Sam Swanson

Professor

Academic History

B.S., M.S., UC Davis, 1968, 1970

Ph.D., Stanford University, 1974

1974 - 1976 Assistant Professor, University of North Carolina-Charlotte

1976-1979 Assistant Professor, Appalachian State University (Boone, North Carolina)

1979- 1994 Assistant, Associate, Professor, University of Alaska-Fairbanks

1985-1986 Research Associate Oak Ridge National Laboratory (sabbatical leave)

1986-1993 Head, Department of Geology and Geophysics, University of Alaska-Fairbanks

1993-1994 Adjunct Professor, University of Tennessee-Knoxville (sabbatical leave)

1994- 2000 Head, Department of Geology, University of Georgia

1994-present Professor, University of Georgia

Research Interests

Petrology of Archaeological Materials

I grew up on a ranch in central California. One of our fields contained a Native American, Pomo camp site. After each tilling of the field I would find lots of obsidian fragments and an occasional arrowhead. Grind stones used to make acorn meal were common in a creek at the site. This was my first experience with stony archaeological materials. The geoarchaeology program at UGA provided a way to professionally expand on my boyhood interests in geoarchaeology. This spring (2007) we used this obsidian in GEOL 8170 as a class project and determined the source was in Napa Valley.

Current research projects focus on the application of traditional petrologic tools (petrographic microscope; electron microprobe; X-ray diffraction; major, and isotope geochemistry) to characterize archaeological materials. Soapstone (talc-rich schists) was used as a bowl-making material by Native Americans in the southeast prior to the use of pottery (up to the end of the Archaic Period, about 3500 years ago). Soapstone from Native American quarries in Georgia and North Carolina (Turner et al., 1998; Turner and Swanson, 1998), Maryland, and Nigeria are currently being studied in an effort to identify mineralogic and/or geochemical fingerprints to distinguish the various sources of soapstone. Another project involves the sourcing of artifacts from the Etowah Mounds site in northwest Georgia (Swanson and Wheeler, 2004; Swanson et al., 2005).

My graduates work on a variety of &dsquo;stony’ archaeological materials. Graduates worked with Roman-age slags from Carthage, Tunisia (Nikki Lyle, M.S., UGA, 2002), 3000 year old glass from Iran (Stapleton and Swanson, 2002a, 2002b; Ph.D. 2003), and Spanish ceramics (Cranfill, M.S. 2006) from colonial Maryland. Currently (2007), two students (Cynthia Hotujec and Jennifer Wehby) are working with me. Cynthia is working on turquoise from New Mexico and Jennifer is working on Roman mortars from Pompeii.

References Cited

Stapleton, C.P., and Swanson, S.E., 2002a, Chemical analyses of glass artifacts from Iron Age levels of Hasanlu, northwestern Iran, in Vandiver, P. Goodaway, M., and Mass, J. L., (eds.) Materials Issues in Art and Archaeology VI. Proceedings of the Materials Research Society Symposium v. 712, p. 315-321.

Stapleton, C.P., and Swanson, S.E., 2002b, Batch material processing and glass-making technology of 9th century B.C. artifacts excavated from the site of Hasanlu, northwestern Iran, Journal of Glass Technology, v. 43C, p. 151-157.

Swanson, S. E. and Wheeler, G., 2004, Compositional analysis of Etowah paletts, program and Abstracts of the Fiftieth Midwest Archaeological Conference and the Sixty-First Southeastern Archaeological Conference, p. 127.

Swanson, S. E., Steponaitis, V. P., Wheeler, G. and Johnson, J. S., 2005, Mineralogy and petrology of palette stones from Etowah Mounds, Georgia, Geol. Soc. Am. Abs. with Prog., v. 37, p. 47.

Turner, A.V., Swanson, S.E., and Roden, M.F., 1998, Mineralogic control on archaeological soapstone bowl manufacture, Geol. Soc. Am. Abs. with Prog., v. 30, p. 63-64.

Turner, A.V. and Swanson, S.E., 1998, A mineralogical and geochemical comparison of two Native American soapstone quarries, Geol. Soc. Am. Abs. with Prog., v. 30 p. A17.

