scholarly journals U–Pb zircon geochronology of volcanic deposits from the Permian basin of the Orobic Alps (Southern Alps, Lombardy): chronostratigraphic and geological implications

2014 ◽  
Vol 152 (3) ◽  
pp. 429-443 ◽  
Author(s):  
FABRIZIO BERRA ◽  
MASSIMO TIEPOLO ◽  
VALERIA CAIRONI ◽  
GIAN BARTOLOMEO SILETTO
Keyword(s):  
Volcanic Activity ◽  
Age Distribution ◽  
Volcanic Rocks ◽  
Southern Alps ◽  
Early Permian ◽  
Large Scatter ◽  
Permian Basin ◽  
Icp Ms ◽  
Eruption Age ◽  
Sedimentary Succession

AbstractU–Pb zircon ages from volcanic rocks of Early Permian age (Southern Alps, Lombardy), associated with fault-controlled transtensional continental basins, were determined with the laser ablation (LA)-ICP-MS technique. Four samples were collected at the base and at the top of the up to 1000 m thick volcaniclastic unit of the Cabianca Volcanite. This unit pre-dates the development of a sedimentary succession that still contains, at different stratigraphic levels, volcanic intercalations. Age results from a tuff in the basal part of the unit constrain the onset of the volcanic activity to 280 ± 2.5 Ma. Ignimbritic samples from the upper part of the unit show a large scatter in the age distribution. This is interpreted as the occurrence of antecrystic and autocrystic zircons. The youngest autocrystic zircons (c. 270 Ma) are thus interpreted as better constraining the eruption age, constraining the duration of the volcanic activity in the Orobic Basin to about 10 Ma. The new geochronological results compared with those of other Early Permian basins of the Southern Alps reveal important differences that may reflect (1) a real time-transgressive beginning and end of the volcanic activity or (2) the complex mixing of antecrystic and autocrystic zircon populations in the analysed samples.

scholarly journals LA-ICP-MS U-Pb apatite dating of Lower Cretaceous rocks from teschenite-picrite association in the Silesian Unit (southern Poland)

2014 ◽  
Vol 65 (4) ◽  
pp. 273-284 ◽  
Author(s):  
Krzysztof Szopa ◽  
Roman Włodyka ◽  
David Chew
Keyword(s):  
Volcanic Activity ◽  
Volcanic Rocks ◽  
Weighted Average ◽  
Magmatic Rocks ◽  
Three Samples ◽  
Icp Ms ◽  
Outer Western Carpathians ◽  
Wide Range ◽  
Igneous Province ◽  
Intrusive Rocks

Abstract The main products of volcanic activity in the teschenite-picrite association (TPA) are shallow, sub-volcanic intrusions, which predominate over extrusive volcanic rocks. They comprise a wide range of intrusive rocks which fall into two main groups: alkaline (teschenite, picrite, syenite, lamprophyre) and subalkaline (dolerite). Previous 40Ar/39Ar and 40K/40Ar dating of these rocks in the Polish Outer Western Carpathians, performed on kaersutite, sub-silicic diopside, phlogopite/biotite as well as on whole rock samples has yielded Early Cretaceous ages. Fluorapatite crystals were dated by the U-Pb LA-ICP-MS method to obtain the age of selected magmatic rocks (teschenite, lamprophyre) from the Cieszyn igneous province. Apatite-bearing samples from Boguszowice, Puńców and Lipowa yield U-Pb ages of 103± 20 Ma, 119.6 ± 3.2 Ma and 126.5 ± 8.8 Ma, respectively. The weighted average age for all three samples is 117.8 ± 7.3 Ma (MSWD = 2.7). The considerably smaller dispersion in the apatite ages compared to the published amphibole and biotite ages is probably caused by the U-Pb system in apatite being less susceptible to the effects of hydrothermal alternation than the 40Ar/39Ar or 40K/40Ar system in amphibole and/or biotite. Available data suggest that volcanic activity in the Silesian Basin took place from 128 to 103 Ma with the the main magmatic phase constrained to 128-120 Ma.

