Division of Earth Sciences

Abstract The transformation of sodium and potassium smectite into mixed-layer clay was followed in hydrothermal kinetic experiments. Glasses of beidellite composition and the Wyoming bentonite were used as starting materials. Temperatures ranged between 260 and 490°C at 2 kbar pressure, and run times ranged between 6 hr and 266 days. The course of the reactions was found to be strongly affected by interlayer chemistry. When potassium was the interlayer cation, increasing reaction produced the series: randomly interstratified illite/smectite-ordered interstratified illite/smectite-illite. This sequence is equivalent to that formed in shales during burial diagenesis. With interlayer sodium and temperatures above 300°C, an aluminous beidellite (Black Jack analog)-rectorite-paragonite series was realized. The difference between these two diagenetic families is discussed. Below 300°C, sodium beidellite formed randomly interstratified mixed-layer clay much like potassium beidellite, except that a higher layer charge was required to produce sodium mica-like layers. The higher charge resulted from sodium's higher hydration energy. The difference in hydration energy between potassium and sodium may account for the fixation of potassium rather than sodium in illite during burial diagenesis. The appearance of ordered interlayering in mixed-layer phases is also related to interlayer chemistry. Ordering formed in sodium clays at high expandabilities, whereas it never appeared in the potassium clays above approximately 35% expandable. The appearance of ordering may be partly related to the polarizing power of the mica-like layers. Phase diagrams, constructed from the kinetic experiments and from the composition and occurrence of natural clays, are presented for the systems paragonite and muscovite-2 quartz-kaolinite-excess water. This study also reports the first synthesis of a Kalkberg-type mixed-layer clay.

The incomplete removal of time‐varying effects in the Magsat data leads to the necessity of fitting low‐order polynomial functions in order to minimize differences between passes. This process makes the estimation of the zero level in the crustal anomaly field very difficult. Refinements in main field analysis, ring current estimation, and the identification of other time‐varying field sources should provide us with a physical realization of these differences. The spectral overlap of core and crustal anomaly fields makes it particularly difficult to interpret the longer wavelengths of crustal anomalies and refined filtering techniques may need to be developed to improve their resolution. Equivalent source techniques for the inversion of the satellite data to a constant thickness, varying‐magnetization source layer solution are well developed. Magnetization and reduced‐to‐the‐pole anomaly maps are now available for many regions. Problems of instability of mathematical inversions are still present and are particularly noticeable near the magnetic equator. The equivalent source solutions contain the same lack of information regarding zero level as the data from which they are derived. Forward modeling techniques are available to model discrete source distributions and are useful in testing among various interpretive hypotheses. Forward modeling techniques are inappropriate for complex geological situations, and some hybrid techniques are envisaged, in which the inverted magnetizations are constrained by some a priori estimates of their distribution and variability in order to provide geologically meaningful solutions. There is now sufficient information on the Curie points and magnetic properties of rocks which have been derived from the deep crust and upper mantle to begin to develop magnetization‐depth models for a number of tectonic environments. While the familiar Fe‐Ti oxides are the magnetic minerals characteristic of the crust, relatively nonmagnetic chromium spinels and magnesian ilmenites are characteristic of the subcontinental mantle; thus the Moho is the magnetic bottom of the continents except where the Curie isotherm is elevated within the crust. Intensity of magnetization in the continental crust is strongly dependent on metamorphic grade and, in general, increases with basicity: mafic granulites tend to form the most magnetic laterally extensive zones of the crust. Some large‐scale mafic plutonic complexes also have very large magnetizations. Model studies and laboratory measurements are in agreement that the more magnetic rocks of the crust typically have magnetization values in the range 2–6 A/m. In the deep crust, Curie points are predominantly near that of magnetite, although in hot, anhydrous environments in active tectonic zones, Curie temperatures may be reduced below 300°C. A comprehensive laboratory program to characterize further the magnetic properties of all lithologies important in the crust is in progress, and much work remains. The goal is an understanding of how crustal evolutionary processes have left their imprint in the magnetic mineralogies, and how this in turn is reflected in the anomaly field.

