Over the last half century, the use of traditional radiogenic strontium (87/86Sr) has revolutionized our understanding of ore formation. The stable isotopic ratio of strontium (88Sr/86Sr), until very recently, was believed to be a universal constant and is routinely used for internal normalization to correct for instrumental mass bias. Recognition of mass-dependent strontium isotopic fractionation has opened a new frontier in isotope geochemistry.
Our development of a double-spike Thermal Ionization Mass Spectrometry (TIMS) method establishes the USGS as one of only a few labs in the world capable of measuring this chemical tracer (Neymark et al., 2014). We are the first to apply this nascent systematic to ore deposit studies. Our work on several ore-types in the U.S. midcontinent has already documented the largest range of δ88Sr measured on Earth and shows that paired δ88Sr-87/86Sr systematics have the potential to advance our understanding of the source and evolution of ore fluids, processes of ore deposition, and fluid migration pathways (Pelch et al., 2015; Emsbo et al., 2015). Moreover, this isotopic tool has the potential to allow determination of size of ore systems and to enable vectoring toward ore on a basin scale.
The δ88Sr compositions and processes that drive strontium fractionation in mineralizing systems are completely unknown. We are conducting an empirical baseline study to establish the δ88Sr compositions of different ore types.The midcontinent is an ideal laboratory within which to test the application of this new ore genesis tool because its ore deposits are well characterized, their geologic frameworks are well-established, and ore samples from most of these deposits have already been collected. Topical studies are being conducted for the following ore types:
We have also developed and tested sampling/analytical methodologies to investigate the application of paired 87/86Sr - δ88Sr in chemostratigraphy that open exciting new assessment opportunities for sedex deposits. Moreover, during the development of our δ88Sr chemostratigrapic methods, we made potential discoveries that have implications for stratigraphy, paleontology, paleo- and evolutionary-biology.
Emsbo, P., McLaughlin, P.I., Breit, G.N., du Bray, E.A., and Koenig, A.E., 2015, Rare earth elements in sedimentary phosphate deposits: Solution to the global REE crisis?: Gondwana Research, 27 (2), p. 776-785. doi: 10.1016/j.gr.2014.10.008
Neymark, L.A., Premo, W.R., Mel'nikov, N.N., and Emsbo, P., 2014, Precise determination of δ88Sr in rocks, minerals, and waters by double-spike TIMS: a powerful tool in the study of geological, hydrological and biological processes: Journal of Analytical Atomic Spectrometry, 29, p. 65-75. doi: 10.1039/C3JA50310K
Pelch, M.A., Appold, M.S., Emsbo, P., and Bodnar, R.J., 2015, Constraints from fluid inclusion compositions on the origin of Mississippi Valley-Type mineralization in the Illinois-Kentucky district: Economic Geology, 110 (3), p. 787-808. doi: 10.2113/econgeo.110.3.787
Pribil, M.J., Ridley, W.I., and Emsbo, P., 2015, Sulfate and sulfide sulfur isotopes (δ34S and δ33S) measured by solution and laser ablation MC-ICP-MS: An enhanced approach using external correction: Chemical Geology, 412, 27 September 2015, p. 99-106. doi: 10.1016/j.chemgeo.2015.07.014
Steeman, T., Vandenbroucke, T.R.A., Williams, M., Verniers, J., Perrier, V., Siveter, D.J., Wilkinson, J., Zalasiewicz, J. and Emsbo, P., 2016, Chitinozoan biostratigraphy of the Silurian Wenlock–Ludlow boundary succession of the Long Mountain, Powys, Wales: Geological Magazine, 153 (1), p. 95-109. doi: 10.1017/S0016756815000266
Vandenbroucke, T.R.A., Emsbo, P., Munnecke, A., Nuns, N., Duponchel, L., Lepot, K., Quijada, M., Paris, F., Servais, T., and Kiessling, W., 2015, Metal-induced malformations in early Palaeozoic plankton are harbingers of mass extinction: Nature Communications, 6, Article Number 7966. doi: 10.1038/ncomms8966
Brett, C.E., McLaughlin, P.I., Baird, G.C., Emsbo, P., Thomka, J.R., and Zambito, J., 2015, Silurian-Devonian environmental and biotic change recast in a new time scale: Evidence of changing volatility from the Appalachian basin: Geological Society of America Abstracts with Programs, Vol. 47, No. 7, p. 631. View Brett 2015 GSA abstract.
Hurth, M., McLaughlin, P., Emsbo, P., Brett, C.E., and Sell, B.K., 2013, Composite upper Ordovician chronostratigraphy in eastern North America—Developing a late Ordovician geochronologic reference standard of environmental records: Geological Society of America Abstracts with Programs, Vol. 45, No. 7, p. 747. View Hurth GSA abstract.
Manning, A.H., and Emsbo, P., 2015, Numerical simulation of brine reflex systems and their potential role in mineral deposit formation: Geological Society of America Abstracts with Programs, Vol. 47, No. 7, p. 487. View Manning GSA abstract.
Mauk, J., and Emsbo, P., 2015, Genesis of sediment-hosted stratiform Cu deposits and geologic evolution of the North American Midcontinent rift: constraints from ore-forming brines from the White Pine deposit: 13th SGA Biennial Meeting, 24-27 August 2015, Nancy, France.
