C- and Sr-isotope stratigraphy of the São Caetano complex, Northeastern Brazil: a contribution to the study of the Meso-Neoproterozoic seawater geochemistry

C-isotope and 87Sr/86Sr values for five carbonate successions from the São Caetano Complex, northeastern Brazil, were used to constrain their depositional age and to determine large variations in the C- and Sr-isotopic composition of seawater under the framework of global tectonic events. Three C-isotope stages were identified from base to top in a composed chemostratigraphic section: (1) stage in which delta13C values vary from +2 to +3.7‰ PDB and average 3‰ PDB, (2) stage with delta13C values displaying stronger oscillations (from -2‰ to +‰ PDB), and (3) stage with an isotopic plateau with values around +3.7‰ PDB. Constant 87Sr/86Sr values (~ 0.70600) characterize C-isotope stage 1, whereas slightly fluctuating values (from 0.70600 to 0.70700) characterize C-isotope stage 2. Finally, 87Sr/86Sr values averaging 0.70600 characterize C-isotope stage 3. The C- and Sr- chemostratigraphic pathways permit to state: (a) the C- and Sr-isotope secular curves registered primary fluctuations of the isotope composition of seawater during late Mesoproterozoic- early Neoproterozoic transition in the Borborema Province, and (b) onset of the Cariris Velhos/Greenville cycle, widespread oceanic rifting, continental magmatic arc formation and onset of the agglutination of Rodinia supercontinent, mostly controlled the C- and Sr-isotope composition of seawater during the C-isotope stages 1, 2 and 3.

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Crustal-scale flexural slip folding during late tectonic amplification of an orogenic boundary perturbation in the Paleoproterozoic Torngat Orogen, northeastern Canada

Canadian Journal of Earth Sciences ◽

10.1139/e17-126 ◽

1997 ◽

Vol 34 (12) ◽

pp. 1545-1565 ◽

Cited By ~ 11

Author(s):

M. J. Van Kranendonk ◽

R. J. Wardle

Keyword(s):

Shear Zone ◽

Plate Boundary ◽

Granulite Facies ◽

Boundary Perturbation ◽

Magmatic Arc ◽

Tectonic Events ◽

Deep Crust ◽

High Grade Metamorphism ◽

Continental Magmatic Arc ◽

Northern Segment

Large variations in metamorphic grade over short distances, disparate orientations and diverse kinematics of contemporaneous structures, and a previously unexplained, 90° counterclockwise bend in the orogenic boundary of the amphibolite- to granulite-facies northern segment of the Paleoproterozoic Torngat Orogen are shown to be the result of multiple tectonic events acting upon an orogenic boundary perturbation. The perturbation was initiated when a promontory on the Nain Province margin, composed of a 1910–1885 Ma continental magmatic arc (Burwell domain), indented the Rae Province hinterland during the onset of collisional orogeny at ca. 1870 Ma (Dn+1). Sinistral transpression at ca. 1845–1822 Ma (Dn+2) caused formation of the orogen-parallel Abloviak shear zone and oblique burial of the Nain Province margin beneath a tilted section of the hot, buoyant magmatic arc. Reactivation of the orogen at ca. 1798–1770 Ma (Dn+3) involved crustal-scale flexural slip folding of the perturbation and simultaneous exhumation of the Burwell domain and the previously buried Nain crust across the Komaktorvik shear zone, which represents a sheared, tightened fold train localized along the western limit of thinned Nain crust affected by preorogenic rifting, but which does not represent a fundamental plate boundary. The along-strike heterogeneities in the Torngat Orogen document the influence of geometrical and competency heterogeneities in the colliding margins on subsequent deformation and the fact that heterogeneities in the deep crust persist through high-grade metamorphism.