The potential of neural network controllers is considered in general terms. Some specific methods are then examined. They are supervised control, direct inverse control, neural adaptive control, backpropagation of utility, and adaptive critic methods.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The microbial diversity was investigated in sediments of six acidic to circumneutral hot springs (Temperature: 60-92 °C, pH 3.72-6.58) in the Philippines using an integrated approach that included geochemistry and 16S rRNA gene pyrosequencing. Both bacterial and archaeal abundances were lower in high-temperature springs than in moderate-temperature ones. Overall, the archaeal community consisted of sequence reads that exhibited a high similarity (nucleotide identity > 92%) to phyla Crenarchaeota, Euryarchaeota, and unclassified Archaea. The bacterial community was composed of sequence reads moderately related (nucleotide identity > 90%) to 17 phyla, with Aquificae and Firmicutes being dominant. These phylogenetic groups were correlated with environmental conditions such as temperature, dissolved sulfate and calcium concentrations in spring water, and sediment properties including total nitrogen, pyrite, and elemental sulfur. Based on the phylogenetic inference, sulfur metabolisms appear to be key physiological functions in these hot springs. Sulfobacillus (within phylum Firmicutes) along with members within Sulfolobales were abundant in two high-temperature springs (> 76 °C), and they were hypothesized to play an important role in regulating the sulfur cycling under high-temperature conditions. The results of this study improve our understanding of microbial diversity and community composition in acidic to circumneutral terrestrial hot springs and their relationships with geochemical conditions.

Traditional methods of Curie depth estimation involving spectral analysis of low‐level aeromagnetic data require that depth to the bottom of a magnetic crustal layer be large relative to depth to top, so that spectral separation can be achieved. An alternate method for high‐altitude data, where depth to magnetic layer top and bottom are virtually indistinguishable, is described. Apparent magnetization variation in a thin equivalent layer is obtained by inversion of the anomaly data. The information in such a model is essentially the vertical integral of magnetization in the real layer to some resolution limit and within some ambiguity in level. This can be transformed to a model of thickness variation in a layer of constant magnetization, given some minimal constraints. The thickness variations may reflect Curie isotherm undulations in regions of high crustal heat flow; Curie depth models then provide a constraint on crustal thermal models. The method was first applied to a magnetization model for the western United States derived from Magsat data. A Curie surface model was obtained and used to constrain simple thermal models along two crustal sections. Associated surface heat flow is in agreement with observations. The method was then applied to upward continued aircraft data from the Oregon Cascades. Results are in reasonably good agreement with previous results based on spectral analysis and with measured heat flow.

Over the coming decades, science will play a key role in society’s response to emerging global ‘grand challenges’. The agenda-setting, coordination and conduct of science, and the ways in which scientific knowledge is diffused and used, are therefore critical. Increasingly, such issues need to be framed at a global level, reflecting both the international nature of science itself and the scale of the challenges it seeks to address. Longer-term perspectives must also be incorporated to reflect the time horizons of key global challenges and the uncertainties involved in future global governance regimes. Foresight offers a means to explore these dimensions of science. The International Council for Science (ICSU) has been applying foresight as a central component of its strategic planning. This paper describes the most recent ICSU exercise, which has explored how two decades hence international collaboration in science could foster progress in science and address global challenges.

Spectroscopic observations made of 23 stars near the southern globular cluster NGC 1851 are presented, yielding spectra with resolutions of approximately 4 A. In performing a spectral analysis, several statements regarding the properties of giant stars in NGC 1851 are determined. First, it is indicated by the radial velocity data that several possible asymptotic-giant-branch or supra-horizontal-branch NGC 1851 stars are nonmembers. In addition, the star S368 appears to be a cluster member. Finally, observations suggest a similarity between the strong CN stars in NGC 1851 and an unusual giant ROA 253, in the globular cluster Omega Cen.

