A preliminary stable isotope study on Mogok Ruby, Myanmar

Yui, Tzen‐Fu; Zaw, Khin; Wu, Chao-Ming

doi:10.1016/j.oregeorev.2008.05.001

Cited by 20 publications

(10 citation statements)

References 47 publications

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“…480 °C, very close to the value given above. Red spinels from the Mogok area of Myanmar were previously estimated to have formed below 710 °C (Yui et al 2008).…”

Section: Discussionmentioning

confidence: 99%

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Effects of heat treatment on red gemstone spinel: single-crystal X-ray, Raman, and photoluminescence study

Widmer

Malsy²,

Armbruster

2014

Phys Chem Minerals

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688 nm), and N3 (689 nm). N lines are caused by different Mg, Al environments of Cr 3+ . With increasing inversion parameter (x), the R line decreases in intensity and the N lines become prominent leading to strongly broadened peaks with a maximum shifted toward higher wave lengths (687.5 nm at 1,100 °C). Criteria for the detection of heat treatment on gemstone spinel applicable to gemological routine examination are provided. Extrapolation of u, a, and bond lengths from heat-treated Burma spinel toward the natural crystal suggests a retrograde "closing temperature" of ca. 400 ± 100 °C at which Mg, Al disorder was frozen.

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“…480 °C, very close to the value given above. Red spinels from the Mogok area of Myanmar were previously estimated to have formed below 710 °C (Yui et al 2008).…”

Section: Discussionmentioning

confidence: 99%

“…Gemstone formation is related to fluid infiltration from an external source with an upper temperature estimate of ca. 700 °C for spinel-forsterite-bearing marble as derived from graphite Raman spectral thermometry (Yui et al 2008). …”

Section: Sample Studiedmentioning

confidence: 99%

Effects of heat treatment on red gemstone spinel: single-crystal X-ray, Raman, and photoluminescence study

Widmer

Malsy²,

Armbruster

2014

Phys Chem Minerals

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“…Originally, the metamorphism was thought to be Precambrian to Palaeozoic in age (Bender 1983, Wolfort et al 1984, but more recent geochronological data suggest that it could be as young as Oligocene to Middle Miocene (Mitchell 1993, Bertrand et al 1999, 2001, Barley et al 2003, Win et al 2016). The MMB is famous for producing a variety of the world's finest coloured gemstones, including rubies, sapphires and a variety of other gems (Kammerling et al 1994, Themelis 2008, Yui et al 2008, Zaw et al 2014.…”

Section: Geological Background and Sample Descriptionmentioning

confidence: 99%

MK‐1 Apatite: A New Potential Reference Material for (U‐Th)/He Dating

Shi

Danišík

et al. 2019

Geostandard Geoanalytic Res

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The (U‐Th)/He dating technique has been widely used for several decades to constrain the timing of low temperature geological processes. Recent research has shown that the commonly used reference material (the Durango apatite) often yields dispersed fragment dates that are beyond analytical uncertainties. Here, we report a new apatite (U‐Th)/He dating reference material, MK‐1, which was collected from the Mogok metamorphic belt in Burma. Electron probe microanalysis and backscattered electron images of two randomly selected fragments indicate that this apatite is chemically and structurally homogeneous. We performed single‐grain (U‐Th)/He dating on thirty randomly selected fragments of this material. (U‐Th)/He dating results from multiple laboratories show that fragments of the MK‐1 apatite megacryst yielded reproducible results, with a mean date of 18.0 ± 0.2 Ma. The Th/U ratio of this apatite is homogeneous. Nine randomly selected fragments registered a narrow range of effective uranium (eU) mass fractions (326–354 μg g−1), with a mean value of 336.6 ± 10.3 μg g−1. Twenty‐four in situ (U‐Th)/He dates yielded a mean value of 18.0 ± 0.2 Ma (MSWD = 0.41), indistinguishable from the results obtained by the conventional method. All the results suggest that this apatite has the potential to become a new reference material for (U‐Th)/He geochronology.

