Geochemical polarity of the Early Cretaceous Gambier Group, southern Coast Belt, British Columbia

1995 ◽  
Vol 32 (6) ◽  
pp. 675-685 ◽  
Author(s):  
Gregory Lynch
Keyword(s):  
Early Cretaceous ◽  
Major Element ◽  
Volcanic Rocks ◽  
Age Determination ◽  
Southern Coast ◽  
Element Geochemistry ◽  
Zircon Age ◽  
Structural Style ◽  
Wrangellia Terrane ◽  
Eastern Edge

The Gambier Group of the southern Coast Belt was developed on the eastern edge of the Wrangellia terrane in Early Cretaceous time. A U–Pb zircon age determination from rhyolite produced a date of 112.0 ± 0.3 Ma, consistent with Albian fauna in sedimentary units. Major element geochemistry of volcanic rocks from separate east-northeast and southwest volcanic centres displays both tholeiitic and calc-alkalic affinities across the axis of the Coast Belt. However, assemblages in the east-northeast have higher FeOT/MgO ratios, highlighting a more pronounced tholeiitic trend, and are characterized by high-Al basalts. Volcanic rocks in the southwest are enriched in K. Trace element variations feature a southwesterly increase in Ba, Rb, and Zr/Ti towards more alkalic values, and a decrease in Sr. When compared with across-arc geochemical trends from numerous other arcs, the data may be interpreted to suggest that the Gambier arc was east facing above a west- to southwest-dipping subduction zone. Such an interpretation is consistent with the occurrence of a subduction-melange complex along the southeastern Coast Belt and with a structural style dominated by southwest-verging thrusts in mid-Cretaceous time.

Age of volcanic rocks and syndepositional iron formations, Marquette Range Supergroup: implications for the tectonic setting of Paleoproterozoic iron formations of the Lake Superior region

2002 ◽  
Vol 39 (6) ◽  
pp. 999-1012 ◽  
Author(s):  
D A Schneider ◽  
M E Bickford ◽  
W F Cannon ◽  
K J Schulz ◽  
M A Hamilton
Keyword(s):  
Lake Superior ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Age Determination ◽  
Iron Formation ◽  
Continental Rifting ◽  
The South ◽  
Zircon Age ◽  
Iron Formations ◽  
Northern Michigan

A rhyolite in the Hemlock Formation, a mostly bimodal submarine volcanic deposit that is laterally correlative with the Negaunee Iron-formation, yields a sensitive high-resolution ion microprobe (SHRIMP) U–Pb zircon age of 1874 ± 9 Ma, but also contains inherited Archean zircons as old as 3.8 Ga. This precise age determination for the classic Paleoproterozoic stratigraphic sequence of northern Michigan, the Marquette Range Supergroup (MRS), necessitates modification of previous depositional and tectonic models. Our new data indicate that the Menominee Group, previously ascribed to continental rifting during early, pre-collision phases of the Penokean orogenic cycle, is coeval with arc-related volcanic rocks now preserved as accreted terranes immediately to the south and is more aptly interpreted as a foredeep deposit. We interpret these to be second-order basins created by oblique subduction of the continental margin rather than basins formed on a rifting margin. Along with a recently reported age for the Gunflint Formation in Ontario of 1878 ± 2 Ma, our data suggest that an extensive foredeep in the western Lake Superior region was the locus of iron-formation deposition during arc accretion from the south. Further, we interpret the lower MRS (Chocolay Group), a glaciogenic and shallow-marine succession that lies atop Archean basement, to be equivalent to the upper part of the Huronian Supergroup of Ontario and to represent the original continental rifting and passive-margin phase of the Penokean cycle. The upper MRS (Baraga Group) represents deeper marine basins, dominated by turbidites and lesser volcanic rocks, resulting from increased subsidence and continued collision. A stitching pluton, which cuts correlatives of the Hemlock Formation in a thrust sheet, yielded a U–Pb zircon age of 1833 ± 6 Ma, consistent with other post-tectonic plutons in Wisconsin and northern Michigan, indicating that Penokean convergence lasted no longer than ~40 million years.

