Reconstructing deep-ocean circulation during Cenozoic climate transitions from the marine sediment record

Ocean circulation plays a critical role in the Earth’s climate system through the storage and transfer of heat and carbon dioxide. The North Atlantic and Southern Ocean are of particular interest because these are regions where deep-water components of global circulation develop. Dr. Romans uses the deep-sea sedimentary record to reconstruct past ocean circulation and its relationship to past climatic and tectonic conditions. He integrates information from a broad range of spatial and temporal scales, from seismic-reflection data that reveals regional sedimentation patterns to high resolution records based on quantitative grain-size analysis from cores. Dr. Romans will present research from the North Atlantic Ocean (Expedition 342, Newfoundland Drifts) that shows how vast deep-sea “drift” deposits relate to the onset of and changes in ocean circulation in the Eocene through Miocene. In addition to his work on the North Atlantic, Dr. Romans will also present preliminary findings from new drilling (January-February 2018) in the Ross Sea (Expedition 374, West Antarctic Ice Sheet History), which aims to study interactions of Southern Ocean circulation and Antarctic ice sheet dynamics during significant climate events of the Miocene and Pliocene

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Brian Romans

Brian Romans, Virginia Techhttps://digitalcommons.montclair.edu/sust-seminar-headshots/1067/thumbnail.jp

Climate-driven unsteady denudation and sediment flux in a high-relief unglaciated catchment-fan using 26Al and 10Be: Panamint Valley, California

Environmental changes within erosional catchments of sediment routing systems are predicted to modulate sediment transfer dynamics. However, empirical and numerical models that predict such phenomena are difficult to test in natural systems over multi-millennial timescales. Tectonic boundary conditions and climate history in the Panamint Range, California, are relatively well-constrained by existing low-temperature thermochronology and regional multi-proxy paleoclimate studies, respectively. Catchment-fan systems present there minimize sediment storage and recycling, offering an excellent natural laboratory to test models of climate-sedimentary dynamics. We used stratigraphic characterization and cosmogenic radionuclides (CRNs; 26Al & 10Be) in the Pleasant Canyon complex (PCC), a linked catchment-fan system, to examine the effects of Pleistocene high-magnitude, high-frequency climate change on CRN-derived denudation rates and sediment flux in a high-relief, unglaciated catchment-fan system. Calculated 26Al/10Be burial ages from 13 samples collected in an ~180 m thick outcropping stratigraphic succession range from ca. 1.55 ± 0.22 Ma in basal strata, to ca. 0.36 ± 0.18 - 0.52 ± 0.20 Ma within stratigraphically highest portions of the fan. The mean long-term CRN-derived paleodenudation rate, 36 ± 8 mm/kyr (1σ), is higher than the modern rate of 24 ± 0.6 mm/kyr from Pleasant Canyon, and paleodenudation rates during the middle Pleistocene display some high-frequency variability in the high end (up to 54 ± 10 mm/kyr). The highest CRN-derived denudation rates are associated with stratigraphic evidence for increased precipitation during glacial-pluvial events after the middle Pleistocene transition (post ca. 0.75 Ma), suggesting 100 kyr Milankovitch periodicity could drive the observed variability. We investigated the potential for non-equilibrium sedimentary processes, i.e. increased landslides or sediment storage/recycling, to influence apparent paleodenudation rates; end-member mixing models suggest that a mixture of >50% low-CRN-concentration sediment from landslides is required to produce the largest observed increase in paleodenudation rate. The overall pattern of CRN-derived burial ages, paleodenudation rates, and stratigraphic facies suggests Milankovitch timescale climate transitions drive variability in catchment denudation rates and sediment flux, or alternatively that climate transitions affect sedimentary process regimes that result in measurable variability of CRN concentrations in unglaciated catchment-fan systems

Sedimentation Patterns of the Permian Brushy Canyon Formation, Delaware Basin, Texas and New Mexico

<p>This is my 2003 master's thesis from the Colorado School of Mines including all figures and appendices. This project, under the supervision of Dr. Michael Gardner, examined thickness patterns of the Permian Brushy Canyon Formation in west Texas and southeastern New Mexico with an integrated subsurface and outcrop stratigraphic database. Primary data include numerous isopach maps of stratigraphic cycles over a 6500 km^2 area.</p> <p> </p> <p>Data and findings from this thesis were used in this special publication:</p> <p>Gardner, M.H., Borer, J.M., Romans, B.W., Baptista, N., Kling, E.K., Hanggoro, D., Melick, J.J., Wagerle, R.M., Carr, M.M., Amerman, R., and Atan, S., 2008, Stratigraphic models for deep-water sedimentary systems: 28th Annual Gulf Coast Section SEPM Foundation Bob. F. Perkins Research Conference</p

