Magmatic origins of calc-alkaline intrusions from the Coast Plutonic Complex, southwestern British Columbia

1995 ◽  
Vol 32 (10) ◽  
pp. 1643-1667 ◽  
Author(s):  
Yao Cui ◽  
J. K. Russell
Keyword(s):  
Linear Trend ◽  
Source Region ◽  
Structural Break ◽  
Volcanic Rocks ◽  
Element Ratio ◽  
Calc Alkaline ◽  
Plutonic Complex ◽  
Coast Plutonic Complex ◽  
Compositional Variations ◽  
Intrusive Suite

Major element, trace element, and rare earth element data are presented for Permian to Tertiary calc-alkaline plutonic and volcanic rocks along a transect across the southern Coast Plutonic Complex from Vancouver to Anderson Lake. Late Jurassic to Late Cretaceous plutons are divided into two compositional suites based on mineralogy: (1) the hornblende intrusive suite (tonalite, quartz diorite, diorite, and gabbro) characterized by abundant modal hornblende and little or no K-feldspar, and (2) the K-feldspar intrusive suite (mainly granite and granodiorite) containing significant modal K-feldspar and less hornblende. Compositions of hornblende intrusive suite rocks are effectively portrayed on Pearce element-ratio diagrams utilizing axes X1 = [0.8571 Si−0.1429(Fe + Mg) + 1.2857 Ca + 1.8574 K]/Zr and Y1 = 1.1428 Ti + Al + Fe + Mg + Ca + 1.5714 Na + 0.4762 P]/Zr, because the diagram accounts for the stoichiometry of PI ± Hbl ± Bt ± Ep ± Ttn + Ap. Rocks from the K-feldspar intrusive suite are studied on diagrams using the element-ratio pair X2 = [2 Ti + Al + 3.3333 P]/Zr and Y2 = [2 Ca + Na + K]/Zr, which creates a linear trend of compositional variations controlled by the phases PI ± Kfs ± Bt ± Ttn + Ap. Mean intercepts of model trends on the element-ratio diagrams suggest differences among plutons that relate to source-region processes. For example, samples belonging to the hornblende intrusive suite represent a minimum of six batches of magma. Mean intercept values for plutons west of the Owl Lake–Harrison fault zone are significantly higher than those situated east of this structural break. These systematic differences allude to fundamental differences in the nature of Mesozoic magmatism in Wrangellia (and Harrison) terrane compared with that in Cadwallader, Bridge River, and Methow terranes, and probably in the Intermontane superterrane east of the structural break.

Upper Paleozoic to lower Mesozoic strata and their conodonts, western Coast Plutonic Complex, British Columbia

1985 ◽  
Vol 22 (9) ◽  
pp. 1329-1344 ◽  
Author(s):  
G. J. Woodsworth ◽  
M. J. Orchard
Keyword(s):  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Late Triassic ◽  
Western Coast ◽  
Upper Paleozoic ◽  
Facies Metamorphism ◽  
Volcanic Suite ◽  
Plutonic Complex ◽  
Coast Plutonic Complex ◽  
Greenschist Facies Metamorphism

Six lithologic units, including two newly named formations, were mapped on Randall, Dunira, and nearby islands. The islands are characterized by greenschist-facies metamorphism and westerly directed thrusting. The oldest unit is a Late Mississippian, massive limestone on Ducie Island. The Dunira Formation, composed of thin-bedded limestone and siltstone, is Early and Middle Pennsylvanian in age. It is unconformably overlain by limestone and dolomite of the Upper Triassic Randall Formation. The Randall Formation grades upwards into a green phyllitic unit of Late Triassic(?) age. Rhyolitic and more mafic volcanic rocks may represent a bimodal volcanic suite of Early Jurassic age, based on a U–Pb date of 188 Ma on zircons. These five units correlate with rocks in the Alexander Terrane in southeastern Alaska. The sixth and presumed youngest unit consists of flysch-like sedimentary rocks of probable Middle Jurassic to Early Cretaceous age that may correlate with rocks of the Gravina–Nutzotin belt. The three older units yielded 15 conodont genera from 29 localities. The 13 Paleozoic genera are described and illustrated.

scholarly journals Origin of the High-K Tertiary magmatism in Northern Greece: Implications for mantle geochemistry and geotectonic setting.

