Sequence Stratigraphy and Depositional Facies of Lower Ordovician Cyclic Carbonate Rocks, Southern Missouri, U.S.A.

Lower Ordovician cyclic carbonate strata of southern Missouri were deposited in a warm, shallow, epeiric sea on a fully aggraded carbonate platform. Sedimentological characteristics distinguish the Jefferson City and Cotter dolomites from the underlying Gasconade and Roubidoux formations. Mixed carbonate-siliciclastic sedimentation characterizes the Roubidoux Formation, with sandstones accounting for up to 60% of sedimentation. The Gasconade, Jefferson City, and Cotter dolomites exhibit an increased occurrence of chalcedonic chert nodules in very similar shape and texture to the gypsum and anhydrite nodules common on modern sabkha supratidal flats. Casts of halite and ghosts of gypsum laths also exist in the Jefferson City and Cotter strata but are rarely found in the underlying units. Facies analysis from drill cores and outcrop sections provides the basis for identifying two major meter-scale cycle types. Type I cycles consist of algal stromatolites, tidal-flat laminites (mechanical and algal), ooid grainstones, wavy peloidal wackestones, and quartz sandstones interpreted as peritidal facies. They are the dominant components of the Roubidoux Formation, Jefferson City Dolomite, and Cotter Dolomite. Type II cycles consist mostly of subtidal facies such as strongly burrowed mudstone, thrombolite boundstone, and stromatolites. Type I cycles are thinner and represent highstand systems tracts, whereas the thicker type II cycles represent transgressive systems tracts and are dominant in the Gasconade Dolomite. The cycle stacking patterns, facies changes, and the intrabasinal correlatability of Fischer plots made from the widely spaced sections argue for a eustatic control on sea-level fluctuation on the platform. Interbasinal correlation with other North American basins is possible using biostratigraphic information and comparison of Fischer plots. Five Missouri sequences correlate with those described for other regions. The continent-wide uniformity in cycle stacking patterns indicates a primarily eustatic control on Lower Ordovician meter-scale cycle development. Regional tectonic and autocyclic controls probably account for general differences in sedimentation pattern among the correlated basins

Direct Measurements of Meltwater Runoff on the Greenland Ice Sheet Surface

Meltwater runoff from the Greenland Ice Sheet surface influences surface mass balance (SMB), ice dynamics and global sea level rise, but is estimated with climate models and thus difficult to validate. We present a way to measure ice surface runoff directly, from hourly in situ supraglacial river discharge measurements and simultaneous high-resolution satellite/drone remote sensing of upstream fluvial catchment area. A first 72-hour trial for a 63.1 square kilometer moulin-terminating internally drained catchment (IDC) on Greenland's mid-elevation (1207-1381 meters above sea level) ablation zone is compared with melt and runoff simulations from HIRHAM5, MAR3.6.1 (Modele Atmospherique Regionale 3.6.1), RACMO2.3 (Regional Atmospheric Climate Model 2.3), MERRA-2 (Modern Era Retrospective-analysis for Research and Applications-2) and SEB climate/SMB models. Current models cannot reproduce peak discharges or timing of runoff entering moulins, but are improved using synthetic unit hydrograph theory (SUH). Retroactive SUH applications to two older field studies reproduces their findings, signifying that remotely sensed IDC area, shape, and river-length are useful for predicting delays in peak runoff delivery to moulins. Applying SUH to HIRHAM5, MAR3.6.1, RACMO2.3 gridded melt products for 799 surrounding IDCs suggests their terminal moulins receive lower peak discharges, less diurnal variability, and asynchronous runoff timing relative to climate/SMB model output alone. Conversely, large IDCs produce high moulin discharges, even at high elevations where melt rates are low. During this particular field experiment models overestimated runoff by plus 21 percent to plus 58 percent, linked to overestimated ablation and possible meltwater retention in bare, low-density ice. Direct measurements of ice surface runoff will improve climate/SMB models, and incorporating remotely sensed IDCs will aid coupling of surface mass balance with ice dynamics and subglacial systems

