| 刘方方,王幻,冯翼鹏,鲁扬,申萍.智利劳斯奎洛斯晚白垩世岩浆岩年代学及岩石地球化学:岩石成因及构造意义[J].矿产勘查,2026,17(8):1454-1463 |
| 智利劳斯奎洛斯晚白垩世岩浆岩年代学及岩石地球化学:岩石成因及构造意义 |
| Petrogenesis and tectonic significance of Late Cretaceous magmatic rocks in Los Quilos, Chile: Constraints from geochronology and geochemistry |
| 投稿时间：2025-10-29 |
| DOI：10.20008/j.kckc.202608012 |
| 中文关键词: K-Ar测年 晚白垩世 I型花岗岩 陆缘弧 劳斯奎洛斯 智利 |
| 英文关键词: K-Ar dating Late Cretaceous I-type continental arc Los Quilos Chile |
| 基金项目:本文受中央财政国外矿产资源风险勘查项目(10254A019)资助。 |
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| 中文摘要: |
| 智利劳斯奎洛斯地区位于著名的安第斯中部铜金成矿带，发育大规模晚白垩世岩浆活动，是探讨安第斯陆缘弧构造-岩浆演化及其成矿背景的理想区域。本文通过对该区闪长玢岩、安山岩及凝灰岩开展全岩 K-Ar年代学与主、微量元素地球化学研究，旨在厘定其岩石成因及构造动力学背景。测年结果显示，闪长玢岩的侵入时代为 81.53~70.28 Ma，表明其为晚白垩世岩浆活动的产物。地球化学分析表明，劳斯奎洛斯岩浆岩属于高钾钙碱性-钾玄质系列，表现出显著的 Nb、Ta、Ti、P及 Sr亏损，并强烈富集 K、Ba、Rb、Th、U等大离子亲石元素；其 10000 Ga/A比值较低(均值 2.04)且 P2O5含量随 SiO2增加而递减，具有典型的中等分异 I型花岗岩特征。岩浆演化主要受控于角闪石、斜长石，及磷灰石的分离结晶作用。较低的 Sr/Y比值(主体<35)和(La/Yb)N比值(4.10~7.97)指示其形成于中等厚度的地壳环境(30~35 km)，尚未达到石榴子石稳定域。结合区域演化资料，认为劳斯奎洛斯岩浆岩产于由早期弧内伸展向秘鲁造山期挤压体制转换的过渡阶段。这一岩浆活动响应了岩浆弧东移及陆壳初始增厚的动力学过程，为认识安第斯带晚白垩世成岩-成矿背景提供了关键的地质约束。 |
| 英文摘要: |
| The Los Quilos area in central Chile, situated within the prolific Central Andean copper-gold metal.logenic belt, preserves a critical record of Late Cretaceous tectono-magmatic evolution. This study presents whole-rock K-Ar geochronology and high-precision major and trace element geochemistry of diorite porphyrite, andesite,and tuff units to elucidate their petrogenesis and geodynamic setting. K-Ar dating results yield ages ranging from 70.28 to 81.53 Ma, confirming their emplacement during the Late Cretaceous. Geochemically, the Los Quilos mag.matic suites belong to the high-K calc-alkaline to shoshonitic series, characterized by pronounced depletions inNb, Ta, Ti, P, and Sr, coupled with strong enrichments in large-ion lithophile elements (LILE) such as K, Ba, Rb,Th, and U. Low 10000Ga/A ratios (averaging 2.04) and a definitive negative correlation between P2O5 and SiO2 iden. tify these rocks as moderately differentiated I-type granitoids. Trace element modeling suggests that magmatic dif.ferentiation was primarily governed by the fractional crystallization of amphibole, plagioclase, and apatite. Rela.tively low Sr/Y ratios (predominantly <35) and (La/Yb)N values (4.10-7.97) indicate that the magmas evolved withina normal to moderately thickened crust (ca. 30-35 km), consistent with a setting above the garnet stability field. In.tegrated with regional geological evidence, we propose that the Los Quilos magmatism occurred during a transitionalstage from early intra-arc extension to the compressional regime driven by the Peruvian Orogenic Phase. This mag.matic pulse represents a dynamic response to the eastward migration of the magmatic arc and initial crustal thicken.ing of the Andean margin, providing essential geodynamic constraints for understanding the regional Late Creta.ceous ore-forming environment. |
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