Julie D. Morris

Research Associate Professor
Ph.D., Massachusetts Institute of Technology, 1984

As a research associate professor, I don't teach formal classes. I do like, though, working with students at all levels, in seminars and research settings. Recent reading groups and seminars have focused on fluids in subduction zones, sedimentary geochemistry, the seismogenic zone (with Doug Wiens), plumes and ocean island basalt volcanism (with Roger Phillips) and an undergraduate seminar on Hawaiian hydrology, volcanic alteration mineralogy, and land use (with Ray Arvidson). Currently (Fall, 2001), Everett Shock, Rachel Lindvall and I are running a users group seminar series for our Finnegan high-resolution ICP-MS. In Spring, 2002, Doug Wiens and I plan a research seminar on the geodynamics of convergent margins, with a focus on the arc and back-arc mantle from a geophysical and geochemical view. I have been involved with NSF-sponsored research opportunities for high school students and science teachers, working on projects from subduction zones to lead transport in the vicinity of a southeast Missouri smelter.

Isotope Geochemistry, Magmatism and Tectonics

In addition to my long-standing interest in subduction zones, I also have research projects that study the transport of anthropogenic Pb in southeast Missouri and continental paleoclimate using cosmogenic ¹⁰Be in Missouri and Nebraska loess deposits. 

Mobility and bioavailability of smelter-derived lead in southeast Missouri

A smelter in southeast Missouri, which began operation in 1969, is a point source of isotopically distinct Pb,. Working with faculty members Everett Shock (E&PS) and Jay Turner (Environmental Engineering), we've been carrying out a tracer and transport study of lead from the smelter through the atmosphere, soil and oak-hickory forests. Trace element and Pb isotope compositions measured by ICP-MS trace the isotopically distinct ore lead, and speciation and transport models identify some of the controlling factors. This study built on the PhD work of Kate Crombie, which showed high concentrations of smelter Pb in leaves from surrounding white oak trees, suggesting that particulate Pb from the smelter became groundwater soluble and bioavailable. High school student Lara Douglas and science teacher Linda Gaither have worked on this project. 

•  In her PhD thesis in 2001, Panjai Prapaipong studied the depth-dependent variation of Pb in soil profiles around the smelter, and its partitioning amongst the different soil constituents and soil water. Quite unexpectedly, her analytical and theoretical work showed little role for surface adsorption on clays or organo-metallic compounds in Pb binding/solubility. Rather, Pb coprecipitation with Mn and Fe oxyhydroxides seems to be the dominant control. 
•  As part of his master's program in Environmental Sciences, Colin Enssle has been studying the uptake of Pb and other heavy metals in the white oaks around the smelter. Now continuing in the E&PS PhD program, Colin's measurements on tree rings are showing the increased uptake of smelter Pb in the surrounding white oaks, appearing about 10-12 years after the smelter began operations. His work is also showing significant trace element transport in the phloem, which he is investigating to better understand the mechanisms for metal uptake and transport in vascular plants. 
•  As part of an Environmental Science masters program, Jim Scheff worked with the St. Louis Department of Health to test whether Pb measurements by ICP-MS could be used to distinguish gasoline and paint as sources of dust and soil Pb in St. Louis city housing.

Continental Paleoclimate and Cosmogenic ¹⁰Be

Combined radiocarbon, ¹⁰Be, optically stimulated luminesce dating and pedogenesis studies of Wisconsonian loess and paleosol deposits from Nebraska and Missouri have recently started, in collaboration with U. Iowa faculty Art Bettis, Aberysthyth staff Ann Wintle and U. Nebraska faculty Joe Mason. The precise chronologies emerging from these studies will be used to document nature and timing of environmental change during the last two glacial/interglacial cycles, interpret the loess record in terms of long-term climate change and provide a basis for modeling the effects of dust flux on global change.

