 0.82) combined with moderately positive Nd isotopic compositions (εNd(i) = +3.89 – +5.77) are used to argue for emplacement of the eclogite protoliths in a transitional supra-subduction to continental-rift setting. Conversely, heterogeneously enriched large ion lithophile elements and highly radiogenic Sr isotopic ratios (87Sr/86Sr = 0.705–0.720) are interpreted to have been modified following fluid infiltration subsequent to eclogite-facies metamorphism.U-Pb laser ablation inductively coupled plasma mass spectrometry dating of magmatic zircon from the rift-type eclogite indicates Early Cambrian emplacement (c.535 Ma) following episodic Ediacaran volcanic arc activity. Moreover, a continental setting is emphasised by zircon dating of a mylonitic orthogneiss, revealing a fragment of Palaeoproterozoic (c.2000 Ma) basement, the first such finding within the Brunovistulian Terrane sensu stricto.The new data from eclogite confirm that rifting in this segment of Gondwana pre-dated the Ordovician opening of the Rheic Ocean and therefore that the suture between Brunovistulia and the rest of the Bohemian Massif likely represents the vestige of an older hyperextended basin or oceanic tract.Supplementary material: Previously unpublished single zircon evaporation ages from Ediacaran orthogneiss from the Velké Vrbno Dome (supplement A); detailed analytical methodology (supplement B); whole rock geochemical data (supplement C); and U-Pb LA-ICP-MS zircon data (supplement d). https://doi.org/10.6084/m9.figshare.c.5233079

scholarly journals Composition of Trace Metals in Dust Samples Collected from Selected High Schools in Pretoria, South Africa

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
J. O. Olowoyo ◽  
L. L. Mugivhisa ◽  
Z. G. Magoloi
Keyword(s):  
High Schools ◽  
Trace Metals ◽  
Trace Metal ◽  
Inductively Coupled Plasma ◽  
Common Source ◽  
Residential Areas ◽  
Potential Health ◽  
Inductively Coupled ◽  
Positive Effects ◽  
Recess Period

Potential health risks associated with trace metal pollution have necessitated the importance of monitoring their levels in the environment. The present study investigated the concentrations and compositions of trace metals in dust samples collected from classrooms and playing ground from the selected high schools In Pretoria. Schools were selected from Pretoria based on factors such as proximity to high traffic ways, industrial areas, and residential areas. Thirty-two dust samples were collected from inside and outside the classrooms, where learners often stay during recess period. The dust samples were analysed for trace metal concentrations using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The composition of the elements showed that the concentrations of Zn were more than all other elements except from one of the schools. There were significant differences in the concentrations of trace metals from the schools (p<0.05). Regular cleaning, proximity to busy road, and well maintained gardens seem to have positive effects on the concentrations of trace metals recorded from the classrooms dust. The result further revealed a positive correlation for elements such as Pb, Cu, Zn, Mn, and Sb, indicating that the dust might have a common source.

Petrogenesis of the southern Qiangtang mafic dykes, Tibet: Link to a late Paleozoic mantle plume on the northern margin of Gondwana?

2019 ◽  
Vol 131 (11-12) ◽  
pp. 1907-1919 ◽  
Author(s):  
Ming Wang ◽  
Cai Li ◽  
Xiao-Wen Zeng ◽  
Hang Li ◽  
Jian-Jun Fan ◽  
...  
Keyword(s):  
Partial Melting ◽  
Mantle Plume ◽  
Inductively Coupled Plasma ◽  
Crustal Contamination ◽  
Late Paleozoic ◽  
Magmatic Zircon ◽  
Early Permian ◽  
Northern Margin ◽  
Inductively Coupled ◽  
Gondwana Margin