2013 ◽  
Vol 47 (1) ◽  
pp. 416
Author(s):  
K. Pipera ◽  
A. Koroneos ◽  
T. Soldatos ◽  
G. Poli ◽  
G. Christofides
Keyword(s):  
Mantle Source ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Calc Alkaline ◽  
Northern Greece ◽  
Mafic Rocks ◽  
High K ◽  
Depleted Mantle ◽  
Subducted Oceanic Crust ◽  
Compositional Variations

Tertiary plutonic and volcanic rocks cropping out in the Rhodope Massif (N. Greece) are studied using existing and new geochemical and isotopic data. Most of these rocks belong to the post-collisional magmatism formed as part of the prolonged extensional tectonics of the Rhodope region in Late Cretaceous– Paleogene time. This magmatism is considered to be of mantle origin; however, the character of the mantle source is controversial. Rock bulk chemistry and compositional variations show magmas with calc-alkaline to high-K calc-alkaline and shoshonitic features associated with magmatism at convergent margins. Initial 87Sr/86Sr, 143Nd/144Nd ratios, Pb isotopes and REE composition of the mafic rocks indicate mainly an enriched mantle source, even if some rocks indicate a depleted mantle source. Low- and High-K mafic members of these rocks coexist indicating a strongly heterogeneous mantle source. The High-K character of some of the mafic rocks is primarily strongly related to mantle enrichment by subduction-related components, rather than crustal contamination. The geochemical characteristics of the studied rocks (e.g Ba/Th,Th/Yb,Ba/La, U/Th, Ce/Pb) indicate that primarily sediments and/or sediment melts, rather than fluid released by the subducted oceanic crust controlled the source enrichment under the Rhodope Massif.

Alteration of volcanic rocks and genesis of kaolin deposits in the Şile Region, northern İstanbul, Turkey. Part II: differential mobility of elements

Clay Minerals ◽  
2003 ◽  
Vol 38 (4) ◽  
pp. 529-550 ◽  
Author(s):  
O. I. Ece ◽  
Z.-E Nakagawa
Keyword(s):  
Upper Cretaceous ◽  
Source Region ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Aegean Sea ◽  
Calc Alkaline ◽  
Tectonic Zone ◽  
Nw Turkey ◽  
Parent Rocks ◽  
Kaolin Deposit

AbstractIn the area of S° ile, NW Turkey, Upper Cretaceous calc-alkaline volcanic rocks with compositions ranging from andesite to rhyolite have been recognized. The most widespread rocks of the suite are andesites, which can be grouped into altered and fresh. The oldest altered andesites are the parent rocks for the kaolin deposits of the study area. The Upper Cretaceous volcanic suite consists of spilite, basalt, andesite, trachyandesite, trachyandesitic and hyaloandesitic dacite, rhyolite lavas, tuffs and agglomerates. The highly altered andesites are composed of plagioclase, pyroxene, hornblende, biotite, augite and very fine opaque minerals. During the Turonian, an E –W trending extensional magmatic arc was developed in the Istanbul Tectonic Zone of the oceanic Western Black Sea basin and intermediate volcanic rocks were emplaced, mostly calc-alkaline andesites, suggesting multi-stage magmatism. The significant features of the andesites are: (1) enrichment of LILE (Rb, Ba, K) over HFSE (Zr, Nb, Hf, Ti, Th, U, Y) and LREE (La –Sm), resulting in high Ba/Nb, Th/Nb, Ba/La, K/Ti and Th/La ratios; (2) depletion of LREE over HFSE, MREE and HREE, generating high La/Nb, Ce/Ti, La/Sm and La/Y values; and (3) depletion of Nb, Sr and Ti; all of which are typical of island arc magmatism, with possible back arc signature. The Th-Hf-Ta diagram for tectonomagmatic classification shows that the S° ile calc-alkaline rocks are similar to volcanic rocks from the Mariana Arc, the Aeolian Arc of Salina, Italy, the Skaros island in the Aegean Sea and Sardinia's ignimbrites. Moreover, relatively low La/Th and Ce/Pb ratios suggest that the source region of volcanism was enriched in LILE with respect to REE, indicating crustal contamination during melting.Highly weathered andesitic rocks, rich in smectite, were transported gradually and deposited in a lacustrine basin, a coal-forming dysaerobic environment, in which they were subject to post-depositional alteration, or in situkaolinization, to form a kaolin deposit in the presence of humic and fulvic acids. The mobility of major and trace elements and REEs during the progressive kaolinization of andesitic materials has been investigated to reveal the geochemical characteristics of Upper Cretaceous volcanic parent rocks and to explain mineralogical processes in a kaolin deposit as a daughter rock ‘end-product’ . Alteration is characterized by the loss of Si, Fe, Ca, Na and K, and by the gain of Al, Ti, Zr and LOI. Moreover, Ho, Er and Yb are immobile, and Hf, Zr and Nb are mobile. Th and U are slightly enriched in clay horizons with respect to the andesitic rocks. In addition, Cr, Ga, Nb and Ta enrichments indicate variable sources of terrigenous sediments and differential mobilities of elements in lake waters rich in organic acids. The anatase concentration increases in the <2 mm size fractions as subspherical particles and these precipitate at acidic conditions (pH ≈ 5) during early diagenesis.

