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USGS1995

Paleoecology of the Springfield Coal Member (Desmoinesian, Illinois Basin) near the Leslie Cemetery paleochannel, southwestern Indiana

The Springfield Coal Member (Carbondale Group, Petersburg Formation of Indiana) is split locally in Warrick and Gibson Counties, Indiana, by clastic rocks of the Folsomville Member (Carbondale Group, Petersburg Formation) that represent the Leslie Cemetery paleochannel, part of a large, interconnected paleochannel system in the Springfield coal bed. This study incorporated analysis of miospore and megaspore assemblages, coal petrography, plant compression fossils and conodonts from the coal and clastic split to document changes in the swamp and its vegetation in response to the activity of the Leslie Cemetery paleochannel. Palynological and petrographic data indicate that environmental conditions and vegetation in the lower bench of coal near the Leslie Cemetery paleochannel were similar to those found in profiles through the coal bed at sites near the larger, more extensive Galatia paleochannel. Miospore floras of the high-vitrinite, lower bench of coal were dominated by tree-fern miospores, with those of lycopsids ranking second in abundance; megaspore assemblages were dominated by lycopsid megaspores. Near the contacy between the lower bench of coal and clastic split, medullosan prepollen increases in abundance and fusain bands are more common, which may indicate the occurrence of fire, either within or outside the swamp. Vegetation in the Folsomville Member and upper bench of coal differ markedly from that of the lower bench of coal. Plant megafossils from the Folsomville Member indicate dominance by pteridosperms and/or lycopsids and Folsomville Member miospore assemblages are dominated by lycopsid miospores most typically found in mudstones, including Lycospora torquifer and higher than normal abundances of Granasporites medius . In the transition from clastic rocks of the Folsomville Member to the upper bench of coal, miospores of ‘ecotonal’ lycopsids ( Paralycopodites ) reach their peak abundance, pteridosperms dominate megafossil assemblages and inertinite levels are relatively high. At higher levels of the upper bench of coal, vitrinite levels are higher and miospore assemblages are dominated by lycopsid miospores typical of coal swamps ( Lycospora granulata, L. pusilla ). The presence of conodonts in coalballs in the upper bench of coal and spirorbid worms in the split indicate that the paleoswamp may have received some marine or brackish water influence. Higher than normal salinity levels may explain the vegetational changes observed in the upper bench of coal near the Leslie Cemetery paleochannel.

Indiana↗

USGS2014

Analysis of projected water availability with current basin management plan, Pajaro Valley, California

The projection and analysis of the Pajaro Valley Hydrologic Model (PVHM) 34 years into the future using MODFLOW with the Farm Process (MF-FMP) facilitates assessment of potential future water availability. The projection is facilitated by the integrated hydrologic model, MF-FMP that fully couples the simulation of the use and movement of water from precipitation, streamflow, runoff, groundwater flow, and consumption by natural and agricultural vegetation throughout the hydrologic system at all times. MF-FMP allows for more complete analysis of conjunctive-use water-resource systems than previously possible with MODFLOW by combining relevant aspects of the landscape with the groundwater and surface-water components. This analysis is accomplished using distributed cell-by-cell supply-constrained and demand-driven components across the landscape within “water-balance subregions” (WBS) comprised of one or more model cells that can represent a single farm, a group of farms, watersheds, or other hydrologic or geopolitical entities. Analysis of conjunctive use would be difficult without embedding the fully coupled supply-and-demand into a fully coupled simulation, and are difficult to estimate a priori. The analysis of projected supply and demand for the Pajaro Valley indicate that the current water supply facilities constructed to provide alternative local sources of supplemental water to replace coastal groundwater pumpage, but may not completely eliminate additional overdraft. The simulation of the coastal distribution system (CDS) replicates: 20 miles of conveyance pipeline, managed aquifer recharge and recovery (MARR) system that captures local runoff, and recycled-water treatment facility (RWF) from urban wastewater, along with the use of other blend water supplies, provide partial relief and substitution for coastal pumpage (aka in-lieu recharge). The effects of these Basin Management Plan (BMP) projects were analyzed subject to historical climate variations and assumptions of 2009 urban water demand and land use. Water supplied directly from precipitation, and indirectly from reuse, captured local runoff, and groundwater is necessary but inadequate to satisfy agricultural demand without coastal and regional storage depletion that facilitates seawater intrusion. These facilities reduce potential seawater intrusion by about 45% with groundwater levels in the four regions served by the CDS projected to recover to levels a few feet above sea level. The projected recoveries are not high enough to prevent additional seawater intrusion during dry-year periods or in the deeper aquifers where pumpage is greater. While these facilities could reduce coastal pumpage by about 55% of the historical 2000–2009 pumpage for these regions, and some of the water is delivered in excess of demand, other coastal regions continue to create demands on coastal pumpage that will need to be replaced to reduce seawater intrusion. In addition, inland urban and agricultural demands continue to sustain water levels below sea level causing regional landward gradients that also drive seawater intrusion. Seawater intrusion is reduced by about 45% but it supplies about 55% of the recovery of groundwater levels in the coastal regions served by the CDS. If economically feasible, water from summer agricultural runoff and tile-drain returnflows could be another potential local source of water that, if captured and reused, could offset the imbalance between supply and demand as well as reducing discharge of agricultural runoff into the National Marine Sanctuary of Monterey Bay. A BMP update (2012) identifies projects and programs that will fund a conservation program and will provide additional, alternative water sources to reduce or replace coastal and inland pumpage, and to replenish the aquifers with managed aquifer recharge in an inland portion of the Pajaro Valley.

