Evolution of metamorphic fluids in shear zones: The record from the emeralds of Habachtal, Tauern Window, Austria

Nwe, Yin Yin; Grundmann, Günter

doi:10.1016/0024-4937(90)90027-x

Cited by 32 publications

(18 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is also in accordance with the observation that microscopic features characteristic of Sandawana emeralds-amphibole inclusions (actinolite, tremolite, and cummingtonite) and decrepitated fluid inclusions-are not observed in the Saint Louis emerald. In addition, mica crystals and aqueous-carbonic fluid inclusions comparable to those described for the Habachtal emeralds (12,13) liave been identified in the Saint Louis emerald. The S180 value of the emerald from the Gallo-Roman eamng discovered in Miribel shows that emerald sources other than Egypt , and Austria were exploited in the world during antiquity.…”

Section: Oxygen Isotopes and Emerald Trade Routes Since Antiquitymentioning

confidence: 67%

Oxygen Isotopes and Emerald Trade Routes Since Antiquity

Giuliani

Chaussidon

Schubnel

et al. 2000

Science

View full text Add to dashboard Cite

Oxygen isotopic compositions of historical emerald artifacts from the Gallo-Roman period to the 18th century indicate that during historical times, artisans worked emeralds originating from deposits supposedly discovered in the 20th century. In antiquity, Pakistani and Egyptian emeralds were traded by way of the Silk Route. Together with Austrian stones, they were the only source of gem-quality emeralds. Immediately after the discovery of the Colombian mines by Spaniards in the 16th century, a new trade route was established, first via Spain to Europe and India and then directly via the Philippines to India. Since then, Colombian emeralds have dominated the emerald trade, and most of the high-quality emeralds cut in the 18th century in India originated from Colombia.

show abstract

Section: Oxygen Isotopes and Emerald Trade Routes Since Antiquitymentioning

confidence: 67%

Oxygen Isotopes and Emerald Trade Routes Since Antiquity

Giuliani

Chaussidon

Schubnel

et al. 2000

Science

View full text Add to dashboard Cite

show abstract

“…This is unusual for emeralds foom other deposits, which normally contain a greater pooportion of liquid phase (Grundmann and Morteani, 1989;Nwe and Grundmann, 1990;Cheilletz et al, 1994;Gavrilenko et al, 2001;Groat et al, 2002;Marshall et al, 2004). According to micoothermometric data, all fluid inclusion assemblages may correspond to the same stage of fluid circulation, responsible for emerald mineralization.…”

Section: Discussionmentioning

confidence: 99%

Emeralds from the Delbegetey deposit (Kazakhstan): mineralogical characteristics and fluid-inclusion study

Gavrilenko¹,

Pérez²,

Bolíbar³

et al. 2006

Mineral. mag.

View full text Add to dashboard Cite

AB5TRACTThe aim of this study is to provide the first detailed mineralogical and fluid-inc1usion description of emeralds from the Delbegetey deposit (Kazakhstan). The characteristic features of Delbegetey emeralds are established: they have dissolution figures on crystal faces, bluish colour and distinct colour zoning; the refractive indices are ro = 1.566-1.570, E = 1.558-1.562, and the specific gravity is 2.65±0.005, relatively low for natural emeralds; they have very small concentrations of the impurities (Fe, Mg, Na and others) typical of other emeralds, and contain Cr and V; there is a significant preponderance of vapour in fluid inc1usions of all types and there is liquid-to-vapour homogenization of primary fluid inc1usions (at 395-420°C). The lattice oxygen isotope composition data obtained (0 18 0 SMOW value of 11.3%0) situate the deposit within the range characteristic of other granite-related emerald deposits. Emerald crystallization took place in low-density (0.40-0.55 g/cm 3 ) aqueous fluid, with the following chemical composition (mol.%): 75.6-97.4 HzO, 0.0-18.4 caz, 0.0-0.9 C~, and 4.06-9.65 wt.% NaCI equiv. salinity. According to the calculated isochores, the pressure offormation ofthe Delbegetey emeralds can be estimated at 570-1240 bar.