The earth's far ultraviolet dayglow (1080–1515 Å) was observed at ∼3.5 Å resolution during a period of high solar activity near solar maximum on June 27, 1980. The observations were made at local noon by rocket‐borne spectrometers viewing toward the earth's northern limb at 90° zenith angle (ZA) at altitudes between 100 and 245 km, and at 98° ZA between 245 and 260 km. The solar zenith angle was 8.9°. These spectra are compared with earlier lower‐resolution dayglow data obtained during a period of lower solar activity and with auroral spectra. The brightness ratio of O I λ1356 to the N 2 Lyman‐Birge‐Hopfield (LBH) system, an indicator of the O to N 2 density ratio, is lower than that previously measured at mid‐latitudes and closer to the value found in aurorae. In the LBH system a depletion of the bands originating on the υ′ = 3 vibrational level of the excited state is found. Some weak N 2 Birge‐Hopfield bands and N I lines only marginally detected previously in the dayglow are confirmed.

In 1982, a report dealing with the nation's research needs in high-speed computing called for increased access to supercomputing resources for the research community, research in computational mathematics, and increased research in the technology base needed for the next generation of supercomputers. Since that time a number of programs addressing future generations of computers, particularly parallel processors, have been started by U.S. government agencies. The present paper provides a description of the largest government programs in parallel processing. Established in fiscal year 1985 by the Institute for Defense Analyses for the National Security Agency, the Supercomputing Research Center will pursue research to advance the state of the art in supercomputing. Attention is also given to the DOE applied mathematical sciences research program, the NYU Ultracomputer project, the DARPA multiprocessor system architectures program, NSF research on multiprocessor systems, ONR activities in parallel computing, and NASA parallel processor projects.

In this review we discuss the contributions during the last quadrennium which involved both Magsat and aeromagnetic data, including new techniques for interpreting this data, specific regional investigations, and laboratory studies intended to understand the connection between magnetic anomalies and the magnetic mineralogy of their sources. In recent years it has become commonplace to present the data obtained from magnetic surveys in the form of digital images. Techniques for applying special filters appropriate for potential fields and the image enhancement tricks developed by the remote sensing community have come in to widespread use, and were very much in vogue among U.S. investigators during this quadrennium. A key paper by Cordell and Grauch (1985) described a procedure for extracting full information from an aeromagnetic survey for the purpose of mapping basement units under variable‐thickness sedimentary cover; it combines a Taylor series approximation with standard FFT computations (Hildenbrand, 1983). A topographically draped survey is continued to a level surface just above the highest topography using the Taylor series technique, downward continued to the mean basement level via FFT and applying a low‐pass filter, then draped over the basement surface. Aliasing problems exist, but are minor. Magnetization boundaries are then delineated by the horizontal gradient of the pseudogravity distribution. Using sparse well data for constraint, it was possible to make a basement magnetization map for the San Juan Basin, New Mexico, in a detail which would not have been possible with the original data as flown. Blakely and Simpson (1986) developed an automated procedure for delineating magnetization (or density) boundaries for machine application of the Cordell‐Grauch method; this is simply an efficient way of finding the loci of maxima in the horizontal gradient for a grid of data.

The Geo-Launchpad Program is a pre-Research Experience for Undergraduates (pre-REU) providing a summer internship and professional development for two-year college (2YC) students from Colorado. The program goal was to build students’ interest and capacity to engage in geoscience-focused STEM career pathways. The pre-REU helped students develop skills necessary to conduct scientific research. Students worked on a project that supported scientific research under the direction of a science mentor. The program also provided multi-level mentoring, information about career pathways in geosciences, and professional development. Multi-level mentoring included engagement with 2YC faculty, researchers and professionals, and students in other internship programs. Career pathways were illuminated through informal weekly discussions with guest speakers. Evaluation data from 2015-2018 indicated the program succeeded in building students’ interest in and capacity to pursue geoscience-focused STEM careers. Annual program modifications were informed by evaluation data. Data were collected using a modified version of the Undergraduate Research Student Self-Assessment instrument and findings were aligned with the Framework for 21st Century Learning. The internship experience was valuable for students both from the scientific research preparation perspective and developing soft skills through professional development. Overall, the professional development component of Geo-Launchpad was demonstrated to be a highly valuable component of the intern experience. In particular, data showed that exposure to a wide array of geoscience career options and pathways through the Geoscience Career Circles was one of the most impactful elements of the Geo-Launchpad internship.

