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<p class="MsoNormal"><span style="font-size:14.0pt">Good morning, <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">Please join us for Charlie Smith$B!G(Bs Thesis Defense on Tuesday, May 5<sup>th</sup> at 1:00 PM (EST).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">Title: Local Expansion of Reducing Conditions During the Late Ordovician: Implications for the Great Ordovician Biodiversification Event<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">Name: Charlie Smith<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">Date: May 5<sup>th</sup>, 1:00 PM – 3:00 PM<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">Location: EOA 5067<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">Major Professor: Dr. Jeremy Owens<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">Zoom: </span><a href="https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Ffsu.zoom.us%2Fj%2F93470688741&data=05%7C02%7Ceoas-seminar%40lists.fsu.edu%7Cbfeb4b45396149488c3c08dea9e533b8%7Ca36450ebdb0642a78d1b026719f701e3%7C0%7C0%7C639134999024248157%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=THsyk6i17Qk6FhObUkgBTiukYOgumgh%2BiTqLILgDRao%3D&reserved=0" originalsrc="https://fsu.zoom.us/j/93470688741"><span style="font-family:"Aptos",sans-serif">https://fsu.zoom.us/j/93470688741</span></a><span style="font-size:14.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Aptos",sans-serif;color:black">Abstract: The Great Ordovician Biodiversification Event (GOBE) was a transformative period for marine ecosystems. During this time familial diversity increased more than any other
time in Earth$B!G(Bs history coinciding with an expansion and restructuring of marine ecosystems. The cause of this radiative event has been attributed to a multitude of biotic and abiotic factors which include the proliferation of phytoplankton, enhanced nutrient
supply and a long-term global cooling event. Additionally, increased marine oxygenation has been proposed as a driver for many dynamic biotic events, with oxygenation improving metabolic conditions that may contribute to the global radiation. A range of redox
proxies have been used to investigate shallow marine carbonate shelves; however significantly fewer studies have explored deep water settings.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Aptos",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Aptos",sans-serif;color:black">This study focuses on the Trail Creek Summit section of central Idaho which is a 200-meter-thick sequence of organic-rich mudstones with an interval thinly interbedded siltstone.
This section contains the lower to upper Ordovician (Floian to Katian stages encompassing 470 to 449 Ma) using graptolite and conodont biostratigraphy in concert with carbon isotope chemostratigraphy. The Guttenberg Isotopic Carbon Excursion (GICE) is encountered
during the bifidus biozone with a +2.6$B"s(B $B&D(B13Corg (VPDB) excursion. A multiproxy approach was employed to better constrain the local redox conditions at Trail Creek Summit. Iron speciation supports the presence of persistently ferruginous, anoxic bottom waters
with dissolved Fe. Depleted Mn concentrations throughout the section indicate the presence of manganese reduction. The D. caudatus biozone (Katian) shows enrichments up section in V and U alongside a moderate rise in Mo concentrations. Trace metal covariation
suggests that the basin is not overly restricted and its general agreement with Fe speciation values lend evidence that enrichments are likely dependent on local redox conditions. Combined with the local Fe speciation suggests a migrating chemocline where
porewaters near the sediment water interface transitioned from Fe reduction to sulfate reduction during the Katian. The $B&D(B34Spyr record shifts toward more positive values during this inferred rise in sulfate reduction which seems to correspond with published
data for the marine sulfate record. Thus, this shift is likely a global record which can be attributed to a global increase in pyrite burial during the GICE which likely decreased the size of the marine sulfate reservoir. In context of the GOBE, locally this
basin was consistently anoxic at least near the sediment water interface although there is record of sedimentary bioturbation, but importantly is locally more reducing near the sediment water interface by the Katian and was probably inhospitable for most infaunal
and benthic animals. Local redox conditions provide a framework for future work on other global redox proxies that will provide global insight into this highly dynamic period for marine life.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Segoe Script"">Adea Arrison<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Segoe Script"">Sr. Academic Program Specialist<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Segoe Script"">Department of Earth, Ocean & Atmospheric Science<o:p></o:p></span></p>
<p class="MsoNormal"><a href="https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.eoas.fsu.edu%2F&data=05%7C02%7Ceoas-seminar%40lists.fsu.edu%7Cbfeb4b45396149488c3c08dea9e533b8%7Ca36450ebdb0642a78d1b026719f701e3%7C0%7C0%7C639134999024272171%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=jT7gXH10AIFrWSuaGGtJrErI28YtHwZpQDBY7z2tgO0%3D&reserved=0" originalsrc="https://www.eoas.fsu.edu/"><span style="font-size:11.0pt;color:blue;text-decoration:none"><img border="0" width="92" height="55" style="width:.9583in;height:.5729in" id="Picture_x0020_1" src="cid:image001.png@01DCDBAC.895CA400"></span></a><span style="font-size:11.0pt"><o:p></o:p></span></p>
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