Rhyacian evolution of the eastern São Luís Craton: petrography, geochemistry and geochronology of the Rosário Suite

ABSTRACT: The São Luís Cráton comprises an area between northeast Pará state and northwest Maranhão that exposes Paleoproterozoic granitic suites and meta-volcanosedimentary sequences. In the east of this geotectonic unit, about 70 km south of São Luís, there is a portion of the São Luís Craton, represented by the intrusive Rosario Suite (RS). This work is focused on rocks of this suite, including petrographic, lithochemical and geochronological studies to understand the crustal evolution of these granitoid rocks. The rock spectrum varies from tonalitic to granodioritic, quartz dioritic and granitic compositions, and there are partial structural and mineralogical changes related to deformation along transcurrent shear zones. The geochemical studies show granitic metaluminous compositions of the calc-alkaline series with I-type affinity typical of magmatic arc. Rare earth elements show marked fractionation and slight Eu positive or negative anomalies (Eu/Eu* = 0.82 to 1.1). Zircon U-Pb data provided consistent ages of 2165 ± 7 Ma, 2170 ± 7 Ma, 2170 ± 7 Ma, 2161 ± 4 Ma and 2175 ± 8 Ma, dating emplacement of these granitoids as Paleoproterozoic (Rhyacian). Sm-Nd isotopic data provided model ages (TDM) of 2.21 to 2.31 Ga with positive values of εNd +1.9 to +3.2 (t = 2.17 Ga), indicating predominantly Rhyacian crustal sources for the parental magmas, similar to those ones found in other areas of the São Luís Craton. The data, integrated with published geological and geochronological information, indicate the occurrence of an important continental crust formation event in this area. The Paleoproterozoic evolution between 2.17 and 2.15 Ga is related to the Transamazonian orogeny. The granitoids of the Rosario Suite represent the main phase of continental arc magmatism that has continuity in other parts of the São Luís Craton and can be correlated with Rhyacian accretionary magmatism in the northwestern portion of the Amazonian Craton that amalgamated Archean terrains during the Transamazonian orogeny.

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Lower Palaeozoic and Precambrian igneous rocks from eastern England, and their bearing on late Ordovician closure of the Tornquist Sea: constraints from U-Pb and Nd isotopes

Geological Magazine ◽

10.1017/s0016756800023190 ◽

1993 ◽

Vol 130 (6) ◽

pp. 835-846 ◽

Cited By ~ 80

Author(s):

S. R. Noble ◽

R. D. Tucker ◽

T. C. Pharaoh

Keyword(s):

Volcanic Rocks ◽

Igneous Rocks ◽

Calc Alkaline ◽

Nd Isotopes ◽

Nd Isotope ◽

Magmatic Arc ◽

The North ◽

Basement Rocks ◽

Continental Arc ◽

Lower Palaeozoic

AbstractThe U-Pb isotope ages and Nd isotope characteristics of asuite of igneous rocks from the basement of eastern England show that Ordovician calc-alkaline igneous rocks are tectonically interleaved with late Precambrian volcanic rocks distinct from Precambrian rocks exposed in southern Britain. New U-Pb ages for the North Creake tuff (zircon, 449±13 Ma), Moorby Microgranite (zircon, 457 ± 20 Ma), and the Nuneaton lamprophyre (zircon and baddeleyite, 442 ± 3 Ma) confirm the presence ofan Ordovician magmatic arc. Tectonically interleaved Precambrian volcanic rocks within this arc are verified by new U-Pb zircon ages for tuffs at Glinton (612 ± 21 Ma) and Orton (616 ± 6 Ma). Initial εNd values for these basement rocks range from +4 to - 6, consistent with generation of both c. 615 Ma and c. 450 Ma groups of rocksin continental arc settings. The U-Pb and Sm-Nd isotope data support arguments for an Ordovician fold/thrust belt extending from England to Belgium, and that the Ordovician calc-alkaline rocks formed in response to subductionof Tornquist Sea oceanic crust beneath Avalonia.

