1. Detrital Zircon Geochronology of the Devonian Dutch Creek Sandstone in the Southern Illinois Basin
WALLENBERG, Alexandra1, MALONE, David H.1, DAY, Jed1, and DEVERA, Joseph2.
Geography-Geology, Illinois State University, Normal,
Illinois State Geological Survey, Prairie Research Institute, University of Illinois
ABSTRACT
The Dutch Creek Sandstone is the basal member of the Grand Tower Formation that accumulated in a shallow subtropical marine shelf between the Ozark Uplift and Cincinnati Arch in the southern Illinois Basin. In Union and Jackson counties, the Dutch Creek consists of fossiliferous crossbedded quartz arenites that accumulated in the Sparta-Wabash platform of the southern Illinois Basin during the Early Devonian. Conodonts document an upper Emsian age for the Dutch Creek at the Grand Tower Formation type section in Jackson County. For this investigation, detrital zircon U-Pb geochronology was used to determine ages that assess the likely provenance of source rocks of Dutch Creek Member sandstones sampled near the town of Alto Pass, Union County, Illinois. 209 zircons were recovered and analyzed at the Laserchron Center at the University of Arizona. Detrital zircon U-Pb dates of the Dutch Creek sands have major peak ages at 1082 Ma, 1858 Ma, and 2702 Ma; indicating that the zircons were contributed from the Grenville orogen (16%), the Pennokian orogen (10%), and Archean basement (67%) respectively. Other minor peaks include zircons were also derived from the Paleozoic ( Ma), Midcontinent Granite-Rhyolite ( Ma), and Yavapai-Mazatzal ( ) terrane sources; however, most of the grainages are between ~2460 Ma and 3030 Ma, which demonstrates that the majority of detrital zircons in the Dutch Creek Sandstone were derived from an Archean source. Paleogeographic reconstructions position the Sparta-Wabash platform in the South East Trade Winds belt favoring eolian and surface current transport of sands from Archean-Cambrian sources presently located to the north of the study area. This is significant as other Paleozoic samples from the Cambrian and Ordovician (see Konstantinou) have peak ages around ~2700 Ma; other early Paleozoic (Cambrian-Ordovician) detrital zircon populations which have similar morphology and grain sizes to the Dutch Creek sands have originally been interpreted as reworked clastics from the St. Peter Sandstone (Ordovician) out of the eastern side of the Ozark Dome during a low-stand event (Sub-kaskaskia unconformity). However, the DZ data suggests that an Ozark Dome source for the Dutch Creek sands may be incorrect, suggesting that a source further north of the St. Peter Sandstone, such as the Paleozoic quartz arenites found the Wisconsin Arch, are likely to be possible sources for the Dutch Creek Sandstone.
METHODS
The sandstones garnered for this project were collected from the Dutch Creek Sandstone unit near the town of Alto Pass, Union County, Illinois. These samples were prepared and analyzed at the Arizona LaserChron Center, where the samples were split and crushed prior to standard separation techniques using a Wilfley Table, Frantz Magnetic Separator, and heavy liquids separation which allows heavy minerals, such as zircons, to be separated and collected from the lighter minerals (Chisholm, Sircombe, and DiBugnara, 2014). After extraction, the zircon samples are mounted onto a sanded down epoxy plug that is roughly an inch in diameter. Cathodoluminescence images are garnered prior to laser ablation, in which a beam ranging from 10 to 35 μm (depending on the spatial resolution) ablates individual zircons. The isotopic analysis of the ablated material is completed through plasma–mass spectrometry (Gehrels, Valencia, and Ruiz, 2008).
DISCUSSION
The original hypothesis for the origin of the Dutch Creek Sandstone surmised that the sands were recycled from the St. Peter Sandstone in the proximal Ozark Dome because of its textural and compositional maturity. Due to the comparison of our zircon age spectra with St. Peter Sandstone ages determined by Konstantinou et al. 2014, an alternate hypothesis may be more viable and admissible as the proportion of Archean grains are too high in the Dutch Creek for it to have been recycled from St. Peter exposures in the Ozarks. The K-S statistical analysis revealed that upper St. Peter Sandstone collected from Oregon, Illinois were statistically similar to the Dutch Creek Sandstone, which welcomes the hypothesis that the Dutch Creek sands were derived from the north and transported to the south; factors such as enhanced rounding of quartz clasts (Konstantinou, et al., 2014) and “floaters” found within the carbonate strata (Summerson and Swann, 1970) indicate that eolian transport and deposition is a viable alternative (photomicrographs shown in figures 8 and 9).
