Rb-Sr and40Ar/39Ar age constraints on the Variscan metamorphism recorded by Ordovician acidic metavolcanic rocks in the Eastern Southalpine basement

2004 ◽  
Vol 15 (3) ◽  
pp. 205-223 ◽  
Author(s):  
Sandro Meli
Keyword(s):  
Metavolcanic Rocks ◽  
Southalpine Basement ◽  
Variscan Metamorphism ◽  
Age Constraints

U–Pb age constraints on arenaceous and volcanic rocks of the Wakeham Group, eastern Grenville Province

2005 ◽  
Vol 42 (10) ◽  
pp. 1677-1697 ◽  
Author(s):  
O van Breemen ◽  
L Corriveau
Keyword(s):  
Volcanic Rocks ◽  
Detrital Zircons ◽  
Morphological Evidence ◽  
Ionization Mass ◽  
Grenville Province ◽  
Metavolcanic Rocks ◽  
Southeastern Margin ◽  
Depositional Age ◽  
Age Constraints ◽  
Group Yield

Combined sensitive high-resolution ion microprobe (SHRIMP) and thermal ionization mass spectrometry (TIMS) U–Pb zircon data from a tightly constrained stratigraphic context of the Wakeham Group provide a precise depositional age for sedimentation within this extensive basin of the Grenville Province. Metavolcanic rocks at the eastern exposure of the Wakeham Group yield ages of 1511 ± 13, 1506 ± 11, 1502 ± 9, and 1491 ± 7 Ma. A crosscutting 1493 ± 10 Ma porphyry vein marks the end of volcanism. The older two volcanic rocks rest stratigraphically above metasediments, with a 1517 ± 20 Ma maximum age of sedimentation derived from the youngest detrital zircons of an arenite. Five 1.61–1.55 Ga inherited zircons in the volcanics, reinforced by coeval inheritance in nearby plutons, indicate a Labradorian basement source to the supracrustals. The predominant arenite detrital zircons dates are in the 1.95–1.75 Ga range, however, and feature both trace element and morphological evidence for metamorphism in the source terrane. Together with zircons as old as 2.95 Ga, the detrital age spectrum is consistent with a circum-Superior provenance. The ages obtained imply that Wakeham Group volcanism and sedimentation were, at least in part, coeval with the onset of 1.52–1.46 Ga Pinwarian plutonism along the southeastern margin of Laurentia. U–Pb zircon analyses record a late Grenvillian metamorphic event around 1019 Ma. U–Pb monazite analyses from one sample yield 1010–1000 Ma ages, and the end of Grenvillian metamorphism is marked by 990 Ma U–Pb titanite ages.

Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland

1999 ◽  
pp. 65-78
Author(s):  
Henrik Rasmussen ◽  
Lars Frimodt Pedersen
Keyword(s):  
Tectonic Setting ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
West Greenland ◽  
North West ◽  
North East ◽  
Metavolcanic Rocks ◽  
Arc Setting ◽  
Area North ◽  
Back Arc

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, H., & Frimodt Pedersen, L. (1999). Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 65-78. https://doi.org/10.34194/ggub.v181.5114 _______________ Two Archaean supracrustal sequences in the area north-east of Disko Bugt, c. 1950 and c. 800 m in thickness, are dominated by pelitic and semipelitic mica schists, interlayered with basic metavolcanic rocks. A polymict conglomerate occurs locally at the base of one of the sequences. One of the supracrustal sequences has undergone four phases of deformation; the other three phases. In both sequences an early phase, now represented by isoclinal folds, was followed by north-west-directed thrusting. A penetrative deformation represented by upright to steeply inclined folds is only recognised in one of the sequences. Steep, brittle N–S and NW–SE striking faults transect all rock units including late stage dolerites and lamprophyres. Investigation of major- and trace-element geochemistry based on discrimination diagrams for tectonic setting suggests that both metasediments and metavolcanic rocks were deposited in an environment similar to a modern back-arc setting.

AGE CONSTRAINTS AND CORRELATION OF “SUR SERIES” METASEDIMENTARY FRAMEWORK ROCKS: IMPLICATIONS FOR THE ORIGIN OF THE SALINIAN TERRANE, CENTRAL CALIFORNIA

2017 ◽  
Author(s):  
Owen A. Anfinson ◽  
◽  
Alan D. Chapman ◽  
Robert Grace ◽  
James P. Peoples ◽  
...  
Keyword(s):  
Central California ◽  
Age Constraints

NEW RE-OS AND U-PB AGE CONSTRAINTS FOR THE BIOLOGICAL INNOVATIONS AND GEOCHEMICAL AND CLIMATIC PERTURBATIONS OF THE NEOPROTEROZOIC

2017 ◽  
Author(s):  
Alan D. Rooney ◽  
◽  
Justin V. Strauss ◽  
Phoebe Cohen ◽  
Daniel Condon ◽  
...  
Keyword(s):  
Age Constraints ◽  
Biological Innovations

GARNET SM-ND AGE CONSTRAINTS ON GRANULITE METAMORPHISM IN THE LOWER CRUST OF THE FIORDLAND MAGMATIC ARC, NEW ZEALAND

2018 ◽  
Author(s):  
Ryan L. Rogers ◽  
◽  
James W. Yelverton ◽  
Harold H. Stowell ◽  
Elizabeth M. Bollen ◽  
...  
Keyword(s):  
New Zealand ◽  
Lower Crust ◽  
Magmatic Arc ◽  
Granulite Metamorphism ◽  
Age Constraints

LARAMIDE THRUSTING IN SE CALIFORNIA: NEW AGE CONSTRAINTS FROM LATE SYN-KINEMATIC PEGMATITES AND ACCESSORY MINERAL PETROCHRONOLOGY

2019 ◽  
Author(s):  
Tarryn Cawood ◽  
◽  
Amy C. Moser ◽  
Ariel Borsook
Keyword(s):  
New Age ◽  
Accessory Mineral ◽  
Age Constraints
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