Project Info

Geochronology of granitoid phases of the northern half of the Mount Evans 7.5’ quadrangle, Colorado Front Range

The granitoid phases to be dated are probably part of the ~1.4 Ga Mount Evans batholith that makes up most if not all of the granitoids in the Mount Evans region. However, some may be part of the ~1.1 Ga Pikes Peak batholith that exists to the southeast and some may be as old as the ~1.7 Ga Boulder Creek Granodiorite and associated rocks of the Routt Plutonic Suite. The project is part of a larger ‘EDMAP’ mapping project for which the mapping is carried out in summer 2018 by MS student Logan Powell and BS student Lauren Miller. The field relationships between the various granitoid phases, and their deformation histories will be clear by the end of the summer. The ductile deformation in the area has generally been thought to be ~1.7 Ga. However, it is possible that some or all of the deformation is part of the increasingly recognized Picuris orogeny, or perhaps, though unlikely, a younger event. The ages of the granitoid rocks will help constrain the ages of deformation.

More Information

Aleinikoff, J.N., Reed, J.C., Jr., and Dewitt, Ed, 1993, The Mount Evans batholith in the Colorado Front Range—Revision of its age and reinterpretation of its structure: Geological Society of America Bulletin, v. 105, p. 791–806.

Daniel, C.G., Pfeifer, L.S., Jones III, J.V., and McFarlane, C.M., 2013, Detrital zircon evidence for non-Laurentian provenance, Mesoproterozoic (ca. 1490-1450 Ma) deposition and orogenesis in a reconstructed orogenic belt, northern New Mexico, USA: Defining the Picuris orogeny: Geological Society of America Bulletin, v. 125, p. 1423–1441.

Jones III, J.V., Siddoway, C.S., and Connelly, J.N., 2010, Characteristics and implications of ca. 1.4 Ga deformation across a Proterozoic mid-crustal section, Wet Mountains, Colorado, USA: Lithosphere, v. 2, p. 119–135.

Mahatma A.A., Powell, L., Kuiper, Y.D., and Ruleman, C.A., 2017, Geology of the southern half of the Mount Evans 7.5 minute quadrangle, central Colorado Front Range: Geological Society of America Abstracts with Programs, Vol. 49, No. 6. (I will make map and report available also)

Grand Engineering: Not applicable

Student Preparation

Qualifications

A good work ethic and aptitude for conducting lab work without cross contaminating samples. Must be able to work in a meticulously clean manner and be well organized. A basic understanding of geology and especially tectonics (especially of the Mount Evans region) would make the project more interesting but is not required.

Time Commitment

30 hours/month

Skills/Techniques Gained

Will learn anything that is involved with sample preparation and mineral separation required for U-Pb geochronology, including grain mounting and polishing. This may be a big advantage in future work (e.g. graduate studies) where such skills may be needed. Will have an opportunity to visit the laser ablation inductively coupled plasma mass spectrometry lab at the USGS and participate in the mineral imaging and analysis.

Mentoring Plan

I will meet with the student regularly, as needed. I meet most of my students individually once a week for an hour. The mineral separation process will be taught by my graduate students and/or me. The student will learn along with two of my other students who will need to learn the same during the Fall semester. There will be lots of opportunity for scientific interaction with others and learning about their projects.