Neoproterozoic evolution of the basement of the South-American platform

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Highlights

  • The South-American platform is composed by two different major domains.

  • In the Amazonian domain (NNW) Archean nuclei and pre-Neoproterozoic belts predominate.

  • The eastern domain is marked by complex Neoproterozoic branching system of orogens.

  • This latter domain present two orogenic collages: a Tonian and a Cryogenian–Cambrian.

Abstract

Neoproterozoic geologic and geotectonic processes were of utmost importance in forming and structuring the basement framework of the South-American platform. Two large domains with distinct evolutionary histories are identified with respect to the Neoproterozoic era: the northwest-west (Amazonian craton and surroundings) and the central-southeast (the extra-Amazonian domain).

In the first domain, Neoproterozoic events occurred only locally and were of secondary significance, and the geologic events, processes, and structures of the pre-Neoproterozoic (and syn-Brasiliano) cratonic block were much more influential. In the second, the extra-Amazonian domain, the final evolution, structures and forms are assigned to events related to the development of a complex net of Neoproterozoic mobile belts. These in turn resulted in strong reworking of the older pre-Neoproterozoic basement. In this domain, four distinct structural provinces circumscribe or are separated by relatively small pre-Neoproterozoic cratonic nuclei, namely the Pampean, Tocantins, Borborema and Mantiqueira provinces. These extra-Amazonian provinces were formed by a complex framework of orogenic branching systems following a diversified post-Mesoproterozoic paleogeographic scenario. This scenario included many types of basement inliers as well as a diversified organization of accretionary and collisional orogens. The basement inliers date from the Archean to Mesoproterozoic periods and are different in nature. The escape tectonics that operated during the final consolidation stages of the provinces were important to and responsible for the final forms currently observed. These latest events, which occurred from the Late Ediacaran to the Early Ordovician, present serious obstacles to paleogeographic reconstructions.

Two groups of orogenic collage systems are identified. The older system from the Tonian (>850 Ma) period is of restricted occurrence and is not fully understood due to strong reworking subsequent to Tonian times. The second group of orogenies is more extensive and more important. Its development began with diachronic taphrogenic processes in the Early Cryogenian period (ca. 850–750 Ma) and preceded a complex scenario of continental, transitional and oceanic basins. Subsequent orogenies (post 800 Ma) were also created by diachronic processes that ended in the Early Ordovician. More than one orogeny (plate interaction) can be identified either in space or in time in every province. The orogenic processes were not necessarily synchronous in different parts of the orogenic system, even within the same province. This particular group of orogenic collage events is known as the “Brasiliano”.

All of the structural provinces of the extra-Amazonian domain exhibit final events that are marked by extrusion processes, are represented by long lineaments, and are fundamental to unraveling the structural history of the Phanerozoic sedimentary basins.

Introduction

The Neoproterozoic era, encompassing a long time interval around ca. 500 Ma, has been considered as one of the most important stages of the continental crust evolution and the transition from the dominant processes of large continental masses during the Mesoproterozoic era to the present-day plate tectonics (e.g. Stern, 2005). The Neoproterozoic events and records are better preserved in southern hemisphere continents because these continents were components of Gondwana, a supercontinent formed during the Neoproterozoic era as the result of gradual fusion of many continental fragments inherited from the Rodinia breakup. The Gondwana amalgamation is especially well documented in the basement of the South American and African platforms.

Within the South American platform, two large domains stand out due to their general geologic and geotectonic features as well as for their role in the history of Gondwana. In the northernmost domain, the Amazonian region and surroundings appear as one of the largest and best-preserved descendants of Rodinia, the Amazonian craton (Fuck et al., 2008; Li et al., 2008). In this large domain (>4.3 × 106 km2) of remarkable pre-Neoproterozoic evolution, Neoproterozoic events and records are restricted as secondary and/or local. The Amazonian portion shows clear pre-Mesozoic drift links to the continents of the northern hemisphere (Almeida, 1978; Fuck et al., 2008; Li et al., 2008). The inferred links have been the subject of several correlation attempts for the Archean cratonic nuclei and Paleo- and Mesoproterozoic mobile belts that evaluated possible previous supercontinental arrangements (e.g. Rogers and Santosh, 2004).

