The Clays of Yucatan, Mexico: A Contrast in Genesis

Isphording, Wayne C.

doi:10.1016/s0070-4571(08)70029-3

Cited by 24 publications

(25 citation statements)

References 10 publications

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“…In these deposits, palygorskite layers with thicknesses of 4-8 m are regularly observed. Palygorskite may form by dissolutionprecipitation or by neoformation processes (Isphording 1973(Isphording , 1984, by transformation of illite, smectite, or sepiolite (Rogers et al 1954;Galán and Castillio 1984;Singer 1984;Sánchez and Galán 1995), by reaction involving montmorillonite, dolomite, and silicates (e.g., Jones 1986), or by alteration of serpentine minerals (Dhannoun and AlDabbagh 1988). Furthermore, it can form by hydrothermal alteration of montmorillonite-group clays (Bonatti and Joensuu 1968) or in hydrothermal veins in mafic rocks (e.g., Gibbs et al 1993 ?Ca ?…”

Section: Palygorskite-bearing Pelitesmentioning

confidence: 99%

Protoliths and phase petrology of whiteschists

Franz

Romer

Capitani

2013

Contrib Mineral Petrol

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Whiteschists appear in numerous high-and ultrahigh-pressure rock suites and are characterized by the mineral assemblage kyanite ? talc (?-quartz or coesite). We demonstrate that whiteschist mineral assemblages are well stable up to pressures of more than 4 GPa but may already form at pressures of 0.5 GPa. The formation of whiteschists largely depends on the composition of the protolith, which requires elevated contents of Al and Mg as well as low Fe, Ca, and Na contents, as otherwise chloritoid, amphibole, feldspar, or omphacite are formed instead of kyanite or talc. Furthermore, the stability field of the whiteschist mineral assemblage strongly depends on XCO 2 and fO 2 : already at low values of XCO 2 , CO 2 binds Mg to carbonates strongly reducing the whiteschist stability field, whereas high fO 2 enlarges the stability field and stabilizes yoderite. Thus, the scarcity of whiteschist is not necessarily due to unusual P-T conditions, but to the restricted range of suitable protolith compositions and the spatial distribution of these protoliths: (1) continental sedimentary rocks and (2) hydrothermally and metasomatically altered felsic to mafic rocks. The continental sedimentary rocks that may produce whiteschist mineral assemblages typically have been deposited under arid climatic conditions in closed evaporitic basins and may be restricted to relatively low latitudes. These rocks often contain large amounts of the clay minerals palygorskite and sepiolite. Marine sediments generally do not yield whiteschist mineral assemblages as marine shales commonly have too high iron contents. Sabkha deposits may have too high CO 2 contents. Protoliths of appropriate geochemical composition occur in and on continental crust. Therefore, whiteschist assemblages typically are only found in settings of continental collision or where continental fragments were involved in subduction. Our calculations demonstrate that whiteschists can form by closed-system metamorphism, which implies that the chemical and isotopic composition of these rocks provide constraints on the development of the protoliths.

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Section: Palygorskite-bearing Pelitesmentioning

confidence: 99%

Protoliths and phase petrology of whiteschists

Franz

Romer

Capitani

2013

Contrib Mineral Petrol

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“…Japan (Imai et al, (1969) Bakkasetter, Shetland Isles, Scotland (Stephen, 1954) Tafraout, Morocco (Caill6re andHenin, 1957) Mr. Flinders, Queensland, Australia (Rogers et at., 1954) Eastern Saudi Arabia (Shadfan et al, 1985) Timsanpalli, Deccan, India (Siddiqui, 1984) Mao Kou Limestone, Sichuan province, China (Zheng, 1991) Anhui province, China (Zbeng, 1991) Jiansu province, China (Zheng, 1991) Attapulgus, Georgia, USA (Bradley, 1940) Metaiine Fails, Washington, (Huggins et al, 1962) Jordan Valley, Israel (Wiersma, 1970) Attapulgus, Georgia (Robertson, 1961) Bercimuel, Segovia, Spain (Suarez et al, 1991) Umm Radhuma, Saudi Arabia (Dahab and Jarjarah, 1989) Bercimuel, Segovia (Suarez et al, 1995) Yagca formation, Turkey (Yalqin and Bozkaya, 1995) (Millot et al, 1977) Kizilyalak formation, Turkey (Yal$in and Bozkaya, 1995) Ugurlu formation, Turkey (Yal$in and Bozkaya, 1995) Taodeni, Algeria (Caill6re, 1934b) Bakkasetter, Shetland (Stephen, 1954) Dogniaska, USSR (Fersmann, 1913) Permsk, USSR (Fersmann, 1913) Northwestern Transvaal, South Africa (Botha and Huhes, 1992) Dornboom, South Africa (Heystek andSchmidt, 1953) Padasjoki, Finland (Linqvist andLaitakari, 1981) (1-5) from Newman and Brown (1987); (ll) from Imai and Otsuka (1984); (12) and (13) from Weaver and Pollard (1973); (14) and (27) from Isphording (1984); (19) from Suarez et al (1994); (22-25) from Caill6re and H~nin (1972). lies between 6.95-8.1 1 (average 7.72) for eight holes, or between 2.6-3.02 on the basis of three octahedral positions (one-half unit cell) (T...…”