Times Associated With Source-to-Sink Propagation of Environmental Signals During Landscape Transience

International audienceSediment archives in the terrestrial and marine realm are regularly analyzed to infer changes in climate, tectonic, or anthropogenic boundary conditions of the past. However, contradictory observations have been made regarding whether short period events are faithfully preserved in stratigraphic archives; for instance, in marine sediments offshore large river systems. On the one hand, short period events are hypothesized to be non-detectable in the signature of terrestrially derived sediments due to buffering during sediment transport along large river systems. On the other hand, several studies have detected signals of short period events in marine records offshore large river systems. We propose that this apparent discrepancy is related to the lack of a differentiation between different types of signals and the lack of distinction between river response times and signal propagation times. In this review, we (1) expand the definition of the term ‘signal’ and group signals in sub-categories related to hydraulic grain size characteristics, (2) clarify the different types of ‘times’ and suggest a precise and consistent terminology for future use, and (3) compile and discuss factors influencing the times of signal transfer along sediment routing systems and how those times vary with hydraulic grain size characteristics. Unraveling different types of signals and distinctive time periods related to signal propagation addresses the discrepancies mentioned above and allows a more comprehensive exploration of event preservation in stratigraphy – a prerequisite for reliable environmental reconstructions from terrestrially derived sedimentary records

Times associated with source-to-sink propagation of environmental signals during landscape transience

International audienceSediment archives in the terrestrial and marine realm are regularly analyzed to infer past changes in climate and tectonic boundary conditions. However, contradictory observations have been made regarding whether short period events are faithfully preserved in stratigraphic record. For example, short period events were hypothesized to be non-detectable in terrestrially derived sediments offshore large river system due to buffering during sediment transport. Other studies, however, have detected signals of short period events in sediments that were transported along large river systems. We think that this apparent discrepancy is related to the lack of a differentiation between different types of signals and the lack of distinction between river response times and times related to signal propagation.To overcome these issues, we propose to define environmental signals more generally as “a measurable change in any sedimentary parameter of interest through time that can be linked to an environmental change” and to further group signals in sub-categories related to hydraulic grain-size characteristics. Also, we review the different types of ‘times’ and suggest a precise and consistent terminology for future use to clearly distinguish times of landscape response from times of signal transfer. We compile and discuss factors influencing the times of signal transfer along sediment-routing systems, how those times vary with hydraulic grain-size characteristics, as well as consequences regarding signal preservation in stratigraphy.Unravelling different types of signals and distinctive time periods related to signal propagation addresses the discrepancies mentioned above and allows a more comprehensive exploration of event preservation in stratigraphy – a prerequisite for reliable environmental reconstructions from terrestrially derived sedimentary records

Times associated with source-to-sink propagation of environmental signals during landscape transience

International audienceSediment archives in the terrestrial and marine realm are regularly analyzed to infer past changes in climate and tectonic boundary conditions. However, contradictory observations have been made regarding whether short period events are faithfully preserved in stratigraphic record. For example, short period events were hypothesized to be non-detectable in terrestrially derived sediments offshore large river system due to buffering during sediment transport. Other studies, however, have detected signals of short period events in sediments that were transported along large river systems. We think that this apparent discrepancy is related to the lack of a differentiation between different types of signals and the lack of distinction between river response times and times related to signal propagation.To overcome these issues, we propose to define environmental signals more generally as “a measurable change in any sedimentary parameter of interest through time that can be linked to an environmental change” and to further group signals in sub-categories related to hydraulic grain-size characteristics. Also, we review the different types of ‘times’ and suggest a precise and consistent terminology for future use to clearly distinguish times of landscape response from times of signal transfer. We compile and discuss factors influencing the times of signal transfer along sediment-routing systems, how those times vary with hydraulic grain-size characteristics, as well as consequences regarding signal preservation in stratigraphy.Unravelling different types of signals and distinctive time periods related to signal propagation addresses the discrepancies mentioned above and allows a more comprehensive exploration of event preservation in stratigraphy – a prerequisite for reliable environmental reconstructions from terrestrially derived sedimentary records