Lower crustal arc construction

Fiordland, New Zealand

Investigating the magmatic plumbing system of continental arcs

Studies of continental magmatic arcs often emphasize the non-steady-state character of magmatism whereby episodic and relatively short-lived, high-flux events significantly contribute to the overall budget of new crust added to the continental lithosphere. These intense, high-flux events exert primary controls on orogenic belts including widespread thermal and mass transfer from the mantle to the crust, vertical uplift and exhumation, and erosion at the surface.

In this project, I investigate rates and processes of continental crust generation during high-flux magmatism in the exhumed roots of the Jurassic-Cretaceous continental arc in Fiordland, New Zealand. My primary tools are U-Pb geo- and thermochronology (zircon, titanite, apatite, rutile), and major, trace and isotope geochemistry (whole rock and mineral). Goals of this project are to understand the processes that trigger high flux magmatic events through direct investigation of a deep-crustal arc section.

Related publications:

• Miranda, E.A., *Brown, V., Schwartz, J.J., and Klepeis, K.A., 2023, Making Sense of Shear Zone Fabrics that Record Multiple Episodes of Deformation: EBSD and CVA-Enhanced Petrochronology, Geology, 51 (6): 591–596. https://doi.org/10.1130/G50982.1

• Turnbull, R.E., Schwartz, J.J., Klepeis, K.A., Miranda, E.A., Fiorentini, M.L., Evans, N., Ludwig, T., Waight, T.D., Faure, K., and McDonald, B., 2023, Mapping the 4D lithospheric architecture of Zealandia using zircon O and Hf isotopes in plutonic rocks, Gondwana Research, 121, 436-471. https://doi.org/10.1016/j.gr.2023.05.010

• *Brackman, A. and Schwartz, J.J., 2022, The Formation of High Sr/Y Plutons in Cordilleran-Arc Crust by Crystal Accumulation and Melt Loss, Geosphere, 18 (2): 370–393 https://doi.org/10.1130/GES02400.1

• Klepeis, K.A., Schwartz, J.J., Miranda, E.A., Lindquist, P., Jongens, R., Turnbull, R., and Stowell H.H., 2022, The initiation and growth of transpressional shear zones through continental arc lithosphere, southwest New Zealand, Tectonics, https://doi:10.1029/2021TC007097

• Stowell, H.H., Schwartz, J.J., Bollen, E., Tulloch, A.J., Ramezani, J., and Klepeis, K. A., 2022, Timescales and rates of intrusive and metamorphic processes determined from zircon and garnet in migmatitic granulite, Fiordland, New Zealand, American Mineralogist, v. 107, p. 1116-1132, DOI: https://doi.org/10.2138/am-2022-7967

• *Carty, K., Schwartz, J.J., Wiesenfeld, J., Klepeis, K.A., Stowell, H.H., Tulloch, A.J., and Barnes, C.G., 2021, The Generation of Arc Andesites and Dacites in the Lower Crust of a Cordilleran arc, Fiordland, New Zealand, Journal of Petrology, v. 62, 1-41, https://doi.org/10.1093/petrology/egab043.

• *Ringwood, M., Schwartz, J.J., Turnbull, R.E., and Tulloch, A.J., 2021, Phanerozoic Record of mantle-dominated arc magmatic surges in the Zealandia Cordillera, Geology, 49 (10): 1230–1234, https://doi.org/10.1130/G48916.1.

• Schwartz, J.J., *Andico, S., Turnbull, R., Klepeis, K.A., Tulloch, A.J., Kitajima, K., and Valley, J., 2021, Stable and Transient Isotopic Trends in the Crustal Evolution of Zealandia Cordillera, American Mineralogist, v. 106 (9), p. 1369–1387 https://doi.org/10.2138/am-2021-7626.