Mauk, J., Emsbo, P., and Theodorakos, P., 2015, Evaporated seawater formed sediment-hosted stratiform copper orebodies and second-stage copper mineralization in the Mesoproterozoic Nonesuch Formation of the Midcontinent Rift: Proceedings of the 61st ILSG Annual Meeting - Part 1, p. 63-64. View 61st ILSG Proceedings [PDF file, 7.8 MB]
McLaughlin, P., Emsbo, P., Brett, C.E., Vandenbroucke, T., and Saltzman, M., 2015, Mass extinction and diachronism: Reconciling the end Ordovician rock record: Geological Society of America Abstracts with Programs. Vol. 47, No. 7, p. 65. View McLaughlin 2015 GSA abstract.
McLaughlin, P.I., Brett, C.E., Emsbo, P., and Sell, B., 2014, Composite chronostratigraphy: pathway to comprehensive geochronology: GeoFrankfurt 2014, 21-24 September 2014, Frankfurt, Germany.
McLaughlin, P.I., Emsbo, P., Brett, C.E., 2015, The lithuanicus Event in the Michigan Basin: Rapid platform accretion in response to a perturbation of the mid-Telychian ocean-climate system: 5th International Symposium on the Silurian System and 5th Annual Meeting of IGCP 591, Quebec City, Canada, 3-20 July 2015, Abstract Volume (eds. M. Melchin and J. Jin), p. 30.
McLaughlin, P., Emsbo, P., Brett, C., Hurth, M., Sell, B., and Johnson, C., 2014, Testing the limits of high-resolution whole-rock 13Ccarb stratigraphy: AGU Fall Meeting, 15-19 December 2015, San Francisco, CA. View McLaughlin AGU abstract.
McLaughlin, P.I., Emsbo, P., Desrochers, A., Premo, W., Neymark, L., Brett, C.E., 2015, Interpreting two kilometers of Ordovician chemostratigraphy beneath Anticosti Island: 5th International Symposium on the Silurian System and 5th Annual Meeting of IGCP 59, Quebec City, Canada, 3-20 July 2015, Abstract Volume (eds. M. Melchin and J. Jin), p. 31.
Meighan, C.J., Hofstra, A.H., Marsh, E.E., Lowers, H.A., Emsbo, P., and Hitzman, M.W., 2014, Generation of monazite and other REE-bearing phases by secondary fluid events, Pea Ridge iron oxide-apatite-REE deposit, Southeast Missouri, USA: Abstract Volume, Pan-American Current Research on Fluid Inclusions (PACROFI XII), Denver and Pingree Park, Colorado, 2 p.
Munnecke, A., Jarochowska, E., Männik, P., Vandenbroucke, T. R. A., Hints, O., Hartinger, N., Lehnert, O., Huff, W., Kozłowski, W., and Emsbo, P. 2014. Lower Telychian ironstone deposits in the Podlasie Basin, NE Poland: δ13C and conodont stratigraphy: 4th Annual Meeting of IGCP 591 ‘The Early to Middle Paleozoic Revolution’, Estonia, Abstracts and Field Guide, p. 97.
Scott, R., Emsbo, P., and Goemann, K., 2015, Still Stuck in the Mud: Reevaluation of Stratiform Gold in the Upper Popovich Formation, Northern Carlin Trend, Nevada: Society of Economic Geologists 2015 Annual Conference Proceedings, 27-30 September 2015, Hobart, TAS, Australia. View Scott SEG abstract. [PDF file, 118 KB]
Sullivan, N., McLaughlin, P.I., Emsbo, P., and Barrick, J.E., 2014, Integrated conodont biostratigraphy and chemostratigraphy (δ13Ccarb, 87Sr/86Sr, major and trace elements) of the Waubakee Formation (upper Silurian) in eastern Wisconsin: A new approach to an unresolved chronostratigraphic problem: Geological Society of America Abstracts with Programs, Vol. 46, No. 6, p. 755. View Sullivan 2014 GSA abstract.
Vandenbroucke, T.R.A., Emsbo, P., and Munnecke, A. 2014, Death metal in the early Paleozoic: Geological Society of America Abstracts with Programs, Vol. 46, No. 6, p. 399. View Vandenbroucke 2014 abstract.
Vandenbroucke, T.R.A., Emsbo, P., and Munnecke, A., 2014, 'Death Metal' in the Early Palaeozoic: Programme and abstracts for the 58th Annual Meeting of the Palaeontological Association,16-19 December 2007, Leeds, UK, p. 50.
Vandenbroucke, T.R.A., Emsbo, P., Munnecke, A. and Quijada, M., 2015, Harbingers of Silurian Extinction: 5th International Symposium on the Silurian System and 5th Annual Meeting of IGCP 59, Quebec City, Canada, 3-20 July 2015, Abstract Volume (eds. M. Melchin and J. Jin), p. 54.
Vandenbroucke, T.R.A., Rohrssen, M., Munnecke, A., Hints, O., Love, G.D., Fischer, W.W. and Emsbo, P., 2014, Reconstructing the environmental conditions around the Silurian Ireviken Event combining the carbon isotope composition of bulk and palynomorph organic matter and biomarker data: 4th Annual Meeting of IGCP 591 ‘The Early to Middle Paleozoic Revolution’, Estonia, Abstracts and Field Guide, p. 66.
Central Mineral and Environmental Resources Science Center