Inside the crater of Cerro Negro volcano in Nicaragua, following its 1999 and 1995 eruptions. Morris and U. Minnesota graduate student Rebecca Williams collected samples here for combined 10Be-U series studies. Photo taken July 2001.  Click on image for enlargement.

Subduction Zone Studies

I'm interested in the entirety of subduction zones, from the plate outboard of the trench to the arc and deep mantle, and everything in between (and above). Using cosmogenic ¹⁰Be, Li and B isotopes, and collaborating extensively, we're trying to understand physical as well as chemical processes in subduction zones. High school student Don Duncan worked on some aspects of this program. 

•  We've developed methods at Washington University for very low blank separation of Be from volcanic rocks, and Lawrence Livermore Center for Accelerator Mass Spectrometry provides high-sensitivity measurements. As a result, ¹⁰Be detection limits are now 0.1 million atoms/gram. Recent analyses show significant ¹⁰Be enrichment (0.5-4 million a/g) in lavas from the Tonga and Aleutian (with Bristol post-doc Rhiannon George), Izu and Scotia arcs (Morris et al., Reviews in Mineralogy, in press). 
•  ¹⁰Be in sediments on the incoming plate and the forearc sediment prism can be used to quantify sediment dynamics, even where biostratigraphy and magnetostratigraphy are disturbed, as in the Costa Rica forearc. ¹⁰Be measurements in Japan forearc sediments have a depth profile expected for accreted imbricate thrust packets younging downward; in Costa Rica, all sediments above the decollement are older than 3-5 Ma, indicating no frontal accretion for an extended period (Morris et al. Geology 2001). PhD candidate Robby Valentine has shown that underplating of ca. 100m of the incoming sediment section, or large amounts of subduction erosion are required to explain low, but real ¹⁰Be enrichments (0.2-1.2 million a/g) in the Costa Rican volcanoes (Valentine, in prep, 2001). Work with WHOI graduate student Robyn Kelly and her advisors is investigating the role of sediment subduction in grabens vs. sediment variation in ¹⁰Be concentration as a factor in the ¹⁰Be systematics of the Central American arc. 
•  Robby Valentine sailed on ODP Leg 185, which drilled the oldest subducting crust, outboard of the Mariana and Izu trenches. Robby is doing Li and B isotope analyses of sediments and altered oceanic crust at the Dept of Terrestrial Magnetism to determine the subduction flux and bulk isotopic composition of the subducting plate. He is also working on discrete alteration phases in the basement, to identify the primary hosts of subducting Li and B, and their isotopic compositions. This work ties both to the alteration history of the oceanic crust and the likely effects of prograde subduction metamorphism on Li and B systematics (Valentine et al. AGU abstract, fall 2001 meeting). 
•  I am co-chief for ODP Leg 205, which will investigate the active fluid flow and subduction fluxes across the Costa Rica margin, and their implications for the seismogenic zone and subduction factory. Previous work (Silver et al, Geology, 2000) showed that there are three active hydrological systems: flow of cold seawater to the incoming oceanic crust, advection of deeply sourced fluids along the decollement from depths of the seismogenic zone, and compaction dewatering of the underthrusting sediments. We will install long-term sea floor observatories (CORKs) that will monitor pressure and temperature and sample fluids and gases in each system (Morris, Villinger et al., 2001). Graduate student Dawn Cardace also plans to sail on Leg 205. Working with Miriam Kastner at Scripps, we're interested in the element flux (e.g. Ba, B, Rb, As, Cs, U, Pb) out of the downgoing plate in the fluids leaving the subduction zone, and Dawn is working with faculty Jan Amend and post-doc Melanie Summit to investigate the microbiology of the prism sediments and advected fluids. 

  Julie Morris and Rutgers professor Mike Carr on the 1772 lava flow from Masaya Volcano in Nicaragua, which has the highest 10Be measured for any arc volcano.  Photo taken by T. Vogel, July 2001.

