SHRIMP U–Pb geochronology from Mount Kirkby, northern Prince Charles Mountains, East Antarctica

Sensitive High Resolution Ion MicroProbe (SHRIMP) U–Pb zircon dating of pegmatites from Mount Kirkby, northern Prince Charles Mountains, east Antarctica indicates felsic intrusive activity at 991 ± 22 Ma and 910 ± 18 Ma. Pegmatite emplacement occurred during prolonged high-grade early Neoproterozoic tectonism. These ages correlate well with previously published U–Pb zircon ages obtained from felsic intrusive bodies elsewhere within the northern Prince Charles Mountains. Early Palaeozoic activity at Mount Kirkby is restricted to the emplacement of minor planar pegmatites at 517 ± 12 Ma, which provide a maximum age for local development of discrete extensional mylonites. No conclusive evidence of tectonic or metamorphic events at c. 800 Ma and c. 500 Ma, which have been recently postulated for the region, can be identified from the presently available U–Pb zircon data.

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Geochemistry and geochronology of high-grade rocks from the Grove Mountains, East Antarctica: Evidence for an Early Neoproterozoic basement metamorphosed during a single Late Neoproterozoic/Cambrian tectonic cycle

Precambrian Research ◽

10.1016/j.precamres.2007.04.005 ◽

2007 ◽

Vol 158 (1-2) ◽

pp. 93-118 ◽

Cited By ~ 26

Author(s):

Xiaochun Liu ◽

Bor-Ming Jahn ◽

Yue Zhao ◽

Guochun Zhao ◽

Xiaohan Liu

Keyword(s):

East Antarctica ◽

High Grade ◽

Late Neoproterozoic ◽

Grove Mountains ◽

Early Neoproterozoic

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A two-stage evolution of the Neoproterozoic Rayner Structural Episode: new U–Pb sensitive high resolution ion microprobe constraints from the Oygarden Group, Kemp Land, East Antarctica

Precambrian Research ◽

10.1016/s0301-9268(02)00028-1 ◽

2002 ◽

Vol 116 (3-4) ◽

pp. 307-330 ◽

Cited By ~ 121

Author(s):

N Kelly

Keyword(s):

High Resolution ◽

East Antarctica ◽

Ion Microprobe ◽

Two Stage

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Deciphering early Neoproterozoic and Cambrian high-grade metamorphic events in the Archean/Mesoproterozoic Rauer Group, East Antarctica

Precambrian Research ◽

10.1016/j.precamres.2021.106392 ◽

2021 ◽

Vol 365 ◽

pp. 106392

Author(s):

Xiaochun Liu ◽

Longyao Chen ◽

Wei-RZ Wang ◽

Yue Zhao ◽

Xiaoxiao Ling ◽

...

Keyword(s):

East Antarctica ◽

High Grade ◽

Early Neoproterozoic

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BIMG-04. MAPPING HETEROGENEITY OF HIGH-GRADE GLIOMA METABOLISM USING HIGH RESOLUTION 7T MRSI

Neuro-Oncology Advances ◽

10.1093/noajnl/vdab024.003 ◽

2021 ◽

Vol 3 (Supplement_1) ◽

pp. i1-i1

Author(s):

Gilbert Hangel ◽

Cornelius Cadrien ◽

Philipp Lazen ◽

Sukrit Sharma ◽

Julia Furtner ◽

...

Keyword(s):

High Resolution ◽

Imaging Techniques ◽

Basis Set ◽

Metabolic Imaging ◽

Tumor Segmentation ◽

Low Grade ◽

High Grade ◽

Isotropic Resolution ◽

Contrast Enhanced ◽

Definition Of

Abstract OBJECTIVES Neurosurgical resection in gliomas depends on the precise preoperative definition of the tumor and its margins to realize a safe maximum resection that translates into a better patient outcome. New metabolic imaging techniques could improve this delineation as well as designate targets for biopsies. We validated the performance of our fast high-resolution whole-brain 3D-magnetic resonance spectroscopic imaging (MRSI) method at 7T in high-grade gliomas (HGGs) as first step to this regard. METHODS We measured 23 patients with HGGs at 7T with MRSI covering the whole cerebrum with 3.4mm isotropic resolution in 15 min. Quantification used a basis-set of 17 neurochemical components. They were evaluated for their reliability/quality and compared to neuroradiologically segmented tumor regions-of-interest (necrosis, contrast-enhanced, non-contrast-enhanced+edema, peritumoral) and histopathology (e.g., grade, IDH-status). RESULTS We found 18/23 measurements to be usable and ten neurochemicals quantified with acceptable quality. The most common denominators were increases of glutamine, glycine, and total choline as well as decreases of N-acetyl-aspartate and total creatine over most tumor regions. Other metabolites like taurine and serine showed mixed behavior. We further found that heterogeneity in the metabolic images often continued into the peritumoral region. While 2-hydroxy-glutarate could not be satisfyingly quantified, we found a tendency for a decrease of glutamate in IDH1-mutant HGGs. DISCUSSION Our findings corresponded well to clinical tumor segmentation but were more heterogeneous and often extended into the peritumoral region. Our results corresponded to previous knowledge, but with previously not feasible resolution. Apart from glycine/glutamine and their role in glioma progression, more research on the connection of glutamate and others to specific mutations is necessary. The addition of low-grade gliomas and statistical ROI analysis in a larger cohort will be the next important steps to define the benefits of our 7T MRSI approach for the definition of spatial metabolic tumor profiles.

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