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Unraveling sedimentary precursors and metal enrichment of high-grade metamorphosed manganese-rich rocks from the Borborema Province, northeastern Brazil

Ore Geology Reviews ◽

10.1016/j.oregeorev.2021.104283 ◽

2021 ◽

pp. 104283

Author(s):

Felipe Holanda dos Santos ◽

Wagner da Silva Amaral ◽

Kurt Konhauser ◽

Douglas Teixeira Martins ◽

Marco Paulo de Castro ◽

...

Keyword(s):

Northeastern Brazil ◽

High Grade ◽

Metal Enrichment ◽

Borborema Province

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Nd, Pb, and Sr isotope composition of juvenile magmatism in the Mesozoic large magmatic province of northern Chile (18–27°S): indications for a uniform subarc mantle

Contributions to Mineralogy and Petrology ◽

10.1007/s00410-006-0119-y ◽

2006 ◽

Vol 152 (5) ◽

pp. 571-589 ◽

Cited By ~ 35

Author(s):

Friedrich Lucassen ◽

Wolfgang Kramer ◽

Viola Bartsch ◽

Hans-Gerhard Wilke ◽

Gerhard Franz ◽

...

Keyword(s):

Isotope Composition ◽

Northern Chile ◽

Sr Isotope

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Correlated Millennial-Scale Changes in Surface Hydrography and Terrigenous Sediment Yield Inferred from Last-Glacial Marine Deposits off Northeastern Brazil

Quaternary Research ◽

10.1006/qres.1998.1992 ◽

1998 ◽

Vol 50 (2) ◽

pp. 157-166 ◽

Cited By ~ 226

Author(s):

Helge W. Arz ◽

Jürgen Pätzold ◽

Gerold Wefer

Keyword(s):

North Atlantic ◽

Isotope Composition ◽

Sediment Cores ◽

Ice Cores ◽

Northeastern Brazil ◽

Salt Flux ◽

Terrigenous Sediment ◽

The North ◽

North Brazil ◽

The North Atlantic

The stable isotope composition of planktonic foraminifera correlates with evidence for pulses of terrigenous sediment in a sediment core from the upper continental slope off northeastern Brazil. Stable oxygen isotope records of the planktonic foraminiferal species Globigerinoides sacculiferand Globigerinoides ruber(pink) reveal sub-Milankovitch changes in sea-surface hydrography during the last 85,000 yr. Warming of the surface water coincided with terrigenous sedimentation pulses that are inferred from high XRF intensities of Ti and Fe, and which suggest humid conditions in northeast Brazil. These tropical signals correlate with climatic oscillations recorded in Greenland ice cores (Dansgaard-Oeschger cycles) and in sediment cores from the North Atlantic (Heinrich events). Trade winds may have caused changes in the North Brazil Current that altered heat and salt flux into the North Atlantic, thus affecting the growth and decay of the large glacial ice sheets.

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Epithermal Fluorite Deposits in Transbaikalia (Geochemical Features, Sources of Matter and Fluids, and Genesis)

Russian Geology and Geophysics ◽

10.2113/rgg20194128 ◽

2021 ◽

Vol 62 (4) ◽

pp. 415-426

Author(s):

E.I. Lastochkin ◽

G.S. Ripp ◽

D.S. Tsydenova ◽

V.F. Posokhov ◽

A.E. Murzintseva

Keyword(s):

