Ediacaran Águas Belas pluton, Northeastern Brazil: Evidence on age, emplacement and magma sources during Gondwana amalgamation

Adejardo F. da Silva Filho; Ignez P. Guimarães; Valderez P. Ferreira; Richard Armstrong; Alcides N. Sial

doi:10.1016/j.gr.2009.10.002

Ediacaran Águas Belas pluton, Northeastern Brazil: Evidence on age, emplacement and magma sources during Gondwana amalgamation

Adejardo F. da Silva Filho^*, Ignez P. Guimarães, Valderez P. Ferreira, Richard Armstrong, Alcides N. Sial

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

26 Citations (Scopus)

Abstract

Ediacaran syenogranites from the Águas Belas pluton, Borborema Province, Northeastern Brazil were investigated in this work. The studied granitoids show high SiO₂, Fe# [FeO / (FeO + MgO)], total alkalis (K₂O + Na₂O) and BaO contents and medium Sr and low Nb contents. They show gentle fractionated rare earth patterns with discrete Eu negative anomalies. Major and trace element data point to chemical features of transitional high-K calc-alkaline to alkaline post-collisional magmatism. Structural data coupled with geochronological data suggest that NNE-SSW-trending sinistral movements at shear zones were initiated at ca. 590 Ma and have activated E-W pre-existing structures at the current crustal level. The synchronism of these shear zones allowed the dilation to generate the necessary space for the emplacement of the Águas Belas pluton. U-Pb SHRIMP zircon data show a cluster of ages around 588 ± 4 Ma which is interpreted as the crystallization age. Some zircon grain cores yielded ages within 2060-1860 Ma and 1670-1570 Ma intervals. Oxygen isotope compositions of zircon grains with distinct ages were measured using SHRIMP techniques. Twenty three analyses in the same zircon spots previously analyzed for U-Pb show δ¹⁸O values ranging from 5.79‰ to 10.30‰ SMOW. This large range of values results from variations both between grains and within grains (core-mantle/rim), and is interpreted as the result of mixing of components with distinct oxygen isotope compositions. The U-Pb zircon ages and the δ¹⁸O values associated with Paleoproterozoic Nd T_DM model ages suggest that the protolith of these granitoids involved a mantle component (Paleoproterozoic lithospheric mantle), Paleoproterozoic and Mesoproterozoic igneous rocks. Interactions with Mesoproterozoic or Neoproterozoic supracrustal rocks, may have occurred during the intrusion. The resulting magma evolved through biotite and K-feldspar fractionation.

Original language	English
Pages (from-to)	676-687
Number of pages	12
Journal	Gondwana Research
Volume	17
Issue number	4
DOIs	https://doi.org/10.1016/j.gr.2009.10.002
Publication status	Published - May 2010

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@article{46fca1fcf6eb423392e68826e0677315,

title = "Ediacaran {\'A}guas Belas pluton, Northeastern Brazil: Evidence on age, emplacement and magma sources during Gondwana amalgamation",

abstract = "Ediacaran syenogranites from the {\'A}guas Belas pluton, Borborema Province, Northeastern Brazil were investigated in this work. The studied granitoids show high SiO2, Fe# [FeO / (FeO + MgO)], total alkalis (K2O + Na2O) and BaO contents and medium Sr and low Nb contents. They show gentle fractionated rare earth patterns with discrete Eu negative anomalies. Major and trace element data point to chemical features of transitional high-K calc-alkaline to alkaline post-collisional magmatism. Structural data coupled with geochronological data suggest that NNE-SSW-trending sinistral movements at shear zones were initiated at ca. 590 Ma and have activated E-W pre-existing structures at the current crustal level. The synchronism of these shear zones allowed the dilation to generate the necessary space for the emplacement of the {\'A}guas Belas pluton. U-Pb SHRIMP zircon data show a cluster of ages around 588 ± 4 Ma which is interpreted as the crystallization age. Some zircon grain cores yielded ages within 2060-1860 Ma and 1670-1570 Ma intervals. Oxygen isotope compositions of zircon grains with distinct ages were measured using SHRIMP techniques. Twenty three analyses in the same zircon spots previously analyzed for U-Pb show δ18O values ranging from 5.79‰ to 10.30‰ SMOW. This large range of values results from variations both between grains and within grains (core-mantle/rim), and is interpreted as the result of mixing of components with distinct oxygen isotope compositions. The U-Pb zircon ages and the δ18O values associated with Paleoproterozoic Nd TDM model ages suggest that the protolith of these granitoids involved a mantle component (Paleoproterozoic lithospheric mantle), Paleoproterozoic and Mesoproterozoic igneous rocks. Interactions with Mesoproterozoic or Neoproterozoic supracrustal rocks, may have occurred during the intrusion. The resulting magma evolved through biotite and K-feldspar fractionation.",

keywords = "Ediacaran, Geochemistry, Oxygen isotopes, Syenogranite, U-Pb SHRIMP geochronology",

author = "{da Silva Filho}, {Adejardo F.} and Guimar{\~a}es, {Ignez P.} and Ferreira, {Valderez P.} and Richard Armstrong and Sial, {Alcides N.}",

year = "2010",

month = may,

doi = "10.1016/j.gr.2009.10.002",

language = "English",

volume = "17",

pages = "676--687",

journal = "Gondwana Research",

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T1 - Ediacaran Águas Belas pluton, Northeastern Brazil

T2 - Evidence on age, emplacement and magma sources during Gondwana amalgamation

AU - da Silva Filho, Adejardo F.