AbstractThis study presents 13 new U-Pb zircon ages obtained by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) together with whole-rock geochemical, Sr-Nd isotopic and zircon Hf isotopic data for a mafic dike swarm in the southern Qiangtang area of Tibet. These data provide the basis for a new model of the late Paleozoic evolution of the Tethys. Combined with the results of previous zircon U-Pb dating, the magmatic zircon grains extracted from mafic dikes yield latest Carboniferous to Early Permian ages (317–279 Ma). The geochemistry of the southern Qiangtang mafic rocks indicates the presence of low-Ti (QLT) and high-Ti (QHT) suites. The magmas that formed the QLT suite underwent higher degrees of partial melting (>5%) and display evidence of crustal contamination, whereas the QHT suite was derived from magmas generated by low-degree (1%–5%) partial melting of a garnet-bearing mantle source, with a greater extent of fractional crystallization than the QLT suite, and no evidence of crustal contamination. We propose that the QHT and QLT suites may have been derived from magmas from different parts of a single mantle plume. The formation of the southern Qiangtang mafic dikes (latest Carboniferous to Early Permian; 317–279 Ma) may have been related to the northward drift of the Cimmerian continent from the northern Gondwana margin, which resulted in the opening of the Meso-Tethys Ocean.

scholarly journals Retroarc Jurassic burial and exhumation of Barrovian metamorphic rocks dated by monazite petrochronology, Funeral Mountains, California

2022 ◽  
Author(s):  
Suzanne Craddock Affinati ◽  
Thomas D. Hoisch ◽  
Michael L. Wells ◽  
Samuel Wright
Keyword(s):  
Sierra Nevada ◽  
Inductively Coupled Plasma ◽  
North American Plate ◽  
Pressure Increase ◽  
Metamorphic Rocks ◽  
Lower Grade ◽  
Inductively Coupled ◽  
Plate Margin ◽  
The Matrix ◽  
T Path

ABSTRACT In this study, we determined the timing of burial and subsequent exhumation of Barrovian metamorphic rocks from the Chloride Cliff area of the Funeral Mountains in southeastern California by constraining the ages of different portions of a pressure-temperature (P-T) path. Using a split-stream laser-ablation inductively coupled plasma–mass spectrometry (ICP-MS) system, we analyzed 192 domains from 35 grains of monazite within five samples with a spot size of 8 µm to determine U-Pb ages and trace-element abundances from the same samples (same polished sections) that were analyzed to produce the P-T paths. Changes that took place within individual monazite grains reflect localized equilibrium and captured the changes in heavy rare earth element (HREE) abundances in the matrix reservoir that occurred as garnet grew, resorbed, and then regrew, thus constraining ages on different portions of the P-T path. The results show that garnet began growing ca. 168 Ma, began resorbing ca. 160 Ma, began retrograde regrowth ca. 157 Ma, and continued to regrow at least through ca. 143 Ma. The early garnet growth corresponds to a period of pressure increase along the P-T path. The subsequent partial resorption corresponds to the prograde crossing of a garnet-consuming reaction during decompression, and the retrograde garnet regrowth occurred when this same reaction was recrossed in the retrograde sense during further decompression. These results are consistent with previously determined ages, which include a Lu-Hf garnet age of 167.3 ± 0.72 Ma for the early pressure-increase portion of the P-T path, and 40Ar/39Ar muscovite cooling ages of 153 and 146 Ma in the lower-grade Indian Pass area 10 km southeast of Chloride Cliff. The 40Ar/39Ar muscovite ages document cooling at the same time as retrograde garnet regrowth was taking place at Chloride Cliff. The oldest monazite age obtained in this study, 176 ± 5 Ma, suggests that southeast-directed thrusting within the Jurassic retroarc was ongoing by this time along the California portion of the western North American plate margin, as a consequence of east-dipping subduction and/or arc collision. The Funeral Mountains were likely located on the east side of the northern Sierra Nevada range in the Jurassic, taking into account dextral strike-slip displacement along the Cretaceous Mojave–Snow Lake fault. The Late Jurassic timing of burial in the Funeral Mountains and its Jurassic location suggest burial was associated with the East Sierran thrust system. The timing of prograde garnet resorption during exhumation (160–157 Ma) corresponds to a change from regional dextral transpression to sinistral transtension along the Jurassic plate margin inferred to have occurred ca. 157 Ma. The recorded exhumation was concurrent with intrusion of the 148 Ma Independence dike swarm in the eastern Sierra Nevada and Mojave regions, which developed within a regime of northeast-southwest extension.

