Radiation Measurements 39 (2005) 669–673 www.elsevier.com/locate/radmeas Thermotectonic and fault dynamic analysis of Precambrian basement and tectonic constraints with the Parana basin L.F.B. Ribeiroa,∗, P.C. Hackspachera, M.C.S. Ribeiroa, J.C. Hadler Netob, S.C.A. Telloc, P.J. Iunesb, A.O.B. Francoa, D.F. Godoya aIGCE/UNESP, P.O. Box 178, 132506-900 Rio Claro, SP, Brazil bIFGW/UNICAMP, P.O. Box 6152, 13081-970 Campinas, SP, Brazil cDF/UNESP, P.O. Box 178, 13506-700 Presidente Prudente, SP, Brazil Received 13 February 2004; accepted 30 September 2004 Abstract The Precambrian crystalline basement ofsoutheast Brazil is affectedby many Phanerozoic reactivations ofshear zones that developed during the end ofthe Neoproterozoic in the Brasiliano orogeny. These reactivations with specific tectonic events, a multidisciplinary study was done, involving geology, paleostress, and structural analysis offaults,associated with apatite fission track methods along the northeastern border ofthe Parana basin in southeast Brazil. The results show that the study area consists ofthree main tectonic domains, which record differentepisodes ofuplift and reactivation of faults. These faults were brittle in character and resulted in multiple generations of fault products as pseudotachylytes and ultracataclasites, foliated cataclasites and fault gouges. Based on geological evidence and fission track data, an uplift of basement rocks and related tectonic subsidence with consequent deposition in the Parana basin were modeled. The reactivations ofthe basement record successive upliftevents during the Phanerozoic dated via corrected fission track ages, at 387±50 Ma (Ordovician); 193±19 Ma (Triassic); 142±18 Ma (Jurassic), 126±11 Ma (Early Cretaceous); 89±10 Ma (Late Cretaceous) and 69 ± 10 Ma (Late Cretaceous). These results indicate differential uplift of tectonic domains of basement units, probably related to Parana basin subsidence. Six major sedimentary units (supersequences) that have been deposited with their bounding unconformities, seem to have a close relationship with the orogenic events during the evolution of southwestern Gondwana. © 2005 Elsevier Ltd. All rights reserved. Keywords: Fission track dating; Reactivations; Thermochronology in Brazil; Parana basin 1. Introduction generation and deformation of pseudotachylites and catacl- asites. These tectonic features have probably become closer The correlation ofbasement tectonics with basin for- correlations with the subsidence and depositional cycles in mation can be studied associated with the basement uplift the sedimentary basin. In the case ofthe Parana basin, the and the reactivation ofthe brittle faultsdemonstrated by evolution seems to have been strongly influenced by com- pressive and extensional events that developed during the ∗ Corresponding author. Tel.: +55 19 35262831; fax: +55 19 524 subduction ofPanthalassan plate under the southwestern 9689. Gondwana margin. These pulses are recorded as important E-mail address: [email protected] (L.F.B. Ribeiro). unconformities in the stratigraphic framework of the basin 1350-4487/$ - see front matter © 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.radmeas.2004.09.007 670 L.F.B. Ribeiro et al. / Radiation Measurements 39 (2005) 669–673 Fig. 1. Simplified structural sketch with brittle faults at the border between Mantiqueira Mountain range and Parana basin. and differential uplift and denudation histories of the base- The evolution ofeach supersequence was affectedby a par- ments record these tectonics effects (Milani, 1997; Milani ticular tectonic and climatic setting. and Zalán, 1999). The basement neighboring northeast Parana basin has a The study area is located in southeastern Brazil, at rheology and mechanical behavior determined by its com- the limit between the Mantiqueira Mountain range and position and structural fabric. Thus, it is important to under- Parana basin, where near Mantiqueira Mountain range and stand basement evolution. This knowledge ofthe basement Parana basin the fault system prolongated into Parana basin structures allows models that can predict which structures (Fig. 1). are development reactivated and how they will move under an applied stress and its relations with the Parana basin. Us- ing plate tectonic reconstructions, the far-field stress state 2. Structuration of Parana basin during past events can be estimated and kinematic recon- structions produced for each event can be reconstructed. The Parana basin constitutes the large sedimentary deposit Basin sediments deform in response to movements in the located in centraleastern South America, developed during basement and to gravity. Knowing how and when the base- Paleozoic and Mesozoic times and contains a stratigraphic ments move, provides a basis for