Intra-Ordovician deformation in southeast Ireland: evidence from the geological setting, geochemical affinities and U—Pb zircon age of the Croghan Kinshelagh granite

1994 ◽  
Vol 131 (5) ◽  
pp. 669-684 ◽  
Author(s):  
V. Gallagher ◽  
P. J. O'Connor ◽  
M. Aftalion
Keyword(s):  
Subduction Zone ◽  
Hanging Wall ◽  
Volcanic Rocks ◽  
Age Determination ◽  
Volcanic Belt ◽  
Zircon Age ◽  
Regional Deformation ◽  
Iapetus Ocean ◽  
Granite Type

AbstractThe Croghan Kinshelagh alkali granite intrudes a cleaved volcano-sedimentary sequenceon the border of counties Wicklow and Wexford in southeast Ireland. U-Pb dating of zircons fromthe granite indicate a mid-Caradoc emplacement age of 454 ± 1 Ma. The Duncannon Group hostrocks form the southwestern end of the Avoca Volcanic Belt, a Mid-Ordovician (Caradoc) sequenceof acid and intermediate lavas and volcaniclastics. Dolerite dykes intrude the granite; elsewhere in theregion dolerites are generally associated with volcanic rocks. The main, Dl deformation within theDuncannon Group rocks is manifest as a steep Dl cleavage generally regarded as a product of LateCaledonian regional deformation in southeast Ireland. The Croghan Kinshelagh granite showsstrong geochemical coherence with subalkaline varieties of the Caradoc volcanic rocks; relativelyhigh Th, Y, Nb and REE contents set it apart from any other known granite type in southeastIreland. Together with the geochemical evidence, the age determination of 454 Ma indicates that theCroghan Kinshelagh granite was generated and emplaced during Ordovician volcanism in southeastIreland. Volcanism was closely followed by penetrative deformation and emplacement of the granite.The intra-Ordovician deformation may have been a consequence of closure of the Iapetus Ocean ormore localized events such as accretion on the hanging wall of the subduction zone. The age of theCroghan Kinshelagh granite provides an important datum for Ordovician volcanism and subductionin southeast Ireland.

Deformation of Early Cretaceous volcanic-arc assemblages, southern Coast Belt, British Columbia

1992 ◽  
Vol 29 (12) ◽  
pp. 2706-2721 ◽  
Author(s):  
Gregory Lynch
Keyword(s):  
British Columbia ◽  
Early Cretaceous ◽  
Late Cretaceous ◽  
Large Amplitude ◽  
Late Jurassic ◽  
Volcanic Rocks ◽  
Strike Slip ◽  
Southern Coast ◽  
Pyroclastic Deposits ◽  
Volcanic Arc

Early Cretaceous clastic volcanic-arc rocks of the Gambier Group in the southern Coast Belt were deposited in estuarine and marine environments on a deeply incised unconformity exposing Jurassic plutonic and arc assemblages. The Cretaceous arc was deformed in response to Late Cretaceous oblique subduction, producing orogen-parallel and orogen-normal shortening. Supracrustal Early Cretaceous rocks are preserved, in part, within the footwalls of overthrust sheets.Basal conglomerate and transgressive clastic successions underlie the volcanic edifices, with clasts reflecting volcanic – plutonic provenance. Volcanic rocks are calc-alkalic and span the complete basalt–andesite–dacite–rhyolite association typical of composite volcanoes. Extensive coarse pyroclastic deposits record an explosive volcanic environment.The Gambier Group occurs within the foreland of the major structural and metamorphic culmination of the southeastern Coast Belt. Early thin-skinned thrusting occurred to the east, repeating the Cretaceous stratigraphy. Overturned detached folds are associated with southerly directed thrusting developed during orogen-parallel shortening, likely in relation to large strike-slip fault systems. Later southwest-directed thrusting and associated large-amplitude folding occurred during Late Cretaceous arc-normal shortening, folding the earlier thrusts. To the southwest, tectonic wedging developed, with much of the Gambier Group preserved in the footwall of opposite southwest- and northeast-facing thrust systems; here southwest-directed thrusts emplaced Late Jurassic plutonic rocks, an unconformity, and lower Gambier strata over younger members, whereas concomitant or younger northeast-directed back thrusts emplaced the mid-Cretaceous plutonic roots of the arc above its volcanic derivative.

