The Tonian Embu Complex in the Ribeira Belt (Brazil): revision, depositional age and setting in Rodinia and West Gondwana

G.A.C. Campanha; F.M. Faleiros; P. A. Cawood; D.I.G. Cabrita; B.V. Ribeiro; M.A.S. Basei

doi:10.1016/j.precamres.2018.10.010

The Tonian Embu Complex in the Ribeira Belt (Brazil): revision, depositional age and setting in Rodinia and West Gondwana

G.A.C. Campanha, F.M. Faleiros, P. A. Cawood, D.I.G. Cabrita, B.V. Ribeiro, M.A.S. Basei

School of Earth & Environmental Sciences

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Abstract

The Embu Complex in the Neoproterozoic Ribeira Belt of Brazil provides a record of sedimentation associated with the Rodinia supercontinent and its subsequent deformation and metamorphism during assembly of West Gondwana. It is composed of a succession of variably migmatized pelitic schists and paragneisses, as well as minor calcsilicate rocks with quartzite intercalations, and orthogneiss. Detrital zircon U-Pb (LA-ICP-MS and SHRIMP) determinations for key samples of the Embu Complex in its type-area (West and Southwest of São Paulo City), and samples from neighboring units (Votuverava and São Roque groups) indicate distinct provenance histories and in combination with other data, discrete times of sediment accumulation. Detrital zircons from the Embu Complex are characterized by ages in the range 1500-1000 Ma and 2000-1700 Ma, with a very minor number of older ages. The youngest detrital grain is dated at 974 ± 12 Ma. Metamorphic zircon overgrowths range from 850 to 570 Ma with age peaks at ca. 820-790 and 650-570 Ma. Thus, the depositional age of the Embu Complex is constrained to 970-850 Ma. The detrital zircons of the Votuverava and São Roque groups are dominated by ages in the range 2200-2000 Ma, along with minor Paleoproterozoic and Archean ages. The youngest detrital grains are ∼1400 Ma (Votuverava Group) and ∼1750 Ma (São Roque Group). Metamafic rocks from the Votuverava Group have crystallization ages of ca. 1300 Ma, with a higher metamorphic grade amphibolite showing a range of discordant ages with upper and lower intercepts of 1300 Ma and ∼800 Ma, respectively. These results demonstrate that the Embu Complex was probably accreted to the Apiaí Terrane during a Tonian (820-790 Ma) orogenic event, prior to final development of the Ediacaran Ribeira belt arc-related magmatism and a transcurrent shear zone system. The main source area for detrital zircons of the Embu Complex is likely to be the Grenville-Sveconorwegian-Sunsás orogen or time-equivalent regions rather than the central portions of the neighboring cratons. The Embu Complex geological context is consistent with accumulation on the margin of the Rodinia supercontinent.

Original language	English
Journal	Precambrian Research
Volume	In press
Early online date	23 Oct 2018
DOIs	https://doi.org/10.1016/j.precamres.2018.10.010
Publication status	E-pub ahead of print - 23 Oct 2018

Keywords

Neoproterozoic
Mesoproterozoic
Votuverava Group
São Roque Group
Apiaí Terrane
Detrital zircon
U-Pb geochronology

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10.1016/j.precamres.2018.10.010

Campanha_2018_PR_TonianEmbuComplex_AAM
Copyright © 2018 Elsevier B.V. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at: https://doi.org/10.1016/j.precamres.2018.10.010
Accepted author manuscript, 9.33 MBLicence: CC BY-NC-ND

Cite this

@article{66bce8f16ae3456a9d2e633a413a41c0,

title = "The Tonian Embu Complex in the Ribeira Belt (Brazil): revision, depositional age and setting in Rodinia and West Gondwana",

