Abstract. A 40 feet core was sampled from the Mattawoman Creek in Maryland to analyze grain-size

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2 Abstract A 4 feet core was sampled from the Mattawoman Creek in Maryland to analyze grain-size changes during the Paleocene-Eocene Thermal Maximum (PETM). Grain-size decreases abruptly at the onset of the PETM and remains largely constant for the remainder of the event. The decrease is thought to reflect the increase in relative sea level at the onset of the PETM and change from a nearshore to inner shelf environment of deposition. Much of the PETM is dominated by clay, but sandy intervals likely indicate storm deposits.

3 Table of Contents Abstract... 1 Table of Contents... 2 Acknowledgements Introduction Methods Results Discussion Conclusion References Cited List of Tables and Figures Appendix A

4 Acknowledgment I would like to express my sincere acknowledgement and gratitude to my adviser Dr. Timothy J. Bralower for giving me the opportunity, and undivided guidance throughout the different stages of my thesis. His encouragement, patience, and knowledge during the writing and research process of this paper will not be forgotten. I would also like to express my deep appreciation for my family s unwavering love and words of motivation all the way from Saudi Arabia. My father Abdulaziz, mother Sharifa and my siblings, Maram, Amin, Abdullah and Muath were the bedrock throughout my research and academic life leading me to the success that I owe to them. 2

5 Introduction Earth s climate has changed throughout geological time with colder intervals characterized by the development of extensive glaciers alternating with extreme warming events. The warm events are of significant relevance to modern climate change. One of the most abrupt warming events currently known occurred at the Paleocene Eocene boundary. This warming, known as the Paleocene-Eocene Thermal Maximum (PETM), lasted for a period of 17 thousand years (kyr). At the onset of the PETM, about 6 C warming occurred in a -2 kyr interval (Kennett and Stott, 1991; Thomas and Shackleton, 1996; Zachos et al., 23; Rohl et al., 27). The origin of this warming is not well constrained, but can be explained by input of massive amounts of fossil fuels (Dickens et al., 1995; Svenson et al., 24; DeConto et al., 211). The PETM is associated with a significant change in sea level (Gibson et al., 1993; Stassen et al., 212). This changed facies distribution on the continental shelf and is well represented in the Atlantic Coastal Plain from New Jersey to Virginia. The base of the PETM interval corresponds to the glauconite-rich sandstone, the Aquia Formation of Late Paleocene age, overlain by silty clay-rich Marlboro Clay spanning the lower Eocene (Gibson et al., 1993). As carbon dioxide surged in the atmosphere and leaked in the seas, global temperatures increased and the waters acidified causing the dissolving of the present shells of the Paleocene. (Zachos et al., 21) 3

6 Cores that correspond to the PETM boundary were obtained from the Mattawoman Creek (MCBR-2) in Maryland (Figure 1). The goal of the current project is to analyze grainsize changes across the event in core samples to observe changes in the facies composition and as well as the characteristics of storm beds. Methods The core of 4ft depth from Mattawoman Creek, MD was sampled in intervals of.6ft, totaling in 71 samples from throughout the core. Samples were dispersed in deionized water and left overnight to disaggregate. The grain sizes of samples were analyzed using a Malvern Mastersizer which determines particle size by measuring the scattered light intensity of the laser beam passing through the disaggregated sample. Duplicates were made for every 3ft to make sure that the experimental results come back in agreement with actual characteristics of the samples. The observed results and the advised research show that the results are of high resolution and accuracy. The parameters set for operating the Mastersizer were implied with inputting a refractive index of and using the provided density of 2.71 kg/m 3. For the Mastersizer to produce the correct analysis, the presentation parameter must be chosen properly. The presentation is a mode of analysis that is specified by the researcher that incorporates the different characteristics of the sampled specimen. The presentation includes 4

7 four characters; each signifying a part of the analysis. 3SHE was the specified presentation that included the refractive index of the samples. Microsoft Excel was used to compile the data for each sample in a spreadsheet format for easier access from other graphing software. Matlab was used to plot the data obtained from the Mastersizer generating the depth vs. grain-size plot (Figure 2). Results Figure 2 shows the combined sample data sets of grain-size plotted using Matlab. The compilation shows a gradual decrease in grain-size from the base of the section towards the top. At a depth of approximately 4ft near the base of the core, grain-size is very coarse with the majority of the sediment ranging between µ to 31µ (sand and coarse silt fraction). The grain-size then takes a sharp decrease up to 3ft where the majority of the sediment lies between 1µ and µ (clay fraction). There are a few cycles of coarser grain size but much of the sediment in the upper 3ft of core is clay. Figure 3 shows the Bulk carbon stable isotope record (δ 13 C in parts per thousand) from the Mattawoman Creek core showing the negative excursion at the onset of the PETM from the base of the core to a depth of 37ft. The plot shows a maintained low δ 13 C at depths 37 to 35ft and later starts increasing and recovering. 5