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The 1590-1520 Ma Cachoeirinha magmatic arc and its tectonic implications for the Mesoproterozoic SW Amazonian craton crustal evolution

Anais da Academia Brasileira de Ciências ◽

10.1590/s0001-37652004000400013 ◽

2004 ◽

Vol 76 (4) ◽

pp. 807-824 ◽

Cited By ~ 16

Author(s):

Amarildo S. Ruiz ◽

Mauro C. Geraldes ◽

João B. Matos ◽

Wilson Teixeira ◽

William R. Van Schumus ◽

...

Keyword(s):

Crystallization Process ◽

Major And Trace Elements ◽

Magmatic Arc ◽

Rio Negro ◽

Intrusive Rocks ◽

Amazonian Craton ◽

Granitoid Rocks ◽

Geologic Setting ◽

Fractional Crystallization Process ◽

Tectonic Relationship

Isotopic and chemical data of rocks from the Cachoeirinha suite provide new insights on the Proterozoic evolution of the Rio Negro/Juruena Province in SW Amazonian craton. Six U-Pb and Sm-Nd analyses in granitoid rocks of the Cachoeirinha suite yielded ages of 1587-1522 Ma and T DM model ages of 1.88-1.75 Ga (EpsilonNd values of -0.8 to +1.0). In addition, three post-tectonic plutonic rocks yielded U-Pb ages from 1485-1389 Ma (T DM of 1.77-1.74 Ga and EpsilonNd values from -1.3 to +1.7). Variations in major and trace elements of the Cachoeirinha suite rocks indicate fractional crystallization process and magmatic arc geologic setting. These results suggest the following interpretations: (1) The interval of 1590-1520 Ma represents an important magmatic activity in SW Amazonian craton. (2) T DM and arc-related chemical affinity supportthe hypothesis that the rocks are genetically associated with an east-dipping subduction zone under the older (1.79-1.74 Ga) continental margin. (3) The 1590-1520 Ma age of intrusive rocks adjacent to an older crust represents similar geological framework along the southern margin of Baltica, corroborating the hypothesis of tectonic relationship at that time.

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Geology and tectonic setting of Paleoproterozoic granitoid suites in the Island Harbour Bay area, Makkovik Province, Labrador

Canadian Journal of Earth Sciences ◽

10.1139/e00-086 ◽

2001 ◽

Vol 38 (3) ◽

pp. 441-463 ◽

Cited By ~ 13

Author(s):

S M Barr ◽

C E White ◽

N G Culshaw ◽

J WF Ketchum

Keyword(s):

Earth Element ◽

Tectonic Setting ◽

Mafic Magma ◽

Shear Zones ◽

Magmatic Activity ◽

Magmatic Arc ◽

Bay Area ◽

Granitoid Rocks ◽

Andean Type ◽

Variable Interaction

Paleoproterozoic granitoid rocks in the Island Harbour Bay area (Kaipokok domain, Makkovik Province, Labrador) are divided into four separate suites on the basis of field relations, petrology, and age. The redefined Island Harbour Bay plutonic suite consists of ca. 18951870 Ma dioritic to granitic (mainly granodioritic and granitic) units. The rocks are variably foliated as a result of emplacement under amphibolite-facies conditions in a dextral transpressive regime during Andean-type subduction. The dominant mafic mineral is biotite, and accessory epidote, allanite, and titanite are abundant. The suite is calc-alkalic, but with rare-earth element patterns similar to those of Archean tonalitictrondhjemiticgranodioritic suites. It is interpreted to have formed deep in an Andean-type magmatic arc at the margin of the Nain continent. In contrast, the younger Hares Islands and Drunken Harbour granites (emplaced at ca. 1805 and 1790 Ma, respectively) were part of widespread late-orogenic magmatic activity in the Makkovik Province. In contrast to the Island Harbour Bay plutonic suite, these units retain igneous textures and are either unfoliated or display magmatic foliation, locally modified by emplacement in active shear zones. The ca. 1716 Ma Blacklers Bight granite varies from porphyritic to equigranular, is fluorite-bearing, and has chemical features approaching those of continental A-type granites. Similar granite occurs farther south in the Makkovik Province, reflecting widespread anorogenic magmatic activity at that time, perhaps related to mafic magma underplating. Variable interaction with Archean (Nain Province) crust by granitic magmas of all three ages is evidenced by εNd values ranging from 7.2 to 2.5.

