B.S. Western Carolina University, 1983
Ph.D. Columbia University, 1989

Geochemistry and Petrology of Subduction Zones, Modern and Ancient
Geochemical Evolution of the Earth's Mantle
Petrogenesis of Ultramafic Rocks
Appalachian Geology and Tectonics
Analytical Geochemistry
Meteoritic/Planetary Geochemistry

Email address:
Telephone: (813) 974-1598

Links to:

Classes Taught:
GLY 3311 The Solid Earth - Petrology and Geochemistry
GLY 4780, Geological Field Studies: Blue Ridge Mountains
GLY 4045, Moons, Planets and Meteors
GLY 4947L, Practical and Applied Geology
GLY 6285, Analytical Techniques
GLY 6739, Tracer Geochemistry
GLY 6315C: Topics In Igneous and Metamorphic Petrology GLY 2030, Environmental Geology (Summer Session)

2000-2002 REU Student Research Program in the Blue Ridge Mountains

Information on the New Geology Undergraduate Curriculum

Zeta Psi Chapter, Sigma Gamma Epsilon Homepage

Graduate Students and Research:

Petrology/Geochemistry/Planetary Research at USF

Ph.D. students

Ivan Savov - B.S. University of Sofia, M.S. Univ. South Florida (Chemical cycling in subduction zones as constrained by forearc ultramafic rocks, ODP Legs 125 and 195)

Masters candidates:

Andy VanCleave - B.A. (History) Univ. South Florida (Bioprecipitates in Mg-silicate/carbonate systems: insights into ALH84001 carbonate genesis)

Megan Davis Hendren - B.S. Eckerd College (Li isotope and B-Be-Li studies of New Georgia/Woodlark volcanic rocks)

Judy Harden - B.S. University of South Florida (Li isotope and B-Be-Li studies of "hotspot" and other intraplate volcanic rocks)

Recent Masters Graduates

Suzie Norrell - Petrogenesis of Alkaline lavas, Eastern Siberia

Michael Emilio - Metamorphic and Tectonic Evolution of Buck Creek Ultramafic Complex, Southern Appalachians

Ivan Savov - Petrogenesis of the Balkan-Carpathian Ophiolite Complex, Bulgaria and Serbia

Monica Palaseanu (Environmental Science and Policy) - A study of Metals Contamination in Baia Mare City, Romania

Livio Tornabene - The Gatun Structure: Geological assessment of a newly recognized impact structure near Gatun Lake in the Republic de Panama (An E-Thesis: Check it out!!)

The science I do is very strongly instrument-based: I examine unusual and often difficult-to-measure elemental and isotopic tracers in rocks and waters as a means of gaining new insights into the origins and history of these materials, and to characterize and understand large-scale geochemical processes in the Earth. Toward these ends I manage the Geology department's elemental analysis laboratories at USF, which now include a DC plasma emission spectrometer as our primary in-house tool for elemental analysis, and an X-ray powder diffractometer for the identification of minerals. Students also have the opportunity to analyze samples for Rare Earth Elements (REE) and other low abundance trace elements using the Inductively Coupled Plasma Mass Spectrometry (ICP-MS) laboratory available at the USF Department of Marine Sciences. My ongoing collaborations with researchers at the Department of Terrestrial Magnetism of the Carnegie Institution of Washington provides us with access to their extensive analytical facility, including thermal ionization mass spectrometry facilities for traditional radiogenic isotopes, and their new doubly focusing, multicollector ICP-source MS instruments for B and Li isotopic analyses. A new addition to our analytical capabilities (funded by NSF) is a regional electron microprobe/SEM facility. The instrument is housed at Florida International University, in the Florida Center for Analytical Electron Microscopy , and we have remote operation capabilities at USF via an Internet 2 operational link, which means that we run the instrument in real time off of our desktop computers in Tampa (it's WAY cool.).

