61st Annual Report on Research 2016

Overview: This project tests the hypothesis that distinctive quartz microtextures are imparted by wet-based glacial activity, and such textures survive for a significant transport distance and can thus be used to infer the influence of glaciation, even in the deep-time geologic record. Beyond focusing on glacial systems, this work expanded to encompass a systematic study of quartz microtextures in end-member fluvial environments (including nonglacial and glacial), with the ultimate goal of quantifying the use of microtextural analysis as a means to refine interpretations of fluvial paleoenvironments in Earth's "deep-time" record. During the 2012-13 grant year, PhD student Leslie Keiser studied quartz microtextures in the Permian Cutler Formation of western Colorado, a unit proposed (in previous studies) to be of both non-glacial "hot-fan" and proglacial "cold-outwash" origin. This unit formed in the tropical region of the Pangaean supercontinent, so the possibility that it may record cold paleoclimatic conditions is quite significant to global climatic reconstructions for this time. Additionally, this unit forms frontier hydrocarbon prospects in the Paleozoic section of the San Juan Basin (currently untapped at this deep level), so understanding its depositional origin is of applied interest. Ms. Keiser collected a large amount of data on quartz microtextures from various subenvironments of this unit -- proximal lacustrine (possibly proglacial) to distal fluvial. She then applied a series of both semi-quantitative and rigorous quantitative tests to look for patterns in the data. The latter entailed a series of statistical treatments, including multidimensional scaling (MDS), a non-parametric multivariate ordination technique. This approach represents a significant advance over published approaches that do not employ quantitative treatments. Her results his support the inference of a proglacial origin for the (Permian) Cutler Formation, and demonstrate the utility of a quantitative approach in discerning this. The results of this research were published in the Journal of Sedimentary Research.

During the last years of funding, we expanded this work by investigating quartz textures from modern alluvial and fluvial systems, with MS student Curtis Smith. Curtis has now analyzed quartz micro textures from fluvial sediment collected in Puerto Rico (a warm-wet fluvial system), Norway (a cold-wet fluvial system), Anza Borrego (hot desert), and Peru (cold desert) to assess the ability to infer climatic parameters. He conducted extensive statistical analyses on the dataset and has found robust patterns in suites of textures characteristic of certain climates. He successfully defended his thesis in May 2016 and is preparing this work for submission for publication in a peer-reviewed journal. This work also supported the work of postdoctoral researcher Dr. Young Ji Joo who is studying these sediments to assess physical and chemical weathering in differing climates; this research is in preparation for publication as well.

Impact on Students: This grant provided partial support for PhD student Leslie Keiser; support critical to sustaining Leslie through to completion of her PhD (May 2013). PRF support enabled Leslie to conduct the fieldwork, and the extensive lab work with the scanning electron microscope (SEM) to collect a large dataset on quartz grain microtextures that enabled her to craft two primary manuscripts and one secondary manuscript; all currently either in revision or in review at peer-reviewed journals. Leslie grew enormously in confidence in the latter stages of her PhD, and is now employed full time as a petroleum geologist at Conoco-Phillips.

The PRF grant also supported field work and academic-year support for MS student Curtis Smith, who travelled to Puerto Rico for this work, and was aided by two undergraduates from the University of Puerto Rico. These two students (Fabioloa Cartegena and Alan Velez) accompanied us the entire time, and learned about the work we conducted. Both wish to attend graduate school, and noted that this experience was extremely valuable to them. Finally, it also enabled Dr. Young Ji Joo to complete her post doctoral research, and she is now assuming a new position in the Korean polar institute.

Impact on PI: This grant has taken me (the PI) in new research directions in several ways. Firstly, this PRF research includes plans to immerse myself and students into the realm of the sedimentology of modern systems, with the promise of developing "proxies" for climate applicable to ancient strata. To date, I have focused on Earth's "deep-time" record, so this is very new for me, and has inspired me to craft additional projects based on sediments from modern systems. Secondly, this research involves intensive work with scanning electron microscopy, physical weathering and fracture formation, quartz microtextural analysis, and advanced statistical analysis-- all new subdisciplines for me.

Impact on Field: If our approach is successful, it will enable clarification of paleoenvironmental interpretations for fluvial systems from various geologic ages, even given one-dimensional (e.g., core) access to a system. Such information is critical for prediction of reservoir character, owing to the influence of paleoenvironmental setting on channel belt geometry, proportion, and sand connectedness. It will also be of great benefit to paleoclimatic interpretations, because it is otherwise very difficult to assess whether a fluvial system emanated from a proglacial or nonglacial drainage basin in the deep-time record, yet this determination has major implications for paleoclimatic reconstructions.