Abstract The Atmospheric Chemistry Experiment–Fourier Transform Spectrometer (ACE-FTS) on SCISAT-1 and Microwave Limb Sounder (MLS) on NASA’s Aura satellite have contributed significantly to understanding the impacts of human activities on the stratospheric ozone layer. The two-decade-long data record from these instruments has allowed quantification of ozone depletion caused by human-released ozone-depleting substances, the effects of extreme natural events like major volcanic eruptions including Hunga in 2022, and events amplified by human-caused climate change such as wildfires that inject material into the stratosphere, as happened over Australia in early 2020. The Aura platform is nearing the end of its operational lifetime, and SCISAT-1 is over 20 years old. Their decommissioning will cause a substantial gap in the measurement of critical atmospheric components, including water vapor, inorganic chlorine species, and tracers of stratospheric transport. This upcoming “data desert” poses significant challenges for monitoring the recovery of the ozone layer and assessing the effects on stratospheric composition of future extreme events, threats posed by increases in space debris from satellite burn-up, and the possible injection of stratospheric aerosol to mitigate global warming. The lack of confirmed future missions that can provide daily near-global profile measurements of stratospheric composition highlights the need for observational strategies to bridge this impending gap. This paper discusses the essential role of ACE-FTS and MLS in advancing our understanding of the stratosphere, the impact of data loss after the cessation of one or both instruments, and the urgency of developing strategies for mitigating the impact of these observational losses at a time marked by dramatic changes in the stratosphere due to human and natural factors. Significance Statement We highlight the critical role that data from the ACE-FTS and Microwave Limb Sounder (MLS) satellite instruments have played in advancing our understanding of stratospheric composition and the impacts of human activities on the ozone layer. As these instruments near the end of their operational lifetimes, the imminent loss of data, particularly of stratospheric water vapor, chlorine species, and tracers of transport, portends profound and irrevocable gaps in atmospheric observations. This loss of observational capability will occur at a time of rapid climate change and hinder our understanding of the stratosphere’s response to, and its coupled role in, continued climate forcing. This paper emphasizes the urgency of addressing this data desert, highlighting the need for sustained, coordinated, global measurement capabilities for these crucial constituents.

Photometric observations of RR Lyr in the ultraviolet have been obtained using the Astronomical Netherlands Satellite. The observations are compared with theoretical light curves calculated using synthetic spectra and angular diameters determined as a function of phase for RR Lyr by Manduca et al. from photometry at longer wavelengths. A good agreement is found. A bump in the observed light curves in the phase range 0.6 to 0.8 supports the existence of a shock as predicted by Hutchinson, Hill, and Lillie.

