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VERSION:2.0
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CALSCALE:GREGORIAN
X-WR-CALNAME:Dissertation Defense: Molly Paul
X-WR-TIMEZONE:Mountain Time (US & Canada)
BEGIN:VEVENT
DTSTAMP:20260617T035630Z
UID:tag:localist.com\,2008:EventInstance_49491505487592
DTSTART:20250508T210000Z
DTEND:20250508T220000Z
DESCRIPTION:Title: USING GEOCHRONOLOGY AND GEOCHEMISTRY OF KIMBERLITE AND C
 ARBONATE-RICH OLIVINE LAMPROITE XENOLITHS TO ASSESS THE EVOLUTION OF THE S
 UB-CONTINENTAL LITHOSPHERIC MANTLE OF THE KAAPVAAL CRATON\, SOUTHERN AFRIC
 A\n\nProgram: Geosciences PhD\n\nCommittee Chair: Mark Schmitz\n\nCommitte
 e: Mark Schmitz\, Linda Reynard\, CJ Northrup\, Darin Schwartz\n\nAbstract
 : The striking bimodal nature of Earth’s lithosphere — which can be su
 bdivided into ancient\, thick continents and young\, tectonically recycled
  ocean basins — is a fundamental observation that makes our planet uniqu
 e. This work seeks to understand how the ancient\, stable continental regi
 ons of lithosphere were formed and the processes which have modified them 
 since. The Kaapvaal craton of southern Africa is an ideal natural laborato
 ry for this work\, as its rich kimberlite- and lamproite-borne xenolith re
 cord readily samples both ancient and recent mantle processes. The first c
 hapter of my dissertation focuses on mantle zircon as records of temporal 
 and geochemical linkages between alkali magmatism and phlogopite-dominated
 \, mica-amphibole-rutile-ilmenite-diopside (MARID) metasomatism. I suggest
  carbonate-rich olivine lamproites (CROLs) are derived from primary MARID 
 metasomes\, which may become introduced as early as the Mesoproterozoic du
 ring oceanic plate subduction beneath the craton. Additionally\, pulses of
  kimberlitic melt infiltration prior to kimberlite eruption modify the com
 positions of MARID assemblages. My second chapter\, while still focused on
  zircon isotope and trace element systematics\, expands this metasomatic h
 istory into the Archean through the xenolithic eclogite record. Here\, I d
 ocument a ~3 Ga eclogitization event during assembly of the Kaapvaal crato
 n\, pulses of thermally and chemically activated metasomatism\, and a perv
 asive carbonatitic overprint coeval with CROL magmatism\, all within a uni
 quely metasomatized eclogite from the Roberts Victor kimberlite. The metas
 omatic history of the craton archived in this sample\, as well as its peri
 ods of quiescence\, are mirrored the diamond inclusion record. Lastly\, in
  my third chapter I reassess the U-Pb isotope systematics of a perovskite 
 standard from the Ice River Complex\, Canada using high-precision U-Pb zir
 con geochronology and a novel single-grain separation protocol to constrai
 n the initial Pb composition. This work is valuable to the scientific comm
 unity due to the paucity of phases amenable to geochronology in ultramafic
  systems\, which has encouraged the widespread use of U-Pb perovskite geoc
 hronology for dating kimberlites\, and a pressing need for matrix-matched 
 standards for in situ approaches.
GEO:43.600767;-116.199525
LOCATION:Micron Center for Materials Research (MCMR)\, 105
SUMMARY:Dissertation Defense: Molly Paul
URL;VALUE=URI:https://events.boisestate.edu/event/dissertation-defense-moll
 y-paul
CATEGORIES:Lectures and Presentations
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