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Labradorian and Grenvillian crustal evolution of the Goose Bay region, Labrador: new U–Pb geochronological constraints

Canadian Journal of Earth Sciences ◽

10.1139/e93-201 ◽

1993 ◽

Vol 30 (12) ◽

pp. 2315-2327 ◽

Cited By ~ 14

Author(s):

S. Philippe ◽

R. J. Wardle ◽

U. Schärer

Keyword(s):

Crustal Evolution ◽

Calc Alkaline ◽

Crust Formation ◽

Pb Isotope ◽

Grenville Province ◽

Previous Evidence ◽

Anorthosite Massif ◽

Thrust System ◽

Grenvillian Orogeny ◽

Geochronological Constraints

Major initial crust formation in the northeastern Grenville Province of Labrador occurred during the Labradorian orogeny (1710–1620 Ma) prior to re-deformation in the Grenvillian orogeny between 1050 and 950 Ma. The Goose Bay region includes several types of juvenile Labradorian crust, including calc-alkaline (arc-related?) terranes and the granite–anorthosite massif of the Mealy Mountains Terrane. New U–Pb dates corroborate previous evidence that calc-alkaline plutonism occurred ca. 1672 Ma and was followed closely by Labradorian metamorphism ca. 1659 Ma. Dates from strongly deformed rocks at the base of the Mealy Mountains Terrane have yielded ca. 1712, 1754, and 1775 Ma maximum upper intercept ages of plutonic and (or) metamorphic origin. These apparent ages represent the oldest component of the Labradorian crust that has been recognized to date and appear to be a distinctive feature of Mealy Mountains Terrane. The initial Pb isotope signature of these rocks, however, precludes the presence of significantly earlier (pre-1.8 Ga) crust.New U–Pb ages also support previous models for episodic Grenvillian metamorphism and indicate metamorphic pulses ca. 1035, 1010, 990, and 970 Ma, which probably represent the metamorphic response to progressive overthrusting by Mealy Mountains Terrane. Overthrusting of this terrane occurred along the Grand Lake thrust system, which is highlighted as a fundamental structure of the eastern Grenville Province and one that may have developed by reactivation of a Labradorian terrane boundary.

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Late Ordovician to Silurian ensialic magmatism in Liverpool Land, East Greenland: new evidence extending the northeastern branch of the continental Laurentian magmatic arc

Geological Magazine ◽

10.1017/s0016756811000781 ◽

2011 ◽

Vol 149 (4) ◽

pp. 561-577 ◽

Cited By ~ 20

Author(s):

LARS EIVIND AUGLAND ◽

ARILD ANDRESEN ◽

FERNANDO CORFU ◽

HANS KRISTIAN DAVIKNES

Keyword(s):

Late Ordovician ◽

Geochemical Data ◽

Calc Alkaline ◽

East Greenland ◽

Magmatic Arc ◽

Granitoid Rocks ◽

Two Phases ◽

Laurentian Margin ◽

New Evidence ◽

Northern Branch

AbstractNew U–Pb ID-TIMS geochronological and whole-rock geochemical data from the Hurry Inlet Plutonic Terrane in Liverpool Land provide evidence of a Late Ordovician to Silurian magmatic arc in the East Greenland Caledonides. These voluminous granitoid rocks range from meladiorite to monzonite and granite, they are alkali-calcic to calc-alkaline and magnesian, and have characteristic arc granitoid trace element signatures. Zircon data give ages of 446 ± 2 and 438 ± 4 Ma for two phases of the Hurry Inlet Composite Pluton, 426 ± 1 Ma for a meladioritic xenolith in the anatectic Triaselv granite, and 424 ± 1 Ma for the Hodal-Storefjord Pluton. The Late Ordovician plutons can be correlated with similar plutons in the uppermost nappes of the Scandinavian Caledonides, likely representing the northern branch of magmatic arcs formed on the Laurentian margin. Magmatism appears to have continued sporadically until about 425 Ma when a major, short-lived, magmatic event formed the bulk of the batholith on Liverpool Land. This activity was likely mantle-driven and can be correlated with the Newer Granites in Scotland, for which a slab break-off mechanism has been proposed. The increased heat flow from this process can also explain the generation of the crustally derived, syntectonic, two-mica granites, which are the areally most important Caledonian suite in East Greenland.