abstract = "The Embu Complex in the Neoproterozoic Ribeira Belt of Brazil provides a record of sedimentation associated with the Rodinia supercontinent and its subsequent deformation and metamorphism during assembly of West Gondwana. It is composed of a succession of variably migmatized pelitic schists and paragneisses, as well as minor calcsilicate rocks with quartzite intercalations, and orthogneiss. Detrital zircon U-Pb (LA-ICP-MS and SHRIMP) determinations for key samples of the Embu Complex in its type-area (West and Southwest of S{\~a}o Paulo City), and samples from neighboring units (Votuverava and S{\~a}o Roque groups) indicate distinct provenance histories and in combination with other data, discrete times of sediment accumulation. Detrital zircons from the Embu Complex are characterized by ages in the range 1500-1000 Ma and 2000-1700 Ma, with a very minor number of older ages. The youngest detrital grain is dated at 974 ± 12 Ma. Metamorphic zircon overgrowths range from 850 to 570 Ma with age peaks at ca. 820-790 and 650-570 Ma. Thus, the depositional age of the Embu Complex is constrained to 970-850 Ma. The detrital zircons of the Votuverava and S{\~a}o Roque groups are dominated by ages in the range 2200-2000 Ma, along with minor Paleoproterozoic and Archean ages. The youngest detrital grains are ∼1400 Ma (Votuverava Group) and ∼1750 Ma (S{\~a}o Roque Group). Metamafic rocks from the Votuverava Group have crystallization ages of ca. 1300 Ma, with a higher metamorphic grade amphibolite showing a range of discordant ages with upper and lower intercepts of 1300 Ma and ∼800 Ma, respectively. These results demonstrate that the Embu Complex was probably accreted to the Apia{\'i} Terrane during a Tonian (820-790 Ma) orogenic event, prior to final development of the Ediacaran Ribeira belt arc-related magmatism and a transcurrent shear zone system. The main source area for detrital zircons of the Embu Complex is likely to be the Grenville-Sveconorwegian-Suns{\'a}s orogen or time-equivalent regions rather than the central portions of the neighboring cratons. The Embu Complex geological context is consistent with accumulation on the margin of the Rodinia supercontinent.",

keywords = "Neoproterozoic, Mesoproterozoic, Votuverava Group, S{\~a}o Roque Group, Apia{\'i} Terrane, Detrital zircon, U-Pb geochronology",

author = "G.A.C. Campanha and F.M. Faleiros and Cawood, {P. A.} and D.I.G. Cabrita and B.V. Ribeiro and M.A.S. Basei",

note = "Funding: Conselho Nacional de Desenvolvimento Cient{\'i}fico e Tecnol{\'o}gico – CNPq, grants 443439/2014-1 and 305074/2015-6, the Funda{\c c}{\~a}o de Amparo {\`a} Pesquisa do Estado de S{\~a}o Paulo – FAPESP, grant 2015/04487-7, and the Australian Research Council, grant FL160100168.",

year = "2018",

month = oct,

day = "23",

doi = "10.1016/j.precamres.2018.10.010",

language = "English",

volume = "In press",

journal = "Precambrian Research",

issn = "0301-9268",

publisher = "Elsevier Science BV",

}

TY - JOUR

T1 - The Tonian Embu Complex in the Ribeira Belt (Brazil)

T2 - revision, depositional age and setting in Rodinia and West Gondwana

AU - Campanha, G.A.C.

AU - Faleiros, F.M.

AU - Cawood, P. A.

AU - Cabrita, D.I.G.

AU - Ribeiro, B.V.

AU - Basei, M.A.S.

N1 - Funding: Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq, grants 443439/2014-1 and 305074/2015-6, the Fundação de Amparo à Pesquisa do Estado de São Paulo – FAPESP, grant 2015/04487-7, and the Australian Research Council, grant FL160100168.