Southwesterly oriented paleocurrent wind direction is indicated by transgressive characteristics, such as cross-bedding, in lower Paleozoic sandstones including the St. Peter Sandstone (paleogeographic reconstruction shown in figure 10). The relationship between Paleozoic sandstones in similarity of composition, sedimentology and stratigraphy imply the presence of a paleoslope trending towards the south and the southwest (Potter and Pryor, 1961). This direction of relief influences, and is consistent, with depositional direction in the paleo-trade wind belt (see paleogeographic reconstruction in figure 10) as periods of subaerial erosion transported Paleozoic sands across the craton (Johnson and Winter, 1999).
INTRODUCTION
The goal of this project is to test previous interpretations that the sands of the Lower Devonian Dutch Creek Member (Grand Tower Formation) were derived from the St. Peter Sandstone (Ordovician) exposed along the flanks of the Ozark Dome, and reassess the provenance of Dutch Creek sands using Detrital Zircon (DZ) geochronology. The DZ data suggests that a source further north, versus being sourced from local St. Peter Sandstone in eastern Missouri. The DZ data indicate Paleozoic quartz arenites found the Wisconsin Arch, are the most likely sources for the bulk of the DZs recovered from Dutch Creek Sandstone outcrops in southern Jackson county (see sample location map; figure 1).
The Dutch Creek Sandstone is the basal member of the Grand Tower Formation and occurs in much of the Illinois Basin. It’s discontinuous and about 5 meters at outcrops in Jackson and Union counties. It on-laps the older Pragian and Emsian age Clear Creek Chert in all surface localities in southern Illinois. The Dutch Creek exposures at Grand Tower and Alto Pass in Jackson and Union counties consists of well-sorted, fine-grained quartz arenites (see outcrop photos; figures 2 and 3). Meents and Swann (1965) report coarser sandstones—medium to coarse grained—from some of their samples. “Floating sand grains” within crinoidal packstones in the upper un-named Member of the Grand Tower overlay the Dutch Creek Member (stratigraphic column with sample locality depicted in figure 3).
During the Lower Devonian the Illinois Basin was north of the Ouachita continental margin of Euramerica in the subtropics of the southern hemisphere within the southeast trade winds belt. Deposition of the Grand Tower Formation began during the major marine transgression that began during the very late Emsian Stage of the Lower Devonian (serotinus Zone) coinciding with Euramerican eustatic Devonian Transgressive-Regressive cycle Ic of Johnson et al. (1985) based on conodonts reported by Day et al. (2012), Gouwy et al. (2013), Day et al. (2016). In the Early Devonian, a U-shaped embayment had formed as a result of regression that extended to southeastern Illinois, and created the sub-Kaskaskia unconformity, which exposed older Paleozoic bedrock units in the region. Continuous deposition occurred over the sub-Kaskaskia unconformity as sea-levels rose, resulting in the deposition of the Dutch Creek Sandstone and overlying the upper Member of Grand Tower Formation (Devera and Fraunfelter, 1988).
Figure 7. A basement provenance map of the Archean through the Proterozoic with structural features depicted (from Karlstrom and Whitmeyer, 2007).
Figure 1. Map of the Illinois basin with strata and sample locations identified (red star corresponds to the Dutch Creek Sandstone; green stars correspond to St. Peter Sandstone analyzed by Konstantinou et al. 2014).
RESULTS
The U-Pb ages for the zircon samples are identified through the stacked probability plot and the cumulative probability curve (depicted in red) in figures 5 and 6 respectively. Of the 209 zircons analyzed, major peak ages are shown at 1082 Ma, 1858 Ma, and 2702 Ma; indicating that these grains derived from Grenville orogen (16%), the Pennokian orogen (10%), and Archean basement (67%). Minor peaks are shown from the Paleozoic ( Ma), Midcontinent Granite-Rhyolite ( Ma), and Yavapai-Mazatzal ( ) as terrane sources; however, most of the ages congregate around ~2460 Ma and 3030 Ma, indicating that the primary sources of these zircon grains are likely provenanced from the Archean (see basement provenance map; figure 7).
Figure 8. Photomicrograph depicting “floating sand grains”. The clear, rounded grains are quartz while the other materials are crinoidal packstones with lime-mud (attained from Joseph Devera).
Figure 5. Stacked probability density plot that compares the Dutch Creek Sandstone to the underlying Ordovician and overlying Chesterian Strata.
