Análise integrada via TTF e U-Pb em apatita para estudos de geo-termocronologia nas Montanhas Ellsworth, Antártica

Abstract

Fission Track Thermochronology (FTT) can be combined with other geochronological methods to form what is defined as multi-proxy. The primary method among the various techniques is U-Pb dating. This is because, while FTT provides data on low-temperature events, U-Pb dating determines the crystallization age of rocks at high-intermediate temperatures. Together, these methodologies are effective for studies of sedimentary provenance, magmatism, metamorphism, sedimentation, and crustal accretion. Specifically, in this project, the methods were applied to apatite samples from the Antarctic Peninsula, a geologically complex region with little thermochronological exploration. The research focused on the western portion, emphasizing the Ellsworth Mountains, a strategic area for understanding the tectonic processes that acted on the Antarctic Peninsula. Four samples were analyzed using optical microscopy to obtain spontaneous track density (and dating) within TTF dating and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) for U-Pb dating. TTF analysis of the Ellsworth Mountains samples gave ages ranging from 205 to 23 Ma, with a peak around 180 Ma related to rifting in the Transantarctic Mountains. Ages between 141 and 117 Ma indicate the age of uplift of the Ellsworth Mountains, while significant denudation events occurred between 50 and 45 Ma during the Paleogene. The U-Pb ages indicate an Antarctic uplift event in the Cambrian, after plutonic and metamorphic events, with ages around 500 Ma. The results reinforce the effectiveness of the integration between TTF and U-Pb in the reconstruction of the thermal and tectonic history of the region, highlighting the potential of TTF as a robust tool to investigate areas of great geological interest.