U–Pb petrochronology of deep crustal xenoliths and outcrops across northeastern Tanzania track the thermal evolution of the Mozambique Belt and Tanzanian Craton following the Neoproterozoic East African Orogeny (EAO) and subsequent Neogene rifting. At the craton margin, the upper–middle crust record thermal quiescence since the Archean (2.8–2.5 Ga zircon, rutile, and apatite in granite and amphibolite xenoliths). The lower crust of the craton documents thermal pulses associated with Neoarchean ultra-high temperature metamorphism (ca. 2.64 Ga, > 900 °C zircon), the EAO (600–500 Ma rutile), and fluid influx during rifting (< 5 Ma apatite). Rutile in garnet granulite xenoliths exhibits partial Pb loss related to slow cooling of the lower crust after the EAO and suggests residence at 500–600 °C prior to entrainment. In contrast to the craton, the entire crust of the Mozambique Belt underwent differential cooling following the EAO. Both the upper and middle crust record metamorphism from 640 to 560 Ma (zircon, monazite, and titanite) and rapid exhumation at 510–440 Ma (rutile and apatite). Lower crustal xenoliths contain Archean zircon, but near-zero age rutile and apatite, indicating residence > 650 °C (above Pb closure of rutile and apatite) at the time of eruption. Zoned titanite records growth during cooling of the lower crust at 550 Ma, followed by fluid influx during slow cooling and exhumation (0.1–1 °C/Myr after 450 Ma). Permissible lower-crustal temperatures for the craton and orogen suggest variable mantle heat flow through the crust and reflect differences in mantle lithosphere thickness rather than advective heating from rifting.

中文翻译：

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东非造山带四维热演化：坦桑尼亚东北部坦桑尼亚克拉通和莫桑比克带地壳剖面的副相岩石年代学

坦桑尼亚东北部深部地壳捕虏体和露头的 U-Pb 岩石年代学追踪了在新元古代东非造山运动 (EAO) 和随后的新近纪裂谷之后莫桑比克带和坦桑尼亚克拉通的热演化。在克拉通边缘，上中地壳记录了自太古宙以来的热静止（花岗岩和角闪石捕虏体中的 2.8-2.5 Ga 锆石、金红石和磷灰石）。克拉通下地壳记录了与新太古代超高温变质作用（约 2.64 Ga，> 900 °C 锆石）、EAO（600-500 Ma 金红石）和裂谷期间流体流入（< 5 Ma 磷灰石）相关的热脉冲）。石榴石麻粒岩捕虏体中的金红石表现出部分 Pb 损失与 EAO 后下地壳的缓慢冷却有关，并表明在夹带之前停留在 500-600 °C。与克拉通相反，在 EAO 之后，莫桑比克带的整个地壳都经历了差异冷却。上地壳和中地壳均记录了 640 至 560 Ma（锆石、独居石和钛石）的变质作用和 510-440 Ma（金红石和磷灰石）的快速剥露。下地壳捕虏体包含太古代锆石，但金红石和磷灰石的年龄接近零，表明在喷发时停留 > 650 °C（高于金红石和磷灰石的铅闭合）。分区的钛铁矿记录了在 550 Ma 下地壳冷却过程中的生长，随后在缓慢冷却和折返过程中流体流入（450 Ma 后为 0.1-1 °C/Myr）。克拉通和造山带允许的较低地壳温度表明通过地壳的地幔热流是可变的，反映了地幔岩石圈厚度的差异，而不是来自裂谷的平流加热。