Petrology of Granitic Rocks

My interest in granitic rocks comes from a summer internship with the USGS mapping in the Sierra Nevada batholith. I mapped and did a petrologic study of a granitic pluton in the western Sierra Nevada for my Masters thesis and documented the transition from metaaluminous (hb+bt) to peraluminous (musc+bt) compositions during fractional crystallization (Swanson, 1978). I worked with one of my USGS mentors on a small granitic pluton east of Yosemite National Park and we documented the subvolcanic character of this pluton (Kistler and Swanson, 1981). In Alaska, I worked closely with my colleagues Rainer Newberry and a number of graduate students on the petrology of granitic rocks and their relation to mineralization (Swanson et al., 1988; Swanson et al., 1990).

More recently I have worked on the granitic rocks of the Spruce Pine (NC) area. Spruce Pine granitic rocks contain abundant pegmatitic zones and the very coarse grain size promoted mining and hand-sorting of feldspar and mica. This mining tradition continues today (flotation is now used to separate the minerals) and high purity quartz is the current “hot” product produced from Spruce Pine (Swanson and Veal, 2006). Examination of mineralogy and oxygen isotope geochemistry reveals a post-magmatic metamorphic history in these rocks (Swanson, 1998). Brian Veal , (M. S. UGA, 2004) completed a study of mineralogy of Spruce Pine pegmatites and associated granites.

References Cited

Kistler, R.W., and Swanson, S.E., 1981, Petrology and geochronology of metamorphosed volcanic rocks and a middle-Cretaceous volcanic neck in the east-central Sierra Nevada, Jour. Geophys. Res., v. 86, p. 10489-10501.

Swanson, S. E., 1978, Petrology of the Rocklin pluton and associated rocks, western Sierra Nevada, California, Bull. Geol. Soc. Am., v. 89, p. 679-686.

Swanson, S. E., 1998, Metamorphic history of the Spruce Pine granites, western North Carolina, Geol. Soc. Am. Abs. with Prog., v. 30, p. 62.

Swanson, S.E., Bond, J.F., and Newberry, R.J., 1988, Petrogenesis of the Ear Mountain tin granite, Seward Peninsula, Alaska, Econ. Geol., v. 83, p. 46-61.

Swanson, S.E., Newberry, R.J., Coulter, G.A., and Dyehouse,T.M., 1990, Mineralogical variation as a guide to the petrogenesis of the tin granites and related skarns, Seward peninsula, Alaska, in Ore-bearing Granite Systems; Petrogenesis and Mineralizing Processes, H.J. Stein and J. L. Hannah (eds.), Geol. Soc. Am. Special Paper 246, p. 143-159.

Swanson, S. E., and Veal, B., 2006, Texture: Its what makes Spruce Pine granites special, in Reid, J. C. (Ed.), Proceedings of the 42nd Forum on the Geology of Industrial Minerals; North Carolina Geological Survey Circular 34, p. 538 (CD).

Crystal Growth and Development of Igneous Textures

I was part of the Luth-Tuttle -Jahns experimental petrology group during my Ph. D. Studies at Stanford University. I continued my experimental studies at Stanford for several summers after my graduation in 1974. The main focus of my work was the growth of feldspar and quartz from undercooled granitic melts. These studies (Swanson, 1977; 1979) documented the fundamental difference between textural development in plutonic rocks (low undercoolings) and volcanic rocks (crystallization at high undercoolings). Metastable crystallization of some phases at the expense of others (Naney and Swanson, 1980) and the effect of volatile components on nucleation (Swanson 1979; Swanson and Fenn, 1992) emphasizes the importance of nucleation kinetics in igneous systems. The quantification of the undercooling required to produce cellular quartz (Swanson and Fenn; 1986) led to the recognition of the importance of undercooling even in plutonic systems.

Crystallization kinetics help to explain textures in igneous rocks. Recognition of cellular textures in olivine and plagioclase in metapillow basalts (Swanson and Schiffman, 1979) or in hornblende and feldspar-quartz spherulites in rhyolite (Swanson et al.,1989) furnish clues about the cooling conditions of the lavas.

Current work revolves around the use of cellular textures produced at some undercooling to explain the crystallization of granitic pegmatites. The Stone Mountain (near Atlanta) contains both euhedral and cellular tourmaline produced over a range of undercoolings (Swanson et al., 2001). Graphic granite, found in many pegmatitic granites, records crystallization at some undercooling (Swanson and Fenn, 1986) and the distribution of this texture in pegmatitc systems will provide clues about crystallization and fluid evolution in pegmatitic systems. Work at Spruce Pine documents the distribution of zones of undercooling in some deep-seated pegmatitic granitic rocks. A similar project could be done of pegmatitic dikes in granitic rocks of the Georgia Piedmont crystallized over a range of depths.