I currently maintain active research programs on modern subduction zones, and on the origins and metamorphic/tectonic evolution of igneous rock units in the southern Appalachians. Both of these research lines are supported by NSF grant funds.  My subduction zone studies follow two separate, but related tracks:

1) Elemental fluxes in subduction zones. Tracers such as Li, B, 11/10 B and 10/9 Be indicate that materials and particularly fluids from the subducting plate are involved in the generation of lavas at volcanic arcs. I am examining a wide variety of volcanic and metamorphic materials to constrain the physical processes behind fluid-mediated slab/mantle chemical exchanges, and to quantify chemical fluxes between the Earth's surface and its deep interior. My most recent efforts have involved examining lithium isotope variations in suites of arc lavas, volcanic rocks from several different "hotspot" settings, and in arc mantle-derived ultramafic xenoliths with the goal of characterizing both subduction-related fluxes of Li into the mantle, and to try and identify subduction-generated Li reservoirs in the mantle.

2) The petrogenesis of igneous and metamorphic rocks at subduction zones. I am studying the origins of igneous rocks from a variety of volcanic arcs (the Woodlark Basin/New Georgia volcanic arc, the Mexican Volcanic Belt, Kuril-Kamchatka arc, the Central American volcanic arc, and the Aleutians, among others). I have also been examining the origins and history of subduction-related metamorphic rocks, including samples from the "subduction complex" association of the Catalina Schist (Calif.), and in particular samples of diapiric serpentinites extruding as seamounts in the forearc regions of the Marianas and Izu-Bonin arcs.

The mass transfer pathways indicated by our forearc and cross-arc studies have led me to examine the role that subduction plays in defining the chemical signature of the deep mantle. A recently funded project will examine the B and Li isotopic systematics of lavas from Mt. Erebus, Antarctica, with the intention of identifying subducted components in the deep mantle sources of intraplate lavas.  Newly funded research will use Li isotope systematics along with B-Be-Li abundance systematics to assess the development of mantle heterogeneities in subduction systems, focusing on off-axis volcanism in Mexico and Guatemala; and to fully characterize the OIB-source mantle reservoirs for Li isotopes.

My Appalachian research focuses primarily on unraveling the metamorphic evolution and igneous origins of mafic/ultramafic rock associations in southwest North Carolina. These units are emplaced in late Precambrian-age basement and lowermost cover sequence rocks, and thus will provide insights into the earliest stages of the evolution of the southern Appalachians, in particular into the possibility of late Precambrian rifting, as is recorded in metavolcanic sequences to the northeast. In concert with Drs. Virginia Peterson, Steven Yurkovich, and John Burr of Western Carolina University, Dr. Sarah Kruse and I are pursuing a combined field, geophysical and geochemical research program oriented toward undergraduates, which will focus on chemically characterizing the major rock units in the region, and detailed mapping and structural analysis efforts to infer the current orientation and deformational history of the ultramafic units. Graduate student-driven efforts in this program have focused on a careful documentation of the metamorphic histories of these units, as a tool to use in the reconstruction of their tectonic histories. This year, the focus of our research efforts will be the Carroll Knob mafic-ultramafic complex, in which we have discovered new and unreported lithologic variability.

My work on Appalachian mafic-ultramafic associations has (thanks in large part to a highly motivated graduate student!) expanded to include the study of the Balkan-Carpathian Ophiolite in Bulgaria, which, though substantially less metamorphosed than the complexes we examine in the Blue Ridge, may be time correlative and thus relate to the same global episode of rifting. Aspects of our research on Appalachian ultramafics and of subduction zone fluxes are currently trying to dovetail, as we begin to pursue (from both perspectives) the examination of small, podiform ultramafic bodies in the Blue Ridge and Piedmont belts of NC and VA, some of which preserve textures and mineralogies remarkably similar to those of the Mariana forearc serpentinites.

