Coexisting zoisite and clinozoisite in biotite schists from the Hohe Tauern, Austria

Ackermand, D.; Raase, P.

doi:10.1007/bf00372611

Cited by 18 publications

(7 citation statements)

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“…1) but have been little studied (Majer, 1978;Nikitin and Klemen, 1938;Simi6 and Simi6, 1963;Petkovi~, 1952). They lie near contacts between metamorphic complexes and ophiolite belts in Serbia and Macedonia, in a comparable tectonic setting to blueschists in the Alps, Greece, and Turkey (Ackermand and Raase, 1973;Okrusch et al, 1978;Okay, 1978).…”

Section: Copyright the Mineralogical Societymentioning

confidence: 95%

High-pressure metamorphism between the pelagonian Massif and Vardar Ophiolite Belt, Yugoslavia

Majer¹

1983

Mineral. mag.

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A n S T R A C T. A reported occurrence of metamorphic rocks containing sodic pyroxenes, in the transition zone between the Pelagonian Crystalline Massif and the Vardar Ophiolite Belt, in Macedonia, Yugoslavia, has been re-investigated, and pyroxenes, micas, plagioclase, and clinozoisite analysed by microprobe. The presence of the high-pressure metamorphic assemblage quartz + omphacite+albite is confirmed, giving the first definite indication of blueschist-facies metamorphic conditions in Yugoslavia.

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Section: Copyright the Mineralogical Societymentioning

confidence: 95%

High-pressure metamorphism between the pelagonian Massif and Vardar Ophiolite Belt, Yugoslavia

Majer¹

1983

Mineral. mag.

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“…In low-medium pressure rocks, zoisite and clinozoisite-epidote have been recorded occurring together in individual rocks or in separate but interlayered rocks (Myer 1966;Ackermand and Raase 1973;Tanner 1976;Coombs et al 1977;Frey 1978;Frank 1983;Franz and Selverstone 1992). The occurrences recorded by Tanner (1976) and Frank (1983) have been described above.…”

Section: Zoisite-clinozoisitementioning

confidence: 99%

“…T-X Fe diagram for coexisting zoisite-clinozoisite in low-medium pressure metamorphic rocks. Composition gaps from previous studies where temperatures were estimated are plotted as X Fe ranges connecting fi lled circles; thin horizontal lines show the extent of composition gaps; AR = Ackermand and Raase (1973); F 1 = Frey (1978); F 2 = Frank (1983). The form of the zoisite-clinozoisite miscibility gap is determined on the basis of analytical data from three samples described by Franz and Selverstone (1992) and are considered to have been metamorphosed at 5 kbar (thick horizontal lines; see text).…”

Section: Metabasitementioning

confidence: 99%

Epidote Group Minerals in Low-Medium Pressure Metamorphic Terranes

Grapes

Hoskin

2004

Reviews in Mineralogy and Geochemistry

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Grapes & Hoskin 302 state, as epidote Fe 3+ -content is strongly dependent on ƒ O 2 (Holdaway 1972;Liou 1973). Again, consideration of these variables is relevant both to whole-rock compositions and sub-domains in rocks. For example, in sub-greenschist facies metabasites, epidote with different compositions may occur in amygdules with or without calcite, and in the rock matrix where it may replace pumpellyite or has replaced volcanic glass and grown together with pumpellyite, chlorite, etc. In the two sub-domains (amygdules and matrix), X CO 2 , X H 2 O and ƒ O 2 can signifi cantly differ.These interrelated controls, as well as other kinetic factors, determine the composition of single growth-generation epidote at any particular pressure and temperature. Nevertheless, general trends of epidote compositional changes in a number of metamorphic terranes have established that in metabasaltic and quartzofeldspathic rocks epidote tends to become more aluminous with increasing grade (Miyashiro and Seki 1958;Apted and Liou 1983). On the other hand, zoisite and clinozoisite, for example in meta-marl and Ca-rich metapelite, become more Fe-rich with increasing metamorphic grade.This chapter reviews the changes in composition, the textures, epidote-producing and consuming reactions, conditions of oxidation, fl uid composition, and P-T conditions during zoisite and clinozoisite-epidote formation in various rock types from selected low to medium pressure regional and contact metamorphic terranes. The review is intended to be broad but not comprehensive; it is focused on occurrences where epidote composition and textual data for a range of related rocks within a single terrane are available. Additional data for a range of epidote group mineral occurrences can be found in the summary of Deer et al. (1997). Data on compositional varieties such as Mn-(excluding piemontite; see Bonazzi and Menchetti 2004), Sr-and Cr-bearing members of the epidote group are included. Evidence for composition gaps in the zoisite-clinozoisite and clinozoisite-epidote series for natural occurrences is discussed in relation to experimental verifi cation of miscibility gaps in the epidote group series. Finally, critical mineral associations and reactions relevant to epidote group mineral paragenesis in metabasaltic and Al-marl rocks are summarized. Nomenclature, mineral abbreviationsIn this chapter, epidote group mineral compositions are expressed as 100(Fe 3+ /(Fe 3+ + Al)) and denoted as X Fe throughout the text. Mineral abbreviations used in the text and fi gures are listed in Table 1. EPIDOTE GROUP MINERALS IN DIFFERENT LITHOLOGIES MetabasiteKarmutsen Metabasite, Vancouver Island, Canada. In the low grade Karmutsen metabasite, Vancouver Island, epidote is one of the most common Ca-Al silicates and occurs in amygdules, veins and as fi ne-grained aggregates in the rock matrix. Cho et al. (1986) show that in low-variance (calcite-free, 3-phase assemblages with excess chlorite + quartz) amygdule assemblages of epidote, pumpellyite, chlorite, quartz laumo...

