Wan Yang, PhD , Wichita State University
First, undergraduate students Tyler Foster and Jonathan Obrist have conducted sample preparation, microscopic examination of slabs and 43 thin sections of sandstone, limestone, paleosol, and mudrock, drafting five measured sections (total ~900 m), and interpretation of depositional environment, lake type, and climatic and tectonic conditions. Tyler was supported with a stipend from the grant in the spring of 2011. He wrote a short article for and presented a poster at the Wichita State University 5th Undergraduate Research Symposium, titled “Lithofacies, Stratigraphic Architecture, and Controls of Alluvial Fan Deposits in a Half Graben, Daheyan Formation vs. Modern Alluvial Fans, Southern Bogda Mountains, NW China.” The rich research and cultural experiences prepared Tyler well for a Master’s study. He entered the MS program in University of Oklahoma in the fall of 2011 and has been praised by his supervisor as a “gem.” Jonathan Obrist also completed his undergraduate research with a high mark. He entered the MS program in Wichita State University in fall of 2010 and transferred to the Ph.D. program in Missouri S&T in spring of 2011 to extend his undergraduate study of the Middle-Upper Permian Quanzijie low-order cycle for his dissertation research (see below). In summary, the originally-proposed goal of undergraduate research was successfully accomplished. Both students obtained invaluable scientific as well as cultural experiences and have been well prepared and highly motivated to pursue advanced studies in geology.
Second, three major tasks were accomplished during the 38-day field season in summer of 2011. In the first half of the season, PI, student Jonathan Obrist, two incoming MS students from China University of Petroleum, and Dr. Yi Yang from Xi’an Petroleum University mapped the structurally-complex southern Tarlong area, measured a 572-m-thick section of Upper Carboniferous volcanic, volcaniclastic, and continental slope and shelf siliciclastic deposits in southern Tarlong. The U.S. participants were supported by the PI’s grant from University of Missouri Research Board; the Chinese participants by their respective institutes. PI’s research in the previous year provided critical preliminary data for the UM grant award. The Bogda exposure provides a rare window of basement rocks of the Turpan-Junggar basin in the easternmost part of the Central Asia Tectonic Belt. The section will shed light into the enigmatic crustal building processes in the region. Jonathan Obrist has re-sampled the Quanzijie cycle. His working hypothesis generated from his previous preliminary data is that the cycle is composed dominantly of mixed loess, fluvial, and paleosol deposits. If true, the research will have great implications on the paleoclimatic conditions at the mid-latitude eastern Pangea coast during an icehouse-greenhouse transition. In addition, we have collected potentially datable samples from Upper Carboniferous, Quanzijie, and Lower Triassic for improved geochronology of the Tarlong-Taodonggou record. The PI also led a 3-day field trip for a group of exploration geologists and geophysicists from Shengli Petroleum Bureau of SinoPec Company on Permian and modern alluvial fan deposits to aid in petroleum exploration of Lower Tertiary alluvial-fan conglomerate reservoirs in eastern China. Tyler Foster’s work was used in the trip.
The second half of field season was spent in the Dalongkou area in northern Bogda Mountains, ~100 km north of the Tarlong-Taodonggou area. The area was mapped using high-resolution Google Earth satellite images as the base map. A 370-m-thick section was measured in a cm-dm scale, covering the upper part of Lower Permian Hongyanchi, Middle-Upper Permian Quanzijie, and basal part of Upper Permian Wutonggou low-order cycles. The Dalongkou section, although historically well-known, lacks a detailed Permian-Lower Triassic cyclostratigraphic framework. Our fieldwork is a start of detailed paleoenvironmental, paleoclimatic, and geochronological studies to be continued in the future. The work will delineate basin-wide paleogeographic and paleoclimatic variations and stratigraphic correlation to better understanding sediment infilling and history of the Turpan-Junggar rift basin. Preliminary data show that the Quanzijie strata are dominantly coarse-grained fluvial deposits with a local source, in contrast to loessite(?)-dominated deposits in southern Bogda, although the long-term semi-arid-to-humid climatic trend is similar between the two areas. Eight promising datable samples, in addition to ~100 sedimentary samples, were collected for future petrographic, geochemical, and geochronological analyses.
Third, major endeavor has been devoted for geochronological analysis of potentially-datable samples collected in the previous grant year. The analysis includes 10 CA-TIMS ages and 575 LA-ICPMS spots of zircon grains separated from 13 samples. Some useful radiometric age dates were generated, further improving the chronostratigraphy of the fluvial-lacustrine strata in the Tarlong-Taodonggou area. They are critical to eventual candidacy of the Tarlong-Taodonggou section as a Permian-Lower Triassic GSSP; and also serve as the anchor points for sequence stratigraphic interpretation and correlation.
Finally, the lithologic, stratigraphic, and geochronologic data and interpretation from the previous grant year were used to improve a NSF grant proposal. It was re-submitted in July of 2011, titled “Collaborative Research: Dynamic Evolution of Mid-Latitudinal Latest Carboniferous-Early Triassic Pangean Paleoenvironment, Paleoclimate, and Paleoecology, Bogda Mountains, China.” The PI serves as the lead PI in collaboration with four co-PIs from four U.S. institutions and six domestic and international collaborators. In addition, four presentations have been made in international meetings; three invited lectures were given at U.S. and Chinese institutions; and an article was published in peer-reviewed journal “Global and Planetary Changes.” during this grant year.
In summary, great undergraduate research and educational experience has been gained by two undergraduate students and four Chinese students; and great progress has been made in the research of fluvial-lacustrine sediment infilling and sequence stratigraphy in southern Bogda Mountains through the ACS-PRF support in the last 2.5 years. We anticipate greater and lasting impact of the funded research through continuing research in the Turpan-Junggar basin.