A fledgling field of research in my lab, born of a new undergraduate course ( GLY 4045: Moons, Planets, and Meteors: see below) and the excitment and energy of students from that class, relates to meteor impacts, meteorite geochemistry and planetary sciences. Currently, a graduate student and I are examining the petrology and shock metamorphic effects in rocks from a probable Cenozoic impact site in the Panama Canal Zone. I'm also collaborating with Rachel Lentz, Harry McSween and coworkers of the Univ. Tennesee at Knoxville on examining B-Be-Li abundance variations in SNC meteorites via ion microprobe, and with my colleague Lisa Robbins at the USGS Coastal Research Lab in trying to understand the origins of the carbonate minerals in the Martian meteorite ALH 84001. A fledgling project in this direction is the study of Li and B isotopic variability in silicate meteorites. Our work currently focuses on Li isotopic systematics, and involves a comparison of the major achondrite meteorite classes with their probable chondritic progenitors. Our goals are a) to use the Li isotopic signatures of meteorites to place constraints on the Li isotopic composition of the primitive Earth, which will give us a starting point for quantitative modeling of the effects of subduction on the Earth's mantle over time, and b) to try and assess the degree of Li isotopic heterogeneity that existed in the early Solar Nebula.

Among the non-petrologic studies done in my lab was an examination of sediments from a polluted estuary in southern Spain, and baseline chemical studies of Florida wetland soils. Active student projects include a survey of metal abundances in the local host rocks of the Floridan Aquifer (including the unconsolidated, "surficial aquifer" materials with which there is direct hydraulic communiation). Recently, working with Robert Brinkmann and Graham Tobin of the USF Geography department we have undertaken more extensive studies of soil chemistry (toward understanding soil pollution at minesites and other locales) and a substantial project to chemically characterize street sweepings, both to provide disposal recommendations to state and local agencies, and to assess the role of street debris in municipal water pollution problems. And currently, I have a student pursuing her degree through the new Environmental Science and Policy graduate program at USF, looking into heavy metal contamination problems in soils from the city of Baia Mare, Romania.

I teach a variety of courses at both the undergraduate and graduate levels. I teach our junior level mineralogy/petrology course, called The Solid Earth: Petrology and Geochemistry , a hands-on course where one learns how to identify minerals, as well as how to "read" the mineral assemblages of igneous and metamorphic rocks to find out how and where in the Earth they came to be; and a section of our Geologic Field Studies course which focuses on the geologic evolution of the southern Appalachians through in-class study and a ten day field trip at the end of each Spring term. I also teach a number of sections of GLY 4947L Practical and Applied Geology , which are short courses open to Senior Geology Majors (+others via my permit) in which students participate hands-on in defining and solving real Earth Science problems.

For graduates I teach Analytical Techniques in Geology , a course in which students learn to use analytical instruments necessary to their research efforts; Tracer Geochemistry , in which students learn how to use trace element and isotopic tracers to both discover and to track geologic processes; and a variety of upper-level seminars, covering topics from B and Li isotope geochemistry, through the petrogenesis of mafic and ultramafic rocks, to planetary geology. A Senior-level undergraduate course I am teaching, called Moons, Planets, and Meteors , is an introduction to the interdisciplinaryfields of planetary science and meteoritics. Class activities include hands-on study of meteorites, examination of thin sections of lunar and meteoritic samples, World Wide Web investigations of geomorphologic data for the Moon, Venus, and Mars, and field trips to the Kennedy Space Center and local planetariums. The course has proven to be very popular, so to meet demand I have been teaching it as a Distance Learning course offering since the Summer of 1998. The two-way videoconferencing technology we are using in the course affords the students some unique opportunities, including real-time exchanges with experts in the field who are linked into the class from distant sites, and days that I teach remotely from international scientific meetings, to which I can bring newly presented discoveries and advances into the classroom, essentially "hot off the presses."

Funded Research Grants and Contracts: (new and active grants in bold)

National Science Foundation: "The Role of the Slab and the Mantle in Arc Petrogenesis: A Li-Be-B and Li Isotope Study of Off-Axis Volcanoes in Mexico and Guatemala" (NEWLY FUNDED!)

