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Accepted Manuscript An overview of the Mesozoic-Cenozoic magmatism and tectonics in Eastern Paraguay and central Andes (Western Gondwana): Implications for the composition of mantle sources Ricardo H. Omarini, Massimo Gasparon, Angelo De Min, Piero Comin-Chiaramonti PII: S0895-9811(16)30224-3 DOI: 10.1016/j.jsames.2016.10.002 Reference: SAMES 1619 To appear in: Journal of South American Earth Sciences Received Date: 21 March 2016 Revised Date: 14 September 2016 Accepted Date: 3 October 2016 Please cite this article as: Omarini, R.H., Gasparon, M., De Min, A., Comin-Chiaramonti, P., An overview of the Mesozoic-Cenozoic magmatism and tectonics in Eastern Paraguay and central Andes (Western Gondwana): Implications for the composition of mantle sources, Journal of South American Earth Sciences (2016), doi: 10.1016/j.jsames.2016.10.002. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 1 ACCEPTED MANUSCRIPT An overview of the Mesozoic-Cenozoic magmatism and tectonics in Eastern Paraguay and central Andes (western Gondwana): implications for the composition of mantle sources. by Ricardo H. Omarini 1, Massimo Gasparon 2* Angelo De Min 3, Piero Comin-Chiaramonti 3 1Facultad de Ciencias Naturales, Universidad Nacional de Salta, Argentina 2School of Earth Sciences, The University of Queensland, St Lucia, Qld 4072, Australia 3Department of Mathematics and Geosciences, Università di Trieste, Via Weiss 8. I-34127 Trieste, Italy *corresponding author: [email protected] PREFACE The paper is dedicated to Ricardo Héctor Omarini, full professor at the Salta University and president of the “Centro de Estudios Geologicos Andinos”. He planned this publication in January 2015 together with Piero Comin-Chiaramonti. Unfortunately, Ricardo passed away on June 28, 2015, but always remains in our hearts. ABSTRACT The amalgamation of the Western Gondwana (including the Greater Gondwana supercraton) occurred at 600 Ma during the Brazilian – Pan African orogeny. A plate junction related to this event is marked by the Transbrazilian lineament which separates the South American continent into two sectors: the Eastern Paraguay-Brazilian and Central Andean domains. An overview of the geodynamic data from these two sectors indicates that the two domains were subjected to distinct evolutions from the Proterozoic to the present. The Andean domain is characterized by long-lived subduction processes linked to the convergence and consequent collision of microplates since the MiddleMANUSCRIPT Proterozoic (western Amazonian Craton) with a peak at about 600-580 Ma. The Paraguay-Brazilian do main remained relatively stable but was affected by extension episodes that reactivated ancient (Early and Middle Proterozoic) suture zones. These different geodynamic evolutions seem to reflect broadly distinct mantle compositions. In the subduction zones of the Andean domain the mantle was deeply modified by metasomatic processes following the subduction of oceanic plates. Consequently, the Andean type magma sources show a clear HIMU imprint inherited from the MORB, whereas the Paraguay-Brazilian sector shows a prevalent EMI and subordinate EMII character. The petrological data mainly from Mesozoic and Cenozoic magmatic events in the two sectors are reviewed to investigate the current mantle plume and mantle dome models for the uprising of the asthenospheric (or sub-lithospheric) material. Key Words: Magmatism; South America; Eastern Paraguay; Mantle Plumes ; End-member source . 1. Introduction This paper presents a revision of petrological, geological, geochemical and geophysical studies of continental magmatism in the central sector of Eastern Paraguay and the central Andes (South American Platform) during the ACCEPTEDMesozoic-Cenozoic time, to elucidate the parental mantle sources (Cristiani et al., 2005 and Comin-Chiaramonti et al., 2009). The area considered in this paper is characterized by potassic, sodic and alkaline-peralkaline continental magmatic rocks associated to the continental tholeiitic basalts of two LIPs (large igneous provinces), namely the Central Atlantic Magmatic and the Parana Etendeka provinces exposed over different geographic domains from eastern to western sides of the Transbrazilian lineament (TBL of Cordani et al., 2013 and references therein; see also Figure 1). The largest volume of tholeiitic and alkaline rocks are located on the eastern sector of the TBL, parallel to the continental margin of the South American (Atlantic) domain. Magmatic activity in the western sector of the TBL is minor in volume