Meteoric Water ◽

Isotope Composition ◽

Spatial Proximity ◽

Thermal Waters ◽

Sr Isotope ◽

Light Isotope ◽

Geochemical Parameters ◽

Nd Systems ◽

Deep Source ◽

The Impact

Abstract —We consider the isotope-geochemical features of epithermal fluorite deposits in Transbaikalia, including the REE compositions, Sr isotope ratios, Sm–Nd systems, and isotope compositions of oxygen, carbon, hydrogen, and sulfur. The 87Sr/86Sr ratios in fluorites are within 0.706–0.708, and the εNd values are negative. Oxygen in quartz, the main mineral of the deposits, has a light isotope composition (δ18O = –3.4 to +2.6‰), and the calculated isotope composition of oxygen in the fluid in equilibrium with quartz (δ18O = –9 to –16‰) indicates the presence of meteoric water. The latter is confirmed by analysis of the isotope compositions of oxygen and hydrogen in gas–liquid inclusions in fluorites from three deposits. These isotope compositions are due to recycling caused by the impact of shallow basic plutons. The isotope composition of sulfur indicates its deep source. During ascent, sulfur became enriched in its light isotope (δ34S = –1.8 to –7.7‰). We assess the association of fluorite ores with basaltoids widespread in the study area. The isotope and geochemical parameters suggest their spatial proximity. Probably, the basaltoids were responsible for the recycling of meteoric water. It is shown that the epithermal fluorite deposits formed by the same mechanism as fissure–vein thermal waters in western Transbaikalia.

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Jurassic–Cretaceous arc magmatism along the Shyok–Bangong Suture from NW Himalaya: Formation of the peri-Gondwana basement to the Ladakh Arc

Journal of the Geological Society ◽

10.1144/jgs2021-035 ◽

2021 ◽

pp. jgs2021-035

Author(s):

Wanchese M. Saktura ◽

Solomon Buckman ◽

Allen P. Nutman ◽

Renjie Zhou

Keyword(s):

Late Cretaceous ◽

Nw Himalaya ◽

Content Type ◽

Magmatic Arc ◽

Basement Rocks ◽

Ladakh Himalaya ◽

Accreted Terranes ◽

Volcaniclastic Rocks ◽

Supplementary Material ◽

Depositional Age

The Jurassic–Cretaceous Tsoltak Formation from the eastern borderlands of Ladakh Himalaya consists of conglomerates, sandstones and shales, and is intruded by norite sills. It is the oldest sequence of continent-derived sedimentary rocks within the Shyok Suture. It also represents a rare outcrop of the basement rocks to the voluminous Late Cretaceous–Eocene Ladakh Batholith. The Shyok Formation is a younger sequence of volcaniclastic rocks that overlie the Tsoltak Formation and record the Late Cretaceous closure of the Mesotethys Ocean. The petrogenesis of these formations, ophiolite-related harzburgites and norite sill is investigated through petrography, whole-rock geochemistry and U–Pb zircon geochronology. The youngest detrital zircon grains from the Tsoltak Formation indicate Early Cretaceous maximum depositional age and distinctly Gondwanan, Lhasa microcontinent-related provenance with no Eurasian input. The Shyok Formation has Late Cretaceous maximum depositional age and displays a distinct change in provenance to igneous detritus characteristic of the Jurassic–Cretaceous magmatic arc along the southern margin of Eurasia. This is interpreted as a sign of collision of the Lhasa microcontinent and the Shyok ophiolite with Eurasia along the once continuous Shyok–Bangong Suture. The accreted terranes became the new southernmost margin of Eurasia and the basement to the Trans-Himalayan Batholith associated with the India-Eurasia convergence.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5633162

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Lithospheric and sublithospheric deformation under the Borborema Province of northeastern Brazil from receiver function harmonic stripping

Solid Earth ◽

10.5194/se-10-893-2019 ◽

2019 ◽

Vol 10 (3) ◽

pp. 893-905 ◽

Cited By ~ 3

Author(s):

Gaelle Lamarque ◽

Jordi Julià

Keyword(s):