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Timing and Metamorphic Evolution of the Ross Orogeny in and around the Mountaineer Range, Northern Victoria Land, Antarctica

Minerals ◽

10.3390/min10100908 ◽

2020 ◽

Vol 10 (10) ◽

pp. 908

Author(s):

Sang-Bong Yi ◽

Mi Lee ◽

Jong Lee ◽

Hwayoung Kim

Keyword(s):

Continuous Process ◽

Shear Zones ◽

Boundary Region ◽

Metamorphic Evolution ◽

Magmatic Arc ◽

The Pacific ◽

Victoria Land ◽

Continental Arc ◽

Before And After ◽

Gondwana Margin

The Ross(–Delamerian) Orogeny significantly impacted the formation of the tectonic structure of the Pacific Gondwana margin during the early Paleozoic era. Northern Victoria Land (NVL) in Antarctica preserves the aspect of the Ross Orogeny that led to the union of the Wilson (WT)–Bowers (BT)–Robertson Bay Terrane. The aspect of the Ross Orogeny in the NVL is characterized by subduction of oceanic domains toward the continental margin (continental arc) and the accretion of the associated marine–continental substances from 530–480 Ma. In the Mountaineer Range in NVL, the Ross Orogeny strain zone is identified at the WT/BT boundary regions. In these areas, fold and thrust shear zones are observed and aspects of them can be seen at Mt. Murchison, the Descent Unit and the Black Spider Greenschist zone. The Dessent Unit corresponds to a tectonic slice sheared between the WT and BT. The metamorphic evolution phase of the Dessent Unit is summarized in the peak pressure (M1), peak temperature (M2) and retrograde (M3). The sensitive high-resolution ion microprobe (SHRIMP) zircon U–Pb ages of 514.6 ± 2.0 Ma and 499.2 ± 3.4 Ma obtained from the Dessent Unit amphibolite are comparable to the M1 and M2 stages, respectively. The Dessent Unit underwent intermediate pressure (P)/temperature (T)-type metamorphism characterized by 10.0–10.5 kbar/~600 °C (M1) and ~7 kbar/~700 °C (M2) followed by 4.0–4.5 kbar/~450 °C (M3). Mafic to intermediate magmatism (497–501 Ma) within the WT/BT boundary region may have given rise to the M2 stage of the Dessent Unit, and this magmatism is synchronous with the migmatization period of Mt. Murchison (498.3 ± 3.4 Ma). This indicates that a continuous process of fold-shearing–magmatic intrusion–partial melting, which is typically associated with a continental arc orogeny, occurred before and after c. 500 Ma in the Mountaineer Range. During the Ross Orogeny, the Dessent unit was initially subducted underneath the WT at depth (10.0–10.5 kbar, ~35 km) and then thrust into the shallow (~7 kbar, ~23 km), hot (≥700 °C) magmatic arc docking with the Mt. Murchison terrain, where migmatization prevailed.

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Melt-enhanced deformation during emplacement of gabbro and granodiorite in the Sunnhordland Batholith, west Norway

Geological Magazine ◽

10.1017/s0016756800022068 ◽

1991 ◽

Vol 128 (3) ◽

pp. 207-226 ◽

Cited By ~ 8

Author(s):

Torgeir B. Andersen ◽

Peter Nielsen ◽

Erling Rykkelid ◽

Hanne Sølna

Keyword(s):

Internal Structure ◽

Shear Zones ◽

Island Arc ◽

Upper Crust ◽

Calc Alkaline ◽

Magmatic Arc ◽

Plate Convergence ◽

Relative Age ◽

Early Ordovician ◽

Partial Melts

AbstractThe Caledonian Sunnhordland Batholith comprises calc-alkaline plutons that have been assigned to three units according to their relative age and composition: a gabbro-diorite unit, a granodiorite unit and a later granodiorite-granite unit. The batholith was emplaced into an envelope including ophiolite and island-arc complexes, sediments and volcanites of early Ordovician age that were developed in a zone of plate convergence. Continued convergence resulted in the formation of a mature magmatic arc and a thickened crust; the late granitoids (unit 3), which commenced their crystallization at pressures around 6 to 7 kb, rose as permitted diapiric intrusions. The ingress and ascent of the magmas in this setting is considered to have been facilitated by the presence of major shear zones developed in relation to plate convergence. In this model, plastic instabilities were formed in an otherwise elastic middle and upper crust. Non-coaxial deformation was accelerated by the emplacement of magmas and the formation of abundant partial melts in water-rich sediments of the envelope. The deformation, which was accelerated by magma and melt lubrication in aureoles, controlled both the shape and internal structure in the gabbro and granodiorite plutons.