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“…There might have also been

X_{{normalCO}_{2}}

contrast between the marble and calcsilicate rock. Yui, Zaw, and Wu () analysed δ 13 C–δ 18 O compositions of ruby‐bearing and related marble from the Mogok metamorphic belt, and concluded that the formation of ruby might have resulted from CO 2 ‐rich fluid–rock interaction, while spinel‐ and forsterite‐bearing marble was genetically recrystallized under low

X_{{normalCO}_{2}}

. Some major constituent minerals in the marble and calcsilicate rock are richer in F and Cl respectively.…”

Section: Discussionmentioning

confidence: 99%

Evolution of metamorphic fluid recorded in granulite facies metacarbonate rocks from the middle segment of the Mogok metamorphic belt in central Myanmar

Thu

Enami

2018

Journal Metamorphic Geology

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The Mogok metamorphic belt of Palaeogene age, which records subduction‐ and collision‐related events between the Indian and Eurasian plates, lies along the western margin of the Shan plateau in central Myanmar and continues northwards to the eastern Himalayan syntaxis. Reaction textures of clinohumite‐ and scapolite‐bearing assemblages in Mogok granulite facies metacarbonate rocks provide insights into the drastic change in fluid composition during exhumation of the collision zone. Characteristic high‐grade assemblages of marble and calcsilicate rock are clinohumite+forsterite+spinel+phlogopite+pargasite/edenite+calcite+dolomite, and scapolite+diopside+anorthite+quartz+calcite respectively. Calculated petrogenetic grids in CaO–MgO–Al2O3–SiO2–H2O–CO2 and subsets of this system were employed to deduce the pressure–temperature–fluid evolution of the clinohumite‐ and scapolite‐bearing assemblages. These assemblages suggest higher temperature (>780–810°C) and XnormalCO2 [=CO2/(CO2+H2O) >0.17–0.60] values in the metamorphic fluid for the peak granulite facies stage, assuming a pressure of 0.8 GPa. Calcite grains commonly show exsolution textures with dolomite particles, and their reintegrated compositions yield temperatures of 720–880°C. Retrograde reactions are mainly characterized by a reaction zone consisting of a dolomite layer and a symplectitic aggregate of tremolite and dolomite grown between clinohumite and calcite in marble, and a replacement texture of scapolite by clinozoisite in calcsilicate rock. These textures indicate that the retrograde reactions developed under lower temperature (<620°C) and XnormalCO2 (<0.08–0.16) conditions, assuming a pressure of 0.5 GPa. The metacarbonate rocks share metamorphic temperatures similar to the Mogok paragneiss at the peak granulite facies stage. The XnormalCO2 values of the metacarbonate rock at peak metamorphic stage are, however, distinctly higher than those previously deduced from carbonate mineral‐free paragneiss. Primary clinohumite, phlogopite and pargasite/edenite in marble have F‐rich compositions, and scapolite in calcsilicate rock contains Cl, suggesting a contrast in the halogen compositions of the metamorphic fluids between these two lithologies. The metamorphic fluid compositions were probably buffered within each lithology, and the effective migration of metamorphic fluid, which would have extensively changed the fluid compositions, did not occur during the prograde granulite facies stage throughout the Mogok metamorphic belt. The lower XnormalCO2 conditions of the Mogok metacarbonate rocks during the retrograde stage distinctly contrast with higher XnormalCO2 conditions recorded in metacarbonate rocks from other metamorphic belts of granulite facies. The characteristic low XnormalCO2 conditions were probably due to far‐ranging infiltration of H2O‐dominant fluid throughout the middle segment of the Mogok metamorphic belt under low‐amphibolite facies conditions during the exhumation and hydration stage.

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A preliminary stable isotope study on Mogok Ruby, Myanmar

Cited by 20 publications

References 47 publications

Effects of heat treatment on red gemstone spinel: single-crystal X-ray, Raman, and photoluminescence study

Effects of heat treatment on red gemstone spinel: single-crystal X-ray, Raman, and photoluminescence study

MK‐1 Apatite: A New Potential Reference Material for (U‐Th)/He Dating

Evolution of metamorphic fluid recorded in granulite facies metacarbonate rocks from the middle segment of the Mogok metamorphic belt in central Myanmar

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