Lithospheric Mantle ◽

Seismic Anisotropy ◽

Receiver Function ◽

Seismic Station ◽

Atlantic Coast ◽

Shear Zones ◽

Receiver Functions ◽

Azimuthal Anisotropy ◽

Northeastern Brazil ◽

Borborema Province

Abstract. The depth-dependent anisotropic structure of the lithosphere under the Borborema Province in northeast Brazil has been investigated via harmonic stripping of receiver functions developed at 39 stations in the region. This method retrieves the first (k=1) and second (k=2) degree harmonics of a receiver function dataset, which characterize seismic anisotropy beneath a seismic station. Anisotropic fabrics are in turn directly related to the deformation of the lithosphere from past and current tectonic processes. Our results reveal the presence of anisotropy within the crust and the lithospheric mantle throughout the entire province. Most stations in the continental interior report consistent anisotropic orientations in the crust and lithospheric mantle, suggesting a dominant northeast–southwest pervasive deformation along lithospheric-scale shear zones developed during the Brasiliano–Pan-African orogeny. Several stations aligned along a northeast–southwest trend located above the (now aborted) Mesozoic Cariri–Potiguar rift display large uncertainties for the fast-axis direction. This non-azimuthal anisotropy may be related to a complex anisotropic fabric resulting from a combination of deformation along the ancient collision between Precambrian blocks, Mesozoic extension and thermomechanical erosion dragging by sublithospheric flow. Finally, several stations along the Atlantic coast reveal depth-dependent anisotropic orientations roughly (sub)perpendicular to the margin. These results suggest a more recent overprint, probably related to the presence of frozen anisotropy in the lithosphere due to stretching and rifting during the opening of the South Atlantic.

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Jurassic Arc: Reconstructing the Lost World of eastern Gondwana

Geology ◽

10.1130/g49328.1 ◽

2021 ◽

Author(s):

Elliot K. Foley ◽

R.A. Henderson ◽

E.M. Roberts ◽

A.I.S. Kemp ◽

C.N. Todd ◽

...

Keyword(s):

Detrital Zircon ◽

Tectonic Setting ◽

Magmatic Arc ◽

Continental Arc ◽

Key Factor ◽

Igneous Activity ◽

Competing Models ◽

Juvenile Crust ◽

Sedimentary Fill ◽

Continental Magmatic Arc

The tectonic setting of the Australian sector of the eastern Gondwanan margin during the Jurassic and Cretaceous is enigmatic. Whether this involved convergent tectonism and a long-lived continental magmatic arc or rift-related extension unrelated to subduction is debated. The paucity of Australian Jurassic–Cretaceous igneous outcrops makes resolving these competing models difficult. We used the detrital zircon record of the Jurassic–Cretaceous Great Australian Superbasin (GAS) as a proxy for igneous activity. We attribute the persistent magmatism recorded in GAS sedimentary fill throughout the Mesozoic to ca. 95 Ma to continuation of the established Paleozoic continental arc system. The detrital zircon record signals short (~10 m.y.) pulses of elevated Jurassic and Cretaceous magmatic activity and strongly positive εHf values, indicating juvenile crust or mantle-derived magmatism. Margin reconstruction indicates sustained continental growth at rates of at least ~55 km3 km–1 m.y.–1, mainly to the tract now represented by submerged northern Zealandia, due to the retreat of this arc system. We posit that arc retreat was a key factor in rapid crust generation and preservation, and that continental sedimentary systems globally may host cryptic records of juvenile crustal addition that must be considered in estimating crustal growth rates along convergent plate margins.

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Zircon U-Pb Geochronology of a Manganese-rich Supracrustal Succession in Northeast Brazil: Adding a New Piece to the Paleoproterozoic Manganese Mineralization Puzzle

10.21203/rs.3.rs-905723/v1 ◽

2021 ◽

Author(s):

Felipe Holanda Santos ◽

Wagner Amaral ◽

Douglas Martins

Keyword(s):

