Schorl-oxy-schorl to dravite-oxy-dravite tourmaline from granitic pegmatites; examples from the Moldanubicum, Czech Republic

Novák, Milan; Povondra, P.; Selway, Julie B.

doi:10.1127/0935-1221/2004/0016-0323

Cited by 75 publications

(46 citation statements)

References 21 publications

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“…4a-b), together with the scarcity of crystal zonation (Fig. 3c-d), could be also a result of rapid crystallization (Novák et al 2004), whilst the coexistence of tourmaline with ore minerals suggests fluid boiling (Slack and Trumbull 2011). However, the scarce zoned tourmaline crystals, showing a Fe increase towards the margins (Fig.…”

Section: Crystallization Conditionsmentioning

confidence: 93%

Age and origin of the tourmaline-rich hydraulic breccias in the Tatra Granite, Western Carpathians

Gawęda¹,

Müller²,

Stein³

et al. 2013

J. Geosci.

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In the crystalline basement of the Tatra Mountains (Poland/Slovakia) two types of tourmaline-rich breccia zones are described, both having originated from magmatic fluids and showing a 350 ± 1 Ma Re-Os model age. Both T1 brecciated pegmatites and T2 vein-breccias are cemented by a tourmaline-quartz matrix. In T1 breccias, the metasomatic replacement of feldspars by tourmaline and overgrowths of small Tur 2 tourmalines on the primary pegmatitic Tur 1 tourmaline crystals suggest an important role for metasomatic processes. The microcrystalline nature of the quartz-tourmaline matrix and high vacancy ratios in the X-site in tourmaline from T2 breccias reflect relatively rapid crystallization from an oxidized fluid. The formation of both types of breccias is related to the internal structure of the Tatra granitoid intrusion. The layered character of the granitoid body probably stimulated the formation of pegmatite-like pockets, with local overpressure causing metasomatic alteration, rock brecciation and cementation by tourmaline (T1 breccias), the final hydrofracturing of overburden rocks and fluid escape. The resulting fracture zones (T2) are interpreted as the paths for fluid migration and rapid crystallization as the pressure and temperature dropped from 7.5-6 kbar and 630-570 ºC in the case of the T1 brecciated pegmatites to 2.5-1.5 kbar and 465-430 ºC in the vein T2 breccias.

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Section: Crystallization Conditionsmentioning

confidence: 93%

Age and origin of the tourmaline-rich hydraulic breccias in the Tatra Granite, Western Carpathians

Gawęda¹,

Müller²,

Stein³

et al. 2013

J. Geosci.

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“…c) Coarse-grained, cordierite-rich leucosomes (cordierite + biotite + schorl-dravite ± dumortierite) occur in migmatized gneisses of the Bory Granulite Massif and locally show pegmatitic textures (Povondra et al 1992). d) Simply zoned, common (likely anatectic) pegmatites with accessory andalusite and cordierite are abundant mainly in the Strážek Moldanubicum, which mostly show transitional (diffuse) contacts to their country rocks (migmatized gneisses and granulites) and locally contain large crystals of smoky quartz, feldspars, muscovite and tourmaline (schorl, oxy-schorl, dravite, foitite, magnesio-foitite) typically developed in pockets Novák et al 2004;Povondra 1981). e) Common pegmatites (sensu London 2008) are enclosed in a variety of rocks; anatectic origin is very likely.…”

Section: Tectono-metamorphic and Magmatic Evolution Of The Moldanubiamentioning

confidence: 99%

“…Less evolved common pegmatites are characterized by the presence of dravite, oxy-dravite, oxy-schorl to schorl (Novák et al 2004), locally andalusite, cordierite and garnet. More fractionated beryl-type pegmatites, locally with some accessory minerals (oxy-schorl, schorl, dravite, oxy-dravite, beryl, fluorapatite, niobian rutile, ilmenite, monazite-(Ce), xenotime-(Y), zircon, cordierite, garnet, columbitetantalite, Y,REE-oxide minerals; e.g., Povondra 1981;Černý et al 1997, 2000Novák et al 2004Novák et al , 2008Breiter et al 2005b;Škoda et al 2011), are less abundant than the more evolved complex pegmatites (Li-bearing; Li-micas > Li-tourmalines > amblygonite > petalite; Povondra et al 1985;Němec 1989Němec , 1990Černý et al 1995, 2003Teertstra et al 1995;Novák et al 1999bNovák et al , 2013, some with variety of accessory minerals (see Novák and Cempírek 2010 and references therein). Their mineral assemblages with common andalusite, sekaninaite and petalite suggest an emplacement and crystallization at P < ~0.2-0.3 GPa.…”

Section: Tectono-metamorphic and Magmatic Evolution Of The Moldanubiamentioning

confidence: 99%

Geological position, mineral assemblages and contamination of granitic pegmatites in the Moldanubian Zone, Czech Republic; examples from the Vlastějovice region