• Turnbull, R.E., Schwartz., J.J., Fiorentini, M.L., Jongens, R., Evans, N.J., Ludwig, T., McDonald, B.J., and Klepeis, K.A., 2021, A Hidden Rodinian Lithospheric Keel Beneath Zealandia, Earth’s Newly Recognized Continent, Geology, 49(8), p. 1009-1014, https://doi.org/10.1130/G48711.1

• *Buritica, L.F., Schwartz, J.J., Klepeis, K.A., Miranda, E.A., Tulloch, A.J., Coble, M.A., and Kylander-Clark, A.R.C., 2019, Temporal and spatial variations in magmatism and transpression in a Cretaceous arc, Median Batholith, Fiordland, New Zealand: Lithosphere, 11 (5), p. 652-682. https://doi.org/10.1130/L1073.1

  Klepeis, K., Webb, L., †Blatchford, H., Schwartz, J.J., Jongens, R., Turnbull, R., and Stowell, H.H., 2019, Crust-mantle interactions about the Puysegur subduction zone in Fiordland, New Zealand: GSA Today, 29 (9).

  *Decker, M., Schwartz, J.J., Stowell, H.H., Klepeis, K.A., Tulloch, A., Kouki, K., Valley, J., and Kylander-Clark, 2017, Slab-Triggered Arc Flare-up in the Cretaceous Median Batholith and the Growth of Lower Arc Crust, Fiordland, New Zealand: Journal of Petrology, v.58, No. 6, p. 1145-1172; doi: 10.1093/petrology/egx049.

  Schwartz, J.J., Klepeis, K.A., *Sadorski, J.F., Stowell, H.H., Tulloch, A.J., and Coble, M., 2017, The Tempo of Continental Arc Construction in the Mesozoic Median Batholith, Fiordland, New Zealand: Lithosphere, 9 (3): 343-365; doi:10.1130/L610.1.

The unique geology of Fiordland National Park comes alive in this video which follows a group of international scientists on their journey to understand the science of this wonderful region.

Tectonic development
of the western North American Cordillera

Blue Mountains Province, NE Oregon

Phanerozoic crustal growth during arc-arc collision

Phanerozoic crustal growth involves a combination of lateral tectonic collisions and magmatic addition by mantle melting. This project focuses on understanding the timing of arc-arc collision in the Blue Mountains province (NE Oregon) and changes in crustal thickness as a result of contractional deformation. The lab has focused on the Baker terrane which is the center of the Late Jurassic collisional orogen and the location of intense deformation. NSF-Funded.

Projects: 

• The generation of deep crustal partial melts in the Dixie Butte region (Schwartz et al., 2011)

• Timing of magmatism, deformation and metamorphism in the Mountain Home complex (with M.S. student Scott Anderson)

• Detrital zircon geochronology of the Baker terrane

• Magmatic construction of a high Sr/Y batholith following arc-arc Collision: Evidence from the Bald Mountain Batholith, NE Oregon (in press)

Related publications:

• Zak, J, Verner, K., Johnson, K., Schwartz, J.J., 2012, Magnetic fabric of Late Jurassic arc plutons and kinematics of terrane accretion in the Blue Mountains, northeastern Oregon, Gondwana Research, v. 22, p. 341-352 doi:10.1016/j.gr.2011.09.013. 

• Zak, J, Verner, K., Johnson, K., Schwartz, J.J., 2012, Magma emplacement process zone preserved in the roof of a large Cordilleran batholith, Wallowa Mountains, northeastern Oregon, Journal of Volcanology and Geothermal Research, v. 227-228, p. 61-75. 

• Schwartz, J.J., Snoke, A.W., Frost, C.D., Johnson, K., Barnes, C., LaMaskin, T., and Wooden, J., 2011, Late Jurassic magmatism, deformation and metamorphism inthe Blue Mountains province, NE Oregon, Geological Society of America Bulletin, v. 123, 2083-2111.

• Schwartz, J.J., Johnson, K., Miranda, E.A., and Wooden, J., 2011, The Generation of Late Jurassic High Sr/Y magmas following arc-arc collision, Lithos, v. 126, p. 22-41

• Schwartz, J.J., Snoke, A.W., Frost, C.D, Barnes, C.G., Gromet, L.P., and Johnson, K., 2010, Analysis of the Wallowa-Baker terrane boundary: Implicationsfor tectonic accretion in the Blue Mountains province, northeastern Oregon, Geological Society of America Bulletin, v. 122, p. 517-536.

