{"688849":{"#nid":"688849","#data":{"type":"event","title":"EAS Seminar Series - Dr. Gilby Jepson","body":[{"value":"\u003Cp\u003EWestern North America is the archetypical Cordilleran orogenic system that preserves a Mesozoic to Cenozoic record of oceanic Farallon plate subduction-related processes. After prolonged Late Jurassic through mid-Cretaceous normal-angle Farallon\u0026nbsp;plate subduction that produced the western North American batholith belt and retroarc fold-thrust belt, a period of low-angle, flat-slab subduction during Late Cretaceous-Paleogene time caused upper plate deformation to migrate eastward in the form of the Laramide basement-involved uplifts, which partitioned the original regional foreland basin.\u0026nbsp;Major questions persist about the mechanism and timing of flat-slab subduction, the trajectory of the flat-slab, inter-plate coupling mechanism(s), and the upper-plate deformational response to such processes. Critical for testing various flat-slab hypotheses are the timing, rate, and distribution of exhumation experienced by the Laramide uplifts as recorded by low-temperature thermochronology. In this contribution, we address the timing of regional exhumation of the Laramide uplifts by combining apatite fission-track (AFT) and (U-Th-Sm)\/He (AHe) data from 29 new samples with 564 previously published AFT, AHe, and zircon (U-Th)\/He ages from Laramide structures in Arizona, Utah, Wyoming, Colorado, Montana, and South Dakota. We integrate our results with existing geological constraints and with new regional cross-sections to reconstruct the spatial and temporal history of exhumation driven by Laramide deformation from the mid-Cretaceous to Paleogene. Our analysis suggests a two-stage exhumation of the Laramide province, with an early phase of localized exhumation occurring at ~100 \u2013 80 Ma in Wyoming and Montana, followed by a more regional period of exhumation at ~70 \u2013 50 Ma. Generally, the onset of enhanced exhumation occurs earlier in the northern Laramide province (~90 Ma) and later in the southern Laramide province (~80 Ma). Thermal history models of selected samples along regional cross-sections through the Utah-Arizona-New Mexico and Wyoming-South Dakota show that exhumation occurred contemporaneously with deformation, implying that Laramide basement block exhumation is coupled with regional deformation. These results have implications for testing proposed migration pathway models of Farallon flat-slab and for how upper-plate deformation is expressed in flat-slab subduction zones in general.\u003C\/p\u003E\u003Cp\u003E*Refreshments: 10:30 AM - 11:00 AM (Atrium)\u003C\/p\u003E","summary":"","format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EWestern North America is the archetypical Cordilleran orogenic system that preserves a Mesozoic to Cenozoic record of oceanic Farallon plate subduction-related processes. After prolonged Late Jurassic through mid-Cretaceous normal-angle Farallon\u0026nbsp;plate subduction that produced the western North American batholith belt and retroarc fold-thrust belt, a period of low-angle, flat-slab subduction during Late Cretaceous-Paleogene time caused upper plate deformation to migrate eastward in the form of the Laramide basement-involved uplifts, which partitioned the original regional foreland basin.\u0026nbsp;Major questions persist about the mechanism and timing of flat-slab subduction, the trajectory of the flat-slab, inter-plate coupling mechanism(s), and the upper-plate deformational response to such processes. Critical for testing various flat-slab hypotheses are the timing, rate, and distribution of exhumation experienced by the Laramide uplifts as recorded by low-temperature thermochronology. In this contribution, we address the timing of regional exhumation of the Laramide uplifts by combining apatite fission-track (AFT) and (U-Th-Sm)\/He (AHe) data from 29 new samples with 564 previously published AFT, AHe, and zircon (U-Th)\/He ages from Laramide structures in Arizona, Utah, Wyoming, Colorado, Montana, and South Dakota. We integrate our results with existing geological constraints and with new regional cross-sections to reconstruct the spatial and temporal history of exhumation driven by Laramide deformation from the mid-Cretaceous to Paleogene. Our analysis suggests a two-stage exhumation of the