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“…The chemical composition of these coexisting phases is plotted in fig. 3, the inferred phase diagram of Enami and Banno (1980), together with data given by Ackermand and Raase (1973). All zoisite data are plotted on a straight line, in accordance with the procedure followed by Enami and Banno (1980).…”

Section: Copyright the Mineralogical Societymentioning

confidence: 99%

“…Coexisting zoisite and clinozoisite have been reported by many authors (Banno, 1964;Myer, 1966;Ackermand and Raase, 1973;Hietanen, 1974;Raith, 1976;Enami and Banno, 1980). The stability relations between the two minerals are, however, not fully understood.…”

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confidence: 98%

The iron content and optic axial angle in zoisites from Galicia, NW Spain

Maaskant

1985

Mineral. mag.

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ABSTRACT. Electron probe microanalyses of zoisites from high-grade metamorph, ic rocks in Galicia, NW Spain have been obtained. The elements Na, Mg, P, K, Ti, and Mn were not detected above the 0.1 wt. ~ level. Assuming all Fe is present as Fe 3+, a clear relation is obtained between the Fe content and the optic axial angle. Zoisite with 1.6 wt. ~o Fe203 proves to be uniaxial at 589 rim; uniaxiality in blue light (470 nm) lies at 1.5 wt. Fe203. A change of the optic sign, from positive to negative, is obtained at 2.9 wt. ~o Fe_~O3. The presence of minor elements greatly affects this relation, as is indicated by analyses of sector-zoned Sr-bearing zoisites of a muscovite-zoisite pegmatite from the same region. Under retrograde conditions Fe-rich ct-zoisite reacts to form less Fe-rich ~t-zoisite or fl-zoisite and clinozoisite.KnYWORDS: zoisite, metamorphism, optic axial angle, iron, Galicia, Spain.T HE existence of two types of zoisite with different optical orientations was first recognized by Termier (t898, 1900). The two types are named a-zoisite and fl-zoisite after the vibration direction which lies parallel to the crystallographic b-axis, along which zoisite is usually prismatically developed, a-zoisite has ct, t, and 7 parallel to b, a, and c, respectively; OAP parallel to (100), varying 2V~ and strong rhombic dispersion r << v. fl-zoisite has ~, t, and 7 parallel to a, b, and c, respectively; OAP parallel to (010) and perpendicular to the cleavage (100), varying 2Vr and rhombic dispersion r > v.These data are usually given in literature on zoisite mineralogy and in determinative tables (Myer, 1966;Saggerson, 1975;Tr6ger, 1982). Deer et al. (1967) and Battey (1975) give a reverse dispersion scheme for both ~-and fl-zoisites. Vogel and Bahezre (1965) note the existence of a zoisite with a large 2V~ with rhombic dispersion r >> v.The connection between the two types of zoisite and their ferric iron content has been much debated (Phillips and Griffen, 1981;Saggerson, 1975; Termier, 1900;Winchell and Winchell, 1959). A relation, which nowadays is generally accepted has been given by Myer (1966) , with later confirmation by Enami and Banno (1977). Myer analysed fiveCopyright the Mineralogical Society non-manganiferous zoisites and measured the optic axial angle 2Vr in Nao light; his data are given in fig. 1. ct-zoisite is generally considered to be the hightemperature zoisite, occurring as a primary mineral in eclogitic rocks of various compositions, whereas during retrograde metamorphism fl-zoisite forms (Raith, 1976;Richter, 1973;Vogel, 1967).The present study was undertaken to refine the extrapolated curves of Myer and of Enami and Banno. Seventeen zoisite-bearing samples were collected from Cabo Ortegal, Galicia, NW Spain. a-zoisite occurs as a stable phase, together with omphacite, garnet and brownish pargasitic hornblende in ~t-zoisite eclogites, ct-zoisite hornblende eclogite and ~-zoisite hornblende pyrigarnites. The primary metamorphic character of the mineral may be deduced from the fact that it oc...

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Coexisting zoisite and clinozoisite in biotite schists from the Hohe Tauern, Austria

Cited by 18 publications

References 10 publications

High-pressure metamorphism between the pelagonian Massif and Vardar Ophiolite Belt, Yugoslavia

High-pressure metamorphism between the pelagonian Massif and Vardar Ophiolite Belt, Yugoslavia

Epidote Group Minerals in Low-Medium Pressure Metamorphic Terranes

The iron content and optic axial angle in zoisites from Galicia, NW Spain

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