CaK-clinoptilolite, KNa-chabazite, KNa-heulandite, KNa-erionite and Na-phillipsite from tuffaceous rocks, Province of the Mesa Central, Mexico

CaK-clinoptilolite, KNa-chabazite, KNa-heulandite, KNa-erionite and Na-phillipsite from tuffaceous rocks, Province of the Mesa Central, Mexico   CaK-clinoptilolita, KNa-chabazita, KNa-heulandita, KNa-erionita y Na-phillipsita de rocas tobáceas, Provincia de la Mesa Central, México   Liberto de Pablo1*, Mercedes Doval†2, Angel La Iglesia3, Jesús Soriano4   1 Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 México D.F., Mexico. *. 2 Departamento de Cristalografía y Mineralogía, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, 28040 Madrid, Spain. 3 Instituto de Geociencias CSIC-UCM, Facultad de Ciencias Geológicas, Avda. Antonio Novais 2, 28040 Madrid, Spain. 4 Laboratorio Central de Estructuras y Materiales CEDEX, Ministerio de Fomento, Madrid, Spain.   Manuscript received: August 14, 2013 Corrected Manuscript received: January 21, 2014 Manuscript accepted: January 26, 2014   ABSTRACT This paper presents the occurrence, mineralogy and process of formation of CaK-clinoptilolite, KNa-chabazite, KNa-heulandite, KNa-erionite and Na-phillipsite in pyroclastic rocks from the Calvillo-Jalpa-Nochixtlán area in the Province of the Mesa Central, Mexico. CaK-clinoptilolite, (Si30.600-30.150Al5760-5.220)(Ca1890-1.800K1080-0.810Mg0.540-0450)O72, of 5.04-5.86 Si/Al, 0.83-0.86 Si/(Si+Al) and 0.26-0.31 (Na+K)/ (Na+K+Ca+Mg) ratios, free of Na, crystallized from siliceous alkaline pore fluids and glasses of composition (Si0.890-0825Al0.202-0.102)(K0.072-020Ca0.020-0.010Fe0.050-0.010)O2 in tuffaceous rocks northeast of Jalpa. KNa-heulandite, (Si28.080Al8.010)(K4.680Na2.250Ca0.270Fe0.180)O72, KNa-chabazite, (Si9.210-9.000Al3.090-2.940)(K0.750-1.180Na0.360-1.260Ca0.150-0.030Fe0.210-0.090Mg0.380-0.210) O24, NaK-erionite, (Si27.990Al7.830)(K2.000)(K4.210Na1.620Ca0.090Fe0.090Mg0.180)O72, and Na-phillipsite, (Si12.080Al3.920(Na3.160K0.240Ca0.160Fe0.040) O32, of 2.91-3.57 Si/Al, 0.74-0.78 Si/(Si+Al) and 0.72-0.97 (Na+K)/ (Na+K+Ca+Mg) ratios, dominant exchange cations K and Na, formed from siliceous alkaline high-pH fluids and glasses of composition (Si0.910-0.833Al0.170-0.092) (K0.101-0.050Na0-0.033-0.027)02 in tuffs northwest of Nochixtlán. The zeolites were formed in the Jalpa area by diagenetic alteration of the tuff; in the Nochixtlán area, enrichment of Na and formation of alkali-rich zeolites was attributed to alkaline saline brines in an open hydrologic system. They occur in Oligocene - early Miocene tuffaceous rocks associated to the volcanism of the Sierra Madre Occidental, exposed in the Calvillo-Jalpa-Nochixtlán area in the states of Aguascalientes and Zacatecas, in the Province of the Mesa Central, Mexico. Keywords: CaK-zeolites, KNa-zeolites, zeolites, Mexico.   RESUMEN Este trabajo presenta la ocurrencia, mineralogía y proceso de formación de CaK-clinoptilolita, KNa-chabazita, KNa-heulandita, KNa-erionita y Na-phillipsita en rocas piroclasticas del área de Calvillo-Jalpa-Nochixtlán, en la Provincia de la Mesa Central, México. CaK-clinoptilolita, (Si30.600-30.150Al5760-5.220)(Ca1890-1.800K1080-0.810Mg0.540-0450)O72, de relaciones 5.04-5.86 Si/Al, 0.83-0.86 Si/(Si+Al) y 0.26-0.31 (Na+K)/(Na+K+Ca+Mg), libre de Na, cristalizó de fluidos de poro silícicos alcalinos y vidrios de composición (Si0.890-0825Al0.202-0.102)(K0.072-020Ca0.020-0.010Fe0.050-0.010)O2 en tobas al noreste de