Laramide province, with an early phase of localized exhumation occurring at ~100 \u2013 80 Ma in Wyoming and Montana, followed by a more regional period of exhumation at ~70 \u2013 50 Ma. Generally, the onset of enhanced exhumation occurs earlier in the northern Laramide province (~90 Ma) and later in the southern Laramide province (~80 Ma). Thermal history models of selected samples along regional cross-sections through the Utah-Arizona-New Mexico and Wyoming-South Dakota show that exhumation occurred contemporaneously with deformation, implying that Laramide basement block exhumation is coupled with regional deformation. These results have implications for testing proposed migration pathway models of Farallon flat-slab and for how upper-plate deformation is expressed in flat-slab subduction zones in general.\u003C\/p\u003E\u003Cp\u003E*Refreshments: 10:30 AM - 11:00 AM (Atrium)\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Regional exhumation of the Laramide Province"}],"uid":"36678","created_gmt":"2026-03-11 12:22:31","changed_gmt":"2026-03-11 12:26:01","author":"tbuchanan9","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2026-04-09T11:00:00-04:00","event_time_end":"2026-04-09T12:00:00-04:00","event_time_end_last":"2026-04-09T12:00:00-04:00","gmt_time_start":"2026-04-09 15:00:00","gmt_time_end":"2026-04-09 16:00:00","gmt_time_end_last":"2026-04-09 16:00:00","rrule":null,"timezone":"America\/New_York"},"location":"EST L1205","extras":["free_food"],"hg_media":{"679574":{"id":"679574","type":"image","title":"Headshot - Jepson","body":null,"created":"1773231885","gmt_created":"2026-03-11 12:24:45","changed":"1773231885","gmt_changed":"2026-03-11 12:24:45","alt":"Headshot - Jepson","file":{"fid":"263750","name":"Headshot---Jepson.png","image_path":"\/sites\/default\/files\/2026\/03\/11\/Headshot---Jepson.png","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2026\/03\/11\/Headshot---Jepson.png","mime":"image\/png","size":2905308,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2026\/03\/11\/Headshot---Jepson.png?itok=B4bNrhfg"}}},"media_ids":["679574"],"related_links":[{"url":"https:\/\/emes.unc.edu\/people\/gilby-jepson\/","title":""}],"groups":[{"id":"364801","name":"School of Earth and Atmospheric Sciences (EAS)"}],"categories":[],"keywords":[{"id":"175623","name":"EAS Seminar"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}},"688816":{"#nid":"688816","#data":{"type":"event","title":"EAS Seminar Series - Dr. Arial Shogren","body":[{"value":"\u003Cp\u003ERivers tell stories: of where water has been, where it is going, and how it might impact downstream ecosystems.\u0026nbsp;\u003Cem\u003EStreams and rivers move more than water and dissolved material \u2014 they also carry a complex blend of fine particles, including seston and sediment.\u0026nbsp;\u003C\/em\u003EI am fundamentally intrigued by these stories, and my group works\u003Cem\u003E\u0026nbsp;\u003C\/em\u003Eto interpret the \u201clanguage\u201d of flowing waters as told by the biogeochemical signals they carry. My research group leverages fundamental tools from stream ecology, biogeochemistry, and watershed science to\u003Cem\u003E\u0026nbsp;\u003C\/em\u003Eunderstand how rivers move and modify materials during their downstream journey. Using these\u003Cem\u003E\u0026nbsp;\u003C\/em\u003Eunique and complimentary perspectives, we measure water-mediated biogeochemical transport\u003Cem\u003E\u0026nbsp;\u003C\/em\u003Eand transformations across variable temporal and spatial scales. With this talk, I will outline my group\u2019s\u003Cem\u003E\u0026nbsp;\u003C\/em\u003Econtributions and progress on three primary research themes: (1)\u0026nbsp;\u003Cem\u003Ethe transport and transformation of particulate material in streams,\u0026nbsp;\u003C\/em\u003E(2)\u0026nbsp;\u003Cem\u003Ethe effects of dynamic hydrologic expansion and contraction on watershed biogeochemical fluxes,\u0026nbsp;\u003C\/em\u003Eand (3)\u0026nbsp;\u003Cem\u003Ethe impact of concurrent stressors on ecosystem structure and function.\u0026nbsp;\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E*Refreshments: 10:30 AM - 11:00 AM (Atrium)\u003C\/p\u003E","summary":"","format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003ERivers tell stories: of where water has been, where it is going, and how it might impact downstream ecosystems.