Another current study involves the ability of geologists to recognize textural variation in granite (Swanson et al., 2005).

References cited

Naney, M.T., and Swanson, S.E., 1980, The effect of Fe and Mg on crystal growth in synthetic granitic and granodioritic liquids, Am. Min., v. 65, p.

Swanson, S.E., 1977, Relation of nucleation and crystal growth rate to the development of granitic textures, Am. Min., v. 62, p. 966-978.

Swanson, S.E., 1979, The effect of CO2 on phase equilibria and crystal growth in the system KAlSi3O8-NaAlSi3O8-CaAl2Si2O8-SiO2-H2O-CO2 to 8000 bars, Am. Jour. Sci., v. 279, p. 703-720.

Swanson, S.E., and Schiffman, P., 1979, Textural evolution and metamorphism of pillow basalts from the Franciscan Complex, western Marin County, California, Contrib. Mineral. Petrol., v. 69, p. 291-299.

Swanson, S.E., and Fenn, P.M., 1986, Crystallization of quartz in igneous systems, Am. Min., v. 71, p. 331-342.

Swanson, S.E., Naney, M.T., Westrich, H.R., and Eichelberger, J.C., 1989, Crystallization history of Obsidian Dome, Inyo Domes, California, Bull. Volcan., v. 51, p.161-176.

Swanson, S.E., and Fenn, P.M., 1992, The effect of F and Cl on the kinetics of albite crystallization: a model for granitic pegmatites ?, Can. Mineral., v. 30, p. 549-559.

Swanson, S.E., Mirante, D.C., Schrader, C.M., Tracy, B.J., Wolak, C.E., and Roden, M.F., 2001, Undercooling in granitoid systems: an example from Stone Mtn.,GA, Geol. Soc. Am. Abs. With Programs, v. 33, p.A-29.

Swanson, S. E., Swanson, R. B., and Hawkins, D. B., 2005, Textural variation in granite, in Roden, M. F., Schroeder, P. A., and Swanson, S. E. (eds.) Geologic Investigations of Elberton Granite and Surrounding Rocks, Georgia Geological Society Guidebook v. 25, no. 1, p. 29-42.

Ultramafic Rocks of the Southern Appalachian Mountains

Ultramafic rocks in the southern Appalachian Mountains have provided resources to people for thousands of years. Ancient Americans carved the soft soapstone into bowls in pre-ceramic times. More recently these deposits yielded a variety of industrial minerals including olivine, asbestos, vermiculite, corundum, and chromite.

Hess wrote about the tectonic significance of these rocks nearly 50 years ago, but the tectonic setting of these enigmatic rocks is still debated. Some early studies (Swanson, 1980, 1981) showed the metamorphic character of these rocks, but many workers continued to refer to the ultramafic rocks are primary igneous rocks. Recent studies (Swanson and Warner, 2001; Swanson, 2001; Raymond et al., 2003) have confirmed the polymetamorphic history of these rocks and attempted to look beyond the metamorphic overprint to determine the petrotectonic significance of these rocks (Swanson et al., 2005). Potential projects involve structural, mineralogic, and petrologic studies of these rocks in different areas (different tectonic settings ?) and at different metamorphic grades.

References Cited

Raymond, L.A., Swanson, S.E., Allan, J.F., and Love, A.B., 2003, Cr-spinel compositions, metadunite petrology, and the petrotectonic history of Blue Ridge ophiolites, southern Appalachian Orogen, USA in Dilek, Y., and Robinson, P. T., (eds.) Ophiolites in Earth History. Geol Soc. London Spec. Pub. 218, p. 253-278.

Swanson, S.E.,1980, Petrology of the Rich Mountain ultramafic and associated rocks, Watauga County, North Carolina, Southeastern Geology, v. 21, p. 209-225.

Swanson, S.E., 1981, Mineralogy and petrology of the Day Book dunite and associated rocks western North Carolina, Southeastern Geology, v. 22, p. 53-77.

Swanson, S.E., 2001, Ultramafic rocks of the Spruce Pine area, western North Carolina: A sensitive guide to fluid migration and metamorphism, Southeastern Geology, v. 40, p. 163-182

Swanson, S.E., and Warner, R.D., 2001, Pyroxene-rich rocks of the Webster-Addie complex, western North Carolina, Geol. Soc. Am. Abs. With Programs, v. 33, p. A-18.