show abstract

“…The Habachtal deposit in the Austrian Alps has been studied in detail [77,[93][94][95][96][97]. This alpine deposit is located in a contact zone, which overthrusts the volcano-sedimentary series of Habachtal (Habach Formation) on the ortho-augengneisses (central gneisses).…”

mentioning

confidence: 99%

“…The metasomatic process involves fluid percolation that extracted Be from the muscovite schists (average Be content = 36 ppm) and Cr from the serpentinites (Cr content = 304 ppm) to facilitate the crystallization of emerald (Figure 22). Fluid inclusions trapped by emerald belong to the H 2 O-CO 2 -NaCl system [96] with two generations of fluid inclusions: An early generation (XCO 2 < 4 vol.%) and a late one (XCO 2 up to 11 vol.%). Emerald-metasomatic fluids were related to hydration phenomena due to the alpine metamorphism [96].…”

mentioning

confidence: 99%

Emerald Deposits: A Review and Enhanced Classification

et al. 2019

View full text Add to dashboard Cite

Although emerald deposits are relatively rare, they can be formed in several different, butspecific geologic settings and the classification systems and models currently used to describeemerald precipitation and predict its occurrence are too restrictive, leading to confusion as to theexact mode of formation for some emerald deposits. Generally speaking, emerald is beryl withsufficient concentrations of the chromophores, chromium and vanadium, to result in green andsometimes bluish green or yellowish green crystals. The limiting factor in the formation of emeraldis geological conditions resulting in an environment rich in both beryllium and chromium orvanadium. Historically, emerald deposits have been classified into three broad types. The first andmost abundant deposit type, in terms of production, is the desilicated pegmatite related type thatformed via the interaction of metasomatic fluids with beryllium-rich pegmatites, or similar graniticbodies, that intruded into chromium- or vanadium-rich rocks, such as ultramafic and volcanic rocks,or shales derived from those rocks. A second deposit type, accounting for most of the emerald ofgem quality, is the sedimentary type, which generally involves the interaction, along faults andfractures, of upper level crustal brines rich in Be from evaporite interaction with shales and otherCr- and/or V-bearing sedimentary rocks. The third, and comparatively most rare, deposit type is themetamorphic-metasomatic deposit. In this deposit model, deeper crustal fluids circulate along faultsor shear zones and interact with metamorphosed shales, carbonates, and ultramafic rocks, and Beand Cr (±V) may either be transported to the deposition site via the fluids or already be present inthe host metamorphic rocks intersected by the faults or shear zones. All three emerald depositmodels require some level of tectonic activity and often continued tectonic activity can result in themetamorphism of an existing sedimentary or magmatic type deposit. In the extreme, at deepercrustal levels, high-grade metamorphism can result in the partial melting of metamorphic rocks,blurring the distinction between metamorphic and magmatic deposit types. In the present paper,we propose an enhanced classification for emerald deposits based on the geological environment,i.e., magmatic or metamorphic; host-rocks type, i.e., mafic-ultramafic rocks, sedimentary rocks, andgranitoids; degree of metamorphism; styles of minerlization, i.e., veins, pods, metasomatites, shearzone; type of fluids and their temperature, pressure, composition. The new classification accountsfor multi-stage formation of the deposits and ages of formation, as well as probable remobilizationof previous beryllium mineralization, such as pegmatite intrusions in mafic-ultramafic rocks. Suchnew considerations use the concept of genetic models based on studies employing chemical,geochemical, radiogenic, and stable isotope, and fluid and solid inclusion fingerprints. The emerald occurrences and deposits are classified into two main types: (Type I) Tectonic magmatic-relatedwith sub-types hosted in: (IA) Mafic-ultramafic rocks (Brazil, Zambia, Russia, and others); (IB)Sedimentary rocks (China, Canada, Norway, Kazakhstan, Australia); (IC) Granitic rocks (Nigeria).(Type II) Tectonic metamorphic-related with sub-types hosted in: (IIA) Mafic-ultramafic rocks(Brazil, Austria); (IIB) Sedimentary rocks-black shale (Colombia, Canada, USA); (IIC) Metamorphicrocks (China, Afghanistan, USA); (IID) Metamorphosed and remobilized either type I deposits orhidden granitic intrusion-related (Austria, Egypt, Australia, Pakistan), and some unclassifieddeposits.

show abstract

Evolution of metamorphic fluids in shear zones: The record from the emeralds of Habachtal, Tauern Window, Austria

Cited by 32 publications

References 27 publications

Oxygen Isotopes and Emerald Trade Routes Since Antiquity

Oxygen Isotopes and Emerald Trade Routes Since Antiquity

Emeralds from the Delbegetey deposit (Kazakhstan): mineralogical characteristics and fluid-inclusion study

Emerald Deposits: A Review and Enhanced Classification

Contact Info

Product

Resources

About