Dr. Jennifer Gifford

Areas of Expertise

Tectonics, Geochemistry, Geochronology, Thermochronology, Petrology, Structural Geology, Geologic Mapping

Recent Projects


A Petrographic Investigation into the Formation of the Medicine Hat Block

The Medicine Hat Block (MHB) of southern Alberta and northern Montana is a largely concealed province of Archean and Paleoproterozoic rock buried by younger supracrustal successions. The MHB was involved in a complex collision between the Archean Hearne and Wyoming provinces during the formation of the Great Falls Tectonic Zone (GFTZ), Trans Hudson Orogen (THO) and Vulcan Zone during the amalgamation of Laurentia. However, its role in this collision is poorly defined by limited high precision geochronolgy and geochemisty. Xenoliths recovered by the Geological Survey of Canada from Eocene minette dikes and boreholes in the MHB north of the Wyoming craton include a population of gneisses, granulites, monozites, tonalities, amphibolites, and diorites sampling the otherwise concealed MHB crust. Through detailed description of these samples will lead to details of formation of the high angle junction between the GFTZ and THO. The improved descriptions should also provide insight into later geologic events potentially influenced by MHB crust reworked in the GFTZ, such as development of the Cenozoic Montana Alkali Province or the structural formation of the Proterozoic Belt-Purcell Basin.





An Investigation into the Geochemical Character of the Medicine Hat Block

The Medicine Hat Block (MHB) of southern Alberta and northern Montana is a largely concealed province of Archean and Paleoproterozoic rock buried by younger supracrustal successions. The MHB was involved in a complex collision between the Archean Hearne and Wyoming provinces during the formation of the Great Falls Tectonic Zone (GFTZ), Trans Hudson Orogen (THO) and Vulcan Zone during the amalgamation of Laurentia. However, its role in this collision is poorly defined by limited high precision geochronolgy and geochemisty. Xenoliths recovered by the Geological Survey of Canada from Eocene minette dikes and boreholes in the MHB north of the Wyoming craton include a population of gneisses, granulites, monozites, tonalities, amphibolites, and diorites sampling the otherwise concealed MHB crust. New whole-rock geochemistry data including major-elements, trace-elements, Nd-isotopes, and Pb-isotopes from these samples will improve understanding of the age and origins of the MHB crust.



An Investigation into the Geochronological Character of the Medicine Hat Block

The Medicine Hat Block (MHB) of southern Alberta and northern Montana is a largely concealed province of Archean and Paleoproterozoic rock buried by younger supracrustal successions. The MHB was involved in a complex collision between the Archean Hearne and Wyoming provinces during the formation of the Great Falls Tectonic Zone (GFTZ), Trans Hudson Orogen (THO) and Vulcan Zone during the amalgamation of Laurentia. However, its role in this collision is poorly defined by limited high precision geochronolgy and geochemisty. Xenoliths recovered by the Geological Survey of Canada from Eocene minette dikes and boreholes in the MHB north of the Wyoming craton include a population of gneisses, granulites, monozites, tonalities, amphibolites, and diorites sampling the otherwise concealed MHB crust. New zircon geochronology from these samples will improve understanding of the age and origins of the MHB crust.


Timing of Late Cretaceous Gulf Coast Volcanism

The Upper Cretaceous Ripley Formation in the Mississippi Embayment consists of ~240 feet (73 m) of fossiliferous clay, sand, and calcareous sand beds. Lateral facies variations have complicated historical stratigraphic correlations between locations, but recent stratigraphic revisions in Mississippi recognize a lower transitional clay facies, a limestone, marl, and calcareous sand facies informally named the Troy beds, a sandy upper Ripley facies, and the formally named Chiwapa Sandstone Member. Ammonite biostratigraphy places the contact between the Chiwapa and the overlying Owl Creek/Prairie Bluff at ~68.5 Ma. The upper Ripley facies contains the Pontotoc Bentonite, which was identified north of the town of Pontotoc, Mississippi, in 1943. No radiometric dates have been obtained from this bentonite, but litho- and biostratigraphy indicate that the bentonite is younger than known volcanism from the Jackson Dome and related structures. Recent investigations resulted in the discovery of a previously unknown bentonite bed south of the town of Pontotoc. The purposes of the present investigation are 1) to test whether the new bentonite bed is correlative to the Pontotoc Bentonite and 2) to recover volcanogenic zircons for U-Pb and Hf dating to better constrain timing of volcanism and chronostratigraphy of the Ripley Formation.



Publications

Gifford, J.N., Mueller, P.A., Foster, D.A., Mogk, D.W., 2014. Precambrian Crustal Evolution in the Great Falls tectonic zone: Insights from Xenoliths from the Montana Alkali Province. Journal of Geology, v. 122, n. 5, p. 531-548.

Foster, D.A., Mueller, P.A., Heatherington, A., Gifford, J.N., Kalakay, T.J., 2012. Lu-Hf systematics of magmatic zircons reveal a Proterozoic crustal boundary under the Cretaceous Pioneer batholith, Montana. Lithos, v. 142-143, p. 216-225.

