@phdthesis{oai:nagoya.repo.nii.ac.jp:00010621,
 author = {森清, 寿郎 and Morikiyo, Toshiro},
 month = {Nov},
 note = {Carbon isotope fractionation between coexisting calcite and graphite ( Δ^13Ccc-gr ) has been determined in metamorphosed limestones and calc-silicate rocks from the Ryoke metamorphic belt in the northern Kiso district. In this district, the Ryoke metamorphic rocks ranging from the lower greenschist facies to the upper amphibolite facies are widely distributed. The fractionation of 13^C/12^C between calcite and graphite decreases regularly with increase of the metamorphic grade and it is independent of absolute δ^13C values of calcite. These lines of evidence suggest that carbon isotopic exchange equilibrium has been attained during the metamorphism even in the greenschist facies and isotopic modification possibly caused by retrogressive metamorphism is not distinguished. For T= 270°- 650℃, the fractionation is expressed by the following equation : Δ^13Ccc-gr=8.9×10^6T^-2-7.1 ( T in °K ). This equation has a slope steeper than the current results on the δ^13Ccc-gr versus 10^6T^-2 diagram. It can be used as a potential geothermometer for almost the entire temperature range of metamorphism.  δ^13C values of carbonaceous matter in unmetamorphosed limestones in this district are approximately -22%｡, which is due to its biogenic origin. Graphite from metamorphosed limestones is also considered to be of biogenic origin but shows enrichment of 13^C due to isotopic exchange with calcite.  δ^13C values of graphite as well as Δ^13Ccc-gr confirm that the zone II represents the lowest grade zone of Ryoke metamorphism. The maximum equilibrium fractionation of δ^13C between calcite and graphite is considered to be approximately 23%｡, which value corresponds to be 270℃. Below this temperature, it seems that carbon isotopic exchange between the minerals does not occur.  Calcite in marble from the higher grade zones has relatively lower δ^13C and δ^18O values. The depletion of heavy isotopes is considered to be caused by the loss of 13^C and 18^O enriched carbon dioxide during decarbonation reactions. For oxygen, it is considered that isotopic exchange with metamorphic fluids plays an important role in lowering the δ^18O value of calcite in some higher grade marbles., 名古屋大学博士学位論文 学位の種類:理学博士(論文) 学位授与年月日: 昭和59年11月12日},
 school = {名古屋大学, Nagoya University},
 title = {Carbon lsotopic Study in Coexisting Calcite and Graphite in the Ryoke Metamorphic Rocks, Northern Kiso District , Central Japan : 北部木曽地方，領家変成岩中に共存する方解石と石墨の炭素同位体的研究},
 year = {1984}
}