\u0026nbsp;\u003Cem\u003EStreams and rivers move more than water and dissolved material \u2014 they also carry a complex blend of fine particles, including seston and sediment.\u0026nbsp;\u003C\/em\u003EI am fundamentally intrigued by these stories, and my group works\u003Cem\u003E\u0026nbsp;\u003C\/em\u003Eto interpret the \u201clanguage\u201d of flowing waters as told by the biogeochemical signals they carry. My research group leverages fundamental tools from stream ecology, biogeochemistry, and watershed science to\u003Cem\u003E\u0026nbsp;\u003C\/em\u003Eunderstand how rivers move and modify materials during their downstream journey. Using these\u003Cem\u003E\u0026nbsp;\u003C\/em\u003Eunique and complimentary perspectives, we measure water-mediated biogeochemical transport\u003Cem\u003E\u0026nbsp;\u003C\/em\u003Eand transformations across variable temporal and spatial scales. With this talk, I will outline my group\u2019s\u003Cem\u003E\u0026nbsp;\u003C\/em\u003Econtributions and progress on three primary research themes: (1)\u0026nbsp;\u003Cem\u003Ethe transport and transformation of particulate material in streams,\u0026nbsp;\u003C\/em\u003E(2)\u0026nbsp;\u003Cem\u003Ethe effects of dynamic hydrologic expansion and contraction on watershed biogeochemical fluxes,\u0026nbsp;\u003C\/em\u003Eand (3)\u0026nbsp;\u003Cem\u003Ethe impact of concurrent stressors on ecosystem structure and function.\u0026nbsp;\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E*Refreshments: 10:30 AM - 11:00 AM (Atrium)\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Streams as sensors: Using modern applications of the watershed ecosystem concept to understand ecosystem dynamics"}],"uid":"36678","created_gmt":"2026-03-09 15:36:01","changed_gmt":"2026-03-09 15:49:22","author":"tbuchanan9","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2026-04-16T11:00:00-04:00","event_time_end":"2026-04-16T12:00:00-04:00","event_time_end_last":"2026-04-16T12:00:00-04:00","gmt_time_start":"2026-04-16 15:00:00","gmt_time_end":"2026-04-16 16:00:00","gmt_time_end_last":"2026-04-16 16:00:00","rrule":null,"timezone":"America\/New_York"},"location":"EST L1205","extras":["free_food"],"hg_media":{"679551":{"id":"679551","type":"image","title":"Headshot - Shogren","body":null,"created":"1773070845","gmt_created":"2026-03-09 15:40:45","changed":"1773070845","gmt_changed":"2026-03-09 15:40:45","alt":"Headshot - Shogren","file":{"fid":"263726","name":"Headshot---Shogren.png","image_path":"\/sites\/default\/files\/2026\/03\/09\/Headshot---Shogren.png","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2026\/03\/09\/Headshot---Shogren.png","mime":"image\/png","size":5317134,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2026\/03\/09\/Headshot---Shogren.png?itok=h7_vqI4e"}}},"media_ids":["679551"],"related_links":[{"url":"https:\/\/sites.google.com\/view\/shogrenscience\/dr-shogren","title":""}],"groups":[{"id":"364801","name":"School of Earth and Atmospheric Sciences (EAS)"}],"categories":[],"keywords":[{"id":"175623","name":"EAS Seminar"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}},"688483":{"#nid":"688483","#data":{"type":"event","title":"EAS Planetary \u0026 Astrobiology Seminar - Dr. Elliott Mueller","body":[{"value":"\u003Cp\u003EFor the first two billion years of Earth history, microbial life and our planet coevolved under an anoxic atmosphere. Today, microbial communities abound in anoxic environments \u2014 like the continental and marine subsurfaces \u2014 where they actively cycle carbon and nutrients. These facts demonstrate that sustainable biospheres do not require molecular oxygen to thrive. Indeed, our best hopes for finding life beyond Earth likely lie with planets and moons that may be anoxic as well. Despite the importance of anaerobic microorganisms to planetary evolution and astrobiology, there are major open questions surrounding their influence on Earth\u2019s carbon cycle. My research program focuses on the rates, mechanisms and limitations of anaerobic organic degradation, which is a key component of global carbon dynamics. Central in this process are organic acids (e.g. acetate), small molecule intermediates generated as organic matter is broken down into greenhouse gases. Organic acids are rapidly turned over by microbial metabolisms and abiotic reactions alike. By combining method development, metabolic