Swanson, S. E., Raymond, L. A., Warner, R. D., Ryan, J. G., Yurkovich, S. P., and Peterson, V. L., 2005, petrotectonics of mafic and ultramafic rocks in Blue Ridge terranes of western North Carolina and northern Georgia, in Hatcher, R. D., Jr., and Merschat, A. J., (eds.), Blue Ridge Geology Geotraverse East of the Great Smoky Mountains National Park, Western North Carolina, NC Geol. Surv., Carolina Geol. Soc. Annual Field Trip Guidebook, p. 73 -90.

Swanson, S. E., Warner, R. D., and Raymond, L. A., 2007, All enstatite is not created equal: A tale of orthopyroxene in metadunites of the eastern Blue Ridge of North Carolina and Georgia, in press, in press, Geol. Soc. Am. Abs. With Programs, v. 39.

Warner, R. D., and Swanson, S. E., 2007, Metamorphism of cpx-rich rocks from Webster-Addie ultramafic complex and a possible explanation for the rarity of clinopyroxene in Blue Ridge ultramafics, Cont. Min. Pet, submitted.

Petrology and Hazards of Aleutian Volcanoes

One of the most exciting aspects of moving to the University of Alaska was the opportunity to study active volcanic systems of the Aleutian arc. Over 40 Aleutian volcanoes have erupted in historic times and over 80 of these volcanic systems recorded activity in the Quaternary. Alaska averages one major eruption per year.

I worked with colleagues at the Geophysical Institute to identify and characterize volcanic systems and relate them to subduction tectonics (Kienle and Swanson, 1983; Swanson, 1990). The active eruptive history of some of the volcanoes provided an opportunity to evaluate hazard potential and then evaluate predictions in a future eruption (Swanson and Kienle, 1988). The interaction of volcanic ash with jet engines presents a unique hazard related mainly to the melting of the volcanic glass component of the ash (Swanson and Beget, 1994). Studies of the melt (glass) component of lavas and ash during an eruption (Swanson et al., 1994; Swanson et al., 1995) provided a way to monitor changes in the volcanic plumbing system during an eruption.

Several volcanic studies are underway or in the planning stage. Courtney Kearny completed a senior thesis with Sam (2002)on the geochemistry of sulfur in erupting andesitic systems and a paper on this work is currently in press (Swanson and Kearney, 2007). Courtney went on to get a Masters degree at the University of Alaska Fairbanks where she worked on remote sensing of volcanoes. She is currently (2007) a Ph.D. student at the University of Bristol. This work is part of a study on the mineralogy of sulfur in several Aleutian volcanic systems. This work involves sulfide mineralogy and relation to oxygen fugacity and the timing of phase saturation in evolving/erupting andesitic systems.

References cited

Kienle, J. and Swanson, S.E., 1983, Volcanism in the eastern Aleutian arc: late Quaternary and Holocene centers, tectonic setting and petrology, Jour. Vol. Geotherm. V. 17, , p. 393-432.

Swanson, S.E., and Kienle, J., 1988, The 1986 eruption of Mt. St. Augustine: Field test of a hazard evaluation, Jour. Geophys. Res., v. 93, p. 4500-4520.

Swanson, S.E., 1990, Descriptions of various volcanoes (Akutan, Pogromni, Westdahl, Kejulik, Martin, Snowy, Denison,Stellar, Kukak, Devils Desk, Kaguyak, Fourpeaked, Douglas) in Alaska, in Volcanoes of North America, C.A. Wood and J. Kienle (eds.), Cambridge University Press, New York, p. 43-46, 66-67, 73-78.

Swanson, S.E., and Beget, J.E., 1994, Melting properties of volcanic ash: U.S. Geol. Surv. Bull. 2047, p. 87-92.

Swanson, S.E., Harbin, M.L., and Riehle, J.R., 1995, Use of volcanic glass from ash as a monitoring tool: an example from the 1992 eruption of Crater Peak, Mount Spurr Volcano, Alaska, U.S. Geol. Surv. Bull., 2139, p. 129-137.

Swanson, S. E., and Kearney, C., 2007, Anhydrite in the 1989-1990 lavas from Redoubt Volcano, Alaska, J. Volc. Geotherm. Res., in press.