Petrogenesis of high Sr/Y magmas

Alabama eastern Blue Ridge

Petrogenesis of high Sr/Y magmas (Alabama eastern Blue Ridge)

Syn- to late-kinematic, high Sr/Y plutons outcrop over more than 450 km in the eastern Blue Ridge of the Southern Appalachian Mountains from Alabama to North Carolina. In Alabama, these plutons define a linear belt of deep-crustal partial melting associated with mid-crustal ductile flow during Neoacadian orogenesis. This project explores the relationship between deep-crustal partial melt generation and mid-crustal ductile flow during contractional orogeny. This project involves collaboration with Professor Harold Stowell (University of Alabama) and Professor Mark Steltenpohl (Auburn University).

Related publications:

Ingram, S., Schwartz, J.J., Johnson, K., 2011, U-Pb zircon and monazite geochronology and Hf isotope geochemistry of Neoacadian and Early Alleghenian plutonic rocks in the Alabama Eastern Blue Ridge, Southern Appalachian Mountains, Geological Society of America Abstracts with Programs, v. 43, No 5., p. 88.

Mid-ocean ridge tectonics
and geochronology

Atlantis Bank oceanic core complex,
and Macquarie Island, Southern Ocean

Construction and cooling of slow-spreading oceanic crust

Mid-ocean ridges cover nearly 60% of the earth, yet the absolute timing of oceanic crustal growth remains one of the least understood aspects of plate tectonic processes. Our research has focused on U-Pb zircon dating of slow-spread oceanic crust at Atlantis Bank oceanic core complex, and Macquarie Island, Southern Ocean. Our U-Pb age determinations provide a unique tool to test current models of crustal growth in slow- and ultraslow-spreading mid-ocean ridge environments.

A second aspect of our research focuses on understanding rates of lower oceanic crustal cooling. We utilize U-Pb zircon geochronology and Ar-Ar (biotite, phlogopite) and (U-Th)/He zircon thermochronology to evaluate time-temperature histories of lower oceanic crustal rocks. These time-temperature paths allow us to understand the rates and processes of thermal transfer at mid-ocean ridges (c.f., Schwartz et al., 2009).

Related publications:

• Schwartz, J.J., John, B.E., Cheadle, M. J., Wooden, J.L., Mazdab, F., Swapp, S., Grimes, C.B., 2010, Dissolution-reprecipitation of igneous zircon in mid-ocean ridge gabbro, Atlantis Bank, Southwest Indian Ridge, Chemical Geology, v. 274, p. 68-81.

• Schwartz, J.J., John, B.E., Cheadle, M. J., Reiners, P. W., and A. G. Baines, 2009, Cooling history of Atlantis Bank oceanic core complex: Evidence for hydrothermal activity 2.6 Ma off axis, Geochem. Geophys. Geosyst., 10, Q08020, doi:10.1029/2009GC002466.

• Baines, A.G., Cheadle, M.J., John, B.E., Grimes, C.G.,  Schwartz, J.J., and Wooden, J.L, 2009, SHRIMP Pb/U zircon ages constrain gabbroic crustal accretion at Atlantis Bank on the ultraslow-spreading Southwest Indian Ridge, Earth and Planetary Science Letters, v. 287, p. 540-550

• Grimes, C. B., John, B.E., Cheadle, M.J., Mazdab, F.K., Wooden, J.L., Swapp, S.M, Schwartz, J.J., 2009, On the occurrence, trace element geochemisty andcrystallization history of zircon from in situ ocean lithosphere, Contributions to Mineralogy and Petrology, v. 158, p. 757-783.

• Baines, A.G., Cheadle, M.J., John, B.E., and Schwartz, J.J., The rate of oceanic detachment faulting at Atlantis Bank, SW Indian Ridge, Earth and Planetary Science Letters, 273(1-2), 105-114, doi:10.1016/j.epsl.2008.06.013.

• Grimes, C.B., John, B.E., Kelemen, P.B., Mazdab, F., Wooden J.L., Cheadle, M.J., Hanghoj, K., and Schwartz, J.J., 2007, The trace element chemistry of zircons from oceanic crust: A method for distinguishingdetrital zircon provenance, Geology, v. 35, p. 643-646.

• Schwartz, J.J., John, B.E., Cheadle, M.J., Miranda, E.A., Grimes, C., Wooden, J.L., and Dick, H.J.B., 2005, Dating the Growth of Oceanic Crust at Slow-Spreading Ridges, Science, v. 310, p. 654-657.