Tectonometamorphic evolution of high-pressure eclogites and associated metasedimentary rocks in the Lanterman Range, northern Victoria Land, Antarctica

• Main Author: 김태환
• Other Authors: 정해명, Kim, Taehwan, 자연과학대학 지구환경과학부
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 서울대학교 대학원 2019
• Subjects: eclogite; episodic zircon growth; late Neoproterozoic rifting; manganiferous quartzite; Lanterman Range; Ross orogen; East Gondwana margin; 550; Antarctic; The Antarctic; Victoria Land; Antarc*; Antarctica
• Online Access: https://hdl.handle.net/10371/162431; http://dcollection.snu.ac.kr/common/orgView/000000156579

학위논문(박사)--서울대학교 대학원 :자연과학대학 지구환경과학부,2019. 8. 정해명. The Lanterman Range eclogites and associated metasedimentary rocks in the Lanterman Range, northern Victoria Land, Antarctica, were investigated to unravel tectonometamorphic evolution of high-pressure (P) terrane in the Andean-type Ross orogeny. The pristine eclogites primarily consisting of garnet + omphacite + calcic/sodic-calcic amphibole + epidote + phengite + rutile + quartz, revealed three stages of prograde metamorphism defining two distinctive P–T trajectories, M1–2 and M3. A combination of pseudosection modelling, mineral parageneses and thermobarometries suggests that the eclogites have initially evolved from ~15–20 kbar and 520–570 °C (M1) through ~22–25 kbar and 630–650 °C (M2), and finally to ~26 ± 3 kbar and 720 ± 80 °C (M3). The SHRIMP U-Pb dating discriminated two distinct episodes of eclogitic zircon growth at 515 ± 4 Ma (tσ; M2) and 498 ± 11 Ma (tσ; M3) from zircon mantle and rim, respectively. Average burial rates are too low (<2 mm/year) for cold subduction regime (~5–10 °C/km), suggesting an intervening exhumation stage between two prograde P–T segments. Thus, two discrete events of burial-exhumation took place with an c. 15 Ma gap during the Ross orogeny. The inherited zircon core ages (590.8 ± 8.3 Ma and 603.2 ± 4.4 Ma, tσ) and mildly alkalic, within-plate to continental basalt-like geochemistry of the eclogites were combined to suggest that their gabbroic protoliths should be a spatial-temporal equivalent to c. 600–580 Ma rift to passive margin magmatic rocks in the Tasmanides of eastern Australia. This is the first discovery of Ediacaran rift-related magmatism in the Ross orogen, thereby fulfilling the Antarctic missing link for paleogeographic linkage between Australia and Antarctica during the Neoproterozoic. Furthermore, I suggest oceanward propagation of rifting along the Australian-Antarctic margins from Cryogenian (c. 670–650 Ma) to Ediacaran (c. 600–580 Ma), followed by two discrete tectonic inversion events at Ediacaran (c. ...