Direct measurements of meltwater runoff on the Greenland ice sheet surface

Meltwater runoff from the Greenland ice sheet surface influences surface mass balance (SMB), ice dynamics, and global sea level rise, but is estimated with climate models and thus difficult to validate. We present a way to measure ice surface runoff directly, from hourly in situ supraglacial river discharge measurements and simultaneous high-resolution satellite/drone remote sensing of upstream fluvial catchment area. A first 72-h trial for a 63.1-km2 moulin-terminating internally drained catchment (IDC) on Greenland?s midelevation (1,207?1,381 m above sea level) ablation zone is compared with melt and runoff simulations from HIRHAM5, MAR3.6, RACMO2.3, MERRA-2, and SEB climate/SMB models. Current models cannot reproduce peak discharges or timing of runoff entering moulins but are improved using synthetic unit hydrograph (SUH) theory. Retroactive SUH applications to two older field studies reproduce their findings, signifying that remotely sensed IDC area, shape, and supraglacial river length are useful for predicting delays in peak runoff delivery to moulins. Applying SUH to HIRHAM5, MAR3.6, and RACMO2.3 gridded melt products for 799 surrounding IDCs suggests their terminal moulins receive lower peak discharges, less diurnal variability, and asynchronous runoff timing relative to climate/SMB model output alone. Conversely, large IDCs produce high moulin discharges, even at high elevations where melt rates are low. During this particular field experiment, models overestimated runoff by +21 to +58%, linked to overestimated surface ablation and possible meltwater retention in bare, porous, low-density ice. Direct measurements of ice surface runoff will improve climate/SMB models, and incorporating remotely sensed IDCs will aid coupling of SMB with ice dynamics and subglacial systemspublishersversionPeer reviewe

Sequence stratigraphy and depositional facies of Lower Ordovician cyclic carbonates, southern Missouri

“The Lower Ordovician cyclic carbonate strata of southern Missouri were deposited in a warm, shallow, epeiric sea environment on a fully aggraded carbonate platform. Sedimentological characteristics distinguish the Jefferson City and Cotter Dolomites from the underlying Gasconade and Roubidoux Formations. The Jefferson City and Cotter Dolomites exhibit an increased occurrence of chalcedonic chert nodules in a very similar shape and texture to the gypsum and anhydrite nodules common on modern sabkha supratidal flats. Casts of halite and gypsum lath ghosts also exist in these strata. Contrastingly, such chert nodules are rarely found in the underlying Roubidoux and Gasconade Formations. Facies analysis from drill-cores and outcrop sections provides the basis for identifying two major meter-scale cycle types: type I (dominated by subtidal facies) and type II cycles (dominated by peritidal facies). The cycle stacking patterns, facies changes, and the overall resemblance of Fischer plots made from the widely spaced sections argue for an eustatic control on sea-level fluctuation on the platform. Interbasinal correlation with other North American basins was established via biostratigraphy and comparison of the Fischer plots. The 3rd-order sequence boundaries from the Ozarks appear correlative with those described for other regions with the exception of sequence 3 from the Ozarks. However, Fischer plots from the separate basins could not be correlated with any certainty, since visual comparison of the plots did not reliably suggest the proper correlation as indicated by biostratigraphy. Regional tectonic and autocyclic controls on meter-scale cycle formation probably mask the eustatic signal on the continent”--Abstract, page iii

Sampling Strategies to Improve Passive Optical Remote Sensing of River Bathymetry

Passive optical remote sensing of river bathymetry involves establishing a relation between depth and reflectance that can be applied throughout an image to produce a depth map. Building upon the Optimal Band Ratio Analysis (OBRA) framework, we introduce sampling strategies for constructing calibration data sets that lead to strong relationships between an image-derived quantity and depth across a range of depths. Progressively excluding observations that exceed a series of cutoff depths from the calibration process improved the accuracy of depth estimates and allowed the maximum detectable depth (dmax) to be inferred directly from an image. Depth retrieval in two distinct rivers also was enhanced by a stratified version of OBRA that partitions field measurements into a series of depth bins to avoid biases associated with under-representation of shallow areas in typical field data sets. In the shallower, clearer of the two rivers, including the deepest field observations in the calibration data set did not compromise depth retrieval accuracy, suggesting that dmax was not exceeded and the reach could be mapped without gaps. Conversely, in the deeper and more turbid stream, progressive truncation of input depths yielded a plausible estimate of dmax consistent with theoretical calculations based on field measurements of light attenuation by the water column. This result implied that the entire channel, including pools, could not be mapped remotely. However, truncation improved the accuracy of depth estimates in areas shallower than dmax, which comprise the majority of the channel and are of primary interest for many habitat-oriented applications

