Palaeomagnetis and rock magnetism of selected intrusive igneous bodies from southern Mexico i reconnaissance study of the Acapulco and Tierra Colorada intrusives
Main Article Content
Abstract
Palaeomagnetic data from a total of 60 oriented samples collected from two intrusive bodies, the Acapulco granite (Rb-Sr date on biotite of 48 ± 0.5 m.y.) and the Tierra Colorada monzonite (Rb-Sr date on biotite of 36.6 ± 2 m.y.), are reported. Alternating field and thermal demagnetization reveal that the palaeomagnetic record of the intrusives is complex. The results sugest that relatively rapid apparent geomagnetic variations are recorded by the intrusives, and different explanations are considered: (1) geomagnetic field variations being recorded by the cooling of the bodies, (2) remagnetization effects, (3) relative tectonic movements within the bodies, (4) tectonic movements of the bodies as coherent units, and (5) extreme magnetic instability. No definitive explanation is given. The magnetic response of the instrusives is dominated by the induced magnetizations (Q-coefficients are very low), which are higher in the monzonite than in the granite.
Article Details
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
References
BECK, M. E., Jr. and P. W. PLUMLEY, 1979. Late Cenozoic subduction and continental margin truncation along the northern Middle America Trench: Discussion, Geol. Soc. Am. Bull., 90, 792-793. DOI: https://doi.org/10.1130/0016-7606(1979)90<792:LCSACT>2.0.CO;2
COLLINSON, D. W., L. MOLYNEUX and D. B. STONE, 1963. A total and anisotropic magnetic susceptibility meter, Sci. Instr., 40, 310-312. DOI: https://doi.org/10.1088/0950-7671/40/6/311
DE CSERNA, Z., 1965. Reconocimiento geológico de la Sierra Madre del Sur de México, entre Chilpancingo y Acapulco, Estado de Guerrero, Bol. lnst. Geol., UNAM, 62, 1-76.
DE CSERNA, Z., 1969. Tectonic framework of southern Mexico and its bearing on the problem of continental drift, Soc. Geol. Mex. Bol., 30, 159-168. DOI: https://doi.org/10.18268/BSGM1967v30n2a4
DE CSERNA, Z., C. FRIES, F. VALDES, C. RINCON, L. T. SILVER, H. WESTLEY, J. SOLORIO and E. SCHMITTER, 1974. Datos geocronométricos adicionales para el magmatismo Cretácico del sur de México, Asoc. Mex. Geol. Petrol., Bol., 26, 225-235.
DE SA, A. and J. W. WIDDOWSON, 1974. A digitally controlled AF demagnetizer for peak fields up to 0.1 Tesla. J. Phys. E, 7, 266-268. DOI: https://doi.org/10.1088/0022-3735/8/4/019
DICKINSON, W. R., 1970. Relations of andesites, granites and derivative sandstones to are trench tectonics, Rev. Geophys. Space Phys., 8, 813-860. DOI: https://doi.org/10.1029/RG008i004p00813
GUERRERO, J., 1973. Paleomagnetismo y relaciones 87Sr/86Sr en ignimbritas del área de Tepalcates - Navíos, Durango, Programa Reunión Anual U. G. M., pp.33-34 (abst.).
GUERRERO, J., 1976. Contributions to paleomagnetism and Rb-Sr geochronology, Ph. D. Thesis, Univ. of Texas at Dallas, 131 pp.
HESS, H. H. and J. C. MAXWELL, 1953. Caribbean research project, Geol. Soc. Am. Bull., 64, 1-6. DOI: https://doi.org/10.1130/0016-7606(1953)64[1:CRP]2.0.CO;2
KARIG, D. E., R. K. CALDWELL, G. F. MOORE and D.G. MOORE, 1978. Late Cenozoic subduction and continental-margin truncation along the northern Middle America Trench, Geol. Soc. Am. Bull., 89, 265-276. DOI: https://doi.org/10.1130/0016-7606(1978)89<265:LCSACM>2.0.CO;2
KESLER, S. E., 1973. Basement rock structural trends in southern Mexico. Geol. Soc. Am. Bull., 84, 1059-1064. DOI: https://doi.org/10.1130/0016-7606(1973)84<1059:BRSTIS>2.0.CO;2
KESLER, S. E. and S. A. HEATH, 1970. Structural trends in the southernmost North American Precambrian, Oaxaca, Mexico, Geol. Soc. Am. Bull., 81, 2471-2476. DOI: https://doi.org/10.1130/0016-7606(1970)81[2471:STITSN]2.0.CO;2
LARSEN, E. S., Jr., D. GOTTFRIED, H. W. JAFFE and C. L. WARING, 1958. Lead-alpha ages of the Mesozoic batholiths of western North America, U. S. Geol. Surv. Bull., 1070 B, 35-62.