AU - Guimarães, Ignez P.

AU - Ferreira, Valderez P.

AU - Armstrong, Richard

AU - Sial, Alcides N.

PY - 2010/5

Y1 - 2010/5

N2 - Ediacaran syenogranites from the Águas Belas pluton, Borborema Province, Northeastern Brazil were investigated in this work. The studied granitoids show high SiO2, Fe# [FeO / (FeO + MgO)], total alkalis (K2O + Na2O) and BaO contents and medium Sr and low Nb contents. They show gentle fractionated rare earth patterns with discrete Eu negative anomalies. Major and trace element data point to chemical features of transitional high-K calc-alkaline to alkaline post-collisional magmatism. Structural data coupled with geochronological data suggest that NNE-SSW-trending sinistral movements at shear zones were initiated at ca. 590 Ma and have activated E-W pre-existing structures at the current crustal level. The synchronism of these shear zones allowed the dilation to generate the necessary space for the emplacement of the Águas Belas pluton. U-Pb SHRIMP zircon data show a cluster of ages around 588 ± 4 Ma which is interpreted as the crystallization age. Some zircon grain cores yielded ages within 2060-1860 Ma and 1670-1570 Ma intervals. Oxygen isotope compositions of zircon grains with distinct ages were measured using SHRIMP techniques. Twenty three analyses in the same zircon spots previously analyzed for U-Pb show δ18O values ranging from 5.79‰ to 10.30‰ SMOW. This large range of values results from variations both between grains and within grains (core-mantle/rim), and is interpreted as the result of mixing of components with distinct oxygen isotope compositions. The U-Pb zircon ages and the δ18O values associated with Paleoproterozoic Nd TDM model ages suggest that the protolith of these granitoids involved a mantle component (Paleoproterozoic lithospheric mantle), Paleoproterozoic and Mesoproterozoic igneous rocks. Interactions with Mesoproterozoic or Neoproterozoic supracrustal rocks, may have occurred during the intrusion. The resulting magma evolved through biotite and K-feldspar fractionation.

AB - Ediacaran syenogranites from the Águas Belas pluton, Borborema Province, Northeastern Brazil were investigated in this work. The studied granitoids show high SiO2, Fe# [FeO / (FeO + MgO)], total alkalis (K2O + Na2O) and BaO contents and medium Sr and low Nb contents. They show gentle fractionated rare earth patterns with discrete Eu negative anomalies. Major and trace element data point to chemical features of transitional high-K calc-alkaline to alkaline post-collisional magmatism. Structural data coupled with geochronological data suggest that NNE-SSW-trending sinistral movements at shear zones were initiated at ca. 590 Ma and have activated E-W pre-existing structures at the current crustal level. The synchronism of these shear zones allowed the dilation to generate the necessary space for the emplacement of the Águas Belas pluton. U-Pb SHRIMP zircon data show a cluster of ages around 588 ± 4 Ma which is interpreted as the crystallization age. Some zircon grain cores yielded ages within 2060-1860 Ma and 1670-1570 Ma intervals. Oxygen isotope compositions of zircon grains with distinct ages were measured using SHRIMP techniques. Twenty three analyses in the same zircon spots previously analyzed for U-Pb show δ18O values ranging from 5.79‰ to 10.30‰ SMOW. This large range of values results from variations both between grains and within grains (core-mantle/rim), and is interpreted as the result of mixing of components with distinct oxygen isotope compositions. The U-Pb zircon ages and the δ18O values associated with Paleoproterozoic Nd TDM model ages suggest that the protolith of these granitoids involved a mantle component (Paleoproterozoic lithospheric mantle), Paleoproterozoic and Mesoproterozoic igneous rocks. Interactions with Mesoproterozoic or Neoproterozoic supracrustal rocks, may have occurred during the intrusion. The resulting magma evolved through biotite and K-feldspar fractionation.

KW - Ediacaran

KW - Geochemistry

KW - Oxygen isotopes

KW - Syenogranite

KW - U-Pb SHRIMP geochronology

UR - http://www.scopus.com/inward/record.url?scp=77349092572&partnerID=8YFLogxK

U2 - 10.1016/j.gr.2009.10.002

DO - 10.1016/j.gr.2009.10.002

M3 - Article

SN - 1342-937X

VL - 17

SP - 676

EP - 687

JO - Gondwana Research

JF - Gondwana Research

IS - 4

ER -

Ediacaran Águas Belas pluton, Northeastern Brazil: Evidence on age, emplacement and magma sources during Gondwana amalgamation

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