Magnetic fabric of a Jurassic clasic sequence from Oaxaca-Puebla, southern Mexico and inferred paleocurrent flow
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Abstract
The magnetic fabric from two sections of a Mesozoic continental sequence from northern Oaxaca-Southern Puebla is interpreted as primary in some sites and secondary in others according to criteria based on (i) the anisotropy degree and its range of variation in each site, (ii) the magnetic fabric geometry and (iii) agreement with other geological indicators. The magnetic fabric was obtained from the low-field anisotropy of magnetic susceptibility (AMS) of 122 specimens from 10 stratigraphical levels. The origin interpretation is related with magnetic mineralogy and with the AMS effects of imparting isothermal remanent magnetization (IRM) and laboratory heating at 130°C and 400°C steps (in pilot specimens). Primary magnetic fabrics suggest a palaeocurrent system oriented NW (270° to 320°) for the lower section (Piedra Hueca Formation) and NNE to NW (24° to 310°) for the upper section (Otlatepec Formation). Secondary fabrics are interpreted near the contact between both units and are related to weathering and to deformation and strain direction. The AMS interpreted as of primary origin show high-coercivity magnetic phases, compare well with other palaeocurrent indicators, have low anisotropy degrees and show similar or equivalent AMS after IRM and heating steps. The AMS interpreted as of secondary origin have some low or low-intermediate coercivities show the higher and more variable anisotropy degrees, and usually loose or show a very different AMS after IRM and heatings teps . Initial AMS, after IRM AMS and after heating steps AMS was measured 3 to 6 times in each specimen in order to determine measurement precision. Statistical analyses of the repetitive measurements were performed in each specimen obtaining specimen-means of the principal AMS directions and identifying some magnetically isotropic specimens.
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References
ABOUZAHM, A. G. and D. H. T ARLING, 1975. Magnetic anisotropy and susceptibility of Late Precambrian tillites from north-western Scotland. J. Geol. Soc., London, 131, 647-652. DOI: https://doi.org/10.1144/gsjgs.131.6.0647
CABALLERO-MIRANDA, C., 1990a. Geología y Anisotropía magnética del Jurásico Continental del área Huajuapan de León-Petlalcingo, Estados de Oaxaca y Puebla. Unpublished Master Thesis, UNAM, Fac. de Ciencias. 142 p.
CABALLERO-MIRANDA, C., 1990b. Efectos de los tratamientos de desmagnetización térmica en Ia anisotropía de susceptibilidad magnética. Inst. Geofísica, México. Comunicaciones Técnicas, Serie lnvestigación 120, 27 p.
CABALLERO-MIRANDA, C., D. J. MORAN-ZENTENO, J. URRUTIA-FUCUGAUCHI, H. BÖHNEL, Z. JURADO-CHICHAY, E. CABRAL-CANO and G. SILVA-ROMO, 1990. Paleogeography of the northern portion of the Mixteca Terrane, Southern Mexico during the Middle Jurassic. J. South American Earth Sciences, 3, 4, 195-211. DOI: https://doi.org/10.1016/0895-9811(90)90003-J
CAMPA, M. F. and P. J. CONEY, 1983. Tectono-stratigraphic terranes and mineral resource distributions in Mexico. Can. J. Earth Sci, 26, 1040-1051. DOI: https://doi.org/10.1139/e83-094
ELLWOOD, B. B., F. HROUDA and J. J. WAGNER, 1988. Symposia on magnetic fabrics. Phys, Earth Planet. Ints., 51, 249-389. DOI: https://doi.org/10.1016/0031-9201(88)90066-0
ERBEN, H. K., 1956. El Jurásico Medio y el Calloviano de Mexico. XX Congr. Geol. Internal., México, 139 p.
FISHER, R. A. 1953. Dispertion on a sphere, Proc. R. Soc. London, A217, 295-305. DOI: https://doi.org/10.1098/rspa.1953.0064
GRANAR, L., 1958. Magnetic measurements on Swedish varved sediments. Arkiv. f Geofysik, 3, 1-40.
HROUDA, F., 1982. Magnetic Anisotropy of Rocks and its application in Geology and Geophysics. DOI: https://doi.org/10.1007/BF01450244
JACKSON, M and L. TAUXE, 1991. Anisotropy of Magnetic Susceptibility and Remanence: Developments in the characterization of tectonic, sedimentary and igneous fabric. Rev. of Geophys., supplement, 371-376. DOI: https://doi.org/10.1002/rog.1991.29.s1.371
JELENSKA, M. and M. KADZIALKO-HOFMOKL, 1990. Dependence of anisotropy of magnetic susceptibility of rocks on temperature. Phys. Earth Planet. Int., 62, 19-31. DOI: https://doi.org/10.1016/0031-9201(90)90189-5
JELINEK, V., 1981. Characterization of Magnetic Fabric of Rocks. Tectonophysics 79, 563-567. DOI: https://doi.org/10.1016/0040-1951(81)90110-4
KING, R. F., The remanent magnetism of artificially deposited sediments. Mon. Not. R. Astr. Soc., 7, 115-134. DOI: https://doi.org/10.1111/j.1365-246X.1955.tb06558.x
MORAN-ZENTENO, D., C. CABALLERO-MIRANDA, G. SILV A-ROMO, B. ORTEGA-GUERRERO and E. GONZALEZ-TORRES, 1993. Jurassic-Cretaceous paleogeographic evolution of Northern Mixteca terrane, southern Mexico. Geofísica Internacional, 32, 3, 453-473. DOI: https://doi.org/10.22201/igeof.00167169p.1993.32.3.522
NAGATA, T., 1961. Rock Magnetism. Maruzen, Tokio.