Subduction-related magmatism of late Ordovician age in eastern England

1993 ◽  
Vol 130 (5) ◽  
pp. 647-656 ◽  
Author(s):  
T. C. Pharaoh ◽  
T. S. Brewer ◽  
P. C. Webb
Keyword(s):  
Volcanic Rocks ◽  
Oceanic Lithosphere ◽  
Late Ordovician ◽  
Igneous Rocks ◽  
Calc Alkaline ◽  
Geochemical Composition ◽  
Magmatic Arc ◽  
Hypabyssal Intrusions ◽  
Deep Boreholes ◽  
Intrusive Suite

AbstractDeep boreholes show that plutonic and volcanic igneous rocks comprise an important component of the Caledonian basement in eastern England. The isotopic compositions of these rocks reveal that many of them are of late Ordovician age (440–460 Ma), and their geochemical compositions suggest calc–alkaline affinities. The intermediate (diorite-tonalite) plutonic rocks are associated with a prominent northwest–southeast trending belt of aeromagnetic anomalies extending from Derby to St Ives, Hunts., which is interpreted to work the plutonic core of a calc-alkaline magmatic arc. It is inferred that this arc was generated by the subduction of oceanic lithosphere, possibly from the Tornquist Sea, in a south or southwest direction beneath the Midlands Microcraton in late Ordovician times. The age and geochemical composition of concealed Ordovician volcanic rocks in eastern England, and hypabyssal intrusions of the Midlands Minor Intrusive Suite in central England, is compatible with such a hypothesis.

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 of the peralkaline Flowers River Igneous Suite and its significance to the development of the southern Nain Batholith

2021 ◽  
pp. 1-26
Author(s):  
Taylor A. Ducharme ◽  
Christopher R.M. McFarlane ◽  
Deanne van Rooyen ◽  
David Corrigan
Keyword(s):  
Trace Element ◽  
Volcanic Rocks ◽  
Second Phase ◽  
Discrete Events ◽  
Volcanic Event ◽  
Volcanic Succession ◽  
Intrusive Suite ◽  
Tectonic Boundaries ◽  
Host Rocks ◽  
Nain Plutonic Suite

Abstract The Flowers River Igneous Suite of north-central Labrador comprises several discrete peralkaline granite ring intrusions and their coeval volcanic succession. The Flowers River Granite was emplaced into Mesoproterozoic-age anorthosite–mangerite–charnockite–granite (AMCG) -affinity rocks at the southernmost extent of the Nain Plutonic Suite coastal lineament batholith. New U–Pb zircon geochronology is presented to clarify the timing and relationships among the igneous associations exposed in the region. Fayalite-bearing AMCG granitoids in the region record ages of 1290 ± 3 Ma, whereas the Flowers River Granite yields an age of 1281 ± 3 Ma. Volcanism occurred in three discrete events, two of which coincided with emplacement of the AMCG and Flowers River suites, respectively. Shared geochemical affinities suggest that each generation of volcanic rocks was derived from its coeval intrusive suite. The third volcanic event occurred at 1271 ± 3 Ma, and its products bear a broad geochemical resemblance to the second phase of volcanism. The surrounding AMCG-affinity ferrodiorites and fayalite-bearing granitoids display moderately enriched major- and trace-element signatures relative to equivalent lithologies found elsewhere in the Nain Plutonic Suite. Trace-element compositions also support a relationship between the Flowers River Granite and its AMCG-affinity host rocks, most likely via delayed partial melting of residual parental material in the lower crust. Enrichment manifested only in the southernmost part of the Nain Plutonic Suite as a result of its relative proximity to multiple Palaeoproterozoic tectonic boundaries. Repeated exposure to subduction-derived metasomatic fluids created a persistent region of enrichment in the underlying lithospheric mantle that was tapped during later melt generation, producing multiple successive moderately to strongly enriched magmatic episodes.

scholarly journals Crustal deformation and regional metamorphism across a terrane boundary, Coast Plutonic Complex, British Columbia

Tectonics ◽  
1987 ◽  
Vol 6 (3) ◽  
pp. 343-361 ◽  
Author(s):  
M. L. Crawford ◽  
L. S. Hollister ◽  
G. J. Woodsworth
Keyword(s):  
British Columbia ◽  
Crustal Deformation ◽  
Regional Metamorphism ◽  
Plutonic Complex ◽  
Coast Plutonic Complex