Figure 10. Early Devonian reconstruction of North America modified from Ron Blakey (retrieved from nau.edu) to show paleogeographic wind direction, paleoequator, and the sample location (red star) for this study.
REFERENCES CITED
Blakey, R Early Devonian Reconstruction of North America. Retrieved from NAU.edu.
Chisholm, E. I., Sircombe, K. N. and DiBugnara, D. L Handbook of Geochronology Mineral Separation Laboratory Techniques. Record 2014/46. Geoscience Australia, Canberra.
Day, J. E. (photographer) September 15. Retrieved via .
Devera, J. A., & Fraunfelter, G. H. (1988). Middle Devonian paleogeography and tectonic relationships east of the Ozark Dome, southeastern Missouri, southwestern Illinois and parts of southwestern Indiana and western Kentucky.
Devera, J. A. (photographer) July 7. Retrieved via .
Nelson, W. J., & Marshak, S. (1996). Devonian tectonism of the Illinois Basin region, US continental interior. SPECIAL PAPERS-GEOLOGICAL SOCIETY OF AMERICA,
Gehrels, G. E., V. A. Valencia, and J. Ruiz (2008), Enhanced precision, accuracy, efficiency, and spatial resolution of U-Pb ages by laser ablation–multicollector–inductively coupled plasma–mass spectrometry, Geochem. Geophys. Geosyst., 9, Q03017, doi: /2007GC
Gouwy, S. A., Day, J. E., and Macleod, K. G. (2012), "UPPER EMSIAN TO LOWER GIVETIAN CONODONT BIOSTRATIGRAPHY AND CONODONT APATITE DELTA 18O RESULTS OF THE GRAND TOWER AND SAINT LAURENT FORMATIONS: SOUTHERN ILLINOIS BASIN-REEL FOOT EMBAYMENT". Presentation.
Gouwy, S. A., and Day, J. E., (2013), “LOWER TO MIDDLE DEVONIAN (PRAGIAN-LOWER GIVETIAN) CONODONT FAUNAS FROM THE CLEAR CREEK, GRAND TOWER AND ST. LAURENT FORMATIONS, SOUTHERN ILLINOIS BASIN, USA. Poster presented at GSA, session No. 376.
Johnson, C. M., & Winter, B. L. (1999). Provenance analysis of lower Paleozoic cratonic quartz arenites of the North American midcontinent region: U-Pb and Sm-Nd isotope geochemistry. Geological Society of America Bulletin, 111(11),
Johnson, J. G., Klapper, G., & Sandberg, C. A. (1985). Devonian eustatic fluctuations in Euramerica. Geological Society of America Bulletin, 96(5),
Johnson, J., Klapper, G., & Elrick, M. (1996). Devonian Transgressive-Regressive Cycles and Biostratigraphy, Northern Antelope Range, Nevada: Establishment of Reference Horizons for Global Cycles. PALAIOS, 11(1), doi:1.
Konstantinou, A., Wirth, K. R., Vervoort, J. D., Malone, D. H., Davidson, C., & Craddock, J. P. (2014). Provenance of Quartz Arenites of the Early Paleozoic Midcontinent Region, USA. The Journal of Geology, 122(2),
Meents, W. F., & Swann, D. H. (1965). Grand Tower limestone (Devonian of southern Illinois). Ill. State Geol. Surv., Circ.;(United States), 389.
Potter, P. E., & Pryor, W. A. (1961). Dispersal centers of Paleozoic and later clastics of the Upper Mississippi Valley and adjacent areas. Geological Society of America Bulletin, 72(8),
Summerson, C. H., & Swann, D. H. (1970). Patterns of Devonian sand on the North American craton and their interpretation. Geological Society of America Bulletin, 81(2),
Whitmeyer, S. J., & Karlstrom, K. E. (2007). Tectonic model for the Proterozoic growth of North America. Geosphere, 3(4),
Figure 2. Photo taken of the Dutch Creek Sandstone member; Joseph Devera for scale (attained from Jed Day).
Figure 9. Phtotomicrograph depicting “floating sand grains”. The clear, rounded grains are quartz while the other materials are crinoidal packstones with lime-mud (attained from Joseph Devera).
Figure 6. Cumulative probability curves of the Dutch Creek Sandstone to Ordovician and Chesterian Strata.
Figure 4. Stratigraphic column of Devonian strata in the Grand Tower Formation, showing the Dutch Creek Sandstone Member; red star indicating sample locality (attained from Jed Day).
Figure 3. Photo taken of the Dutch Creek Sandstone member; showing cross-bedding (attained from Jed Day).