and developed within or close to a series of rift basins parallel to the western border of the South America Continent (proto-Andean domain). Notably, the magmatism, developed within the late Proterozoic to Early Paleozoic basement, contains also marine and continental sediments of 2 ACCEPTED MANUSCRIPT Jurassic/Cretaceous ages. The opening of the Atlantic Ocean, in the context of the breakup of the Gondwana continent, has controlled the magmatic activity in these sectors. In terms of chemical and petrological relationships, these areas have been rarely considered together with the exception of a study on lavas carrying mantle xenoliths (Comin-Chiaramonti et al., 2009). The eastern TBL sector has been extensively studied by Piccirillo and Melfi (1988), Hawkesworth et al.(1992, 2000), Comin-Chiaramonti and Gomes (1996, 2005), Gibson et al. (2006), Velázquez et al. (2006), Comin-Chiaramonti et al. (2007a) and Foulger and Jurdy (2007). The main reviews of the western sector of the TBL (Central Andean domain) are those of Viramonte et al. (1999), Tawackoli et al. (1999), Jaillard et al. (2000), Sempere et al. (2002), Lucassen et al. (2002, 2005), Schultz et al. (2004), Cristiani et al. (2005), Hauser et al. (2010a,b), Omarini et al. (2013) and Rocha Junior et al. (2013). The aim of this review is to propose and illustrate a new interpretation of the Mesozoic-Cenozoic magmatism in the Brazilian Platform and Central Andes domains, and to explore their geochemical and petrological differences in terms of mantle sources. 2. Geodynamic background The tectonic development of the South American platform (20-28°S) (Western Gondwana) includes five major events (Figures 1 and 2): (a) Gondwana amalgamation between 850 and 480 Ma (Tro mpette, 1994; Unrug, 1996; Grunow, 1999; Cordani et al., 2000, 2003 a,b, 2013; Almeida et al., 2000; Fuck et al., 2008 , 2014); (b) development of the extensive Central Atlantic tholeiitic magmatic province (at about 200 Ma; Marzoli et al., 1999); (c) development of the large igneous provinces in connection with the Serra Geral flood tholeiites at 135-133 Ma (Bellieni et al., 1986; Rocha -Campos et al., 1988; Renne et al., 1992); (d) emplacement of potassic magmatism and sodic mafic-ultramafic magmatism in southeast and central Paraguay at 138-59 Ma (Comin-Chiaramonti et al., 1986, 2001, 2005a,b, 2007a,b; Veláz quez et al., 2002, 2006); (e) development of rift-related alkaline-peralkaline magmatism and tholeiitic basaltic sills in the central Andes at 184-60 Ma (Viramonte et al.,MANUSCRIPT 1999; Sempere et al., 2002; Schultz et al., 2004; Hauser et al., 2010a,b ; Cristiani et al., 2005; Lucassen et al, 2005; Comin -Chiaramonti et al., 2009; Omarini et al., 2013). The geodynamic evolution of Western Gondwana during the late Precambrian-early Paleozoic times reflects the paleogeographic reorganization centered on the San Francisco craton that involved the consumption of inter-oceanic ensialic basins during the Brazilian and Panafrican orogeny (Plumb and James, 1986; Trompette, 1994; Unrug, 1996; Brito Neves et al., 1999; Cordani et al., 2000; Figure 1b). The Brazilian cycle, in its original definition (Almeida, 1945, 1968), describes the tectonic activity on the flanks of the Archean and Early Proterozoic proto-South American shields (i.e., Amazonia, Arequipa, Antofalla, Pampia, Río de la Plata, Luis Alves, Río Apa and San Francisco) between 890 and 480 Ma (Cordani et al., 2000 and references therein). In northwestern Argentina, the time-equivalent Pampean cycle (Aceñolaza and Toselli, 1976) defines the late Precambrian reorganization as a consequence of the accretion of the Arequipa-Antofalla microplates (Omarini et al., 1999). The accretion history in the central Andes region during this time (Figure 1 c) is equivalent to the closure of the sutures recognized between 580 and 530 Ma in many Laurentian and proto-Gondwanan terranes (Condie, 1989; Keppie and Dostal, 1998; OmariniACCEPTED et al., 1999). 3 ACCEPTED MANUSCRIPT MANUSCRIPT ACCEPTED 4 ACCEPTED MANUSCRIPT Fig. 1 (A) Location of the studied area within the Gondwana continent. Abbreviations: MS = Mozambique suture. (B) West Gondwana (adapted from De Wit et al., 1999) showing the major Precambrian shields (in grey) surrounded by the Brazilian/Pan African mobile belts (in green). For details, see Unrug (1996); Grunow (1999); Cordani et al.(2000, 2003a,b); Almeida et al.(2000); Fuck et al. (2008).Craton abbreviations: AR = Arequipa; AN = Antofalla; PAM = Pampia; PA = Paraguay; RA = Rio Apa; AM = Amazonia; SF = San Francisco; LA = Luis Alves; KA = Kalahari; CO = Congo;