modeling and experimental geobiology, I harness organic acids as a window into the carbon cycle, informing both our understanding of anoxic microbial ecology and the potential for life elsewhere in the Solar System. In this seminar, I will present new Orbitrap mass spectrometry techniques that I have developed to measure precise isotope ratios of organic acids with unprecedented sensitivity. I will demonstrate how the isotopic signatures of organic acids identify their metabolic origins and quantify their \u003Cem\u003Ein situ \u003C\/em\u003Eturnover rates. These analyses offer unique insights into the microbial activity of anoxic subsurface ecosystems and valuable applications to astrobiology research.\u003C\/p\u003E\u003Cp\u003E*Refreshments: 10:30 AM - 11:00 AM (ES\u0026amp;T L1175)\u003C\/p\u003E","summary":"","format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EFor the first two billion years of Earth history, microbial life and our planet coevolved under an anoxic atmosphere. Today, microbial communities abound in anoxic environments \u2014 like the continental and marine subsurfaces \u2014 where they actively cycle carbon and nutrients. These facts demonstrate that sustainable biospheres do not require molecular oxygen to thrive. Indeed, our best hopes for finding life beyond Earth likely lie with planets and moons that may be anoxic as well. Despite the importance of anaerobic microorganisms to planetary evolution and astrobiology, there are major open questions surrounding their influence on Earth\u2019s carbon cycle. My research program focuses on the rates, mechanisms and limitations of anaerobic organic degradation, which is a key component of global carbon dynamics. Central in this process are organic acids (e.g. acetate), small molecule intermediates generated as organic matter is broken down into greenhouse gases. Organic acids are rapidly turned over by microbial metabolisms and abiotic reactions alike. By combining method development, metabolic modeling and experimental geobiology, I harness organic acids as a window into the carbon cycle, informing both our understanding of anoxic microbial ecology and the potential for life elsewhere in the Solar System. In this seminar, I will present new Orbitrap mass spectrometry techniques that I have developed to measure precise isotope ratios of organic acids with unprecedented sensitivity. I will demonstrate how the isotopic signatures of organic acids identify their metabolic origins and quantify their \u003Cem\u003Ein situ \u003C\/em\u003Eturnover rates. These analyses offer unique insights into the microbial activity of anoxic subsurface ecosystems and valuable applications to astrobiology research.\u003C\/p\u003E\u003Cp\u003E*Refreshments: 10:30 AM - 11:00 AM (ES\u0026amp;T L1175)\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Organic acids, the microbial currency of anoxic environments"}],"uid":"36678","created_gmt":"2026-02-23 20:31:01","changed_gmt":"2026-02-26 22:30:06","author":"tbuchanan9","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2026-04-10T11:00:00-04:00","event_time_end":"2026-04-10T12:00:00-04:00","event_time_end_last":"2026-04-10T12:00:00-04:00","gmt_time_start":"2026-04-10 15:00:00","gmt_time_end":"2026-04-10 16:00:00","gmt_time_end_last":"2026-04-10 16:00:00","rrule":null,"timezone":"America\/New_York"},"location":"EST L1175","extras":["free_food"],"hg_media":{"679466":{"id":"679466","type":"image","title":"Mueller\u0027s Headshot","body":null,"created":"1772141752","gmt_created":"2026-02-26 21:35:52","changed":"1772141752","gmt_changed":"2026-02-26 21:35:52","alt":"Mueller\u0027s Headshot","file":{"fid":"263631","name":"Mueller-s.-Headshot.png","image_path":"\/sites\/default\/files\/2026\/02\/26\/Mueller-s.-Headshot_1.png","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2026\/02\/26\/Mueller-s.-Headshot_1.png","mime":"image\/png","size":2059160,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2026\/02\/26\/Mueller-s.-Headshot_1.png?itok=gH8f-tK_"}}},"media_ids":["679466"],"related_links":[{"url":"https:\/\/www.epm-geomicro.com\/","title":""}],"groups":[{"id":"364801","name":"School of Earth and Atmospheric Sciences (EAS)"}],"categories":[],"keywords":[{"id":"175623","name":"EAS Seminar"},{"id":"722","name":"Astrobiology"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}