Lithogeochemical characteristics of metasandstones of the Chetlas series (Chetlassky Kamen, Middle Timan)

2021 ◽  
pp. 3-12
Author(s):  
N. Y. Nikulova ◽  
◽  
O. V. Udoratina ◽  
I. V. Kozyreva
Keyword(s):  
Inductively Coupled Plasma ◽  
Volcanic Rocks ◽  
Rare Metal ◽  
Weathering Crust ◽  
Terrigenous Material ◽  
Inductively Coupled ◽  
Coastal Marine ◽  
Icp Ms ◽  
Middle Timan ◽  
Destruction Of Rocks

The lithological and geochemical features of the metasandstones of the Svetlinskaya and Vizingskaya formations of the Middle Late Riphean Chetlas series in the Middle Timan, which are a substrate of rare-metal-rare-earth mineralization in several ore occurrences of the Kosyus ore cluster, have been investigated. The interpretation of the results of traditional weight chemical and mass spectrometric inductively coupled plasma (ICP MS) analyses allowed us to identify differences in the material composition of metapesanics, mainly due to changes in the degree of sedimentation maturity of terrigenous material coming from the demolition areas. The composition of metasandstones in various ratios includes both weakly weathered products of destruction of volcanic rocks of intermediate/basic composition, and altered, including under conditions of the weathering crust, metaterrigenous formations. The accumulation of sediments took place in a shallow coastal-marine environment with changing hydrodynamics, which affected the rate of destruction of rocks in paleo-catchments.

Contrasting fold styles in a volcano-sedimentary succession

1996 ◽  
Vol 33 (8) ◽  
pp. 1193-1200
Author(s):  
Pierre A. Cousineau ◽  
Robert Marquis
Keyword(s):  
Sedimentary Basin ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Structural Models ◽  
Sedimentary Basins ◽  
Basaltic Rocks ◽  
Field Evidence ◽  
Sedimentary Succession

Structural analyses of folded volcano-sedimentary basins rely heavily on the identification and use of way-up structures. These structures are more numerous and widespread in sedimentary rocks than in volcanic rocks. Structural models for such basins can therefore be biased by this fact. The Caldwell Group of the Quebec Appalachians is a folded volcano-sedimentary basin bounded bay major faults. It contains locally abundant basalt-rich bands. Near Lac-Etchemin, way-up in basalt flows is determined by pillow shelves that reflect paleohorizontal planes. The strike and dip of these shelf structures were measured and plotted on stereographic projections. Field evidence and the interpretation of stereographic projections indicate that the basalt-rich bands form open folds that plunge gently to the southwest. However, sandstone-rich bands form tight folds with undulating hinge lines (sheath-like). During initial folding, the basalt formed competent bands with limited aerial extent that were fractured by synthetic and antithetic faults rather than folded. The basalt slivers maintained a near-horizontal attitude while adjacent sedimentary rocks were folded and faulted. Further shortening tightened folds in the sediment-rich bands while producing open folds in slivers of basaltic rocks.

scholarly journals Magmatic history of the Oldest Toba Tuff inferred from zircon U–Pb geochronology

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hisatoshi Ito
Keyword(s):  
Caldera Collapse ◽  
Zircon Dating ◽  
Icp Ms ◽  
Zircon Crystallization ◽  
History Of ◽  
Eruption Age ◽  
Magmatic History

Abstract The magmatic history of the Oldest Toba Tuff (OTT), the second largest in volume after the Youngest Toba Tuff (YTT), northern Sumatra, Indonesia, was investigated using U–Pb zircon dating by LA-ICP-MS. Zircon dates obtained from surface and interior sections yielded ages of 0.84 ± 0.03 Ma and 0.97 ± 0.03 Ma, respectively. The youngest OTT zircon ages were in accordance with the 40Ar/39Ar eruption age of ~ 0.8 Ma, whereas the oldest zircon dates were ~ 1.20 Ma. Therefore, the distribution of zircon U–Pb ages is interpreted to reflect protracted zircon crystallization, suggesting that the estimated 800–2,300 km3 of OTT magma accumulated and evolved for at least 400,000 years prior to eruption. This result is comparable to the volume and timescales of YTT magmatism. The similarities of both magmatic duration and geochemistry between OTT and YTT may indicate that they are similar in size and that the caldera collapse that generated OTT might be much larger previously interpreted.

scholarly journals The main pulse of the Siberian Traps expanded in size and composition