•  Combined ¹⁰Be-U series studies are underway or completed for the Aleutians (with Bristol University post-doc Rhiannon George), Tonga (with George and Bristol faculty Simon Turner), Scotia (with BGS staff Phil Leat and Bristol faculty Tim Elliott), Kuriles (with UCSC faculty Jim Gill), and S. Chile (stratovolcanoes with CNRS staff Olgeir Sigmarsson and Jerome Chmeleff, and minor eruptive centers with Miami International faculty Rosemary Hickey Vargas and University of Iowa faculty Mark Reagan). Most striking is the observation that ¹⁰Be and ²²⁶Ra excess, which must be younger than 8ka, are often well correlated in arc lavas, indicating that the excess ²²⁶Ra is related to the subduction component, which must travel through the mantle very rapidly indeed (e.g. Reagan et al., GCA 1994; George et al., Goldschmidt abstract 2000; Sigmarsson et al. EPSL in press 2001; Morris et al, RIM in press, 2001). 
•  E&PS post-doc James Condor and faculty Doug Weins are carrying out a numerical study of mantle flow, lithospheric ablation and decompression (as opposed to fluxed) melting in the back-arc and arc. We're cooperating to add a general subductology and petrology component to the geodynamic modeling (Condor et al., ms in prep for Nature)

•  Co-Chief Scientist, Ocean Drilling Program (ODP) Leg 205 off Costa Rica, September-October, 2002 
•  Steering Committee, Subduction Factory and Seismogenic Zone Studies in Central America, 2000-2001 
•  Steering Committee, Future of Geochemistry in the ODP workshop, 2000 
•  Chair, ODP Science Steering and Evaluation Panel for studies of the Earth's Interior (ISSEP), 1999-2001 
•  Member, ODP ISSEP, 1997-1999 
•  Member, NSF Panel to review the US Science Support Plan for the Ocean Drilling Program, 1996, 1999 
•  Co-Convenor, Subduction Factory Session, COMPLEX International Meeting on the future of the ODP 
•  Convenor, Subduction Factory International Workshop, 1998 
•  Day Medal Committee Member, Geological Society of America, 1998-2000 
•  Distinguished Lecturer, Joint Oceanographic Institutions, Inc., 1998-1999 
•  Member, NSF-EAR Committee of Visitors, 1998

J.D. Morris, 1998 Hot Stuff under S. Chile, Nature, N & V, 394, 523-524.

Morris, Julie and Plank, Terry. The Subduction Factory workshop: A summary, Margins Newsletter and web site 1998

Morris, Julie, The Subduction Factory and Ocean Drilling, Joint Oceanographic Institutions Inc Newsletter and website, 1998

Morris, Julie, Terry Plank and Bob Stern, The Subduction Factory Workshop Report, 35 pp, Margins website, 1998

Plank, Terry, Bob Stern and Julie Morris, Subduction Factory Science Plan, Margins website, 1998

E.A. Silver, M. Kastner, A.T. Fisher, J.D. Morris, K.D. McIntosh, and D.M. Saffer, Fluid Flow Paths, Heat Flow Depression, and Possible Strain Cycling in a Non-Accretionary Subduction Complex: Middle America Trench at Costa Rica, Geology, 28, 679-682

J. Morris, R. Valentine and T. Harrison, ¹⁰Be imaging of sediment accretion, subduction and erosion, NE Japan and Costa Rica, in press, Geology

Morris, J., J. Gosse, S. Brachfeld, 2001, Cosmogenic ¹⁰Be and the Solid Earth: Studies in Active Tectonics, Geomagnetism and Subduction Zone Processes, in press, Reviews in Mineralogy

Morris, J., Villinger, H., Klaus, A. and Baldauf, J. Fluid flow and subduction fluxes across the Costa Rica convergent margin: Implications for the seismogenic zone and subduction factory. In press, Ocean Drilling Program Prospectus, 205.

See also Department Publications

314-935-6926	jmorris@levee.wustl.edu
314-935-7361