Thermal history analysis of selected Chilean, Indonesian and Iranian porphyry Cu-Mo-Au deposits
Thermal history analysis of selected Chilean, Indonesian and Iranian porphyry Cu-Mo-Au deposits
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发表时间：
2005
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通讯作者：
B. McInnes;N. Evans;K. Deckart;F. Fu;S. Garwin;E. Belousova;W. Griffin;Alfredo N. Bertens;D. Sukarna;S. Permanadewi;R. L. Andrew
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作者：
B. McInnes;N. Evans;K. Deckart;F. Fu;S. Garwin;E. Belousova;W. Griffin;Alfredo N. Bertens;D. Sukarna;S. Permanadewi;R. L. Andrew
本文介绍了智利、印度尼西亚和伊朗几个斑岩铜钼金矿床的 U-Pb-He 三重测年年龄，旨在确定其热历史并探索冷却/折返速率对矿石形成和保存过程的影响。对这些矿床测量的时间-温度历史数据进行逆热建模，以定量限制埋藏深度、矿石沉积持续时间、暴露年龄和冷却/折返速率。尽管 Grasberg、Batu Hijau 和 El Teniente 超斑岩矿床的模拟结果表明形成期约为 10 年，但所研究矿床的深成矿形成持续时间一般为 10 年。与斑岩矿化相关的侵入体的侵位深度范围为距古地表 800 m 至 5500 m，其中 Grasberg 和 Rio Blanco 分别是研究的最浅和最深的超斑岩矿床。热年代学数据表明，地下成矿过程中金属品位和冷却速率之间存在正相关性，但仍需进一步研究。折返率从 0.3 至 1.1 公里/米不等。对深生矿床的保存潜力具有影响，像 Sar Cheshmeh 这样的超级斑岩矿床在过去 500 万年中可能因侵蚀而损失 3.5 吨铜。在这种条件下形成表生矿的潜力很高，形成近端奇异型矿床的潜力也很高。
This paper presents U-Pb-He triple-dating age determinations for several porphyry Cu±Mo±Au deposits in Chile, Indonesia and Iran in an effort to determine their thermal histories and to explore the effects of cooling/exhumation rates on ore formation and preservation processes. Inverse thermal modelling of measured time-temperature history data from these deposits was conducted to quantitatively constrain the depth of emplacement, duration of ore deposition, exposure ages and cooling/exhumation rates. The duration of hypogene ore formation for the deposits studied generally occurs within timeframes of 10 years, although modelling results for the Grasberg, Batu Hijau and El Teniente super porphyry deposits suggest formation periods of the order of 10 years. Emplacement depths on intrusions associated with porphyry mineralisation range from 800 m to 5500 m from the palaeosurface, with Grasberg and Rio Blanco being respectively the shallowest and deepest super porphyry deposits studied. The thermochronology data indicates a positive correlation between metal grade and cooling rate during hypogene ore formation, but further investigation is warranted. Exhumation rates varying from 0.3 to 1.1 km/m.y. have implications for the preservation potential of hypogene ore deposits, with super porphyry deposits like Sar Cheshmeh potentially losing 3.5 Mt of copper to erosion over the last 5 million years. The potential for supergene ore formation under such conditions is high, as is the potential for the formation of proximal Exotica-type deposits.