Novák¹,

Kadlec²,

Gadas³

2013

J. Geosci.

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Three groups of pegmatites distinct in their geological position, age, internal structure, mineral assemblages and chemical composition of minerals (tourmaline, amphibole, garnet, and biotite) were distinguished in the Vlastějovice region, Moldanubian Zone: a) tourmaline-bearing pegmatites (Qz + Kfs + Pl + Bt + Ms + Tur) enclosed in the pre-Variscan orthogneiss, b) contaminated amphibole-bearing pegmatites (Pl + Qz + Amp + Kfs + fluorite + allanite) hosted by the Fe-skarn, and c) tourmaline-bearing pegmatites cutting paragneisses (Qz + Kfs + Pl + Bt + Ms + Ab + Tur + Grt) and the Fe-skarn (Qz + Kfs + Pl + Bt + Tur ± Ab, Amp, Grt, elbaite). The pegmatites enclosed in the orthogneiss show simple internal structure and mineral assemblages, together with low degree of tectonometamorphic overprint. The amphibole--bearing pegmatites, likely anatectic and related to the Variscan MP-HT regional metamorphism, are spatially restricted to the Fe-skarn body and highly variable in shape, size, effects of in situ contamination by Ca, Fe ± F and REE from the host Fe-skarn, and degree of hydrothermal overprint. The tourmaline-bearing pegmatites related to the Variscan magmatic event cut different rocks (paragneisses, Fe-skarn bodies) and belong to the Moldanubian rare-element pegmatite province. They show distinct degree of textural differentiation, geochemical fractionation and external contamination by Ca and/or Fe (Ca,Fe-rich Al-poor tourmalines) higher in the less evolved pegmatite bodies in the Fe-skarn. The tourmaline-bearing pegmatites were evidently generated from the granite-pegmatite body in the footwall contact of the Fe-skarn. Degrees of the textural differentiation and geochemical fractionation of the individual tourmaline-bearing pegmatites are comparable to those of the respective parts of the parental Footwall granite-pegmatite body. This observation seems consistent with the model of sequential derivation of pegmatite melts from evolving parental granite. Primitive to highly evolved and usually B-rich pegmatites originated during the Variscan orogeny from the MP (~0.6-0.7 GPa) to the LP conditions (~0.2 GPa), and manifest that formation of various granitic pegmatites was an integral part of the tectonomagmatic evolution of the region.

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“…The oc currence of gra nitic tour ma line is re mark ably rare. The most abundant tour ma line in gra nitic pegmatites from the Bo he mian Mas sif is Fe-rich schorl or oxy-schorl Povondra et al, 1998;Novák et al, 2004;S³aby and Koz³owski, 2005;Burianek and Novák, 2007;Novák and Cempírek, 2010), which is not char ac ter is tic of the de tri tal tour ma line in the Up per Cre ta ceous sand stones. Grains which show such char ac ter is tics are rare and most of ten rounded, suggest ing that they were re cy cled.…”

Section: Discussion Parent Rocks Of the Detrital Tourmalinementioning

confidence: 99%

Provenance of Upper Cretaceous quartz-rich sandstones from the North Sudetic Synclinorium, SW Poland: constraints from detrital tourmaline

Biernacka

2012

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J. (2012) -Prov e nance of Up per Cre ta ceous quartz-rich sand stones from the North Sudetic Synclinorium, SW Po land: constraints from de tri tal tour ma line. Geol. Quart., 56 (2): 315-332, doi: 10.7306/gq.1024Up per Cre ta ceous quartz arenites that fill the North Sudetic Synclinorium on the north ern pe riph ery of the Variscan Bo he mian Mas sif show high compositional but low tex tural ma tu rity. They have been in ter preted for years as de rived largely from nearby gran ite plutons, i.e. as first-cy cle sed i ments. A dif fer ent prov e nance was re vealed on the ba sis of a com bined light and heavy min eral anal y sis, and par ticu larly a de tri tal tour ma line study, given that tour ma line is a sen si tive in di ca tor of gra nitic/meta mor phic/sed i men tary (multi-re cy cling) or i gin. Cenomanian, Turonian, Coniacian and Santonian sand stones con tain abun dant an gu lar tour ma line grains, to gether with zir con and rutile, and subordinately staurolite, gar net, ana tase, kyan ite, sillimanite and monazite. The suc ces sive -Cenomanian to Santoniantour ma line pop u la tions are sim i lar with re gard to shape, col our and chem i cal com po si tion. The lat ter points un am big u ously to var i ous meta mor phic rocks with a pre dom i nant group of Al-rich metapelites (Al-rich, F-poor dravite). It is con cluded that, in the Late Cre taceous, large Sudetic gran ite plutons such as the Karkonosze and Strzegom-Sobótka mas sifs were not ex posed but were bur ied un der a thick siliciclastic cover. These re sults cou pled with pub lished ap a tite fis sion-track data from the gra nitic Karkonosze Pluton and the gneissic/migmatitic Góry Sowie Mas sif re veal that Late Cre ta ceous quartz arenites of the North Sudetic Synclinorium re flect grad ual exhu ma tion of the sur round ing mas sifs, but do not re cord the fi nal ex po sure of crys tal line rocks. Since the lat est Turonian, this ex hu ma tion cor re sponded to the Late Cre ta ceous in ver sion ep i sode in Cen tral Eu rope. The tex tural im ma tu rity of Up per Cre ta ceous sand stones is mis lead ing in terms of their re cy cled or i gin, and it is in her ited from im ma ture clastic source rocks.

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Schorl-oxy-schorl to dravite-oxy-dravite tourmaline from granitic pegmatites; examples from the Moldanubicum, Czech Republic

Cited by 75 publications

References 21 publications

Age and origin of the tourmaline-rich hydraulic breccias in the Tatra Granite, Western Carpathians

Age and origin of the tourmaline-rich hydraulic breccias in the Tatra Granite, Western Carpathians

Geological position, mineral assemblages and contamination of granitic pegmatites in the Moldanubian Zone, Czech Republic; examples from the Vlastějovice region

Provenance of Upper Cretaceous quartz-rich sandstones from the North Sudetic Synclinorium, SW Poland: constraints from detrital tourmaline

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