scholarly journals Zircon at the Nanoscale Records Metasomatic Processes Leading to Large Magmatic–Hydrothermal Ore Systems

Minerals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 364 ◽  
Author(s):  
Courtney-Davies ◽  
Ciobanu ◽  
Verdugo-Ihl ◽  
Slattery ◽  
Cook ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
South Australia ◽  
Dark Field ◽  
Oscillatory Zoning ◽  
Irradiation Damage ◽  
Magmatic Zircon ◽  
Time Interval ◽  
Nanoscale Structures ◽  
Inductively Coupled ◽  
Scanning Transmission

The petrography and geochemistry of zircon offers an exciting opportunity to better understand the genesis of, as well as identify pathfinders for, large magmatic–hydrothermal ore systems. Electron probe microanalysis, laser ablation inductively coupled plasma mass spectrometry, high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging, and energy-dispersive X-ray spectrometry STEM mapping/spot analysis were combined to characterize Proterozoic granitic zircon in the eastern Gawler Craton, South Australia. Granites from the ~1.85 Ga Donington Suite and ~1.6 Ga Hiltaba Suite were selected from locations that are either mineralized or not, with the same style of iron-oxide copper gold (IOCG) mineralization. Although Donington Suite granites are host to mineralization in several prospects, only Hiltaba Suite granites are considered “fertile” in that their emplacement at ~1.6 Ga is associated with generation of one of the best metal-endowed IOCG provinces on Earth. Crystal oscillatory zoning with respect to non-formula elements, notably Fe and Cl, are textural and chemical features preserved in zircon, with no evidence for U or Pb accumulation relating to amorphization effects. Bands with Fe and Ca show mottling with respect to chloro–hydroxy–zircon nanoprecipitates. Lattice defects occur along fractures crosscutting such nanoprecipitates indicating fluid infiltration post-mottling. Lattice stretching and screw dislocations leading to expansion of the zircon structure are the only nanoscale structures attributable to self-induced irradiation damage. These features increase in abundance in zircons from granites hosting IOCG mineralization, including from the world-class Olympic Dam Cu–U–Au–Ag deposit. The nano- to micron-scale features documented reflect interaction between magmatic zircon and corrosive Fe–Cl-bearing fluids in an initial metasomatic event that follows magmatic crystallization and immediately precedes deposition of IOCG mineralization. Quantification of α-decay damage that could relate zircon alteration to the first percolation point in zircon gives ~100 Ma, a time interval that cannot be reconciled with the 2–4 Ma period between magmatic crystallization and onset of hydrothermal fluid flow. Crystal oscillatory zoning and nanoprecipitate mottling in zircon intensify with proximity to mineralization and represent a potential pathfinder to locate fertile granites associated with Cu–Au mineralization.

U-Pb DATING OF HYDROTHERMAL TITANITE RESOLVES MULTIPLE PHASES OF PROPYLITIC ALTERATION IN THE OYU TOLGOI PORPHYRY DISTRICT, MONGOLIA

2020 ◽  
Vol 115 (8) ◽  
pp. 1605-1618
Author(s):  
Lisa Hart-Madigan ◽  
Jamie J. Wilkinson ◽  
Stephanie Lasalle ◽  
Robin N. Armstrong
Keyword(s):  
Inductively Coupled Plasma ◽  
Mineral Chemistry ◽  
Geodynamic Setting ◽  
Porphyry Deposits ◽  
Inductively Coupled ◽  
Close Proximity ◽  
Plasma Mass Spectrometry ◽  
History Of ◽  
Propylitic Alteration ◽  
World Class

