MAGMATIC ARC EVOLUTION IN THE PONGKOR EPITHERMAL GOLD MINERALISATION DISTRICT
The Pongkor epithermal gold mineralisation district is located approximately 80 km southwest of Jakarta. This district hosts the largest gold vein deposits in Java, Indonesia. Although the Pongkor district has been the subject of several geological studies, the arc evolution in relation to gold m...
Saved in:
| Main Authors: | , , |
|---|---|
| 格式: | Article PeerReviewed |
| 語言: | English |
| 出版: |
Jurusan Teknik Geologi
2014
|
| 主題: | |
| 在線閱讀: | https://repository.ugm.ac.id/136277/1/488-503%20P3O-01.pdf https://repository.ugm.ac.id/136277/ |
| 標簽: |
添加標簽
沒有標簽, 成為第一個標記此記錄!
|
| 機構: | Universitas Gadjah Mada |
| 語言: | English |
| 總結: | The Pongkor epithermal gold mineralisation district is located approximately 80 km southwest of
Jakarta. This district hosts the largest gold vein deposits in Java, Indonesia. Although the Pongkor
district has been the subject of several geological studies, the arc evolution in relation to gold
mineralisation is less well understood. The timing and geochemical evolution of the Pongkor
volcanic rocks provide an important background to understanding the volcanic successions of this
magmatic arc in relation to epithermal gold mineralisation. This study presents
40
Ar/
39
Ar age
results, and major and trace element data for the Pongkor volcanic rocks associated with epithermal
gold deposition in the region. A sequence of volcanic rocks of basaltic – dacitic composition,
consisting of volcanic breccias, lapilli tuffs and andesites, form the host volcanic rocks to the
Pongkor epithermal gold mineralisation.
40
Ar/
39
Ar dating of the andesitic samples yielded an
average age of 2.74 ± 0.03 Ma. However, petrographic studies and the younger ages of 2.48 ± 0.01
Ma and 2.09 ± 0.04 Ma obtained from andesitic and basaltic andesite samples, respectively,imply
that these samples were affected by alteration; therefore the ages probably relate more to the time
of hydrothermal alteration than volcanic eruptions. Enriched LILE (Large Ion Lithopile Element)
and LREE (Light Rare Earth Element) compositions for basalt – andesite samples from the
Pongkor district are characteristic of calc-alkaline arcs. On the other hand, some andesite samples
are characterized by more enriched LILE and LREE compositions, which are indicative of high-K
calc-alkaline and shoshonite arcs. Trends in Nb/Y, Th/Nb, and Ce/Yb, ratios of the volcanic
samples reflect temporal evolution of the arcs, from a mature arc (intermediate Nb/Y, Th/Nb and
Ce/Yb ratios) representedby the calc-alkaline volcanic samples, to an evolved arc (high Nb/Y,
Th/Nb and Ce/Yb values) typified by the high-K calc-alkaline – shoshonite volcanic samples.
Keyword:
40
Ar/
39
Ar dating, Magmatic arc evolution, Pongkor District, Volcanism |
|---|