Xuejiping porphyry Cu deposit is located in the south of Yidun island arc, northwest Yunnan. Tectonically, it lies in the middle part of the “Sanjiang Rivers” metallogenic belts. There are ore‐barren quartz diorite, quartz diorite porphyrite (QDP), and ore‐bearing quartz monzonite porphyry (QMP) intruded into clastic‐volcanic rocks of the late Triassic Tumugou Formation. This study focused on determining why the ore‐bearing porphyry is the QMP. It analyzed the correlation between chronology, geochemistry, magmatic oxygen fugacity, and mineralization. Results show that the crystallization age of QDP is 228.7 Ma and that of QMP is 215.0 Ma, which is relatively younger. The molybdenite Re‐Os age is 219.9 Ma. The oxygen fugacity of QDP and QMP magma are higher than Fayalite‐Magnetite‐Quartz buffer, but the oxygen fugacity value of QDP magma is relatively dispersed, with high and low values. While the QMP falls in the high oxygen fugacity range. The δ¹⁸O value of QDP (from 5.66 to 6.27 with an average of 6.02) is higher than that of QMP (from 5.53 to 6.42 with average 5.76). It indicates that the QMP contains more components from the mantle than QDP. It is suggested in this paper that QMP have more potential of ore‐formation in the later stage. The QDP caused ore‐forming elements pre‐enrichment in the region. Millions of years later, the QMP intruded in QDP, the pre‐enriched elements were activated and superimposed with the ore‐forming elements of QMP, then the ore‐forming elements were carried and integrated into the ore deposit, and enriched once again.

中文翻译：

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滇西雪集坪斑岩铜矿床成矿作用：岩浆氧化作用和矿床约束

薛集坪斑岩铜矿床位于滇西北一墩岛弧以南。从构造上看，它位于“三江”成矿带的中部。侵入三叠纪晚期土木沟组碎屑火山岩中的有贫瘠的石英闪长岩，石英闪长的斑岩（QDP）和含矿的石英辉长岩斑岩（QMP）。这项研究的重点是确定为什么含矿斑岩是QMP。它分析了年代学，地球化学，岩浆氧逸度和矿化之间的相关性。结果表明，QDP的结晶年龄为228.7Ma，QMP的结晶年龄为215.0Ma，相对较年轻。辉钼矿的Re-Os年龄为219.9 Ma。QDP和QMP岩浆的氧逸度高于Fayalite-磁铁矿-石英缓冲区，但QDP岩浆的氧逸度值相对分散，有较高和较低的值。而QMP则处于高氧逸度范围内。δQDP的¹⁸ O值（从5.66到6.27，平均为6.02）高于QMP（从5.53到6.42，平均5.76）。这表明QMP包含的地幔成分比QDP还要多。本文建议QMP在后期具有更大的成矿潜力。QDP导致该地区的成矿元素预富集。数百万年后，QMP进入QDP，激活了预富集元素，并将其与QMP的成矿元素叠加，然后携带成矿元素并将其整合到矿床中，并再次富集。