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Isotopic assessment of relative contributions from crust and mantle sources to the magma genesis of Precambrian granitoid rocks

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1984.0010 ◽

1984 ◽

Vol 310 (1514) ◽

pp. 605-625 ◽

Cited By ~ 67

Keyword(s):

Calc Alkaline ◽

Isotopic Data ◽

Late Archaean ◽

Magma Genesis ◽

West Greenland ◽

Sialic Crust ◽

Mantle Sources ◽

Granitoid Rocks ◽

Plutonic Rocks ◽

Source Materials

Rb-Sr, Sm-Nd and U-Th-Pb isotopic data for Precambrian granitoids (i.e. granites and intermediate calc-alkaline plutonic rocks) from Greenland, Scotland and Zimbabwe are used to assess the relative contributions to magma genesis of various source materials. Ancient continental crustal contributions are identified by negative e N d values in the magmas at time of formation. Initial 87 Sr/ 86 Sr (Sr 1 ,) values identify crustal contributions as derived from deep (low Rb/Sr) or upper (high Rb/Sr) crust. Pb isotopic data, expressed as model ( 238 U / 204 Pb) values, permit the distinction between deep (low U/Pb) and upper (high U/Pb) crustal contributions. However, it is not usually possible to distinguish between mantle (low Rb/Sr) and deep crustal sources using Sr 1 values. In contrast, Nd and Pb isotopic data permit such a distinction to be made. The granitoids isotopically analysed for the present study range from calc-alkaline types with mantle or mixed mantle-crust isotopic characteristics (for example, late Archaean orthogneisses from west Greenland) to true granites probably produced solely by anatexis of ancient sialic crust (for example, Badcall Quay red granite, northwest Scotland; Qorqut granite, west Greenland; Mont d’Or granite, Zimbabwe).

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Pb-Pb zircon dating of tuff horizons inthe Cyrtograptus Shale (Wenlock, Silurian) of Bornholm

Bulletin of the Geological Society of Denmark ◽

10.37570/bgsd-2003-49-01 ◽

2002 ◽

Vol 49 ◽

pp. 1-8

Author(s):

Karsten Obst ◽

Gerhard Katzung ◽

Jörg Maletz ◽

Antje Böhnke

Keyword(s):

Volcanic Activity ◽

Southern Coast ◽

Calc Alkaline ◽

Arc Volcanism ◽

Pyroclastic Rocks ◽

Magmatic Arc ◽

Lower Palaeozoic ◽

Caledonian Orogeny ◽

Geochemical Studies ◽

Tornquist Ocean

Waterlain fallout ashes are interbedded in the upper part of the Cyrtograptus Shale of Bornholm, theyoungest preserved member of the Lower Palaeozoic sequence at the southern coast of the island.Graptolite faunas indicate that these tuffaceous sediments belong to the Cyrtograptus lundgreni Zonedeposited during Late Wenlock. A 207Pb/206Pb mean age of 430 ± 1.9 Ma obtained by evaporation of idiomorphic single zircons from the tuff layers supports this observation. Geochemical studies of the pyroclastic rocks point to an explosive, calc-alkaline magmatic arc volcanism which probably occurred along or slightly south of the Tornquist-Teisseyre Lineament, and could have been induced by the collision of Avalonia with the southern margin of Baltica during the Silurian. This assumption is supported by the contemporaneous deposition of bentonites on the Swedish island of Gotland which might represent a distal facies of these fallouts. Further, the subduction-related volcanic activity is interpreted as a fingerprint for closing of the Tornquist Ocean during the Caledonian orogeny.

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