Situated in the southern part of Yidun arc in the southeastern Tibetan Plateau, the Zhongdian arc records magmatic activity that ranges from approximately 270 to 190 Ma, which is likely attributable to subduction of the Garze-Litang slab and involved steady low-volume magmatic lulls punctuated by short-lived high-volume flare-ups. Many porphyry copper deposits have been found in these magmatic rocks, but the temporal-spatial relationships among magmatism, porphyry copper deposits, and subduction processes around the Zhongdian arc have long been debated. Frequency distributions calculated from igneous zircon U-Pb ages are commonly utilized to interpret the duration of magmatic events. Recently, a new concept of fractal density and a local singularity analysis (LSA) method have been applied to analyze the geometric properties of zircon U-Pb age peak anomalies, which are linked to deeply rooted avalanches associated with short spurts of convection during the formation of supercontinents and continental crust growth. In this paper, the igneous zircon U-Pb dating data collected from the Zhongdian arc are analyzed by the LSA method from the perspective of fractal density to interpret the causational relationship between age peak and subduction process of the Garze-Litang oceanic crust. The results show that the age density around the age peak of 215 Ma can be well fitted and described by power law functions, and the strong singularity (k > 0.8) indicates the occurrence of extreme geological events. Meanwhile, systematic changes in the hafnium isotopic composition of igneous zircons with time reflect the upwelling of asthenospheric mantle materials, characterized by a rapid increase in ε_Hf(t) values that reach the highest around the 215 Ma peak. Moreover, the log–log plot that shows the cumulative number-age distribution reveals another transitional age of 235 Ma. By comparison of the magmatic intensity between the western and eastern belts of the Zhongdian arc, it is indicated that the eastward magmatic migration might have begun at ca. 235 Ma. Combined with the previous work, we propose that the Indosinian magmatic flare-up in the Zhongdian arc might have been caused by superimposition of slab subduction, steepening of slab dip, and slab breakoff. This long-term magmatic hydrothermal evolution system and extreme singularity events also provide indispensable conditions for the formation of large-scale and high-grade porphyry copper deposits in the region. Our findings provide new insights into the subduction process of the Garze-Litang oceanic crust and Indosinian magmatic framework around the Zhongdian arc. It is believed that the LSA method has potential applications in depicting the variation of magmatic activity and predicting mineral resources.

中甸弧位于青藏高原东南部义墩弧的南部，记录了大约 270 至 190 Ma 的岩浆活动，这可能归因于甘孜-理塘板块的俯冲，并涉及稳定的低容量岩浆间歇。由短暂的高容量突发事件引起。在这些岩浆岩中发现了许多斑岩铜矿床，但围绕中甸弧的岩浆活动、斑岩铜矿床和俯冲过程之间的时空关系一直存在争议。从火成岩锆石 U-Pb 年龄计算的频率分布通常用于解释岩浆事件的持续时间。最近，分形密度的新概念和局部奇异性分析 (LSA) 方法已被应用于分析锆石 U-Pb 年龄峰值异常的几何特性，这些异常与与超大陆形成过程中短时间对流爆发相关的根深蒂固的雪崩有关和大陆地壳生长。本文从中甸弧采集的火成岩锆石U-Pb定年数据，从分形密度的角度，采用LSA方法进行分析，解读甘孜-理塘洋壳年龄峰值与俯冲过程之间的因果关系。结果表明，215 Ma年龄峰值附近的年龄密度可以很好地拟合并用幂律函数描述，并且具有较强的奇异性（这与在超大陆形成和大陆地壳生长过程中与短时间对流爆发相关的根深蒂固的雪崩有关。本文从中甸弧采集的火成岩锆石U-Pb定年数据，从分形密度的角度，采用LSA方法进行分析，解读甘孜-理塘洋壳年龄峰值与俯冲过程之间的因果关系。结果表明，215 Ma年龄峰值附近的年龄密度可以很好地拟合并用幂律函数描述，并且具有较强的奇异性（这与在超大陆形成和大陆地壳生长过程中与短时间对流爆发相关的根深蒂固的雪崩有关。本文从中甸弧采集的火成岩锆石U-Pb定年数据，从分形密度的角度，采用LSA方法进行分析，解读甘孜-理塘洋壳年龄峰值与俯冲过程之间的因果关系。结果表明，215 Ma年龄峰值附近的年龄密度可以很好地拟合并用幂律函数描述，并且具有较强的奇异性（利用LSA法从中甸弧采集的火成岩锆石U-Pb定年数据，从分形密度的角度进行分析，解释甘孜-理塘洋壳年龄峰值与俯冲过程之间的因果关系。结果表明，215 Ma年龄峰值附近的年龄密度可以很好地拟合并用幂律函数描述，并且具有较强的奇异性（利用LSA法从中甸弧采集的火成岩锆石U-Pb定年数据，从分形密度的角度进行分析，解释甘孜-理塘洋壳年龄峰值与俯冲过程之间的因果关系。结果表明，215 Ma年龄峰值附近的年龄密度可以很好地拟合并用幂律函数描述，并且具有较强的奇异性（k  > 0.8) 表示发生了极端地质事件。同时，火成岩锆石铪同位素组成随时间的系统变化反映了软流圈地幔物质的上涌，其特征是ε _Hf迅速增加(t) 在 215 Ma 峰值附近达到最高值。此外，显示累积数量-年龄分布的对数-对数图揭示了另一个 235 Ma 的过渡年龄。中甸弧东西带岩浆强度的对比表明，岩浆东移可能始于约 10 年。235 马。结合前人的研究，我们认为中甸弧印支期岩浆爆发的原因可能是板块俯冲叠加、板块倾角变陡、板块断裂。这种长期的岩浆热液演化系统和极端奇异事件，也为该地区大规模、高品位斑岩铜矿床的形成提供了不可或缺的条件。我们的发现为研究中甸弧附近的甘孜-理塘洋壳和印支期岩浆框架的俯冲过程提供了新的见解。相信LSA方法在描绘岩浆活动变化和预测矿产资源方面具有潜在的应用价值。