California↗

USGS1997

Crustal structure along the west flank of the Cascades, western Washington

Knowledge of the crustal structure of the Washington Cascades and adjacent Puget Lowland is important to both earthquake hazards studies and geologic studies of the evolution of this tectonically active region. We present a model for crustal velocity structure derived from analysis of seismic refraction/wide-angle reflection data collected in 1991 in western Washington. The 280-km-long north-south transect skirts the west flank of the Cascades as it crosses three tectonic provinces including the Northwest Cascades Thrust System (NWCS), the Puget Lowland, and the volcanic arc of the southern Cascades. Within the NWCS, upper crustal velocities range from 4.2 to 5.7 km s-1 and are consistent with the presence of a diverse suite of Mesozoic and Paleozoic metasediments and metavolcanics. In the upper 2-3 km of the Puget Lowland velocities drop to 1.7-3.5 km s-1 and reflect the occurrence of Oligocene to recent sediments within the basin. In the southern Washington Cascades, upper crustal velocities range from 4.0 to 5.5 km s-1 and are consistent with a large volume of Tertiary sediments and volcanics. A sharp change in velocity gradient at 5-10 km marks the division between the upper and middle crust. From approximately 10 to 35 km depth the velocity field is characterized by a velocity increase from ???6.0 to 7.2 km s-1. These high velocities do not support the presence of marine sedimentary rocks at depths of 10-20 km beneath the Cascades as previously proposed on the basis of magnetotelluric data. Crustal thickness ranges from 42 to 47 km along the profile. The lowermost crust consists of a 2 to 8-km-thick transitional layer with velocities of 7.3-7.4 km s-1. The upper mantle velocity appears to be an unusually low 7.6-7.8 km s-1. When compared to velocity models from other regions, this model most closely resembles those found in active continental arcs. Distinct seismicity patterns can be associated with individual tectonic provinces along the seismic transect. In the NWCS and Puget Lowland, most of the seismicity occurs below the base of the upper crust as defined by a seismic boundary at 5-10 km depth and continues to 20-30 km depth. The region of transition between the NWCS and the Puget Lowland appears as a gap in seismicity with notably less seismic activity north of the boundary between the two. Earthquakes within the Cascades are generally shallower (0-20 km) and are dominated by events associated with the Rainier Seismic Zone.