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
L. E. Augland ◽  
V. V. Ryabov ◽  
V. A. Vernikovsky ◽  
S. Planke ◽  
A. G. Polozov ◽  
...  
Keyword(s):  
Volcanic Activity ◽  
Volcanic Rocks ◽  
West Siberia ◽  
Main Pulse ◽  
Environmental Consequences ◽  
Siberian Traps ◽  
Minimum Age ◽  
Area North ◽  
Permian Mass Extinction ◽  
Compositional Diversity

AbstractEmplacement of large volumes of (sub)volcanic rocks during the main pulse of the Siberian Traps occurred within <1 m.y., coinciding with the end-Permian mass extinction. Volcanics from outside the main Siberian Traps, e.g. Taimyr and West Siberia, have since long been correlated, but existing geochronological data cannot resolve at a precision better than ~5 m.y. whether (sub)volcanic activity in these areas actually occurred during the main pulse or later. We report the first high precision U-Pb zircon geochronology from two alkaline ultramafic-felsic layered intrusive complexes from Taimyr, showing synchronicity between these and the main Siberian Traps (sub)volcanic pulse, and the presence of a second Dinerian-Smithian pulse. This is the first documentation of felsic intrusive magmatism occurring during the main pulse, testifying to the Siberian Trap’s compositional diversity. Furthermore, the intrusions cut basal basalts of the Taimyr lava stratigraphy hence providing a minimum age of these basalts of 251.64 ± 0.11 Ma. Synchronicity of (sub)volcanic activity between Taimyr and the Siberian Traps imply that the total area of the Siberian Traps main pulse should include a ~300 000 km2 area north of Norilsk. The vast aerial extent of the (sub)volcanic activity during the Siberian Traps main pulse may explain the severe environmental consequences.

scholarly journals Hydrogeochemistry and lead contamination of groundwater in the north part of Esfahan province, Iran

2018 ◽  
Vol 16 (4) ◽  
pp. 622-634 ◽  
Author(s):  
Kaveh Pazand ◽  
Davoud Khosravi ◽  
Mohammad Reza Ghaderi ◽  
Mohammad Reza Rezvanianzadeh
Keyword(s):  
Inductively Coupled Plasma ◽  
Arid Regions ◽  
Volcanic Rocks ◽  
Primary Source ◽  
Lead Contamination ◽  
Inductively Coupled ◽  
The North ◽  
Icp Ms ◽  
North Part ◽  
Plasma Mass Spectrometry

Abstract Geochemical and hydrogeochemical studies were conducted to assess the origin and geochemical mechanisms driving lead enrichment in groundwaters of semi-arid regions in Central Iran. In this study, 149 water samples were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Concentrations of Pb and As in about 68% and 27% of the samples, respectively, exceeded WHO guidelines. Analyzing the results of ICP-MS of parental rocks and aquifer sediments shows that unweathered volcanic rocks were the primary source for lead mobilizing to groundwaters.

Controls on Clay Mineral Distribution and Chemistry in the Early Permian Rotliegend of Germany

Clay Minerals ◽  
1993 ◽  
Vol 28 (3) ◽  
pp. 393-416 ◽  
Author(s):  
J. D. Platt
Keyword(s):  
Isotopic Composition ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Tectonic Activity ◽  
Early Permian ◽  
Permian Basin ◽  
Mineral Distribution ◽  
Coal Measures

AbstractAuthigenic clay minerals in the German Rotliegend formed mainly at burial depths >1.5 km. Illite is the dominant cement, although kaolinite, dickite and early radial chlorite are abundant locally. Illites contain more AI and late chlorites more AI and Fe in sequences showing extensive grain dissolution. This relationship between clay chemistry and grain dissolution suggests that clay cementation is linked to grain dissolution. Sequences at relatively shallow burial depths (<3-5 km) contain less clay cement. In the more deeply buried sections, increased illite and kandite cementation, together with extensive grain dissolution, is evident where the Rotliegend is juxtaposed against Carboniferous Coal Measures. Faults also acted as important conduits for acidic fluids. Illite and kandite growth occurred at similar depths and from waters of similar isotopic composition (618O = 1-6‰ SMOW) throughout most of the Southern Permian Basin. However, the timing of illite growth varied between areas and corresponded to periods to tectonic activity.

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