The difficulties in the identification of boudinated bodies happen whenever isolated or isolated look-like boudins structures occur. Figure shows the criteria for identifying micro and meso structures that could be misunderstand with boudins.Co-funded by the European Union through the European Regional Development Fund, based on COMPETE 2020 (Programa Operacional da Competitividade e Internacionalização), project ICT (UID/GEO/04683/2013) with reference POCI-01-0145-FEDER-007690 and national funds provided by Fundação para a Ciência e a Tecnologi

Pamplona, J.

Rodrigues, Benedito Jesus Gonçalves Calejo

English

The difficulties in the identification of boudinated bodies happen whenever isolated or isolated look-like boudins structures occur. Figure shows the criteria for identifying micro and meso structures that could be misunderstand with boudins.The author J. Pamplona was co-funded by the EU, based on COMPETE 2020, project ICT (UID/GEO/04683/2013), reference POCI-01-0145-FEDER-007690, national funds provided by FCT

Universidade do Minho: RepositoriUM

DRT2019: GRAPHICAL ABSTRACTS  				Isolated boudins or isolated look-l ike boudins structures? B. Calejo Rodrigues | J. Pamplona   The difficulties in the identification of boudinated bodies happen whenever isolated or isolated look-like boudins structures occur. Figure shows the criteria for identifying micro and meso structures that could be misunderstand with boudins. 	

Isolated boudins or isolated look-like boudins structures?

