Geochemistry of low-grade metasedimentary rocks from the Biga Peninsula, NW Turkey: Implications for provenance and tectonic setting

2022 ◽  
Author(s):  
Fırat Şengün
Keyword(s):  
Tectonic Setting ◽  
Low Grade ◽  
Biga Peninsula ◽  
Metasedimentary Rocks ◽  
Nw Turkey

scholarly journals Petrography, geochemistry, and Nd isotope systematics of metaconglomerates and matrix-rich metasedimentary rocks: implications for the provenance and tectonic setting of the Labrador Trough, Canada

2019 ◽  
Vol 56 (6) ◽  
pp. 672-687 ◽  
Author(s):  
R. Henrique-Pinto ◽  
C. Guilmette ◽  
C. Bilodeau ◽  
R. Stevenson ◽  
B.B. Carvalho
Keyword(s):  
Tectonic Setting ◽  
Sedimentary Environment ◽  
Low Grade ◽  
Metasedimentary Rocks ◽  
Wide Range ◽  
Supracrustal Belt ◽  
Geochemical Variations ◽  
Grade One ◽  
Superior Craton ◽  
Isotope Systematics

The New Quebec Orogen consists of a supracrustal belt that was reworked when the Superior Craton collided with the Core Zone terrane during the Paleoproterozoic Trans-Hudson Orogeny. Within the New Quebec Orogen, the Kaniapiskau Supergroup can be divided into four terrigenous lithotypes metamorphosed at low-grade: one set with greater compositional and textural sedimentary maturity classified as quartz arenites and subarkoses, and another set with lower textural maturity classified as feldspathic wackes and mudrocks. In contrast, the Laporte Group includes homogeneous lithotypes represented by feldspathic and lithic wackes with a range of matrix contents metamorphosed at low to medium grade. The Kaniapiskau Supergroup rocks have a wide range of SiO2 and Al2O3 contents (SiO2/Al2O3 = 3.7–51) compared to the restricted compositional range of the Laporte Group rocks (SiO2/Al2O3 = 4.4–6.8). In general, the geochemical variations in both formations of the Laporte Group are within the range of the main clast varieties from basal metaconglomerates, although the Deborah Formation (top unit) records higher TiO2, P2O5, MgO, and Ni contents and high Cr/Th, Co/Ba, Th/U, and Rb/Sr ratios indicating additional mafic sources. Our results support the hypothesis that the Kaniapiskau Supergroup was deposited along an intraplate continental margin with predominantly recycled (εNd(1.87Ga) –12) Paleoarchean sources (TDM 3.2 Ga). In contrast, the Laporte Group marks the transition from a continental forearc (Grand Rosoy Fm.) with a typical juvenile source, including granitic clasts (εNd(1.83Ga) –0.1 to +3.1), to a wedge-top depozone (Deborah Fm.) in the context of a collisional proforeland basin. This syncollisional sedimentary environment is characterized by the presence of old crustal components (εNd(1.83Ga) –4.4 to –9.1).

scholarly journals The thrust contact between the Canastra and Vazante groups in the Southern Brasília Belt: structural evolution, white mica crystallinity and implications for the Brasiliano orogeny

2016 ◽  
Vol 46 (4) ◽  
pp. 567-583 ◽  
Author(s):  
Manuela de Oliveira Carvalho ◽  
◽  
Claudio de Morisson Valeriano ◽  
Pamela Alejandra Aparicio González ◽  
Gustavo Diniz Oliveira ◽  
...  
Keyword(s):  
Structural Evolution ◽  
White Mica ◽  
Low Grade ◽  
Kink Bands ◽  
Metasedimentary Rocks ◽  
Kübler Index ◽  
Crenulation Cleavage ◽  
Thrust Sheets ◽  
Brasiliano Orogeny ◽  
Carbonaceous Phyllite

ABSTRACT: Two regional thrust-sheets of Neoproterozoic metasedimentary rocks occur in the Southern Brasília Belt, northwest Minas Gerais. The lower one comprises the Vazante Group, that is formed in the studied area, from base to top, by the Serra do Garrote (metapelites interlayered with carbonaceous phyllite), Serra do Poço Verde (beige to pink stromatolitic metadolomite with interlayered greenish slates), Morro do Calcário (gray stromatolitic metadolomite interlayered with gray slates) and Serra da Lapa (phyllite with dolarenitic lenses interlayered with slates) formations. The upper thrust sheet consists of the Canastra Group (Paracatu formation): laminated sericite phyllites and carbonaceous phyllites interlayered with quartzite. The Braziliano orogeny resulted in four phases of contractional deformation, associated with low-grade metamorphism. The first two (D1 and D2) are ductile, while the third and fourth ones (D3 and D4) are brittle-ductile. D1 developed a slaty S1 cleavage subparallel to the primary layering, with shallow to steep dips to NW. D2 developed a crenulation cleavage (S2) that dips moderately to NW and is associated with tight to isoclinal folds. D3 and D4 phases developed crenulations and open folds and kink bands. S3 dips steeply to NW, while S4 has moderate to steep dips to NE and SW. White mica crystallinity (Kübler index) measurements in metapelites indicate that both the Canastra and Vazante groups reached anchizone/epizone conditions, and metamorphic discontinuities along thrusts indicate that the peak of metamorphism is pre or syn-thrusting.