Mueller, Paul A., Foster, David A., Gifford, J.N., Wooden, Joseph, Mogk, David W., 2008. Tectonic and stratigraphic implications of detrital zircon suites in Cambrian and Precambrian sandstones from the eastern margin of the belt basin. Northwest Geology, v. 37, p. 61-68.

Meert, J.G., Pandit, M.K., Pradhan, V.R., Banks, J., Sirianni, R., Stroud, M., Newstead, B., Gifford, J.N., 2010. Precambrian crustal evolution of Peninsular India: A 3.0 billion year odyssey. Journal of Asian Earth Sciences, v. 39, p. 483-515

Abstracts:

Smith, B., Gifford, J.N., Jamerson, T., Krishnamurthy, S., 2016. An experimental geophysical approach to optical mineralogy. GSA National Meeting, Abstract ID: 324-18 (meeting in Denver, Colorado)

Gifford, J.N., Mueller, P.A., Foster, D.A., 2015. Is the Williston Basin the site of a Proterozoic accretionary triple junction? AGU Joint Assembly, Abstract ID: 36604 (meeting in Montreal, Canada)

Matchinski, E.J., Gifford, J.N., Mueller, P.A., Foster, D.A., 2015. Reassessment of the intersection of the Great Falls Tectonic Zone and the Trans-Hudson Orogen through petrologic and geochronological analysis of Deep Test Well derived samples. AGU Joint Assembly, Abstract ID: 36788 (meeting in Montreal, Canada)

Gifford, J.N., Malone, S.J., Davis, W., 2015. New insights into the character of the Medicine Hat Block (southern Alberta, northern Montana) from whole rock geochemistry, zircon LA-ICPMS U/Pb and Hf isotopic analysis. Geological Society of America Abstracts with Programs, 47 (meeting in Baltimore, MD).

Gifford, J.N., Mueller, P.A., Foster, D.A., 2014. The cratonic crossroads: New U-Pb age control from the Williston Basin basement provides insight into the assembly of Laurentia. Geological Society of America Abstracts with Programs, 46 (meeting in Vancouver, CA).

Gifford, J.N., Mueller, P.A., Foster, D.A., Mogk, D.W., 2013. Geochronology and geochemistry of metasupracrustal xenoliths from the Great Falls tectonic zone. Geological Society of America Abstracts with Programs, 45 (meeting in Denver, CO), no. 7, p. 622.

Gifford, J.N., Foster, D.A., Mueller, P.A., Mogk, D.W., 2012. Crustal xenoliths from a buried Paleoproterozoic convergent margin in the Northern Rocky Mountains. Geological Society of America Abstracts with Programs, 44 (meeting in Charlotte, NC), no. 7, p. 134.

Gifford, J.N., Mueller, P.A., Foster, D.A., Mogk, D.W., 2011. Medicine Hat block exposed in the Little Rocky Mountains. Geological Society of America Abstracts with Programs, 43 (meeting in Minneapolis, MN), no. 5, p. 322.

Gifford, J.N., Foster, D.A., Mueller, P.A., Mogk, D.W., 2011. Geochemistry and geochronology of mid- to lower crustal granitic xenoliths from the Great Falls tectonic zone. Geological Society of America Rocky Mountain/Cordilleran Sections Abstracts with Programs, 43 (meeting in Logan, UT), no. 4, p. 71-72.

Gifford, J.N., Foster, D.A., Mueller, P.A., Mogk, D.W., 2010. Geochemistry of mid- to lower crustal xenoliths from the Great Falls tectonic zone. Geological Society of America Abstracts with Programs, 42 (meeting in Denver, CO), no. 5, p. 517.

Gifford, J.N., 2009. A New view into the Lower Crust and Upper Mantle of the Great Falls Tectonic Zone. EarthScope 2009 National Meeting, (meeting in Boise, ID).

Gifford, J.N., Foster, D.A., Mueller, P.A., 2009. U-Pb zircon and whole-rock geochemistry of basement samples from boreholes and xenoliths: age and tectonic significance of the Great Falls tectonic zone. Geological Society of America Abstracts with Programs, 41 (annual meeting in Portland, OR), no. 7, p. 293.

Gifford, J.N., Foster, D.A., Mueller, P.A., Mogk, D.W., Kamenov, G.D., 2008. Plutonic Imaging: A view into the lower crust and upper mantle of the Great Falls tectonic zone. Geological Society of America Joint Annual Meeting Abstracts with Programs, 40 (annual meeting in Houston, TX), no. 6, p. 379.

Gifford, J.N., Foster, D.A., Howard, K.A., Newman, V. & Donelick, R., 2008. Quantifying Eocene and Miocene extension in the Ruby-East Humbolt Metamorphic Core Complex, Northeastern Nevada. FT2008: 11th International Conference on Thermochronometry Abstracts with Programs, (meeting in Anchorage, AK), p. 92-94.