In the central, eastern and southeastern portions of the South-American continent (the extra-Amazonian domain), the so-called “Brasiliano” structures date back to the Neoproterozoic age. These Brasiliano areas encompass a large fraction of West Gondwana, including cratons and mobile belts. In the extra-Amazonian domain, structures generated by Neoproterozoic fold belts are largely dominant, although cratonic nuclei (relatively smaller than the Amazonian craton) and other pre-Neoproterozoic basement inliers of different types (Brito Neves, 2003) occur and display varied degrees of reworking in the orogenic processes. This observation indicates that several segments of pre-Neoproterozoic basement were involved to some extent in the orogenic processes during the formation of the Neoproterozoic Brasiliano orogenic belts. The basement segments include Archean to Mesoproterozoic high- to medium-grade metamorphic rock units and their Paleoproterozoic to Mesoproterozoic cover rocks.

Within the context of the Neoproterozoic collage that gave birth to the West Gondwana record in South America, it is possible to identify four major structural provinces, all positioned between cratons (see Figs. 1 and 2): Borborema (northeast of the continent), Tocantins (central South America), Mantiqueira (south and southeast) and Pampean (southwest).

These structural provinces were firstly outlined in the work of Almeida et al. (1981) with the exception of the newly added Pampean province (Argentina). Although these provinces may be revised, divided or complemented in the future, the concept of four provinces is quite practical and useful for the purpose of the current work.

Many of the structural provinces of the extra-Amazonian domain continue into the continental platform and show correspondence with the African continent, thus reflecting the Pan-African structures (see Pankhurst et al., 2008 for recent reviews on this subject).

A large polycyclic NNE shear belt is exposed between the major domains discussed above. This important lineament, known as the Transbrasiliano lineament (Schobbenhaus et al., 1975), crosses the South American continent from NW Ceará to Argentina, abutting diagonally against the suture line between the South American platform and the North Patagonian terrane (Ramos, 2008b). From NW Ceará, the lineament extends to northwest Africa, where it is referred to as the Kandi lineament. Little is known of the role of the Transbrasiliano lineament, but Phanerozoic activity has been recorded within the large Paraná and Parnaíba intracontinental sedimentary basins as well as Neogene activity in the Pantanal basin and in the coastal areas of Ceará.

In this work, we stress the differences in framework, composition, and geologic–geochronologic evolution between the two large domains. Additionally, we present the geologic and geochronologic data obtained in recent decades, showing that diachronism is more the rule than the exception in the evolution of the Neoproterozoic mobile belts in South America. We attempt to identify the most important cycles of plate interactions based on available geochronologic data and note possible exceptions. It should be stressed that multiphase processes of continental assemblages are expected to occur, similar to those previously recorded in the African counterpart (see Meert, 2003; Hanson, 2003). The diachronism of the processes is demonstrated by comparing the age data from the different phases of a complete plate interaction cycle (rifting, convergence, accretion, collision, post-collision events etc., Wilson, 1965) within the provinces and inter-provinces in the South-American continent.

The analysis of the Brasiliano provinces of our continent and their surroundings, together with comparison with recent reviews of the African continent, also stresses the diachronic aspect of the mobile belt evolution that resulted in the amalgamation of West and East Gondwana.

Since the publication of the paper by Brito Neves and Cordani (1991) on the Neoproterozoic era in South America, much progress has been gained in the general geological knowledge of both domains, as evidenced by the large number of maps and papers subsequently published. Much of this knowledge was reviewed and synthesized in the books edited by Cordani et al. (2000), Bizzi et al. (2003), Mantesso-Neto et al. (2004) and Pankhurst et al. (2008), which are recommended and obligatory literature on this subject.

