Deerite from Papua New Guinea

Worthing, M. A.

doi:10.1180/minmag.1987.051.363.09

Cited by 7 publications

(5 citation statements)

References 9 publications

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“…In riversideite (tobermorite-9Å), there is no H 2 O, adjacent 2 T 3 chains are forced closer to each other (d 002 = 9.3 Å) and chain condensation does not occur. Multiple heating experiments have yielded the following dehydration reaction; plombièrite (tobermorite-14Å) → Rogov et al (1965), Bissert (1980); (4) Wenk (1974), Wenk (1973), Ghent et al (1990); (5) Wenk (1974), Matsubara (1981), Aoki (1981); (6) Fleet (1977), Agrell et al (1965), Wenk et al 1976, Worthing (1987; (7) (1985), Deriu et al (1994); (26) Wan and Ghose (1978), Ryall and Threadgold (1966), Richmond (1942); (27) (1992). *Indicates the c T r expression of an additional structural unit including a chain, ribbon, tube, cluster or sheet of (TO 4 ) ntetrahedra in the respective mineral.…”

Section: T 4 3 T Ribbonsmentioning

confidence: 99%

A structure hierarchy for silicate minerals: chain, ribbon, and tube silicates

Day

Hawthorne

2020

MinMag

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A structure hierarchy is developed for chain-, ribbon- and tube-silicate based on the connectedness of one-dimensional polymerisations of (TO4)n− tetrahedra, where T = Si4+ plus P5+, V5+, As5+, Al3+, Fe3+, B3+, Be2+, Zn2+ and Mg2+. Such polymerisations are described by a geometrical repeat unit (with ng tetrahedra) and a topological repeat unit (or graph) (with nt vertices). The connectivity of the tetrahedra (vertices) in the geometrical (topological) repeat units is denoted by the expression cTr (cVr) where c is the connectivity (degree) of the tetrahedron (vertex) and r is the number of tetrahedra (vertices) of connectivity (degree) c in the repeat unit. Thus cTr = 1Tr12Tr23Tr34Tr4 (cVr = 1Vr12Vr23Vr34Vr4) represents all possible connectivities (degrees) of tetrahedra (vertices) in the geometrical (topological) repeat units of such one-dimensional polymerisations. We may generate all possible cTr (cVr) expressions for chains (graphs) with tetrahedron (vertex) connectivities (degrees) c = 1 to 4 where r = 1 to n by sequentially increasing the values of c and r, and by ranking them accordingly. The silicate (sensu lato) units of chain-, ribbon- and tube-silicate minerals are identified and associated with the relevant cTr (cVr) symbols. Following description and association with the relevant cTr (cVr) symbols of the silicate units in all chain-, ribbon- and tube-silicate minerals, the minerals are arranged into decreasing O:T ratio from 3.0 to 2.5, an arrangement that reflects their increasing structural connectivity. Considering only the silicate component, the compositional range of the chain-, ribbon- and tube-silicate minerals strongly overlaps that of the sheet-silicate minerals. Of the chain-, ribbon- and tube-silicates and sheet silicates with the same O:T ratio, some have the same cVr symbols (vertex connectivities) but the tetrahedra link to each other in different ways and are topologically different. The abundance of chain-, ribbon- and tube-silicate minerals decreases as O:T decreases from 3.0 to 2.5 whereas the abundance of sheet-silicate minerals increases from O:T = 3.0 to 2.5 and decreases again to O:T = 2.0. Some of the chain-, ribbon- and tube-silicate minerals have more than one distinct silicate unit: (1) vinogradovite, revdite, lintisite (punkaruaivite) and charoite have mixed chains, ribbons and/or tubes; (2) veblenite, yuksporite, miserite and okenite have clusters or sheets in addition to chains, ribbons and tubes. It is apparent that some chain-ribbon-tube topologies are favoured over others as of the ~450 inosilicate minerals, ~375 correspond to only four topologically unique graphs, the other ~75 minerals correspond to ~46 topologically unique graphs.