Benedito C. Rodrigues*1, Jorge Pamplona2 *1 CCT, Universidade do Minho,  4710-057 Braga, Portugal. bjc.rodrigues@gmail.com  2ICT/DCT, Universidade do Minho,  4710-057 Braga, Portugal. Isolated boudins or isolated look-like boudins structures?UNIVERSIDADE DO MINHOCCT /  ICTDRT 2019AcknowledgementsICT  is co-funded by the European Union through the European Regional Development Fund, based on COMPETE 2020 (Programa Operacional da Competitividade e Internacionalização), project ICT (UID/GEO/04683/2013) with reference POCI-01-0145-FEDER-007690 and national funds provided by Fundação para a Ciência e a Tecnologia. We want to acknowledge to Náná by the logistic support.- Arslan, A., Passchier, C.W., Koehn, D., 2008. Foliation boudinage. Journal of Structural Geology 30, 291-309.- Berthé, D., Chokroune, P., Jegouzo, P., 1979. Orthogneiss, mylonite and non-coaxial deformation of granites: the example of South Armoricain shear zone. Journal of Structural Geology 1: 31-42.- Bons, P.D., Druguet, E., Hamann, I., Carreras, J., Passchier, C.W., 2004. Apparent bou- dinage in dykes. Journal of Structural Geology 26: 625–636.- Goscombe, B.D., Passchier, C.W., Hand, M., 2004. Boudinage classication: end-member boudin types and modied boudin structures. Journal of Structural Geology 26: 739-763.- Grasemann, B., Dabrowski, M., 2015. Winged inclusions: Pinch-and-swell objects during high-strain simple shear. Journal of Structural Geology 70: 78-94.- Hanmer, S., 1990. Natural rotated inclusions in non-ideal shear. Tectonophysics 176: 245-255.- Lister, G., Snoke, A., 1984. S-C Mylonites. Journal of Structural Geology 6: 617-638.- Pamplona, J., Rodrigues, B.C., 2011. Kinematic interpretation of shearband boudins: new parameters and ratios useful in HT simple shear zones. Journal of Structural Geology 33 (1), 38-50.- Passchier, C.W., Simpson, C., 1986. Porphyroclast systems as kinematic indicators. Journal of Structural Geology 8: 831-844.- Passchier, C.W., Goscombe, B.D., 2008. Photograph of the month: pseudo-boudins inpegmatite, Arunta, Australia. JJournal of Structural Geology: 30, 273.- Platt, J.P., Vissers, R.L.M., 1980. Extensional structures in anisotropic rocks. Journal of Structural Geology 2, 397-410.- Ponce, C., Druguet, E., Carreras, J., 2013. Development of shear zone-related lozenges in foliated rocks. Journal of Structural Geology 50: 176-186.- Rodrigues, B.C., Pamplona, J., 2018. Boudinage and shearband boudins: A meso to micro-scale tool in structural analysis Jour-nal of Structural Geology 114, 280-287.- Van Den Driessche, J., Brun, J.P., 1987. Rolling structures at large shear strain. Journal of Structural Geology 9: 691-710.- ten Grotenhui, S.M., Trouw, R.A.J,Passchier, C.W., 2003. Evolution ofmica sh in mylonitic rocks. Tectonophysics 372:1–21.- Virgo, S.,  von Hagke, C., Janos, L., Urai, J.L., 2018. Multiphase boudinage: a case study of amphibolites in marble in the Naxos migmatite core. Solid Earth 9: 91–113.Referencesisolated drawnshearbandc´type-ISnSnMINERAL-FISH(ten Grotenhui et al., 2003; Mukherjee, 2011) FOLIATION BOUDINAGE (X-type)(e.g., Platt & Vissers, 1980; Arslan et al., 2008) C´-S STRUCTURESC-S STRUCTURESσ-CLAST δ-CLASTWINGED INCLUSIONS(e.g., Hanmer, 1990; Grasemann & Dabrowski, 2015)(late shearband type)SnSnc´type-ISnc´type-I(domino type)isolated tornWk = 0R <<m >> ROLLING STRUCTURE(e.g., Van Den Driessche & Brun, 1987)dominoWk = 0R <m <<Wk ≤ 1R >>m <<Wk ≤ 1R <<m >>Wk ≈ 1,5R <<m>>Wk ≈ 1,5R >m <<Wk ≤ 1R >m <Wk ≤ 1R < (≈ 1) m >>Wk ≤ 1SIMILAR GEOLOGICAL STRUCTURE Disctintive characteristicsBOUDIN TYPEschematic development of a rolling structure from a “boudin”schematic development of a winged inclusion from a “boudin”geometrical look-like particleless structures geometrical look-like with particles structures (e.g., Passchier & Simpson, 1986)TECTONIC LOZENGE(e.g., Ponce et al., 2013)(e.g., Berthé et al., 1979; Lister, G. & Snoke, 1984)  (e.g., Goscombe et al., 2004; Pamplona & Rodrigues, 2011; Rodrigues & Pamplona, 2018)  (e.g., Goscombe et al., 2004; Pamplona & Rodrigues, 2011; Rodrigues & Pamplona, 2018)  Sn: foliation plane (metamorphic or mylonitic)c’ type-I: secondary synthetic shear planeWk: kinematic vorticity number R: particle axial ratiom: particle/matrix viscosity contrastLEGEND- σ and δ clasts have a monomineral core(porphyroclast) and present pressureshadows parallel to the foliation (Sn)- foliation boudinage, C-S structures , C´-S structures and tectonic lozenge have no particles/layer inside- tectonic lozenge late shearband type has opposite kinematic sensePSEUDO-BOUDIN(e.g., Bons et al., 2004; ; Passchier and Goscombe, 2008) drawn  boudinshearband  boudintorn boudindomino  boudin(Virgo et al., 2018) (adapted from www.travelinggeologist.com) 5 cm5 cm- rolling structures have anking structures  (generate by pressure shadows or by drag), otherwise, on boudins these structures onlycould be generate when boudins are oblique to the fabric and by drag- kinematics between  anking structures and isolated domino is opposite- winged inclusion are reworked pinch-and-swell which rotate toghether with their pinched endsIntroductionDescription and Discussion- tips of mineral-sh generally are paralellto foliation (Sn). Mineral-sh are inlled byporphyroclasts and ned mineral-  have crosscutting relationships, little or no internal deformation and S0, Sn and old veins can be continuous across “inter-boudin space”.The diculties in the identication of boudinated bodies happen whenever isolated or isolated look-like boudins structures occur. ”Description and Discussion” shows the criteria for identifying micro and meso structures that could be misunderstand with boudins. Each of these structures could be related with dierent geological conditions with of kinematics, vorticity ( Wk), axial ratio (R) and viscosity contrast (m).

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Isolated boudins or isolated look-like boudins structures?

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