Section snippets

The Amazonian or “pre-Brasiliano” domain: N-NW region of the South-American continent

The Amazonian block is considered as the largest and best-preserved descendant of the Rodinia fission in South America (Fuck et al., 2008). Encompassing more than 4,300,00 km2, the Amazonian block provides an excellent record of Meso- and Neo-archean rock formation events that resulted in cratonic seed nuclei and mobile belts formed during the Paleoproterozoic and Mesoproterozoic eras (see reviews by Tassinari and Macambira, 2004; Cordani and Teixeira, 2007). The Archean seed nucleus is located

Taphrogeneses

Several Late Stenian and Early Neoproterozoic breakup processes were reported as predecessors of the “Wilsonian” cycles of the Brasiliano orogenies. However, the larger picture is still incomplete. A rough view of the general context is presented in Chart 1. These intraplate processes presumably operated initially within Rodinia, and afterward, in the smaller continental fractions and remnants of this supercontinent.

Attention should be focused on the fact that these breakup processes co-existed

The Tonian orogenic belts

Certain Early Neoproterozoic mobile belts were recognized in the three main Neoproterozoic structural provinces of the Brazilian territory; this is a relatively new finding and is far from being fully understood. With further investigations, their number may increase.

In the central domain of the Borborema province (the so-called Transversal Zone, Cariris Velhos terrains), its southern domain (Poço Redondo, northern region of the Sergipano belt) and in the Riacho do Pontal belt, various

Nature and role of the cratons and basement inliers

The paleogeography of the Neoproterozoic Brasiliano structural provinces is complex (Figs. 2 and 3) and this includes the nature and geometry of the original basins, particularly in terms of the form, number and dimensions of the basins as well as the inter-basin “highs”. A large collection of information is available on the nature of the basins and their tectono-stratigraphic assemblages as well as on the types of plate interactions and the resulting orogenic systems, the closing of which was

Tocantins and Pampean provinces (Chart 2)

Analysis of the available data from the Tocantins and Pampean provinces points out several similarities in the timing of the tectonic processes, suggesting that they may be a component of the same geotectonic context. Therefore, their current longitudinal separation might have been caused by such younger surface processes as erosion and sedimentation. From this point of view, the accretionary phenomena dated from the Late Ediacaran to the beginning of the Cambrian period stand out. In contrast,

Comparative study on the development of the Brasiliano provinces (Chart 6)

New geological maps were produced and new geological data were acquired over the last three decades. Additionally, geological knowledge was greatly improved by a wealth of new geochronological data, mainly due to new laboratories built in Brazil and to the introduction of new analytical methods (e.g., Sm–Nd, U–Pb TIMS, SHRIMP, and ICPMS-Laser Ablation). Combined with increased cooperation from international partners, these developments have led to a general improvement in geological knowledge

The Pan-African counterpart (Chart 7)

From the point of view of geotectonic evolution through geologic time, the panel on the Neoproterozoic Brasiliano mobile belts (encompassing the 850–480 Ma time span) shows a resemblance to the fold belts of the western portion of the African continent, which together with South America correspond to West Gondwana, as previously stated in this paper. Many of these African belts are the natural continuation of portions of the South American structural provinces.

However, with respect to the

Concluding remarks

The Neoproterozoic evolution of the extra-Amazonian domain of the South American platform is marked by a number of tectonic events as summarized in Chart 1, Chart 2, Chart 3, Chart 4, Chart 5, Chart 6 above.

The main breakup events took place during the Cryogenian era, between 850 and 740 Ma. Earlier records of breakup events most likely represent local intraplate events. Younger breakup data (ca. 680 Ma) recorded in SE Bahia of east Brazil do not appear to be related to mobile belt development.

References (78)

  • V.A. Ramos

    Patagonia: a Paleozoic continent adrift?

    Journal of South American Earth Sciences

    (2008)
  • V.A. Ramos et al.

    Pampia: a large cratonic block missing in the Rodinia supercontinent

    Journal of Geodynamics

    (2010)
  • M.L.S. Rosa et al.