Texas A&M Research Foundation (JOI-USSSP)(10/1/01-8/31/04): "The Role of the Forearc in Subduction Zone Chemical Cycles: Fluid-Mobile Element and B-Li isotope signatures of serpentinites from S. Chamorro Seamount, ODP Leg 195"

National Science Foundation "The Role of the Forearc in Subduction Zone Chemical Cycles - Insights from Diapiric Serpentinites, Mariana Forearc - REU Supplement"

National Science Foundation (5/1/00: Current): "Collaborative Research: REU: An integrated field-laboratory experience for undergraduates: Constraints on the evolution of Blue Ridge mafic/ultramafic massifs"

National Science Foundation (2/15/2000: current) $39640 "The Search for Subducted Components in the Mantle: A Boron and Lithium Isotope, and Fluid Mobile Element Study of Mount Erebus"

National Science Foundation (9/1/99-8/31/02) "The Role of the Forearc in Subduction Zone Chemical Cycles - Insights from Diapiric Serpentinites, Mariana Forearc"

National Science Foundation (9/1/99-8/31/00) $563,000 "Acquisition of an Electron Probe Microanalyzer: a Regional Facility" [Collaborative grant with G. Sen, FIU, M. Perfit, UF, and V.Salters, FSU].

Florida Department of Transportation (9/1/98- 4/30/01) $368,000 "Testing Protocol Program for Street Sweeping"

National Science Foundation (4/1/97-3/31/99): $98560 "REU: An integrated field-laboratory experience for undergraduates: Constraints on the tectonic evolution of ultramafic massifs in the Southern Blue Ridge"

Florida Center for Solid and Hazardous Waste Management (4/1/97_4/1/98): $18000 "Chemical Characteristics of Street Sweepings in Florida Cities"

Florida Center for Solid and Hazardous Waste Management (4/1/96_4/1/97): $20000 "Baseline chemical analyses of Florida soils"

National Science Foundation (6/1/92): $104500 "Chemical Recycling in Subduction Zones: B, Li, and 10/9Be Systematics in Rocks from Forearc Regions (with REU Supplement)"

National Science Foundation (9/15/93) $49000 "Acquisition of a Direct Current Plasma Emission Spectrometer"

Current Science - Abstracts of Recent Presentations at National and International Meetings.

REU Program Results: Publications and Presentations at GSA SE-Section and National Meetings.

Publications (students in italics)

If not linked below, please send reprint requests to:

Hickey-Vargas, R., M. Sun, L. Lopez-Escobar, H. Moreno-Roa, M.K. Reagan, J.D. Morris, and J. G. Ryan (2002) Multiple subduction components in the mantle wedge: evidence from eruptive centers in the Central Southern volcanic zone, Chile. Geology, 30: 199-202.

Lentz, R.C.F., H.Y. McSween, Jr., J.G. Ryan, L. Riciputi, (2001) Water in martian magmas: Clues from light lithophile elements in shergottites and nakhlites. Geochimica et Cosmochimica Acta, 65: 4551-4565.

Savov, I . P.J.G. Ryan, I. Haydoutov, and J. Schijf. (2001) Late Precambrian Balkan-Carpathian ophiolite - a slice of Pan-African ocean crust? Geochemical and tectonic insights from the Tcherni Vrah and Deli Jovan masifs, Bulgaria and Serbia. Journal of Volcanology and Geothermal Research, 10: 299-318.

Berger, S, Cochrane, D., Simons, K. Savov I., J.G. Ryan, and V.L Peterson (2001) Insights from rare earth elements into the genesis of the Buck Creek Complex and other Blue Ridge ultramafic bodies. Southeastern Geology, vol. 40, no. 3, pp. 201-212.

Benton, L.D., J.G. Ryan , and F. Tera (2001) Boron isotope systematics of slab fluids as inferred from a serpentinite seamount, Mariana forearc. Earth and Planetary Science Letters, vol. 187, p. 273-282.

McSween, H.Y., Jr., T.L. Grove, R.C.F. Lentz, J.C. Dann, A.H. Holzheid, L.R. Riciputi, and J.G.Ryan (2001) Geochemical evidence for magmatic water within Mars from pyroxenes in the Shergotty meteorite . Nature, vol. 409, p. 487-490.

Dixon, J.E., K. Simons, L. Leist, C. Eck, J. Ricisak, J. Gifford, and J.G. Ryan (2000), Provenance of stone celts from the Miami Circle archaeological site. The Florida Anthropologist , 53, 328-341.