NOLTIMIER, H. C., 1971. Magnetic rock cylinders with negligible shape anisotropy. J. Geophys. Res., 75, 4035-4037. DOI: https://doi.org/10.1029/JB076i017p04035
ORTEGA-GUERRERO, B., 1989. Paleomagnetismo y Geología de las unidades clásticas mesozoicas del área Totoltepec-Ixcaquixtla, Estados de Puebla y Oaxaca, Unpublished Master Thesis, UNAM., Fac. Ciencias.
ORTEGA-GUTIERREZ, F., 1978. Notas sobre Ia Geología del área entre Santa Cruz y Ayuquila, Edos. de Puebla y Oaxaca, UNAM, Inst. Geol., Paleont. Mexicana 44, 17-26, 2 figs. DOI: https://doi.org/10.22201/igl.05437652e.1978.0.44.297
ORTEGA-GUTIERREZ, F., 1981. Metamorphic belts of southern Mexico and their tectonic significance. Geofísica Internacional, 20, 3, 177-202. DOI: https://doi.org/10.22201/igeof.00167169p.1981.20.3.1085
PEREZ-IBARGÜENGOITIA, J. M., A. HOKUTO-CASTILLO and Z. DE CSERNA, 1965. Estratigrafía y paleontología del Jurásico Superior de Ia parte centro-meridional del Estado de Puebla, UNAM, Inst. Geol. Paleont. Mexicana 21, 5-22.
PERARNAU, A. and D. H. TARLING, 1985. Thermal enhancement of magnetic fabric in Cretaceous sandstone. J. Geol. Soc. Lond., 142, 1029-1034. DOI: https://doi.org/10.1144/gsjgs.142.6.1029
ROCHETTE, P., M. JACKSON and C. AUBOURG, 1992. Rock magnetism and the interpretation of anisotropy of magnetic susceptibility. Reviews of Geophysics, 30, 209-226. DOI: https://doi.org/10.1029/92RG00733
SCHULTZ-KRUTISCH, T. and F. HELLER, 1985. Measurement of magnetic susceptibility anisotropy in Buntsandstein deposits from southern Germany. J. Geophys., 56, 51-58.
SCRIBA H. and F. HELLER, 1978. Measurements of anisotropy of magnetic susceptibility using inductive magnetometers. J. Geophys., 44, 341-352.
SILVA-PINEDA, A. 1984. Revisión Taxonómica y Tipificación de las Plantas Jurásicas Colectadas y Estudiadas por Wieland (1914) en Ia Región de El Consuelo, Oaxaca. UNAM Paleont. Mexicana, 49, 103 p., 31 láms. DOI: https://doi.org/10.22201/igl.05437652e.1984.0.49.331
SILVA-PINEDA, A. 1978. Paleobotánica del Jurásico de México, UNAM, Inst. Geol. Paleont. Mexicana, 44, 1-16. DOI: https://doi.org/10.22201/igl.05437652e.1978.0.44.323
TARLING, D. and F. HROUDA, 1993; The Magnetic Anisotropy of Rocks. Chapman and Hall, London.
TARLING, D. 1983. Palaeomagnetism. Chapman and Hall, London, 379 p. DOI: https://doi.org/10.1007/978-94-009-5955-2
URRUTIA-FUCUGAUCHI, J. 1981. Preliminary Results on the Effects of Heating on the Magnetic Susceptibility Anisotropy of Rocks. Jour. Geomag. Geoelectr., 33, 411-419. DOI: https://doi.org/10.5636/jgg.33.411
URRUTIA-FUCUGAUCHI and D. TARLING, 1983. Palaeomagnetic properties of Eocambrian sediments in northwestern Scotland: Implications for world-wide glaciation in the Late Precambrian. Palaeogeog., Palaeoclim., Palaeoecol., 41, 325-344. DOI: https://doi.org/10.1016/0031-0182(83)90093-7
WESTERMAN, G. E. G., R. CORONA and R. CARRASCO, 1984. The andean Mid-Jurassic Neu-queniceras amonite assemblage of Cualac, Mexico. In: Westerman, G. E. G. (Ed), Jurassic-Cretaceous biochronology and paleogeography of North America, Geol. Assoc. Canada, Sp. Paper 27, 99-112.
WIELAND, G. R., 1914. La flora liásica de Ia Mixteca Alta, Inst. Geol. Mexico, Bol. 31, 165 p.