Washington↗

USGS2011

Trends in marine debris in the U.S. Caribbean and the Gulf of Mexico, 1996-2003

Marine debris is a widespread and globally recognized problem. Sound information is necessary to understand the extent of the problem and to inform resource managers and policy makers about potential mitigation strategies. Although there are many short-term studies on marine debris, a longer-term perspective and the ability to compare among regions has heretofore been missing in the U.S. Caribbean and the Gulf of Mexico. We used data from a national beach monitoring program to evaluate and compare amounts, composition, and trends of indicator marine debris in the U.S. Caribbean (Puerto Rico and the U.S. Virgin Islands) and the Gulf of Mexico from 1996 to 2003. Indicator items provided a standardized set that all surveys collected; each was assigned a probable source: ocean-based, land-based, or general-source. Probable ocean-based debris was related to activities such as recreational boating/fishing, commercial fishing and activities on oil/gas platforms. Probable land-based debris was related to land-based recreation and sewer systems. General-source debris represented plastic items that can come from either ocean- or land-based sources; these items were plastic bags, strapping bands, and plastic bottles (excluding motor oil containers). Debris loads were similar between the U.S. Caribbean and the western Gulf of Mexico; however, debris composition on U.S. Caribbean beaches was dominated by land-based indicators while the western Gulf of Mexico was dominated by ocean-based indicators. Beaches along the eastern Gulf of Mexico had the lowest counts of debris; composition was dominated by land-based indicators, similar to that found for the U.S. Caribbean. Debris loads on beaches in the Gulf of Mexico are likely affected by Gulf circulation patterns, reducing loads in the eastern Gulf and increasing loads in the western Gulf. Over the seven years of monitoring, we found a large linear decrease in total indicator debris, as well as all source categories, for the U.S. Caribbean. Lower magnitude decreases were seen in indicator debris along the eastern Gulf of Mexico. In contrast, only land-based indicators declined in the western Gulf of Mexico; total, ocean-based and general-source indicators remained unchanged. Decreases in land-based indicators were not related to human population in the coastal regions; human population increased in all regions over the time of the study. Significant monthly patterns for indicator debris were found only in the Gulf of Mexico; counts were highest during May through September, with peaks occurring in July. Inclement weather conditions before the time of the survey also accounted for some of the variation in the western Gulf of Mexico; fewer items were found when there were heavy seas or cold fronts in the weeks prior to the survey, while tropical storms (including hurricanes) increased the amount of debris. With the development around the globe of long-term monitoring programs using standardized methodology, there is the potential to help management at individual sites, as well as generate larger-scale perspectives (from regional to global) to inform decision makers. Incorporating mechanisms producing debris into marine debris programs would be a fruitful area for future research.

Gulf of Mexico and U.S. Carribean↗

USGS2006

Influence of particle and surface quality on the vitrinite reflectance of dispersed organic matter: Comparative exercise using data from the qualifying system for reflectance analysis working group of ICCP

The development of a qualifying system for reflectance analysis has been the scope of a working group within the International Committee for Coal and Organic Petrology (ICCP) since 1999, when J. Koch presented a system to qualify vitrinite particles according to their size, proximity to bright components and homogeneity of the surface. After some years of work aimed at improving the classification system using photomicrographs, it was decided to run a round robin exercise on microscopy samples. The classification system tested consists of three qualifiers ranging from excellent to low quality vitrinites with an additional option for unsuitable vitrinites. This paper reports on the results obtained by 22 analysts who were asked to measure random reflectance readings on vitrinite particles assigning to each reading a qualifier. Four samples containing different organic matter types and a variety of vitrinite occurrences have been analysed. Results indicated that the reflectance of particles classified as excellent, good or poor compared to the total average reflectance did not show trends to be systematically lower or higher for the four samples analysed. The differences in reflectance between the qualifiers for any given sample were lower than the scatter of vitrinite reflectance among participants. Overall, satisfactory results were obtained in determining the reflectance of vitrinite in the four samples analysed. This was so for samples having abundant and easy to identify vitrinites (higher plant-derived organic matter) as well as for samples with scarce and difficult to identify particles (samples with dominant marine-derived organic matter). The highest discrepancies were found for the organic-rich oil shales where the selection of the vitrinite population to measure proved to be particularly difficult. Special instructions should be provided for the analysis of this sort of samples. The certainty of identification of the vitrinite associated with the vitrinite reflectance values reported has been assessed through a reliability index which takes into account the number of readings and the coefficient of variation. The same statistical approach as that followed in the ICCP vitrinite reflectance accreditation program for single seam coals has been used for data evaluation. The results indicated low to medium dispersion for 17 out of 22 participants. This, combined with data from other sets of comparative analyses over a long period, is considered an encouraging result for the establishment of an accreditation program on vitrinite reflectance measurements in dispersed organic matter. ?? 2006 ICCP.