Davis, R.A., Jr., A.T. Welty , J. Borrego, J.A. Morales, J.G. Pendon, and J.G. Ryan, 2000, Rio Tinto estuary (Spain): 5000 years of pollution. Environmental Geology, vol. 39, 1107-1116.

P.B. Tomascak, J.G. Ryan , and M.J. Defant , 2000 Lithium isotope evidence for light element decoupling in the Panama subarc mantle Geology vol. 28, pp. 507-510.

G. Bebout, J.G. Ryan , W.P. Leeman, and A.E. Bebout, 1999, Fractionation of trace elements during subduction-zone metamorphism - effect of convergent margin thermal evolution Earth and Planetary Science Letters vol. 171, pp. 63-81.

Ryan, J.G., J. Morris, G. Bebout, and W.P. Leeman, 1996, Describing chemical fluxes in subduction zones: insights from "depth profiling" studies of arc and forearc rocks. In: Subduction: Top to Bottom , (G.E. Bebout, et al., eds.) AGU Monograph 96 , pp. 263-268..

Ryan, J.G., Leeman, W.P., Morris, J.D. and Langmuir, C.H., 1996, The boron systematics of intraplate lavas: implications for crust and mantle evolution. Geochimica et Cosmochimica Acta , vol. 60, pp. 415-422.

Tenthorey, E.A., Ryan, J.G. and Snow, E.A., 1996, The petrogenesis of a sapphirine-bearing meta-troctolite in the Buck Creek ultramafic body, Clay County, N.C. Journal of Metamorphic Geology, vol. 14, pp. 103-114.

Hochstaedter, A.F., Ryan, J.G., Luhr, J.F., and Hasenake, T., 1996, On B/Be systematics of the Mexican Volcanic Belt. Geochimica et Cosmochimica Acta , vol. 60, pp. 613-628.

Noll, P.D. , Newsom, H.E., Leeman, W.P., and Ryan, J.G., 1996, The role of hydrothermal fluids in the production of subduction zone magmas: evidence from siderophile and chalcophile trace elements and boron. Geochimica et Cosmochimica Acta , vol. 60, pp. 587-611.

Ryan, J.G., Morris J.D., Tera F., Leeman W.P. and Tsvetkov A.,1995, Cross-arc geochemical variations in the Kurile island arc as a function of slab depth. Science , vol. 270, 625-628.

Bebout, G.E., Ryan, J.G., and W.P. Leeman, 1993, B-Be systematics in subduction-related metamorphic rocks: characterization of the subducted component. Geochimica et Cosmochimica Acta , vol. 57 2227-2237.

Morris, J., Ryan, J.G., and Leeman W.P., 1993, Be Isotope and B-Be investigations of the historic eruptions of Mt. Vesuvius. Journal of Volcanology and Geothermal Research , vol. 58, 345-358.

Ryan, J.G. and C.H. Langmuir,1993, The systematics of boron abundances in young volcanic rocks. Geochimica et Cosmochimica Acta vol. 57, 1489-1498.

Bebout, G.E., Ryan, J.G. and W.P. Leeman, 1991, Boron and beryllium concentrations in subduction_related metamorphic rocks of the Catalina Schist: implications for subduction-zone reycling. 1991 Report to the Director, Geophysical Laboratory , pp. 23-29.

Ryan, J.G. and C.H. Langmuir, 1988, Beryllium systematics in young volcanic rocks: implications for 10Be. Geochimica et Cosmochimica Acta , vol. 52, pp. 237-244.

Ryan, J.G. and C.H. Langmuir, 1987, The systematics of lithium abundances in young volcanic rocks. Geochimica et Cosmochimica Acta , vol. 51, pp. 1727-1741.

Mroz, T.H., J.G. Ryan and C.W. Byrer [Editors] (1983) Methane recovery from coalbeds: a potential energy source. U.S. DOE: Morgantown Energy Technology Center, DOE/METC/83-76, 458 pages.

Link back to USF Geology Homepage</