Determining the Depositional Environment of the Amherstburg Formation Elizabeth Gaines Undergraduate student Western Michigan University Lee Honors College Mentor: Dr. Peter Voice Objectives and Importance ● Goal: Create a paleogeographic reconstruction ○ Basically, I am trying to make a model of what this place looked like during this time in earth’s history. ● To understand the depositional history of this environment to better understand current environments. ○ Tropical vacation? Snorkeling? Source: https://www.thetimes.co.uk Importance: • There have not been many studies on this area. • Quarried for dimension stones (decorative rocks) • Could house natural gas and oil • Gives us the depositional environment of the Michigan Basin during the Devonian Period. Source: ocean-climate-alliance.org Methods and Study Area ● Study Area- Lower Peninsula of Michigan ● Data collected from 3 drill cores. ● Drill Core- a long cylinder of rock obtained by using a core drill. ● Methods ○ Core & Thin Section Description ■ Separated into facies Map of Michigan showing which county the cores are located in. ■ Interpreted Environments Source: Adapted from Scotese, C. R. (2014) Adapted from https://www.researchgate.net/figure/Upper-Sil urian-and-Devonian-stratigraphic-nomenclatur e-of-southwestern-Ontario_fig1_304540332 Source: Adapted from Scotese, C. R. (2014) Source: Adapted from Sun et al. (2014) Facies Associations ● Facies- a distinctive rock unit that forms under certain conditions of sedimentation, reflecting a particular process or environment. ● 20 total facies identified Reef Rubble Lagoonal Lagoonal to Lagoonal to Reef-Rubble Peritidal - St. Charlton #4-30 - Kalman #1-16 - Facies 1, 2, 3A, - Facies 1, 3A, - St. Charlton #4-30 - TB-7 3B, 5, 6, 7, 9 3B, 4, 5, 6 - Facies 4, 8 - Facies 1, 2, 3 - Kalman #1-16 - Kalman #1-16 - Facies 1, 2, 3A - Facies 7, 8 Reef Rubble Facies Association ● Limestone Packstone to Wackestone ● Fossils- stromatoporoids, corals, Coral brachiopods, crinoids, bryozoans, snails ○ Not in growth positions ○ Heavily Abraded, broken shells Brachiopod Stromatoporoid Coral Kalman #1-16 Facies 3 Thin Section St. Charlton #4-30 Facies 3 St. Charlton #4-30 Facies 1 Kalman #1-16 Facies 2 St. Charlton #4-30 Facies 3 A and B St. Charlton #4-30 Facies 3 Lagoonal Facies Association ● Limestone Packstone to Mudstone ● Fossils- stromatoporoids, corals, crinoids, brachiopods ○ Not in growth position, heavily abraded ● Many burrows in the mud ● Laminated with planar to rippled bedding St. Charlton #4-30 Facies 7 Kalman #1-16 Facies 1 Kalman #1-16 Facies 3 St. Charlton #4-30 Facies 7 Lagoonal to Reef-Rubble Facies Association ● Limestone Packstone to Wackestone ● Grain supported ● Fossils- corals, stromatoporoids, bryozoans, brachiopods ○ Not in their growth position ○ Fewer overall fossil grains ● Looks muddy in hand samples but grainy in St. Charlton #4-30 Facies 4 thin sections. St. Charlton #4-30 Facies 8 St. Charlton #4-30 Facies 4 Thin Section Lagoonal to Peritidal Facies Association ● Dolomite to Limestone Packstone or Wackestone ● Very porous ● Plethora of burrows filled with cement ● Laminated ● Mudcracks Burrows Lamination Kalman #1-16 Facies 7 TB-7 Facies 1 Kalman #1-16 Facies 8 TB-7 Facies 2 TB-7 Facies 3 St. Charlton #4-30 Kalman #1-16 TB-7 Walther’s Law ● “Facies adjacent to one another in a continuous vertical sequence also accumulate adjacent to one another laterally.” (C. St. Kendall) ○ Facies that started next to each other laterally will eventually stack on top of each other vertically. SHOREWARD Adapted from http://www.sepmstrata.org/Terminology.aspx?id=aggradational%20parasequence%20set Ramp Depositional Environment Conclusions ● Described 3 cores and interpreted the descriptions into interpretative environments. ● Created stratigraphic columns to represent my 3 cores ● Used Walther’s Law to take my vertical columns into horizontal environments. ● Found the overall depositional environment to be a ramp system. ● We now have more information on the potential of this rock unit. ● Dimension stones, natural gas, oil ● Better understand those beautiful beaches and reefs that make the perfect vacation spots. Source: http://www.alexnovy.com Source: https://www.australia.com References Literary Sources - Scotese, C.R., 2014. Atlas of Devonian Paleogeographic Maps, PALEOMAP Atlas for ArcGIS, volume 4, The Late Paleozoic, Maps 65-72, Mollweide Projection, PALEOMAP Project, Evanston, IL. - Sun, S., Brunton, F.R., Jin, J., 2014. Sequence stratigraphic architecture and bedrock aquifers of upper Silurian to middle Devonian strata, southwestern Ontario: Ontario Geological Survey, Open File Report 6300, p. 31-1, 31-15. - Western Michigan University (1981). Michigan Basin. Retrieved from https://pubs.usgs.gov/ha/ha730/ch_j/jpeg/J013.jpeg. - Map of Michigan. Retrieved from http://worldwindtours.com/maps/michigan-county-map. - https://ocean-climate-alliance.org/project/global-coral-reef-partnership/ - https://www.thetimes.co.uk/article/sun-shield-to-save-great-barrier-reef-ndx7tspmh - http://www.sepmstrata.org/Terminology.aspx?id=aggradational%20parasequence%20set - https://www.australia.com/en/places/cairns-and-surrounds/secret-islands-of-the-great-bar rier-reef.html - http://www.alexnovy.com/2012/12/13/long-reef-beach-collaroy-sydney/ Dunham’s classification Permit Company Well Name County Section Township Core Core Number /Range Initial Initial Top Bottom (ft.) (ft.) 57916 Core Energy State Charlton Otsego 30 31N-1W 3030 3090 #4-30 0500 Michigan DRICXIOTB7 Wayne 2S-11E* 381 456 Department of (TB-7) Transportation 33013 Reef Kalman #1-16 Otsego 16 30N-1W 3179 3235 Petroleum Table 1: Information on the location of the wells examined. *The DRICXIOTB7 is located at 42.2901N, 83.1018W..