    Neoproterozoic anorogenic magmatism in the Southern Bahia Alkaline Province of NE Brazil: U–Pb and Pb–Pb ages of the blue sodalite syenites

    Lithos

    (2007)
  • J.O.S. Santos et al.

    Timing of mafic magmatism in the Tapajos Province (Brazil) and implications for the evolution of the Amazon craton – evidence from baddeleyite and zircon U-–Pb SHRIMP geochronology

    Journal of South American Earth Sciences

    (2002)
  • O. Siga et al.

    Lower and upper Neoproterozoic magmatic records in Itaiacoca belt (Paraná-Brazil): zircon ages and lithostratigraphy studies

    Gondwana Research

    (2009)
  • O. Siga et al.

    Calyminian (1,5–1,45 Ga) magmatic records in Votuverava and Perau sequences, south-southeastern Brazil: zircon ages and Nd–Sr isotopic geochemistry

    Journal of South American Earth Sciences

    (2011)
  • A.F. Trendall et al.

    SHRIMP zircon U–Pb on the age of the Carajás formation, Gão Pará group, Amazon Craton

    Journal of South American Earth Sciences

    (1998)
  • W.R. Van Schmus et al.

    Precambrian history of the Zona Transversal of the Borborema Province

    Journal of South American Earth Sciences

    (2011)
  • F.F.M. Almeida

    A evolução dos crátons Amazônico e do São Francisco comparada com a de seus homólogos do hemisfério norte

  • F.F.M. Almeida et al.

    Brazilian structural provinces: an introduction

    Earth-Science Reviews

    (1981)
  • R.R. Bahia et al.

    O Rift do Amazonas – sistema aulacogênico na Plataforma Amazônica

  • R.C.M. Barbosa et al.

    Paleoambiente da Formação Prosperança, embasamento neoproterozóico da Bacia Amazônica

    Revista Brasileira de Geociências

    (2011)
  • M.A.S. Basei et al.

    West Gondwana amalgamation based on detrital zircon ages from Neoproterozoic Ribeira and Dom Feliciano belts of South America and comparison with coeval sequences from SW Africa

  • B.B. Brito Neves

    A saga dos descendentes de Rodínia na construção de Gondwana

    Revista Brasileira de Geociências

    (2003)
  • B.B. Brito Neves

    The search for the lost (Neoproterozoic) oceans of Western Gondwana

  • B.B. Brito Neves et al.

    Tectonic evolution of South America during the Late Proterozoic

    Precambrian Research

    (1991)
  • B.B. Brito Neves et al.

    A Geologia do Brasil no Contexto da plataforma Sul-Americana

  • K. Burke et al.

    Origin of the rift under the Amazon Basin as a result of continental collision during Pan-African time

    International Geology Review

    (1993)
  • M.C. Campos Neto

    Orogenic systems from Southwestern Gondwana: an approach to Brasiliano-Pan African cycle and orogenic collage in Southeastern Brazil

  • N.A. Cawood

    Terra Australis Orogen: Rodinia break up and development of the Pacific and Iapetus margins of Gondwana, during the Neoproterozoic and Paleozoic

    Earth-Science Reviews

    (2005)
  • Chemale et al.

    Evolução do Arco Magmático São Gabriel

  • T.N. Clifford

    The structural framework of Africa

  • H. Conceição et al.

    Petrology of the Neoproterozoic Itarantim nepheline syenite batholith, São Francisco Craton, Bahia, Brazil

    The Canadian Mineralogist

    (2009)
  • U.G. Cordani et al.

    Tearing up Rodinia: the Neoproterozoic palaeogeography of South American cratonic fragments

    Terra Nova

    (2003)
  • U.G. Cordani et al.

    From Rodinia to Gondwana: a review of the available evidence from South America

    Gondwana Research

    (2006)
  • U.G. Cordani et al.

    Estudo Preliminar de Integração do Pré-Cambriano com os Eventos Tectônicos das Bacias Sedimentares Brasileiras

  • U.G. Cordani et al.

    Proterozoic accretionary belts in Amazonian Craton

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