Sterotyping

This entry reviews research and theory about stereotyping and its connections to mental health and well-being. We review multiple theories and perspectives that understand stereotypes as cognitive generalizations about characteristics of groups, as taught and learned explicitly and implicitly through various social influences, and as tools to justify and sustain oppression. We consider evidence about interpersonal and intrapersonal mechanisms through which stereotyping harms mental health, including stereotyping leading to discrimination, stereotype threat, and internalization of stereotypes. We also highlight theory and research on decreasing stereotyping and addressing its harms, including through intergroup contact, critical consciousness and action, and clinical interventions

Performance Assessment of High Resolution Airborne Full Waveform LiDAR for Shallow River Bathymetry

We evaluate the performance of full waveform LiDAR decomposition algorithms with a high-resolution single band airborne LiDAR bathymetry system in shallow rivers. A continuous wavelet transformation (CWT) is proposed and applied in two fluvial environments, and the results are compared to existing echo retrieval methods. LiDAR water depths are also compared to independent field measurements. In both clear and turbid water, the CWT algorithm outperforms the other methods if only green LiDAR observations are available. However, both the definition of the water surface, and the turbidity of the water significantly influence the performance of the LiDAR bathymetry observations. The results suggest that there is no single best full waveform processing algorithm for all bathymetric situations. Overall, the optimal processing strategies resulted in a determination of water depths with a 6 cm mean at 14 cm standard deviation for clear water, and a 16 cm mean and 27 cm standard deviation in more turbid water

Navigating Sexual Stereotypes Across Time, Space, and Place: Exploring Black Women’s Practices of Resistance, Refusal, and Reclamation

This article engages a Black feminist analysis of sexual stereotyping and its effect on Black women’s health outcomes. Specifically, this work centers the experiences of 29 young Black women (Mage = 23.97) living in New York City, and their practices of resistance, refusal, and reclamation of self in the face of sexual stereotypes. Our qualitative inquiry explores how sexual stereotypes function dynamically across time, space, and place to influence (but not define) Black women’s lives. Using critical thematic analysis, the first author identified three recurring contexts in which Black women discussed how sexual stereotypes affect them in their transitions through adolescence and young Black womanhood: during interpersonal interactions with others, during encounters in health care, and while negotiating their sexual self-making and sexual agency. Across these contexts, the first author situates Black women as critical theorists whose self-analysis, self-theorizing, and self-descriptions are the focus of this article. Their explanations and theorizing emphasize how navigating and negotiating sexuality, pleasure, and agency in a sea of sexual stereotypes is complex, and rarely Black or White. The discussion offers a series of reflections for future research on Black women’s health and sexuality. © 2023 American Psychological Associatio

Content of, sources of, and responses to sexual stereotypes of Black and Latinx women and men in the United States: A qualitative intersectional exploration

Interdisciplinary intersectionality scholars have highlighted that stereotypes are a central basis for intersectional oppression, and psychologists are increasingly incorporating intersectional theory into stereotypes research. In striving to embrace intersectionality\u27s radical core by applying several of its guiding premises, we explored the perspectives of young Black and Latinx individuals in New York City on sexual stereotypes of Black and Latinx women and men. We conducted 11 focus groups with 75 participants. Using a combined deductive and inductive approach to thematic analysis, we found that many subthemes reflected participants identifying content of, sources of, and responses to sexual stereotypes that were consistent with and supported by an intersectional analysis and approach. These subthemes highlighted sexual stereotypes’ roots in long-standing interlocking systems of power and oppression and societal institutions, that stereotypes/oppression can also become internalized within individuals and communities, as well as the power and strength of participants and their communities in coping with and resisting sexual stereotypes and oppression. Findings suggest specific ways psychologists can incorporate intersectional inquiry and praxis to address sexual stereotypes as a critical social issue, in collaboration with oppressed communities and social movements struggling for justice and liberation