钛铁矿是火成岩和热液矿床中常见的副矿物。对榍石的微观结构和原位化学分析有望揭示复杂的岩浆热液过程。桐柏造山带两湾花岗岩体以二长花岗岩为主，具有丰富的镁铁质微粒包体（MMEs）。本文对两湾岩体的LA-ICP-MS U Pb年龄、结构、微量元素和Nd同位素组成进行了综合研究，以破译多个岩浆-热液过程。ü锆石和榍石的 Pb 定年结果表明，两湾二长花岗岩和 MMEs 具有相似的结晶年龄，大约在 100 年左右。130 毫安。结合岩石学和榍石地球化学研究，MMEs被认为是岩浆混合起源。根据榍石的产状、织构和化学特征，在两湾岩体中确定了4种主要类型（Ttn-1至Ttn-4）和几个亚型。其中Ttn-1、Ttn-2 g和Ttn-4 g来自二长花岗岩，而Ttn-2 m、Ttn-3和Ttn-4 m主要形成于MME。Ttn-1 晶粒是自面体并显示核幔结构。它们的岩心具有高 REE、Nb、Ta、Th 和 Y 含量，Th/U、Lu/Hf 和 Y/Zr 比值，以及低 La/Ce、Nb/Ta 比值和相对较低的 εNd (t) （ -13.3 至 -14.6) 值，表明它们是岩浆成因并从宿主二长花岗岩中结晶出来的。然而，Ttn-1 的地幔和 Ttn-3 晶粒显示出与 Ttn-1 核心相反的地球化学特征。它们相对较高的 εNd (t)（-12.1 到 -13.9）值表明它们是从镁铁质岩浆中结晶出来的。Ttn-2 g 和 Ttn-2 m 都含有丰富的磁铁矿和钛铁矿包裹体。它们显示出 Ttn-1 的核心和 Ttn-3 之间的地球化学特征，但分别更接近它们的主岩。这些特征表明它们是Ttn-1在不同岩浆中溶解-再沉淀的产物。Ttn-4 流体包裹体少，多以间隙相存在，具有低 REE、Y、HFSE、Th/U、LREEs 的特点（s 地幔和 Ttn-3 晶粒显示出与 Ttn-1 核心相反的地球化学特征。它们相对较高的 εNd (t)（-12.1 到 -13.9）值表明它们是从镁铁质岩浆中结晶出来的。Ttn-2 g 和 Ttn-2 m 都含有丰富的磁铁矿和钛铁矿包裹体。它们显示出 Ttn-1 的核心和 Ttn-3 之间的地球化学特征，但分别更接近它们的主岩。这些特征表明它们是Ttn-1在不同岩浆中溶解-再沉淀的产物。Ttn-4 流体包裹体少，多以间隙相存在，具有低 REE、Y、HFSE、Th/U、LREEs 的特点（s 地幔和 Ttn-3 晶粒显示出与 Ttn-1 核心相反的地球化学特征。它们相对较高的 εNd (t)（-12.1 到 -13.9）值表明它们是从镁铁质岩浆中结晶出来的。Ttn-2 g 和 Ttn-2 m 都含有丰富的磁铁矿和钛铁矿包裹体。它们显示出 Ttn-1 的核心和 Ttn-3 之间的地球化学特征，但分别更接近它们的主岩。这些特征表明它们是Ttn-1在不同岩浆中溶解-再沉淀的产物。Ttn-4 流体包裹体少，多以间隙相存在，具有低 REE、Y、HFSE、Th/U、LREEs 的特点（它们显示出 Ttn-1 的核心和 Ttn-3 之间的地球化学特征，但分别更接近它们的主岩。这些特征表明它们是Ttn-1在不同岩浆中溶解-再沉淀的产物。Ttn-4 流体包裹体少，多以间隙相存在，具有低 REE、Y、HFSE、Th/U、LREEs 的特点（它们显示出 Ttn-1 的核心和 Ttn-3 之间的地球化学特征，但分别更接近它们的主岩。这些特征表明它们是Ttn-1在不同岩浆中溶解-再沉淀的产物。Ttn-4 流体包裹体少，多以间隙相存在，具有低 REE、Y、HFSE、Th/U、LREEs 的特点（N )/HREEs( N ) 和高 Nb/Ta 表明它们是来自残余熔体的热液成因。不同类型榍岩的结构和地球化学特征表明，镁铁质岩浆的反复补给发生在长英质岩浆的同-晚期结晶分馏过程中。榍石的 Nd 同位素数据记录了在不同的镁铁质岩浆脉冲期间两个端元岩浆之间不同程度的同位素再平衡。我们的研究表明，钛铁矿是揭示复杂岩浆热液过程的可靠指标。
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Multiple magmatic-hydrothermal processes recorded by titanite from the Early Cretaceous Liangwan pluton, Tongbai Orogen
Titanite is a common accessory mineral in igneous rocks and hydrothermal deposits. Micro-texture and in situ chemical analyses on titanite are expected to reveal complex magmatic-hydrothermal processes. The Liangwan granitic pluton in the Tongbai Orogen is dominated by monzogranite with abundant mafic microgranular enclaves (MMEs). In this paper, an integrated study of LA-ICP-MS UPb ages, textural, trace elemental and Nd isotopic compositions of titanites were carried out for the Liangwan pluton to decipher multiple magmatic-hydrothermal processes. UPb dating results of zircon and titanite show that the Liangwan monzogranite and MMEs have similar crystallization ages of ca. 130 Ma. Combined with petrography and titanite geochemistry studies, MMEs are considered as magma mingling origin. According to the occurrence, texture, and chemical characteristics of titanite, four main types (Ttn-1 to Ttn-4) and several sub-types of titanite are identified in the Liangwan pluton. Among these types, Ttn-1, Ttn-2 g, and Ttn-4 g are from the monzogranites, while Ttn-2 m, Ttn-3, and Ttn-4 m mainly form in the MMEs. Ttn-1 grains are euhedral and show core-mantle texture. Their cores are characterized by high REEs, Nb, Ta, Th and Y contents, Th/U, Lu/Hf, and Y/Zr ratios, and low La/Ce, Nb/Ta rations, and relatively lower εNd (t) (−13.3 to −14.6) values, indicating that they are of magmatic origin and crystallized from the host monzogranites. However, Ttn-1's mantles and Ttn-3 grains show a reverse geochemical feature to those of Ttn-1's cores. Their relative higher εNd (t) (−12.1 to −13.9) values, suggest that they crystallized from a mafic magma. Both Ttn-2 g and Ttn-2 m contain abundant magnetite and ilmenite inclusions. They display geochemical characteristics between Ttn-1's cores and Ttn-3 but are closer to their host rocks, respectively. These features suggest that they are the product of the dissolution-reprecipitation of Ttn-1 in different magmas. Ttn-4 with few fluid inclusions, mostly existing as interstitial phases, is characterized by low REE, Y, HFSE, Th/U, LREEs(N)/HREEs(N), and high Nb/Ta, indicating that they are hydrothermal origin that were derived from the residual melt. Textural and geochemical features of various types of titanites indicate that repeated recharges of mafic magmas happened at the syn- to late- fractional crystallization of felsic magmas. Nd isotopic data on titanite recorded various degrees of isotopic re-equilibration between the two end-member magmas during different pulses of mafic magma. Our study demonstrates that titanite is a reliable indicator to reveal complicated magmatic-hydrothermal processes.