predicting the most likely record ranging in age from Late Ordovician to Late Creta- locations ofdepocentres and structures in the sediments. ceous. The geological background ofthe Parana basin was analyzed in the research of Milani (1997) considering it to be pertinent to southwestern Gondwana. Such allostratigraphic 3. Methodologies units were continuously affected during almost all Phanero- zoic by compressional stresses derived from a persistently In this paper, we applied to three different geologic do- active convergent motion between the continental block of mains, paleostress analysis for the reconstruction of the west Gondwana and the oceanic lithosphere ofPhantalassa. basement tectonic uplift and correlations with subsidence The Parana basin, in spite ofbeing supported by a cratonic and deposition ofthe Parana basin. These results were inte- basement since its inception, had in its neighborhood, ac- grated with apatite fission track data. tive collisional belts related to southern Gondwana’s geo- dynamics. Six major allostratigraphic units are recognized: Rio Ivaí (Late Ordovician); Parana (Devonian); Gondwana 4. Paleostress analysis I (Permian/Early Triassic); Gondwana II (Middle to Late Triassic); Gondwana III (Upper Jurassic–Neocomian) and In order to determine the relative chronology between Bauru (Aptian–Maastrichtan–Upper Cretaceous). These su- the fault populations, we applied paleostress analysis. This persequences are the remnant record ofsuccessive phases methodology consists ofstudying faultcharacteristics to ob- ofsediment accumulation alternating with erosion periods. tain the orientation ofstress tensors. This methodological L.F.B. Ribeiro et al. / Radiation Measurements 39 (2005) 669–673 671 Table 1 Relations between fission track ages and subsidence and sedimentation ofsupersequences referredby Milani (1997) and Milani and Zalán (1999) and principal paleostress tensor (1) Geologic ages Correct ages (Ma) Subsidence and sedimentation ofTensor 1 supersequences (see text) Upper Cretaceous 69 Bauru NW Lower Cretaceous 126 Gondwana III NW Jurassic 142 Reactivation offaults — Triassic 193 Gondwana II NE Ordovician 487 Rio Ivaí NE Table 2 Characteristics ofthe collected samples L /L ε /ε / Sample UTM coordinates 0 i 238 s i Fission track age (Ma) Corrected fission track ages (Ma) TF-99 7453649,307172 0.75 0.67 1.21 77 ± 9(11, 7%) 114 ± 1(0.9%) TF-100 7453650,307184 0.72 0.64 0.87 65 ± 14(21%) 142 ± 18(12,6%) TF-96 7544056,410420 0.78 0.72 0.96 62 ± 7(11%) 89 ± 10(11%) TF-107 7421525,273297 0.82 0.77 1.05 43 ± 4(9%) 55 ± 5(9%) TF-92 7544759,41570717 0.78 0.77 1.12 49 ± 6(12%) 69 ± 10(14%) TF-101 7424860,4158719 0.74 0.65 4.07 254 ± 20(7,9%) 470 ± 50(10,6%) TF-106 7421525,273297 1.8 0.67 0.68 139 ± 12(8,6%) 193 ± 19(9,84%) UTM is the coordinates ofsamples; L0/Li is relations ofmean fossiland induced lengths oftracks; ε238/ε, is age corrector factor; / s i, is the fossil (induced) track density. study ofthe stress inversion offault-slipdata is executed The correct fission track ages were calculated using the for the fault population classified to be of a single tectonic standard fission track age equation (Hurford and Green, faulting event, that is, of one stress field. Measured faults are 1982) with corrections outlined by Tello (1994), Tello first classified into several groups on the basis ofstress types (1998), Hadler Neto et al. (2001) and Tello et al. (2003). (normal faults, strike-slip faults and reverse faults), orienta- Conventional errors calculated from the total number of tions ofanticipated stress axes, existence or absence oftilt- tracks counted and reflecting purely Poissonian variation, ing, and possibly, mineral species filling the faults (Table 1). quoted at ±2, using the grain population method (Wagner Technical framework was defined by Angelier and Mechler and Van den Haute, 1992). The used parameters are shown (1977) and refined by Angelier (1994). The principal faults in Table 2. recognized are: this Extrema Fault zone, Camanducaia Fault zone, Campinas Fault zone, Moreiras Fault zone (N direc- tion) and Jundiuvira Fault zone (EW direction) (Fig. 1). Five 6. Results and discussion tectonic phases were defined and one stress tensor obtained for each geological period (Table 1). The integration ofthe results was simulated in the model showed in Fig. 2. The results indicate different phases of basement rocks uplift; these phases were correlated with 5. Apatite fission track thermochronology contemporaneous subsidence and deposition ofthe super- sequences on the Parana basin. This scenario is depicted in In this study, we report new fission track ages for ten 4- Fig. 2A, where the basement is uplifted during the Trias- kg samples ofPrecambrian basement which were collected sic with respective