TY - JOUR
T1 - Diffusion closure temperature and age of a mineral with arbitrary extent of diffusion
T2 - Theoretical formulation and applications
AU - Ganguly, Jibamitra
AU - Tirone, Massimiliano
N1 - Funding Information:
We are grateful to Professor Dodson for helpful discussions, and to Drs. Stephanie Duchêne, Olivier Jaoul, and Oscar Lovera for careful and constructive reviews. Thanks are due to Dr. Weiji Cheng for his help with some of the calculations. This research was supported by a U.S. National Foundation Grant EAR 9805232 and a NASA grant NAG5-7364. [FA]
PY - 1999/6/30
Y1 - 1999/6/30
N2 - The commonly used expression of the closure temperature, T(C), of a diffusing species in a mineral, as derived by M.H. Dodson [Contrib. Mineral. Petrol. 40 (1973) 259-264], is applicable only to systems which have undergone sufficient diffusion so that even the composition at the center of individual grains is significantly removed from that established at the onset of cooling. We have extended Dodson's formulation to include cases with arbitrarily small amount of diffusion, and applied it to calculate T(C) and age profiles, which would develop in single crystals of different geometries. These results permit evaluation of the extent of resetting of mineral age and of ion exchange geothermometers during cooling. The measured age profile of a mineral can also be used to constrain its cooling rate. These applications have been illustrated for the cases of garnet-biotite Fe-Mg exchange geothermometer, and the cooling age and closure temperatures of the Sm-Nd and Lu-Hf decay systems in garnet.
AB - The commonly used expression of the closure temperature, T(C), of a diffusing species in a mineral, as derived by M.H. Dodson [Contrib. Mineral. Petrol. 40 (1973) 259-264], is applicable only to systems which have undergone sufficient diffusion so that even the composition at the center of individual grains is significantly removed from that established at the onset of cooling. We have extended Dodson's formulation to include cases with arbitrarily small amount of diffusion, and applied it to calculate T(C) and age profiles, which would develop in single crystals of different geometries. These results permit evaluation of the extent of resetting of mineral age and of ion exchange geothermometers during cooling. The measured age profile of a mineral can also be used to constrain its cooling rate. These applications have been illustrated for the cases of garnet-biotite Fe-Mg exchange geothermometer, and the cooling age and closure temperatures of the Sm-Nd and Lu-Hf decay systems in garnet.
KW - Age
KW - Crystal chemistry
KW - Crystal zoning
KW - Diffusion
KW - Garnet group
KW - Geologic thermometry
KW - P-T-t paths
UR - http://www.scopus.com/inward/record.url?scp=0033618027&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0033618027&partnerID=8YFLogxK
U2 - 10.1016/S0012-821X(99)00089-8
DO - 10.1016/S0012-821X(99)00089-8
M3 - Article
AN - SCOPUS:0033618027
SN - 0012-821X
VL - 170
SP - 131
EP - 140
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
IS - 1-2
ER -