PY - 2018/10/23

Y1 - 2018/10/23

N2 - The Embu Complex in the Neoproterozoic Ribeira Belt of Brazil provides a record of sedimentation associated with the Rodinia supercontinent and its subsequent deformation and metamorphism during assembly of West Gondwana. It is composed of a succession of variably migmatized pelitic schists and paragneisses, as well as minor calcsilicate rocks with quartzite intercalations, and orthogneiss. Detrital zircon U-Pb (LA-ICP-MS and SHRIMP) determinations for key samples of the Embu Complex in its type-area (West and Southwest of São Paulo City), and samples from neighboring units (Votuverava and São Roque groups) indicate distinct provenance histories and in combination with other data, discrete times of sediment accumulation. Detrital zircons from the Embu Complex are characterized by ages in the range 1500-1000 Ma and 2000-1700 Ma, with a very minor number of older ages. The youngest detrital grain is dated at 974 ± 12 Ma. Metamorphic zircon overgrowths range from 850 to 570 Ma with age peaks at ca. 820-790 and 650-570 Ma. Thus, the depositional age of the Embu Complex is constrained to 970-850 Ma. The detrital zircons of the Votuverava and São Roque groups are dominated by ages in the range 2200-2000 Ma, along with minor Paleoproterozoic and Archean ages. The youngest detrital grains are ∼1400 Ma (Votuverava Group) and ∼1750 Ma (São Roque Group). Metamafic rocks from the Votuverava Group have crystallization ages of ca. 1300 Ma, with a higher metamorphic grade amphibolite showing a range of discordant ages with upper and lower intercepts of 1300 Ma and ∼800 Ma, respectively. These results demonstrate that the Embu Complex was probably accreted to the Apiaí Terrane during a Tonian (820-790 Ma) orogenic event, prior to final development of the Ediacaran Ribeira belt arc-related magmatism and a transcurrent shear zone system. The main source area for detrital zircons of the Embu Complex is likely to be the Grenville-Sveconorwegian-Sunsás orogen or time-equivalent regions rather than the central portions of the neighboring cratons. The Embu Complex geological context is consistent with accumulation on the margin of the Rodinia supercontinent.

AB - The Embu Complex in the Neoproterozoic Ribeira Belt of Brazil provides a record of sedimentation associated with the Rodinia supercontinent and its subsequent deformation and metamorphism during assembly of West Gondwana. It is composed of a succession of variably migmatized pelitic schists and paragneisses, as well as minor calcsilicate rocks with quartzite intercalations, and orthogneiss. Detrital zircon U-Pb (LA-ICP-MS and SHRIMP) determinations for key samples of the Embu Complex in its type-area (West and Southwest of São Paulo City), and samples from neighboring units (Votuverava and São Roque groups) indicate distinct provenance histories and in combination with other data, discrete times of sediment accumulation. Detrital zircons from the Embu Complex are characterized by ages in the range 1500-1000 Ma and 2000-1700 Ma, with a very minor number of older ages. The youngest detrital grain is dated at 974 ± 12 Ma. Metamorphic zircon overgrowths range from 850 to 570 Ma with age peaks at ca. 820-790 and 650-570 Ma. Thus, the depositional age of the Embu Complex is constrained to 970-850 Ma. The detrital zircons of the Votuverava and São Roque groups are dominated by ages in the range 2200-2000 Ma, along with minor Paleoproterozoic and Archean ages. The youngest detrital grains are ∼1400 Ma (Votuverava Group) and ∼1750 Ma (São Roque Group). Metamafic rocks from the Votuverava Group have crystallization ages of ca. 1300 Ma, with a higher metamorphic grade amphibolite showing a range of discordant ages with upper and lower intercepts of 1300 Ma and ∼800 Ma, respectively. These results demonstrate that the Embu Complex was probably accreted to the Apiaí Terrane during a Tonian (820-790 Ma) orogenic event, prior to final development of the Ediacaran Ribeira belt arc-related magmatism and a transcurrent shear zone system. The main source area for detrital zircons of the Embu Complex is likely to be the Grenville-Sveconorwegian-Sunsás orogen or time-equivalent regions rather than the central portions of the neighboring cratons. The Embu Complex geological context is consistent with accumulation on the margin of the Rodinia supercontinent.

KW - Neoproterozoic

KW - Mesoproterozoic

KW - Votuverava Group

KW - São Roque Group

KW - Apiaí Terrane

KW - Detrital zircon

KW - U-Pb geochronology

U2 - 10.1016/j.precamres.2018.10.010

DO - 10.1016/j.precamres.2018.10.010

M3 - Article

SN - 0301-9268

VL - In press

JO - Precambrian Research

JF - Precambrian Research

ER -

The Tonian Embu Complex in the Ribeira Belt (Brazil): revision, depositional age and setting in Rodinia and West Gondwana

Abstract

Keywords

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