Inversion of magnetic and frequency-domain electromagnetic data for investigating lithologies associated with gold mineralization in the Canadian Malartic area, Québec, Canada

2020 ◽  
pp. 1-20
Author(s):  
Mehrdad Darijani ◽  
Colin G. Farquharson
Keyword(s):  
Frequency Domain ◽  
Gold Mineralization ◽  
Volcanic Rocks ◽  
Tetrahedral Mesh ◽  
Iron Formation ◽  
Magnetic Data ◽  
Low Grade ◽  
Metasedimentary Rocks ◽  
Magnetic Inversion ◽  
Northern Edge

Canadian Malartic is an Archean low-grade bulk tonnage native gold deposit. The deposit is mostly located in altered clastic metasedimentary rocks, mafic–ultramafic dykes, and monzodioritic porphyry intrusions. Airborne magnetic and frequency-domain electromagnetic (EM) data were inverted to reconstruct the geological units associated with the mineralization, especially the intrusive masses. The 3-D inversion of magnetic data, which used a tetrahedral mesh to a depth of 2.4 km, shows that mafic volcanic rocks and iron formation rocks extend to depth in the area, more so than diabase dykes. The magnetic inversion also shows that the diorite and monzodiorite rocks of the Lac Fournière A pluton are dipping toward the south on its northern edge at the contact with the metasedimentary rocks. The 1-D inversion of the frequency-domain EM data, for both electrical conductivity and magnetic susceptibility, is able to reconstruct geological structures to a depth of approximately 100 m, providing more details and information about these features. The intrusive masses such as diabase dykes, diorite and monzodiorite rocks, and mafic volcanic rocks are reconstructed as electrically conductive structures in the inversion results. The metasedimentary rocks are resistive, and the overburden is conductive in most of the area. The geophysical data and inversion results suggest the presence of some features (such as diabase dykes and monzodiorite rocks) that are not yet present on some parts of the geology map. A comparison of the EM-derived susceptibility and the magnetic-derived susceptibility over the iron formations can reveal the effect of remanent magnetization.

Tectonic setting and regional correlation of Ordovician–Silurian rocks of the Aspy terrane, Cape Breton Island, Nova Scotia

1991 ◽  
Vol 28 (11) ◽  
pp. 1769-1779 ◽  
Author(s):  
Sandra M. Barr ◽  
Rebecca A. Jamieson
Keyword(s):  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Volcanic Arc ◽  
Cape Breton Island ◽  
Metasedimentary Rocks ◽  
Tectonic History ◽  
Cape Breton ◽  
Metavolcanic Rocks ◽  
High Grade Metamorphism ◽  
Arc Setting

Interlayered mafic and felsic metavolcanic rocks and metasedimentary rocks of Ordovician to Silurian age are characteristic of the Aspy terrane of northwestern Cape Breton Island. These rocks were affected by medium- to high-grade metamorphism and were intruded by synkinematic granitoid orthogneisses during Late Silurian to Early Devonian times. They were intruded by posttectonic Devonian granitic plutons and experienced rapid Devonian decompression and cooling. The chemical characteristics of the mafic metavolcanic rocks indicate that they are tholeiites formed in a volcanic-arc setting. The volcanic rocks of the Aspy terrane differ from many other Silurian and Silurian–Devonian successions in Atlantic Canada, which have chemical and stratigraphic characteristics of volcanic rocks formed in extensional within-plate settings, and are somewhat younger than the Aspy terrane sequences. Aspy terrane units are most similar to Ordovician–Silurian volcanic and metamorphic units in southwestern Newfoundland, including the La Poile Group and the Port aux Basques gneiss. Together with other occurrences of Late Ordovician to Early Silurian volcanic-arc units, they indicate that subduction-related compressional tectonics continued into the Silurian in parts of the northern Appalachian Orogen. The complex Late Silurian – Devonian tectonic history of the Aspy terrane may reflect collision with the southeastern edge of a Grenvillian crustal promentory.

Sign in / Sign up

Export Citation Format

Share Document