MALFAIT, B. T. and M. G. DINKELMAN, 1972. Circum-Caribbean tectonic and igneous activity and the evolution of the Caribbean plate, Geol. Soc. Am. Bull., 83, 251-272. DOI: https://doi.org/10.1130/0016-7606(1972)83[251:CTAIAA]2.0.CO;2
MOLYNEUX, L., 1971. A complete result magnetometer for measuring the remanent magnetization of rocks, Geophys. J. R. Astr. Soc., 24, 429-433. DOI: https://doi.org/10.1111/j.1365-246X.1971.tb02188.x
MOOSER, F., NAIRN, A. E. M. and J. F. W. NEGENDANK, 1974. Paleomagnetic investigations of the Tertiary and Quaternary igneous rocks: VIII - A paleomanetic and petrologic study of volcanics of the Valley of Mexico, Geol. Rundsch., 63, 451-483. DOI: https://doi.org/10.1007/BF01820824
NAIRN, A. E. M., J. F. W. NEGENDANK, H. C. NOLTIMIER and T. J. SCHMIDT, 1975. Paleomagnetic investigations of the Tertiary and Quaternary igneous rocks. X -The ignimbrites and lava units west of Durango, Mexico, Neues. Jb. Geol. Palâont., H11, 664-678.
STEPHENSON, A., 1967. Apparatus for thermal demagnetization by the progressive method, In: D. W. Collinson, K. M. Creer and S. K. Runcom (Eds. Methods in Palaeomagnetism, Elsevier, pp. 296-298. DOI: https://doi.org/10.1016/B978-1-4832-2894-5.50051-3
URRUTIA-FUCUGAUCHI, J., 1979. Preliminary apparent polar wander path for Mexico, Geophys. J. R. Astr. Soc., 56, 227-235. DOI: https://doi.org/10.1111/j.1365-246X.1979.tb04778.x
URRUTIA-FUCUGAUCHI, J., 1980. Palaeomagnetic studies of Mexican rocks. Ph. D. Thesis, Univ. of Newcastle-upon-Tyne, U.K., 682 p.
URRUTIA-FUCUGAUCHI, J., 1981. Palaeomagnetism of the Miocene Jantetelco granodiorites and Tepexco volcanic group and inferences for crustal block rotations in central Mexico, Tectonophysics, 76, 149-168. DOI: https://doi.org/10.1016/0040-1951(81)90257-2
URRUTIA-FUCUGAUCHI, J., 1982. The palaeomagnetic field as inferred from magnetic studies on magmatic are zones. Geophys. J. R. Astr. Soc., 28, 49-56. DOI: https://doi.org/10.1111/j.1365-246X.1982.tb06961.x
URRUTIA-FUCUGAUCHI, J. and S. PAL, 1977. Paleomagnetic data from Tertiary igneous rocks, northeast Jalisco, Mexico, Earth Planet. Sci. Lett., 36, 202-206. DOI: https://doi.org/10.1016/0012-821X(77)90199-6
WALPER, J. L. and C. L. ROWETT, 1972. Plate tectonics and the origin of the Caribbean Sea and the Gulf of Mexico, Gulf Coast Assoc. Geol. Soc. Trans., 22, 105-116. DOI: https://doi.org/10.1306/819A417C-16C5-11D7-8645000102C1865D
WATKINS, N. D., B. M. GUNN, A. K. BAKSI, D. YORK and J. ADE-HALL, 1971. Paleomagnetism geochemistry and potassium - argon ages of the Rio Grande de Santiago volcanics, central Mexico, Geol. Soc. Am. Bull., 82, 1955-1968. DOI: https://doi.org/10.1130/0016-7606(1971)82[1955:PGAPAO]2.0.CO;2
ZIJDERVELD, J. D. A., 1967. AC demagnetization of rocks: Analysis of results, In: D. W. Collinson, K. M. Creer and S. K. Runcom (Eds.), Methods in Palaeomagnetism, Elsevier, pp. 254-286. DOI: https://doi.org/10.1016/B978-1-4832-2894-5.50049-5