Early Cretaceous crust–mantle interaction linked to rollback of the Palaeo-Pacific flat-subducting slab: constraints from the intermediate–felsic volcanic rocks of the northern Great Xing’an Range, NE China

2021 ◽  
pp. 1-22
Author(s):  
Jia-Hao Jing ◽  
Hao Yang ◽  
Wen-Chun Ge ◽  
Yu Dong ◽  
Zheng Ji ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Volcanic Rocks ◽  
Geochemical Data ◽  
Calc Alkaline ◽  
Ne China ◽  
Asthenospheric Mantle ◽  
High K ◽  
Wide Range ◽  
Great Xing’An Range ◽  
Subducting Slab

Abstract Late Mesozoic igneous rocks are important for deciphering the Mesozoic tectonic setting of NE China. In this paper, we present whole-rock geochemical data, zircon U–Pb ages and Lu–Hf isotope data for Early Cretaceous volcanic rocks from the Tulihe area of the northern Great Xing’an Range (GXR), with the aim of evaluating the petrogenesis and genetic relationships of these rocks, inferring crust–mantle interactions and better constraining extension-related geodynamic processes in the GXR. Zircon U–Pb ages indicate that the rhyolites and trachytic volcanic rocks formed during late Early Cretaceous time (c. 130–126 Ma). Geochemically, the highly fractionated I-type rhyolites exhibit high-K calc-alkaline, metaluminous to weakly peraluminous characteristics. They are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs) but depleted in high-field-strength elements (HFSEs), with their magmatic zircons ϵHf(t) values ranging from +4.1 to +9.0. These features suggest that the rhyolites were derived from the partial melting of a dominantly juvenile, K-rich basaltic lower crust. The trachytic volcanic rocks are high-K calc-alkaline series and exhibit metaluminous characteristics. They have a wide range of zircon ϵHf(t) values (−17.8 to +12.9), indicating that these trachytic volcanic rocks originated from a dominantly lithospheric-mantle source with the involvement of asthenospheric mantle materials, and subsequently underwent extensive assimilation and fractional crystallization processes. Combining our results and the spatiotemporal migration of the late Early Cretaceous magmatic events, we propose that intense Early Cretaceous crust–mantle interaction took place within the northern GXR, and possibly the whole of NE China, and that it was related to the upwelling of asthenospheric mantle induced by rollback of the Palaeo-Pacific flat-subducting slab.

Petrogenesis and tectonic implications of Early Cretaceous volcanic rocks from the Shanghulin Basin within the north‐western Great Xing'an Range, NE China: Constraints from geochronology and geochemistry

2019 ◽  
Vol 55 (5) ◽  
pp. 3476-3496 ◽  
Author(s):  
An‐Qi Mao ◽  
De‐You Sun ◽  
Dong‐Guang Yang ◽  
Zong‐Yuan Tang ◽  
Han Zheng
Keyword(s):  
Early Cretaceous ◽  
Volcanic Rocks ◽  
Ne China ◽  
The North ◽  
Tectonic Implications ◽  
Great Xing’An Range ◽  
North Western

Early Cretaceous volcanic rocks and Early Cenozoic extrusions of Cape Mary, Schmidt Peninsula, north Sakhalin: Geochemical study

2007 ◽  
Vol 1 (3) ◽  
pp. 265-275 ◽  
Author(s):  
V. P. Simanenko ◽  
S. V. Rasskazov ◽  
T. A. Yasnygina ◽  
A. I. Malinovskii ◽  
A. A. Chashchin
Keyword(s):  
Early Cretaceous ◽  
Volcanic Rocks ◽  
Geochemical Study ◽  
Early Cenozoic

Petrology and geochemistry of Cambrian volcanic rocks from the Avalon Zone in New Brunswick

1985 ◽  
Vol 22 (6) ◽  
pp. 881-892 ◽  
Author(s):  
John D. Greenough ◽  
S. R. McCutcheon ◽  
V. S. Papezik
Keyword(s):  
New Brunswick ◽  
Volcanic Rocks ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
Middle Cambrian ◽  
Mafic Rocks ◽  
Rock Types ◽  
Petrology And Geochemistry ◽  
Eastern Seaboard ◽  
Highly Evolved

