Abstract
The Ulsan Fe–W skarn deposit is located within the Cretaceous Gyeongsang Basin in the southeastern part of the Korean Peninsula. The skarn and mineralization formed along contacts between the Paleogene Gadaeri granite, limestone, partially serpentinized ultramafic rocks (dunite and harzburgite), and hornfelsed volcanic and siliciclastic rocks. These various country rock types produced a system with multiple types of skarn. Typically, skarn within limestone occurs as clinopyroxene–magnetite skarn, clinopyroxene–garnet skarn, and garnet skarn, but the unique host rocks (ultramafic rocks + albitite) at Ulsan also produced unusual skarn types such as a sodic–calcic skarn system. Na–Ca skarn formed by chemical interactions between albitized granites and adjacent ultramafic rocks. This Na–Ca skarn contains unusual Na-rich clinopyroxene (acmite), Na-rich amphiboles, Cr-rich clinopyroxene, Cr-rich amphiboles, Sr-bearing plagioclase, and Ba-bearing K-feldspar. Clinopyroxene and amphibole have Na2O concentrations up to 6.5 wt%, and these minerals contain up to 12.1 and 2.5 wt% Cr2O3, respectively. Na was derived from albitite, and the formation of Cr-bearing acmite (kosmochlor) and Na-amphibole (richterite) appears to have been related to the release of Cr into the fluid phase by the breakdown of chromite in ultramafic rocks during prograde skarn formation. K-feldspar K–Ar dating yields an age of 50.3 ± 1.7 Ma for the prograde garnet skarn. The related Gadaeri granite exhibits a high-K calc-alkaline signature and a weakly metaluminous to peraluminous I-type affinity with a total alkalinity (Na2O + K2O) of 8.5–8.8 wt%. The Gadaeri granite shows an enriched REE pattern compared with albitite, as well as negative Eu anomalies, which together with the K/Rb values (200–500) are suggestive of a highly evolved magma from a continental-margin setting.
| Original language | English |
|---|---|
| Pages (from-to) | 537-550 |
| Number of pages | 14 |
| Journal | Ore Geology Reviews |
| Volume | 105 |
| DOIs | |
| Publication status | Published - 2019 Feb 1 |
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Keywords
- Albitite
- Korea
- Kosmochlor
- Na–Ca skarn
- Ulsan Fe–W skarn deposit
- Ultramafic skarn
ASJC Scopus subject areas
- Geology
- Geochemistry and Petrology
- Economic Geology
Cite this
Unique sodic–calcic skarn hosted by ultramafic rocks and albitite at the Ulsan skarn deposit, Gyeongsang Basin, South Korea. / Seo, Jieun; Choi, Seon-Gyu; Kim, Ji Won; Ryu, In–Chang C.
In: Ore Geology Reviews, Vol. 105, 01.02.2019, p. 537-550.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Unique sodic–calcic skarn hosted by ultramafic rocks and albitite at the Ulsan skarn deposit, Gyeongsang Basin, South Korea
AU - Seo, Jieun
AU - Choi, Seon-Gyu
AU - Kim, Ji Won
AU - Ryu, In–Chang C.
PY - 2019/2/1
Y1 - 2019/2/1
N2 - The Ulsan Fe–W skarn deposit is located within the Cretaceous Gyeongsang Basin in the southeastern part of the Korean Peninsula. The skarn and mineralization formed along contacts between the Paleogene Gadaeri granite, limestone, partially serpentinized ultramafic rocks (dunite and harzburgite), and hornfelsed volcanic and siliciclastic rocks. These various country rock types produced a system with multiple types of skarn. Typically, skarn within limestone occurs as clinopyroxene–magnetite skarn, clinopyroxene–garnet skarn, and garnet skarn, but the unique host rocks (ultramafic rocks + albitite) at Ulsan also produced unusual skarn types such as a sodic–calcic skarn system. Na–Ca skarn formed by chemical interactions between albitized granites and adjacent ultramafic rocks. This Na–Ca skarn contains unusual Na-rich clinopyroxene (acmite), Na-rich amphiboles, Cr-rich clinopyroxene, Cr-rich amphiboles, Sr-bearing plagioclase, and Ba-bearing K-feldspar. Clinopyroxene and amphibole have Na2O concentrations up to 6.5 wt%, and these minerals contain up to 12.1 and 2.5 wt% Cr2O3, respectively. Na was derived from albitite, and the formation of Cr-bearing acmite (kosmochlor) and Na-amphibole (richterite) appears to have been related to the release of Cr into the fluid phase by the breakdown of chromite in ultramafic rocks during prograde skarn formation. K-feldspar K–Ar dating yields an age of 50.3 ± 1.7 Ma for the prograde garnet skarn. The related Gadaeri granite exhibits a high-K calc-alkaline signature and a weakly metaluminous to peraluminous I-type affinity with a total alkalinity (Na2O + K2O) of 8.5–8.8 wt%. The Gadaeri granite shows an enriched REE pattern compared with albitite, as well as negative Eu anomalies, which together with the K/Rb values (200–500) are suggestive of a highly evolved magma from a continental-margin setting.
AB - The Ulsan Fe–W skarn deposit is located within the Cretaceous Gyeongsang Basin in the southeastern part of the Korean Peninsula. The skarn and mineralization formed along contacts between the Paleogene Gadaeri granite, limestone, partially serpentinized ultramafic rocks (dunite and harzburgite), and hornfelsed volcanic and siliciclastic rocks. These various country rock types produced a system with multiple types of skarn. Typically, skarn within limestone occurs as clinopyroxene–magnetite skarn, clinopyroxene–garnet skarn, and garnet skarn, but the unique host rocks (ultramafic rocks + albitite) at Ulsan also produced unusual skarn types such as a sodic–calcic skarn system. Na–Ca skarn formed by chemical interactions between albitized granites and adjacent ultramafic rocks. This Na–Ca skarn contains unusual Na-rich clinopyroxene (acmite), Na-rich amphiboles, Cr-rich clinopyroxene, Cr-rich amphiboles, Sr-bearing plagioclase, and Ba-bearing K-feldspar. Clinopyroxene and amphibole have Na2O concentrations up to 6.5 wt%, and these minerals contain up to 12.1 and 2.5 wt% Cr2O3, respectively. Na was derived from albitite, and the formation of Cr-bearing acmite (kosmochlor) and Na-amphibole (richterite) appears to have been related to the release of Cr into the fluid phase by the breakdown of chromite in ultramafic rocks during prograde skarn formation. K-feldspar K–Ar dating yields an age of 50.3 ± 1.7 Ma for the prograde garnet skarn. The related Gadaeri granite exhibits a high-K calc-alkaline signature and a weakly metaluminous to peraluminous I-type affinity with a total alkalinity (Na2O + K2O) of 8.5–8.8 wt%. The Gadaeri granite shows an enriched REE pattern compared with albitite, as well as negative Eu anomalies, which together with the K/Rb values (200–500) are suggestive of a highly evolved magma from a continental-margin setting.
KW - Albitite
KW - Korea
KW - Kosmochlor
KW - Na–Ca skarn
KW - Ulsan Fe–W skarn deposit
KW - Ultramafic skarn
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U2 - 10.1016/j.oregeorev.2018.12.026
DO - 10.1016/j.oregeorev.2018.12.026
M3 - Article
VL - 105
SP - 537
EP - 550
JO - Ore Geology Reviews
JF - Ore Geology Reviews
SN - 0169-1368
ER -