One of the main characteristics of the orogenic systems formed during the assembly of southwestern Gondwana in the Late Neoproterozoic is the widespread granitic magmatism. The Florianópolis Batholith in South Brazil is an excellent example of this process, as it is part of a ca. 1400 km long intrusive association that is a key unit in the reconstruction of the paleogeography of Gondwana on both sides of the Atlantic. The Santinho Granitic Association in the Island of Santa Catarina is an exceptionally well-exposed section exhibiting a complex lithological variety that includes orthogneisses intruded by multiple generations of leucogranite injections and associated with mafic magmatic enclaves. We present a detailed geochronological study of this unit based on field and petrographic characterizations, which includes U–Pb LA-ICP-MS geochronology of zircon, titanite and monazite, as well as Lu–Hf isotopy in zircon. Single-spot ages in individual hand samples are widespread and determine a magmatic process that mostly extends between ca. 640 and 600 Ma, with average crystallization ages between 625 and 605 Ma that are in accordance with field relationships. Overlapping ages support the magmatic coexistence of different magma batches with contrasting compositions that reflect heterogeneous source rocks with a predominance of old continental crust, as indicated by negative εHf values (−1.08 to −23.18) and Hf T_DM model ages between 2.95 and 1.57 Ga. The strong crustal affinity of the Hf signatures of mafic enclaves suggests a complex petrogenesis associated with the recycling of older magmatic phases, instead of representing a direct mixing of coeval mantellic magmatism. The new geochronological data, together with the complex magmatic and deformational history recorded in the association, suggest that it represents the early stages of granitic magmatism in the Florianópolis Batholith in a pre-to syn-collisional setting, preserved in the surrounding main intrusions as a mega-xenolith.

新元古代晚期西南冈瓦纳组装期间形成的造山系统的主要特征之一是广泛的花岗岩岩浆作用。巴西南部的Florianópolis岩基层是该过程的一个很好的例子，因为它是ca的一部分。1400公里长的侵入性协会，是大西洋两岸冈瓦纳古地理重建的关键单元。圣卡塔琳娜岛的Santinho花岗岩协会是一个异常暴露的地段，展现出复杂的岩性，包括由多代白云石注入侵入的正片麻岩，并与镁铁质岩浆飞地相关。我们根据田野和岩石学特征，对该单元进行了详细的年代学研究，其中包括锆石，钛矿和独居石的U–Pb LA-ICP-MS年代学，以及锆石中的Lu–Hf同位素。单个手部样本中的单斑年龄分布广泛，并确定了岩浆作用过程，该过程主要在大约两周之间延伸。640和600 Ma，平均晶化年龄在625和605 Ma之间，与场关系一致。重叠年龄支持不同岩浆批次的岩浆共存，其反差成分反映出以旧大陆壳为主的异质烃源岩，如εHf值为负（-1.08至-23.18）和Hf T 平均晶化年龄在625至605 Ma之间，符合场关系。重叠年龄支持不同岩浆批次的岩浆共存，其反差成分反映出以旧大陆壳为主的异质烃源岩，如εHf值为负（-1.08至-23.18）和Hf T 平均晶化年龄在625至605 Ma之间，符合场关系。重叠年龄支持不同岩浆批次的岩浆共存，其反差成分反映出以旧大陆壳为主的异质烃源岩，如εHf值为负（-1.08至-23.18）和Hf T_DM模型的年龄在2.95到1.57 Ga之间。镁铁质飞地的Hf签名具有很强的地壳亲和力，这表明与较早的岩浆相的再循环有关的复杂的成岩作用，而不是代表着远古时代的卫星岩浆作用的直接混合。新的年代学数据以及该组合中记录的复杂的岩浆和变形史，表明它代表了弗洛里亚诺波利斯岩床早期至同碰撞环境下花岗岩岩浆作用的早期阶段，并作为周围主要侵入体保存下来。巨异兽。