Details
| Original language | English |
|---|---|
| Pages (from-to) | 449-461 |
| Number of pages | 13 |
| Journal | Journal of metamorphic geology |
| Volume | 17 |
| Issue number | 4 |
| Publication status | Published - Jul 1999 |
| Externally published | Yes |
Abstract
Garnet from a kinzigite, a high-grade gneiss from the central Black Forest (Germany), displays a prominent and regular retrograde diffusion zoning in Fe, Mn and particularly Mg. The Mg diffusion profiles are suitable to derive cooling rates using recent datasets for cation diffusion in garnet. This information, together with textural relationships, thermobarometry and thermochronology, is used to constrain the pressure-temperature-time history of the high-grade gneisses. The garnet-biotite thermometer indicates peak metamorphic temperatures for the garnet cores of 730-810 °C. The temperatures for the outer rims are 600-650 °C. Garnet-Al2SiO5-plagioclase-quartz (GASP) barometry, garnet-rutile-Al2SiO5-ilmenite (GRAIL) and garnet-rutile-ilmenite-plagioclase-quartz (GRIPS) barometry yield pressures from 6-9 kbar. U-Pb ages of monazite of 341 ± 2 Ma date the low-P high-T metamorphism in the central Black Forest. A Rb/Sr biotite-whole rock pair defines a cooling age of 321 ± 2 Ma. The two mineral ages yield a cooling rate of about 15 ± 2 °C Ma-1. The petrologic cooling rates, with particular consideration of the fO2 conditions for modelling retrograde diffusion profiles, agree with the geochronological cooling rate. The oldest sediments overlying the crystalline basement indicate a minimum cooling rate of 10 °C Ma-1.
Keywords
- Black Forest, Garnet diffusion modelling, Geospeedometry, Kinzigites, Petrological cooling rate
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geology
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Journal of metamorphic geology, Vol. 17, No. 4, 07.1999, p. 449-461.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Quantitative temperature-time information from retrograde diffusion zoning in garnet
T2 - Constraints for the P-T-t history of the central Black Forest, Germany
AU - Weyer, S.
AU - Jarick, J.
AU - Mezger, K.
PY - 1999/7
Y1 - 1999/7
N2 - Garnet from a kinzigite, a high-grade gneiss from the central Black Forest (Germany), displays a prominent and regular retrograde diffusion zoning in Fe, Mn and particularly Mg. The Mg diffusion profiles are suitable to derive cooling rates using recent datasets for cation diffusion in garnet. This information, together with textural relationships, thermobarometry and thermochronology, is used to constrain the pressure-temperature-time history of the high-grade gneisses. The garnet-biotite thermometer indicates peak metamorphic temperatures for the garnet cores of 730-810 °C. The temperatures for the outer rims are 600-650 °C. Garnet-Al2SiO5-plagioclase-quartz (GASP) barometry, garnet-rutile-Al2SiO5-ilmenite (GRAIL) and garnet-rutile-ilmenite-plagioclase-quartz (GRIPS) barometry yield pressures from 6-9 kbar. U-Pb ages of monazite of 341 ± 2 Ma date the low-P high-T metamorphism in the central Black Forest. A Rb/Sr biotite-whole rock pair defines a cooling age of 321 ± 2 Ma. The two mineral ages yield a cooling rate of about 15 ± 2 °C Ma-1. The petrologic cooling rates, with particular consideration of the fO2 conditions for modelling retrograde diffusion profiles, agree with the geochronological cooling rate. The oldest sediments overlying the crystalline basement indicate a minimum cooling rate of 10 °C Ma-1.
AB - Garnet from a kinzigite, a high-grade gneiss from the central Black Forest (Germany), displays a prominent and regular retrograde diffusion zoning in Fe, Mn and particularly Mg. The Mg diffusion profiles are suitable to derive cooling rates using recent datasets for cation diffusion in garnet. This information, together with textural relationships, thermobarometry and thermochronology, is used to constrain the pressure-temperature-time history of the high-grade gneisses. The garnet-biotite thermometer indicates peak metamorphic temperatures for the garnet cores of 730-810 °C. The temperatures for the outer rims are 600-650 °C. Garnet-Al2SiO5-plagioclase-quartz (GASP) barometry, garnet-rutile-Al2SiO5-ilmenite (GRAIL) and garnet-rutile-ilmenite-plagioclase-quartz (GRIPS) barometry yield pressures from 6-9 kbar. U-Pb ages of monazite of 341 ± 2 Ma date the low-P high-T metamorphism in the central Black Forest. A Rb/Sr biotite-whole rock pair defines a cooling age of 321 ± 2 Ma. The two mineral ages yield a cooling rate of about 15 ± 2 °C Ma-1. The petrologic cooling rates, with particular consideration of the fO2 conditions for modelling retrograde diffusion profiles, agree with the geochronological cooling rate. The oldest sediments overlying the crystalline basement indicate a minimum cooling rate of 10 °C Ma-1.
KW - Black Forest
KW - Garnet diffusion modelling
KW - Geospeedometry
KW - Kinzigites
KW - Petrological cooling rate
UR - http://www.scopus.com/inward/record.url?scp=0033165807&partnerID=8YFLogxK
U2 - 10.1046/j.1525-1314.1999.00207.x
DO - 10.1046/j.1525-1314.1999.00207.x
M3 - Article
AN - SCOPUS:0033165807
VL - 17
SP - 449
EP - 461
JO - Journal of metamorphic geology
JF - Journal of metamorphic geology
SN - 0263-4929
IS - 4
ER -