International Journal of Coal Geology↗

USGS2020

Imprint of regional oceanography on foraminifera of eastern Pacific Coral Reefs

The marginal marine environments of the eastern tropical Pacific (ETP) serve as an ideal natural laboratory to study how oceanographic and climatic variability influence coral-reef ecosystems. Reefs along the Pacific coast of Panamá span a natural gradient of nutrients, pH, and temperature as a result of stronger seasonal upwelling in the Gulf of Panamá relative to the Gulf of Chiriquí. The ecosystems are not only influenced by spatial and seasonal variations in oceanography but are affected by the climatic variability of the El Niño-Southern Oscillation (ENSO). Foraminifera can be robust indicators of ecosystem condition because the composition of their assemblages and the geochemistry of their tests can change rapidly in response to environmental variability. We studied benthic foraminifera in sediment samples collected from 3 m below mean sea level in the Gulf of Panamá and the Gulf of Chiriquí. Temperature loggers deployed from 2016 to 2019 showed that average temperatures were lower and more variable in the Gulf of Panamá due to seasonal upwelling. All sites in both gulfs were dominated by heterotrophic foraminifera, which was likely the result of nutrient enrichment due to upwelling, combined with ENSO effects. However, the Gulf of Chiriquí was characterized by higher abundances of symbiont-bearing foraminifera than the Gulf of Panamá. The orders Miliolida and Rotaliida dominated the foraminiferal assemblages in both gulfs, with Quinqueloculina and Rosalina being the most abundant genera in the two orders, respectively. Miliolids were less abundant in the Gulf of Panamá than in the Gulf of Chiriquí, whereas rotaliid densities were not significantly different between the two gulfs. Lower pH in the Gulf of Panamá as a result of upwelling may have contributed to the lower abundance of miliolids, which secrete tests of high-magnesium calcite. Geochemical analysis of tests of the symbiont-bearing miliolid Sorites marginalis revealed that foraminiferal Mg/Ca ratios were lower in the Gulf of Panamá than in the Gulf of Chiriquí. The offset in foraminiferal Mg/Ca is consistent with the lower mean annual temperature observed in the Gulf of Panamá due to stronger seasonal upwelling. Because the geochemistry and assemblages of foraminifera reflect differences in environmental conditions, they could potentially be used in tandem with coral proxies to reconstruct past environmental change and project the future of coral-reef systems within the ETP.

Gulf of Chiriqui, Gulf of Panama↗

USGS2016

Organic petrology and geochemistry of mudrocks from the lacustrine Lucaogou Formation, Santanghu Basin, northwest China: Application to lake basin evolution

Exploration for tight oil in the frontier Santanghu Basin of northwest China has resulted in recent commercial discoveries sourced from the lacustrine Upper Permian Lucaogou Formation, already considered a “world class source rock” in the Junggar Basin to the west. Here we apply an integrated analytical program to carbonate-dominated mudrocks from the Lucaogou Formation in Santanghu Basin to document the nature of organic matter (OM) in the context of an evolving lake system. The organic-rich samples (TOC 2.8–11.4 wt%; n = 10) were widely spaced from an ~ 200 m cored section, interpreted from textural and mineralogical evidence to document transition from a lower under-filled to an overlying balanced-filled lake. Organic matter is dominated by moderate to strongly fluorescent amorphous material with Type I geochemical signature (HI values 510–755; n = 10) occurring in a continuum from lamellar stringers, 10–20 μm thick, some ≥ 1 mm in length (possible microbial mat; preserved only in lower under-filled section) to finely-disseminated amorphous groundmass intimately intermixed with mineral matrix. Biomarkers for methanotrophs and photosynthetic cyanobacteria indicate a complex microbial consortium. A unicellular prasinophyte green alga(?), similar to Tasmanites in marine rocks, is present as discrete flattened discs 50–100 μm in diameter. Type III OM including vitrinite (some fluorescent) and inertinite also is abundant. Solid bitumen, indicating local kerogen conversion, fills voids and occurs throughout the cored section. Vitrinite reflectance values are 0.47–0.58%, consistent with strong OM fluorescence but may be “suppressed”. Other proxies, e.g., biomarker parameters, indicate the Lucaogou Formation is in the early oil window at this location. On average, slightly more amorphous OM and telalginite are present in the lower section, consistent with a shallow, stratified, saline environment with low sediment dilution. More inertinite is present in the upper section, indicating greater terrestrial influx and consistent with higher quartz and plagioclase content (dominantly authigenic chalcedony and albite). Laminated mudstones in the upper section indicate anoxia prevented bioturbation from benthic grazing, also indicating stratified water column conditions. A decrease upsection in authigenic dolomite with reciprocal increase of ankerite/siderite is consistent with decreasing salinity, as is an overall decrease in gammacerane index values. These observations suggest evolution from a shallow, stratified evaporative (saline) setting to a deeper, stratified freshwater basin with higher water input during Lucaogou deposition. The evolution from an under-filled to balance-filled lake in Santanghu Basin is similar to Lucaogou deposition in Junggar Basin, suggesting similar tectonic and climatic controls. Paleoclimate interpretations from other researchers in this area suggested an evolution from semi-arid to humid conditions during the Roadian; we interpret that the evolution from an under-filled to balanced-filled lake seen in our data is in response to climate change, and may represent increased groundwater delivery to the Santanghu Basin.

International Journal of Coal Geology↗