The gabbro–dyke transition zone demonstrated on Tviberg, Solund–Stavfjord Ophiolite Complex

1996 ◽  
Vol 133 (5) ◽  
pp. 573-582 ◽  
Author(s):  
K. P. Skjerlie ◽  
H. Furnes
Keyword(s):  
Transition Zone ◽  
Basaltic Magma ◽  
Source Region ◽  
Geochemical Evolution ◽  
Dyke Swarm ◽  
Gradual Transition ◽  
Ophiolite Complex ◽  
Plutonic Complex ◽  
Plutonic Rocks ◽  
High Level

AbstractThe transition zone between 100 % dykes and high-level plutonic rocks of the Solund-Stavfjord Ophiolite Complex is complex due to the existence of many lithologies with different and variable contact relationships. The rocks of the plutonic complex vary in composition from FeTi basaltic to quartz dioritic, and the grain sizes vary from fine to pegmatitic. Felsic varieties are produced by fractional crystallization of basaltic magma as demonstrated by geochemical evolution and by gradual transition from gabbro to quartz diorite. Patches of fractionated dioritic rocks may show both gradual and intrusive relationships with the surrounding host gabbro. This demonstrates that late-stage liquids commonly left the source region and locally intruded the surrounding parent rocks. The high-level plutonic rocks are thoroughly epidotized and are cut by dykes consisting of granoblastic epidote and quartz. The high-level plutonic complex is associated with irregular bodies of fine- to medium-grained plagioclase-porphyritic diabase of high MgO content. These diabase bodies are intruded by dykes that become progressively more regular in shape. The plutonic complex locally shows intrusive relationships with the overlying 100% dyke complex, but is itself cut by two dyke swarms. The dykes of the first swarm formed while the plutonic complex experienced sinistral shear strain, and the dykes are generally less regular and thinner than the dykes of the second swarm. This indicates that the dykes of the first swarm intruded while the rocks of the plutonic complex were still hot, while the next dyke swarm intruded later when the rock complex was colder. Dykes of both swarms range in composition from slightly to strongly fractionated, suggesting that the magma chambers they were expelled from underwent significant fractionation in between magma replenishment. Numerous dykes of both swarms carry large quantities of glomeroporphyritic aggregates of plagioclase and altered clinopyroxene, indicating that the source area to the dykes very often was a crystal mush.

Age, chemistry, and tectonic setting of Miramichi terrane (Early Paleozoic) volcanic rocks, eastern and east-central Maine, USA

2021 ◽  
Vol 57 ◽  
pp. 239-273
Author(s):  
Allan Ludman ◽  
Christopher McFarlane ◽  
Amber T.H. Whittaker
Keyword(s):  
New Brunswick ◽  
Subduction Zone ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Calc Alkaline ◽  
East Central ◽  
Arc Volcanism ◽  
Middle Ordovician ◽  
Volcanic Suite ◽  
Back Arc

Volcanic rocks in the Miramichi inlier in Maine occur in two areas separated by the Bottle Lake plutonic complex: the Danforth segment (Stetson Mountain Formation) north of the complex and Greenfield segment to the south (Olamon Stream Formation). Both suites are dominantly pyroclastic, with abundant andesite, dacite, and rhyolite tuffs and subordinate lavas, breccias, and agglomerates. Rare basaltic tuffs and a small area of basaltic tuffs, agglomerates, and lavas are restricted to the Greenfield segment. U–Pb zircon geochronology dates Greenfield segment volcanism at ca. 469 Ma, the Floian–Dapingian boundary between the Lower and Middle Ordovician. Chemical analyses reveal a calc-alkaline suite erupted in a continental volcanic arc, either the Meductic or earliest Balmoral phase of Popelogan arc activity. The Maine Miramichi volcanic rocks are most likely correlative with the Meductic Group volcanic suite in west-central New Brunswick. Orogen-parallel lithologic and chemical variations from New Brunswick to east-central Maine may result from eruptions at different volcanic centers. The bimodal Poplar Mountain volcanic suite at the Maine–New Brunswick border is 10–20 myr younger than the Miramichi volcanic rocks and more likely an early phase of back-arc basin rifting than a late-stage Meductic phase event. Coeval calc-alkaline arc volcanism in the Miramichi, Weeksboro–Lunksoos Lake, and Munsungun Cambrian–Ordovician inliers in Maine is not consistent with tectonic models involving northwestward migration of arc volcanism. This >150 km span cannot be explained by a single east-facing subduction zone, suggesting more than one subduction zone/arc complex in the region.

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