Northeast Brazil ◽

Sedimentary Sequences ◽

Borborema Province ◽

Manganese Mineralization ◽

Minimum Age ◽

Leucocratic Granite ◽

Eburnean Orogeny ◽

Depositional Age ◽

Other World ◽

Host Rocks

Abstract A vast accumulation of manganese occurred in the Paleoproterozoic and it is closely related to the Paleoproterozoic Great Oxidation Event. Although the largest Mn deposits are located in the African continent, relevant deposits that potentially correlate with the African ones are found in South America, specifically in the Brazilian territory. The Borborema Province in Northeast Brazil hosts several Mn-rich meta-sedimentary sequences, containing up to 40 wt.% MnO. These sequences are composed of oxidized and manganese silicate lenses that alternate with spessartite-quartzite layers. This succession is hosted by graphite-bearing pelitic gneisses, is metamorphosed to the amphibolite facies, and is intruded by granitic bodies. Although some preliminary studies report Palaeoproterozoic ages for these meta-sedimentary sequences, the age at which the Mn-rich sequences were deposited has not yet been determined. We investigate in this study the Lagoa do Riacho Manganese Deposit, a representative member of the Northern Borborema Province Mn-rich sequences. Not only was the age of the Mn-rich protolith deposition determined by LA-SF-ICP-MS zircon U-Pb geochronology, but also the timing of the metamorphic reworking of the Mn-rich succession was inferred. The youngest detrital zircon population from a meter-sized bed of spessartite-quartzite interlayered with an oxidized manganese ore from drillhole Ocr-1 yielded a maximum depositional age close to 2130 Ma. Similarly, a gneiss hosting the manganese mineralization at the base of drillhole Ocr-1 also yielded a maximum depositional age in the Rhyacian, close to 2156 Ma. We infer from the U-Pb dating of metamorphic overgrowths on zircon from the Mn-bearing sequences and host rocks and the U-Pb crystallization age of an intrusive leucocratic granite that the minimum age of the Mn-rich succession to be 2023-2106 Ma. The metamorphic reworking of the Mn-rich succession is time-equivalent to the Transamazonian/Eburnean orogeny. Thus, these constraints point to a Rhyacian age (ca. 2100-2200 Ma) for the deposition of the Mn-rich protolith, chrono-correlated with other world-class manganese deposits, such as those from the Franceville Basin in Gabon.

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Petrogenesis and U-Pb and Sm-Nd geochronology of the Taquaral granite: record of an orosirian continental magmatic arc in the region of Corumba - MS

Brazilian Journal of Geology ◽

10.1590/2317-488920150030231 ◽

2015 ◽

Vol 45 (3) ◽

pp. 431-451 ◽

Cited By ~ 5

Author(s):

Letícia Alexandre Redes ◽

Maria Zélia Aguiar de Sousa ◽

Amarildo Salina Ruiz ◽

Jean-Michel Lafon

Keyword(s):

Geochemical Data ◽

Alkaline Magmatism ◽

Alluvial Deposits ◽

Mato Grosso ◽

Microgranular Enclave ◽

Magmatic Arc ◽

Rock Types ◽

High K ◽

Continental Magmatic Arc ◽

Shrimp Zircon

The Taquaral Granite is located on southern Amazon Craton in the region of Corumbá, westernmost part of the Brazilian state of Mato Grosso do Sul (MS), near Brazil-Bolivia frontier. This intrusion of batholitic dimensions is partially covered by sedimentary rocks of the Urucum, Tamengo Bocaina and Pantanal formations and Alluvial Deposits. The rock types are classified as quartz-monzodiorites, granodiorites, quartz-monzonites, monzo and syenogranites. There are two groups of enclaves genetically and compositionally different: one corresponds to mafic xenoliths and the second is identified as felsic microgranular enclave. Two deformation phases are observed: one ductile (F1) and the other brittle (F2). Geochemical data indicate intermediate to acidic composition for these rocks and a medium to high-K, metaluminous to peraluminous calk-alkaline magmatism, suggesting also their emplacement into magmatic arc settings. SHRIMP zircon U-Pb geochronological data of these granites reveals a crystallization age of 1861 ± 5.3 Ma. Whole rock Sm-Nd analyses provided εNd(1,86 Ga) values of -1.48 and -1.28 and TDM model ages of 2.32 and 2.25 Ga, likely indicating a Ryacian crustal source. Here we conclude that Taquaral Granite represents a magmatic episode generated at the end of the Orosirian, as a part of the Amoguija Magmatic Arc.

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