8 Discussion The stratigraphy of the sampled core (Figure 4) was studied in order to determine the causes for changes in grain size (Figure 2). The base of the core at 4ft represents the Aquia Formation that is composed of medium to coarse greenish grey glauconitic sand (Glaser et al., 1971). The unit overlying the Aquia Formation is the Marlboro Clay, which is composed of pinkish grey to brown clay with laminated silts and glauconitic sand (Gibson et al., 1994). From Figure 2 and the stratigraphy of the Mattawoman Creek core, the upward decrease in grain size is explained by the change in environment and sea-level rise during the PETM (Stassen et al., 212). The base of the core that corresponds to the Aquia Formation, is a terrestrial or littoral environment with coarse sands reaching grain size of µ. The increased negative excursion in δ 13 C at the PETM onset is related to the input of greenhouse gases that caused the warming event. Associated with the abrupt warming was a marine transgression causing the deposition of finer grained marine Marlboro Clay on top of the Aquia Formation. As δ 13 C started to steadily recover, the grain size remains relatively uniform throughout. At depths of 25ft and 22ft we samples coarser grained layers (Figure 4) and grain size analysis demonstrate that these layers possess grain sizes similar to the sand from the Aquia Formation. The grain sizes of these anomalies reach µ, which is interpreted as storm deposits in the clay-dominated Marlboro Clay. 6

9 Conclusion In conclusion, the decrease in grain-size during the onset of the PETM in the sampled Mattawoman Creek core indicates a shift from littoral to inner shelf depositional environment as a result of transgression. Grain-size shows a sharp decrease from the dominantly sandy Aquia Formation to the dominantly clay-sized Marlboro Clay Formation. Coarse sands were observed in the fine Marlboro Clay suggesting a storm deposits. 7

10 References Cited Ce dric M. John,1,2 Steven M. Bohaty,1,3 James C. Zachos, Appy Sluijs, Samantha Gibbs, Henk Brinkhuis, and Timothy J. Bralower. North American continental margin records of the Paleocene-Eocene thermal maximum: Implications for global carbon and hydrological cyclingpaleoceanography, VOL. 23, PA2217, doi:.29/27pa1465, 28 Dickens, G. R., Castillo, M. M., and Walker, J. C. G., A blast of gas in the latest Paleocene: simulating first-order effects of massive dissociation of oceanic methane hydrate, Geology, 25, Gibson, T.G., and L.M. Bybell Sedimentary patterns across the Paleocene-Eocene boundary in the Atlantic and Gulf Coastal Plains of the United States. Bulletin de la Société belge de Géologie 3: Glaser, J.D Geology and mineral resources of Southern Maryland. Maryland Geological Survey. Kelly, D. C., T. J. Bralower, and J. C. Zachos (21), On the demise of the early Paleogene Morozovella velascoensis lineage: erminal progenesis in the planktonic Foraminifera, Palaios, 16, Kennett, J. P., and L.D. Stott, 1991, abrupt deep-sea warming, palaeoceanographic changes and benthic extinctions at the end of the Paleocene, Nature, 353, Malvern instruments. (n.d.). Retrieved from /mastersizer/ms2e/mastersizer2e.htm?howitworks Thomas, E., 199, Late Cretaceous early Eocene mass extinctions in the deep sea, in Global Catastrophes in Earth History: an Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality, edited by V.L. Sharpton, and P. Ward, GSA Spec. Publ., 247, , 199. Röhl, U., Westerhold, T., Bralower, T.J., and Zachos, J.C., 27. On the duration of the Paleocene-Eocene thermal maximum: Geochemistry, Geophysics, Geosystems, v. 8, no. 12, 3.1MB, doi:.29/27gc

11 Sluijs, A.; Schouten, S.; Pagani, M.; Woltering, M.; Brinkhuis, H.; Damsté, J.S.S.; Dickens, G.R.; Huber, M.; Reichart, G.J.; Stein, R.; Others, (26). "Subtropical Arctic Ocean temperatures during the Palaeocene/Eocene thermal maximum". Nature 441 (793): Bibcode 26Natur S. doi:.38/nature4668. PMID Stassen, P., E. Thomas, and R. Speijer (212), Integrated stratigraphy of the Paleocene-Eocene thermal maximum in the New Jersey Coastal Plain: Towards understanding the effects of global warming in a shelf environment., Paleoceanography, doi:.29/212pa2323, in press. Zachos, J. C., S. Schouten, S.Bohaty, T.Quattlebaum, A. Sluijs, H. Brinkhuis, S. J. Gibbs, and T. J. Bralower (26), Extreme warming of midlatitude coastal ocean during the Paleocene- Eocene thermal maximum: Inferences from TEX86 and isotope data, Geology, 34, , doi:.113/g

12 Figures and Tables Figure 1: New Jersey Maryland Coastal Plain from the Late Paleocene of the MCBR2 (Gibbs et Al., 26)

13 11

14 Figure 2: Bulk carbon isotope record (δ 13 C) from the Mattawoman Creek core. (Bralower et al., 213) 12

15 Figure 3: A photograph of the sampled core from the Mattawoman Creek, MD. The ruler shows a scale of 2ft and a total of 4ft deep core. 13

16 Appendix A Sample Number Depth Sample Number Depth

Rapid Carbon Injection and Transient Global Warming During the Paleocene-Eocene Thermal Maximum

Rapid Carbon Injection and Transient Global Warming During the Paleocene-Eocene Thermal Maximum Appy Sluijs Palaeoecology, Institute of Environmental Biology, Utrecht University, Laboratory of Palaeobotany