Jalpa. KNa-heulandita, (Si28.080Al8.010)(K4.680Na2.250Ca0.270Fe0.180)O72KNa-chabazita, (Si9.210-9.000Al3.090-2.940)(K0.750-1.180Na0.360-1.260Ca0.150-0.030Fe0.210-0.090Mg0.380-0.210) O24,NaK-erionita, (Si27.990Al7.830)(K2.000)(K4.210Na1.620Ca0.090Fe0.090Mg0.180)O72, y Na-phillipsita, (Si12.080Al3.920(Na3.160K0.240Ca0.160Fe0.040) O32, de relaciones 2.91-3.57 Si/Al, 0.74-0.78 Si/ (Si+Al)y 0.72-0.97 (Na+K)/(Na+K+Ca+Mg), cationes intercambiables dominantes K y Na, cristalizaron de fluidos de poro silicicos alcalinos de alto pH y de vidrios de composición (Si0.910-0.833Al0.170-0.092) (K0.101-0.050Na0-0.033-0.027)02 en tobas al noroeste de Nochixtlán. Las zeolitas se formaron, en Jalpa, por diagenesis de la toba;en Nochixtlán, el enriquecimiento de Na y la formación de zeolitas alcalinas se atribuye a la acción de salmueras alcalinas salinas, en un sistema hidrológico abierto. Las zeolitas ocurren en tobas del Oligoceno - Mioceno temprano asociadas al volcanismo de la Sierra Madre Occidental y expuestas en el área de Calvillo-Jalpa-Nochixtlán, estados de Aguascalientes y Zacatecas, en la Provincia de la Mesa Central, México. Palabras clave: CaK-zeolitas, KNa-zeolitas, zeolitas, México.   INTRODUCTION This paper presents the occurrence, mineralogy and process of formation of alkali-rich zeolites in volcanoclastic deposits in the states of Zacatecas and Aguascalientes in the Province of the Mesa Central, México. Alkali-rich zeolites are a not so common rarity, opposed to the widely distributed sedimentary zeolites clinoptilolite-heulandite and mordenite of CaKNaMg-exchange components. Alkali-rich zeolites have not been reported previously in Mexico. Known deposits of sedimentary zeolites in Mexico are mostly of clinoptilolite-heulandite, in the state of Oaxaca in the Province of the Sierra Madre del Sur (Wilson and Clabaugh, 1970; Mumpton, 1973; de Pablo, 1986), in the vicinity of Guanajuato and San Miguel de Allende in the Province of the Mesa Central (de Pablo et al., 1996), in the Mexican Volcanic Belt (de Pablo and Chavez, 1996) and in the state of Sonora in the Basin and Range Province (Münch and Cochemé, 1993; Münch et al., 1996). Extensive deposits of sedimentary zeolites are known in western United States, in the states of Arizona, California, Nevada and Oregon (Passaglia and Sheppard, 2001), in Italy (Passaglia and Vezzalini, 1985) and elsewhere. Alkali-rich zeolites are known from western United States (Passaglia and Sheppard, 2001) and which generally have, relative to their equivalent Italian zeolites, less K and larger Si/Al ratios (Passaglia, 1970; De'Genaro and Franco, 1976; Passaglia and Vezzalini, 1985; Passaglia and Sheppard, 2001). The formation of zeolites in volcanoclastic deposits is associated to the peculiarities of the precursor glass, the percolating fluids and the local environment, thus a close relationship prevails between the newly formed authigenic minerals and the chemistry of the glasses and pore fluids, which may change. The transformation to zeolites is possible in: (1) hydrologic closed alkaline saline systems, (2) hydrologic open systems, (3) marine environments, (4) hydrothermal systems, (5) geoautoclave systems and (6) by burial diagenesis (Hay and Sheppard, 2001). In this paper are presented the mineralogy and origin of CaK-, KNa- and Na-zeolites from the Province of the Mesa Central, Mexico. The area studied is known for a high incidence of pulmonary diseases (Reyes-Veyna, 2007). The interest is on the origin of the alkali-rich zeolites, contribute to the knowledge (...truncated)