A joint project of the Graduate School, Peabody College, and the Jean & Alexander Heard Library

Title page for ETD etd-12012009-133926


Type of Document Master's Thesis
Author Flanagan, Daniel Michael
Author's Email Address daniel.m.flanagan@vanderbilt.edu
URN etd-12012009-133926
Title Zircon from Swift Creek stage eruptions records the assembly and evolution of an intrusive magmatic complex beneath Mount St. Helens
Degree Master of Science
Department Earth and Environmental Sciences
Advisory Committee
Advisor Name Title
Prof. Calvin F. Miller Committee Chair
Prof. John C. Ayers Committee Member
Keywords
  • zircon
  • U-Th geochronology
  • trace element geochemistry
  • Mount St. Helens
  • magmatic processes
Date of Defense 2009-11-19
Availability unrestricted
Abstract
This study employs combined U-Th radiometric age and trace element analyses of zircon from rocks of the Swift Creek stage (16 to 10 ka) of Mount St. Helens in order to obtain time-temperature-composition records of the melts from which these crystals grew. Results illustrate that the Mount St. Helens magmatic system has been constructed over hundreds of thousands of years by repeated intrusion of new magma batches that stall and crystallize within the crust to produce a crystal storage zone (or zones). Zircon trace element signatures primarily record the long-term magmatic conditions and interactions within this active intrusive body and do not record conditions immediately preceding eruption. Pulses of ascending magma rejuvenate and interact with existing intrusions, mixing zircon crystal populations and inducing new phases of zircon growth and melt fractionation, while magmas that do not stall in the crust entrain and mix zircon crystals from the crystal storage zone(s) and carry them to eruption. Geochemical trends with time suggest that the deep-seated magmatic system of Mount St. Helens has been strongly influenced by input of hot, relatively primitive melt since ~100 to 60 ka. This study documents the existence of an intrusive complex beneath an active arc volcano and records a clear connection between Mount St. Helens volcanism and an underlying plutonic magmatic system. It also suggests that, similar to large-scale batholiths, small-scale volcanic systems accumulate in small increments over prolonged periods of time.
Files
  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  D.M._Flanagan_M.S._Thesis.pdf 3.34 Mb 00:15:28 00:07:57 00:06:57 00:03:28 00:00:17
  SHD08-12Z_CL.pdf 645.94 Kb 00:02:59 00:01:32 00:01:20 00:00:40 00:00:03
  SHD08-13Z_CL.pdf 1.28 Mb 00:05:54 00:03:02 00:02:39 00:01:19 00:00:06
  SHD08-14Z_CL.pdf 985.18 Kb 00:04:33 00:02:20 00:02:03 00:01:01 00:00:05
  SHD08-15Z_CL.pdf 2.29 Mb 00:10:36 00:05:27 00:04:46 00:02:23 00:00:12
  SHD08-2Z_CL.pdf 743.64 Kb 00:03:26 00:01:46 00:01:32 00:00:46 00:00:03
  SHD08-3Z_CL.pdf 431.98 Kb 00:01:59 00:01:01 00:00:53 00:00:26 00:00:02
  SHD08-5Z_CL.pdf 611.52 Kb 00:02:49 00:01:27 00:01:16 00:00:38 00:00:03
  SHD08-8Z_CL.pdf 3.38 Mb 00:15:40 00:08:03 00:07:03 00:03:31 00:00:18

Browse All Available ETDs by ( Author | Department )

If you have more questions or technical problems, please Contact LITS.