Section: Sepiolitementioning

confidence: 99%

A New Approach to Compositional Limits for Sepiolite and Palygorskite

Galán

Carretero

1999

Clays and clay miner.

108

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Abstract--Most bulk chemical analyses of sepiolite and palygorskite available in the literature are erroneous because samples analyzed axe admixtures of minerals that are difficult to separate or identity by other techniques. Some chemical analyses performed on selected individual particles by energy dispersive X-ray analysis (EDX) are also influenced by the same problem. Chemical analyses are summarized for sepiolite and palygorskite repotted in the literature (bulk and EDX analyses). The analyses are evaluated by comparison to three sepiolite and three palygorskite pure samples analyzed by EDX techniques. Results indicate that sepiolite is a true trioctahedral mineral, very pure (near end-member) with negligible structural substitution and with eight octaheda-al positions filled with magnesium, close to the theoretical tbrmula MgsSi~2030(OH)4(OH2)4(H20)8. Palygorskite is intermediate between di-and trioctahedral phyllosilicates. The octahedral sheet contains mainly Mg, A1, and Fe with a R2/R 3 ratio close to l, and with four of the five structural positions occupied. The theoretical formula is close to (Mg2R23+[2]~)(Si~_.,AI0020(OH)2(OHz)4.R2+~/2(H20)4, where x = 0-0.5. Sepiolite and palygorskite are thus more compositionally limited than previously reported.

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“…(OH)4(OH2)4.8H20 + 2H20 + 8Ca ++ + 16 HCO3-Absence of dolomite in the sepiolitic claystone in the Hekimhan region shows that sepiolite may have been formed by direct crystallization, as many writers worked in several environments (Millot 1970;Singer 1979;Weaver 1984;Isphording 1984;Est6oule-Choux 1984;Singer 1984;Chahi et al 1993;Torres-Ruiz et al 1994), formulized in the reaction as follow (Jones 1986 Transformation of another clay, for example illite (Galan and Castillo 1984), smectite (Singer 1984), or detrital phyllosilicates (Torres-Ruiz et al 1994) to generate palygorskites are proposed. But there was no evidence on the SEM observations ofpalygorskites which was accompanied by calcite and/or dolomite.…”

Section: Occurrencementioning

confidence: 99%

Sepiolite-Palygorskite from the Hekimhan Region (Turkey)

Yalçın

Bozkaya

1995

Clays and clay miner.

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Abstract--Upper Cretaceous-Tertiary marine clayey-calcareous rocks of the Hekimhan basin contain fibrous clay minerals in significant amounts. Ophiolitic rocks in the provenance area have contributed the elements to form the clay minerals. XRD, SEM, major, trace and REE analyses were applied to samples taken from several stratigraphic sections. Diagenetic minerals such as smectite, dolomite, calcite, gypsum, celestite and quartz/chalcedony are associated with sepiolite-palygorskite group days. Trace and rare earth elements (REE) are more abundant in palygorskite than sepiolite. REE abundances in the sepiolite-palygorskite are characterized by negative Eu and positive Nd anomalies when normalized with respect to chondrite and shale. Sepiolites with sharp XRD peaks are formed by diagenetic replacement of dolomite and diagenetic transformation of palygnrskite, or by direct crystallization from solution. The average structural formula of the sepiolite is:(MgT.l sAloA 3Feo.3~ Cro.06Nio.04)(Si H.gsAlo.02)O30(OH)4(OH2)4Cao.03Nao.o2Ko.02.8H20Palygorskite appears to be authigenic by direct precipitation from solution. It exists in both monodinic and orthorhombic forms with the mean structural formula given below: (Mg2.22A~Ti~.~4Fe~.7~Cr~.~Ni~.~2)(Si7.68Al~.32)~2~(~H)2(~H2)4Ca~.~7Na~.~5K~.~.4H2~

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The Clays of Yucatan, Mexico: A Contrast in Genesis

Cited by 24 publications

References 10 publications

Protoliths and phase petrology of whiteschists

Protoliths and phase petrology of whiteschists

A New Approach to Compositional Limits for Sepiolite and Palygorskite

Sepiolite-Palygorskite from the Hekimhan Region (Turkey)

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