Abstract Oyu Tolgoi is a world-class, Late Devonian porphyry district in southern Mongolia. Because of its age and geodynamic setting, it has undergone a complex geological history that includes major postmineralization magmatic-hydrothermal events in close proximity to the porphyry deposits. The propylitic alteration halos that surround the Cu-Au deposits contain widespread hydrothermal titanite, as do the younger altered volcanic and intrusive rocks. Here, we present a comprehensive laser ablation-inductively coupled plasma-mass spectrometry U-Pb study on in situ, propylitic titanite from the Oyu Tolgoi district. The results identify district-wide hydrothermal alteration episodes that coincide with known magmatic events: Devonian porphyry mineralization (~372 Ma); the intrusion of granodiorite plutons and andesite dikes in the Carboniferous (~320–310 Ma); and the emplacement of the Permian Khanbogd Granite alkaline batholith (~290 Ma). Both Carboniferous and Permian alteration events variably overprint the earlier porphyry alteration halo. Overdispersion in the U-Pb data from some samples, due to Pb and/or U mobility, makes interpretation of some titanite ages more difficult, but further exemplifies the complex alteration history of the district. We conclude that U-Pb dating of propylitic titanite is a viable means by which explorers can identify alteration within a prospect that is synchronous with potentially fertile intrusions of known age. The extent of the coeval propylitic alteration and its mineral chemistry can then be used to assess the likelihood of a major porphyry center being present.

scholarly journals Composition and Structure of Zircon from Hydrothermal Uranium Occurrences of the Litsa Ore Area (Kola Region, Russia)

Geosciences ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 278 ◽  
Author(s):  
Tatiana Kaulina ◽  
Lyudmila Lyalina ◽  
Vadim Kamenetsky ◽  
Vadim Il’chenko ◽  
Vladimir Bocharov ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Hydrothermal Process ◽  
Uranium Content ◽  
Magmatic Zircon ◽  
Inductively Coupled ◽  
Kola Region ◽  
Sequence Of Events ◽  
Composition And Structure ◽  
Plasma Mass Spectrometry ◽  
Hydrothermal Event

Zircon grains from various metagranitoids (plagio- and monzo-granites, gneisses, metasomatic rocks, and pegmatoid veins) from the Skal’noe and Dikoe sites of the Litsa uranium ore area (Kola Region, Russia) were studied in order to reconstruct the sequence and timing of events in the area and to observe effects of hydrothermal process related to uranium mineralization on structure and composition of zircon. Individual zircon grains were studied by means of laser ablation inductively coupled plasma mass spectrometry (LA–ICPMS), ion microprobe and Raman spectroscopy. Isotopic LA–ICPMS data for the Skal’noye and Dikoe ore occurrences suggest the following age sequence of events in the area: intrusion of plagiogranites—2829 ± 12 Ma, formation of magmatic protolith of gneisses—2781 ± 17 Ma, metamorphism of plagiogranites—2636 ± 34 Ma; intrusion of monzogranites and pegmatoid veins—2549–2526 Ma, hydrothermal event with uranium input—2276 ± 21 Ma, last metamorphism of plagio- and monzo-granites—1892–1696 Ma. Ore-bearing rocks in the area are pegmatoid veins and quartz–feldspar metasomatites which contain uraninite. During a 2.3 Ga hydrothermal process, newly formed zircon rims grew simultaneously with the precipitation of uraninite in the veins and metasomatites. These rims are characterized by high U and rare earth elements (REE) contents (up to 6560 and 8760 ppm, respectively), dark cathodoluminescence, low Th-U ratios (0.1–0.007) and a flat LREE-enriched pattern, in some cases inherited from minerals, dissolved during a hydrothermal event (magmatic plagioclase and probably monazite). Hydrothermal zircon rims grew with partial dissolution of the magmatic zircon, as evidenced by the rounded and curved shapes of zircon cores. The degree of alteration caused by hydrothermal events depends on the uranium content in the pre-existing zircon. The effects of zircon alteration and newly formed zircon composition reflect the redistribution of uranium in rocks.

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