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Section: T 4 3 T Ribbonsmentioning

confidence: 99%

A structure hierarchy for silicate minerals: chain, ribbon, and tube silicates

Day

Hawthorne

2020

MinMag

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“…Although Muir Wood (1979) suggested, on the basis of the deerite analyses available to him at the time, that there might be regional compositional differences allowing 'Franciscan' and 'Alpine' types of deerite to be distinguished, such categories have become blurred as more and more analyses have become available (see summary by Deer et al, 1997;see also Schliestedt, 1980;Worthing, 1987;Dudek and Kienast, 1987;Kienast, 1983;Klein-Helmkamp, 1996; for further analyses). Muir FIG.…”

Section: Crystal Chemistrymentioning

confidence: 99%

Petrology and geodynamic significance of deerite-bearing metaquartzites from the Escambray Massif, Cuba

Grevel¹,

Maresch²,

Stanek³

et al. 2006

Mineral. mag.

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Deerite, a typical mineral of Fe-rich metacherts metamorphosed under blueschist conditions, is not rare, but known occurrences have up to now been restricted mainly to the Tethyan collisional zone and the Western Cordillera of North America. We describe a first occurrence in the high-pressure nappes of the Escambray Massif, Cuba, in the assemblage deerite + Mg-Al-poor riebeckite + magnetite + quartz Ô garnet Ô phengite Ô aegirine. This assemblage typically forms during exhumation and accompanies late, stress-free annealing of the quartz matrix. Mg-Al-poor riebeckite overgrows older, large, oriented crystals of glaucophane, ferroglaucophane and Mg-Al-rich riebeckite ('crossite') during deerite formation. Early-formed hematite was largely replaced by magnetite. Deerite is very close to ideal composition, attaining >99% Fe 2+ 12 Fe 3+ 6 Si 12 O 40 (OH) 5 , allowing direct application of the experimentally determined P-T-f O 2 stability field (Lattard and Le Breton, 1994). In combination with oxygen-isotope thermometry on magnetite-quartz, the crystallization conditions of the deerite-bearing assemblage can be constrained to~470ºC, >15 kbar, and an oxygen fugacity restricted closely to the quartz-fayalitemagnetite buffer (f O 2 & 10 À23 bar). Thus, the late-stage P-T path of the metacherts mirrors a steep P-T gradient of 10ºC/km or less, requiring subduction of this part of the Antillean Island Arc to be still active during exhumation of the Escambray nappes.

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“…Fig. 7 shows a plot of some published deerite analyses (Worthing, 1987;Reinecke, 1987; former data recalculated by Verni6 et al, 1986), together with those from Ile de Groix. The ideal formula of deerite requires 12Si per unit, but microprobe analyses recalculated to 30 cations often reveal this value to be higher.…”

Section: Mineral Chemistrymentioning

confidence: 99%

“…According to Muir Wood (1979) it can be caused by variations in the hydroxyl content and octahedral cation vacancies. In the deerites examined here, the Si content varies (Agrell and Gay, 1979;Bocquet and Forette, 1973;Dal Piaz and Molin, 1978;Muir Wood, 1979), open asterisks--Shuksan Unit (Brown, 1974), closed asterisks--Sifnos (Schliestedt, 1978), open squares--Ile de Groix (Kienast, 1983; this study), closed squares--Corsica (Verni6 el al., 1986), open circles--Papua New Guinea (Worthing, 1987), closed circles--Andros (Reinecke, 1987 …”

Section: Mineral Chemistrymentioning

confidence: 99%

Deerite from Ile de Groix, Brittany, France

Dudek¹,

Kiénast

1989

Mineral. mag.

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Deerite has been found in layers of Fe-rich metasediments, metamorphosed under conditions of blueschist to eclogite facies (T--ca. 480 ~ Geochemical comparisons with other deerites described in the literature show that the Ile de Groix deerites most closely resemble the Mn-poor, alpine type, and Sifnos deerites. The P-T conditions of the Ile de Groix metamorphism do not conform with the stability field of deerite. In the assemblages examined here deerite seems to be a relic from earlier stages of prograde metamorphism.

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Deerite from Papua New Guinea

Cited by 7 publications

References 9 publications

A structure hierarchy for silicate minerals: chain, ribbon, and tube silicates

A structure hierarchy for silicate minerals: chain, ribbon, and tube silicates

Petrology and geodynamic significance of deerite-bearing metaquartzites from the Escambray Massif, Cuba

Deerite from Ile de Groix, Brittany, France

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