Lower to Middle Cambrian volcanic rocks occur within the Avalon Zone of southern New Brunswick at Beaver Harbour and in the Long Reach area. The Beaver Harbour rocks are intensely altered, but the major- and trace-element geochemistry indicates that they could be highly evolved (basaltic andesites) within-plate basalts. The mafic flows from the Long Reach area form two chemically and petrologically distinct groups: (1) basalts with feldspar phenocrysts that represent evolved continental tholeiites with some oceanic characteristics; and (2) a group of aphyric basalts showing extremely primitive continental tholeiite compositions, also with oceanic affinities and resembling some rift-related Jurassic basalts on the eastern seaboard. Felsic pyroclastic rocks in the Long Reach area make the suite bimodal. This distribution of rock types supports conclusions from the mafic rocks that the area experienced tension throughout the Early to Middle Cambrian.

Crust–Mantle Interaction Recorded by Early Cretaceous Volcanic Rocks within the Southern Margin of the North China Craton

2021 ◽  
Author(s):  
An-Qi Wang ◽  
Debin Yang ◽  
Wen-Liang Xu ◽  
Hao-Tian Yang ◽  
Mao-Song Mu ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
North China Craton ◽  
North China ◽  
Volcanic Rocks ◽  
The North ◽  
Southern Margin

scholarly journals New constraints on the age, geochemistry, and environmental impact of High Arctic Large Igneous Province magmatism: Tracing the extension of the Alpha Ridge onto Ellesmere Island, Canada

2020 ◽  
Author(s):  
T.V. Naber ◽  
S.E. Grasby ◽  
J.P. Cuthbertson ◽  
N. Rayner ◽  
C. Tegner
Keyword(s):  
Volcanic Rocks ◽  
High Arctic ◽  
Ellesmere Island ◽  
Large Igneous Province ◽  
The Arctic ◽  
Trace Element Geochemistry ◽  
Volcanic Complex ◽  
Northern Coast ◽  
Element Geochemistry ◽  
Igneous Province

The High Arctic Large Igneous Province (HALIP) represents extensive Cretaceous magmatism throughout the circum-Arctic borderlands and within the Arctic Ocean (e.g., the Alpha-Mendeleev Ridge). Recent aeromagnetic data shows anomalies that extend from the Alpha Ridge onto the northern coast of Ellesmere Island, Nunavut, Canada. To test this linkage we present new bulk rock major and trace element geochemistry, and mineral compositions for clinopyroxene, plagioclase, and olivine of basaltic dykes and sheets and rhyolitic lavas for the stratotype section at Hansen Point, which coincides geographically with the magnetic anomaly at northern Ellesmere Island. New U-Pb chronology is also presented. The basaltic and basaltic-andesite dykes and sheets at Hansen Point are all evolved with 5.5−2.5 wt% MgO, 48.3−57.0 wt% SiO2, and have light rare-earth element enriched patterns. They classify as tholeiites and in Th/Yb vs. Nb/Yb space they define a trend extending from the mantle array toward upper continental crust. This trend, also including a rhyolite lava, can be modeled successfully by assimilation and fractional crystallization. The U-Pb data for a dacite sample, that is cut by basaltic dykes at Hansen Point, yields a crystallization age of 95.5 ± 1.0 Ma, and also shows crustal inheritance. The chronology and the geochemistry of the Hansen Point samples are correlative with the basaltic lavas, sills, and dykes of the Strand Fiord Formation on Axel Heiberg Island, Nunavut, Canada. In contrast, a new U-Pb age for an alkaline syenite at Audhild Bay is significantly younger at 79.5 ± 0.5 Ma, and correlative to alkaline basalts and rhyolites from other locations of northern Ellesmere Island (Audhild Bay, Philips Inlet, and Yelverton Bay West; 83−73 Ma). We propose these volcanic occurrences be referred to collectively as the Audhild Bay alkaline suite (ABAS). In this revised nomenclature, the rocks of Hansen Point stratotype and other tholeiitic rocks are ascribed to the Hansen Point tholeiitic suite (HPTS) that was emplaced at 97−93 Ma. We suggest this subdivision into suites replace the collective term Hansen Point volcanic complex. The few dredge samples of alkali basalt available from the top of the Alpha Ridge are akin to ABAS in terms of geochemistry. Our revised dates also suggest that the HPTS and Strand Fiord Formation volcanic rocks may be the hypothesized subaerial large igneous province eruption that drove the Cretaceous Ocean Anoxic Event 2.

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