The incipient charnockite or orthopyroxene-bearing granitic orthogneiss is a relatively common constituent in ancient granulite-facies terranes, and its formation has been often attributed to an influx of CO₂-rich fluid or a removal of aqueous melt. Temporal relationship between the orthopyroxene formation and the fluid or melt migration, however, remains debatable. Here we report the first finding of incipient charnockite hosted by garnet-biotite-bearing granitic gneisses in the Sancheong–Hadong anorthosite complex, Yeongnam Massif. Both lithologies preserve a variety of field and microstructural evidence for partial melting and subsequent melt crystallization, as manifested by granitic leucosomes and biotite-rich residua. Based on the phase equilibria modeling and geothermobarometric calculation, peak metamorphic conditions of migmatities were estimated to be 5.4–6.0 kbar and 800–850 °C, which led to the biotite dehydration melting together with the orthopyroxene formation in incipient charnockite. Sensitive high-resolution ion microprobe (SHRIMP) U–Pb analyses of zircon from an incipient charnockite and a host gneiss yielded the weighted mean ²⁰⁷Pb/²⁰⁶Pb ages identical within errors; 1880 ± 5 Ma and 1872 ± 6 Ma for the cores, and 1862 ± 4 Ma and 1861 ± 4 Ma for the rims, respectively. The former is interpreted to represent the time for magmatic crystallization of granitic protoliths, whereas the latter for subsequent anatexis typified by peritectic growth of orthopyroxene. Such a timeline is consistent with two distinct thermal events previously reported from the Sancheong-Hadong anorthosite complex. By contrast, monazite grains from a biotite-bearing granitic gneiss in the charnockite zone yielded the weighted mean ²⁰⁷Pb/²⁰⁶Pb ages of 1866 ± 14 Ma and 1835 ± 11 Ma for the core and rim, respectively. The latter is consistent with 1842 ± 8 Ma, estimated from monazite neoblasts of incipient charnockite. The monazite growth during a post-peak metamorphic stage at ca. 1.84 Ga is attributed to a fluid influx event, apparently concentrated in the charnockite zone. The charnockite formation in the Yeongnam Massif further attests to the longevity (>ca. 40 m.y.) of hot orogenesis that has governed the Paleoproterozoic crustal evolution in eastern North China Craton.

初期的charnockite或含斜方辉石的花岗正方麻岩是古代麻粒岩相地体中相对常见的成分，其形成通常归因于CO ₂的流入- 富含流体或去除水性熔体。然而，斜方辉石形成与流体或熔体迁移之间的时间关系仍然存在争议。在这里，我们报告了岭南地块 Sancheong-Hadong 斜长岩复合体中含有石榴石黑云母的花岗片麻岩的首次发现。两种岩性都保留了部分熔融和随后熔融结晶的各种现场和微观结构证据，如花岗岩白质体和富含黑云母的残渣所证明的那样。根据相平衡模型和地热气压计算，混合岩的峰值变质条件估计为 5.4-6.0 kbar 和 800-850 °C，这导致黑云母脱水熔融，并在初期的霞石中形成斜方辉石。²⁰⁷ Pb/ ²⁰⁶ Pb 年龄在误差范围内相同；铁芯为 1880 ± 5 Ma 和 1872 ± 6 Ma，轮辋分别为 1862 ± 4 Ma 和 1861 ± 4 Ma。前者被解释为代表花岗岩原岩岩浆结晶的时间，而后者则代表随后的以斜方辉石包晶生长为代表的精矿。这样的时间线与先前从 Sancheong-Hadong 斜长岩复合体报道的两个不同的热事件一致。相比之下，来自黑云母带花岗片麻岩的独居石颗粒产生了加权平均²⁰⁷ Pb/ ²⁰⁶核心和边缘的 Pb 年龄分别为 1866 ± 14 Ma 和 1835 ± 11 Ma。后者与 1842 ± 8 Ma 一致，这是从初期的炭黑的独居石新生细胞估计的。大约在峰后变质阶段的独居石生长。1.84 Ga 归因于流体涌入事件，显然集中在charnockite 区。岭南地块的炭黑岩形成进一步证明了控制华北克拉通东部古元古代地壳演化的热造山作用的寿命（>约 40 米）。