Research Article| August 01, 1983 Comments and Reply on ‘Analogous tectonic evolution of the Ordovician foredeeps, southern and central Appalachians’: COMMENT George C. Stephens; George C. Stephens 1Department of Geology, George Washington University, Washington, D. C. 20052 Search for other works by this author on: GSW Google Scholar Thomas O. Wright Thomas O. Wright 2Division of Earth Sciences, National Science Foundation, Washington, D.C. 20550 Search for other works by this author on: GSW Google Scholar Author and Article Information George C. Stephens 1Department of Geology, George Washington University, Washington, D. C. 20052 Thomas O. Wright 2Division of Earth Sciences, National Science Foundation, Washington, D.C. 20550 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1983) 11 (8): 489–490. https://doi.org/10.1130/0091-7613(1983)11<489:CAROAT>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation George C. Stephens, Thomas O. Wright; Comments and Reply on ‘Analogous tectonic evolution of the Ordovician foredeeps, southern and central Appalachians’: COMMENT. Geology 1983;; 11 (8): 489–490. doi: https://doi.org/10.1130/0091-7613(1983)11<489:CAROAT>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract No Abstract Available. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Attenuation was calculated by using the slope of the logarithm of the amplitude spectrum of first-arriving P waves at each epicentral distance. This was done for arrivals to distances of 90° from three nuclear explosions. Seismic arrivals from two profiles recorded in eastern New Mexico and Nevada by the U. S. Geological Survey were used to determine attenuation to depths immediately below the crust-mantle boundary. For regional and teleseismic distances, data from permanent stations recording the first arrivals on Benioff (short period) instruments were used. A ray-tracing program was employed to compute attenuation structure at shallow depths (60–70 km). The shallow attenuation structure is more complex than the velocity structure given for the eastern New Mexico and Nevada profiles. It is suggested that this type of information could possibly augment conventional interpretation of seismic refraction arrivals. An analysis of wave type is important to such an interpretation. Along refraction profiles, the average Q for the eastern New Mexico area was computed to be 169 ± 42 at 5 cps (frequency of peak amplitude) and that for the Nevada area was calculated to be 116 ± 38 at 4 cps. Ten models were fitted to the attenuation data for the mantle. The interpreted best fitting model yields: Q = 200 for depths to 200 km; Q = 400 for depths between 200 and 600 km; and Q = 2000 for depths greater than 600 km. The upper-mantle data apply to the western United States. There is indication that horizontal as well as vertical variations may occur in the attenuation structure of the mantle.

Three new visiting scientists are joining the National Science Foundation's Division of Earth Sciences. About half the division's program officers are usually employed under the agency's Visiting Scientist program on a temporary basis. These scientists, who are active researchers, continually inject fresh ideas and perspectives into the process of peer review on the merits of competing proposals. They also enhance the scientific and technical skills of NSF's regular professional staff.

The National Science Foundation's Division of Earth Sciences has hired two new rotators to serve as program directors, as part of the ongoing visiting scientists program. The new directors are Jonathan Fink in Geochemistry and Petrology, and L. Douglas James in Hydrological Sciences. Fink has exchanged roles for 1 year with NSF's John Snyder, who is on sabbatical at Arizona State University. Fink's current research includes studies of how the Theological properties of magma govern the emplacement of volcanic domes and lava flows, and the gravitational control on their mass movements. This research extends to the mechanisms of igneous intrusion and interpretation of volcanic features in extraterrestrial and submarine environments.

Potential approaches to the use of the Antarctic as an analog to the lunar and Mars planetary surface segments of the SEI are reviewed. It is concluded that a well-planned and sustained program of ground-based research and testing in environments analogous to the moon and Mars is a rational method for reducing the risks associated with human space missions. Antarctica may provide an ideal setting for testing critical technologies (habitat design, life support, and advanced scientific instrumentation), studying human factors and physiology, and conducting basic scientific research similar to and directly relevant to that planned for the SEI.

A statistically robust set of rules is proposed for trending excursions in environmental monitoring data. These rules were designed to minimize false alarms when the process is in control, but signal quickly when the process goes out of control. An adverse trend is an early warning that the system is drifting from normal operating conditions. Prompt action may prevent further deterioration and avoid costly out-of-specification events. Adverse trends are defined as an alert level excursion rate of &gt;2.5% and an action level excursion rate of &gt;0.15%. These definitions were derived from setting action levels at the 99.85^th percentile and alert levels at the 97.5^th percentile. These percentiles were chosen because they are functional equivalents of control limits and warning limits used in statistical process control charting, which are set at three and two standard deviations above the mean, respectively. In addition, the U.S. Pharmacopeial recommended microbial recovery rates should also be implemented as trend metrics for microbial environmental monitoring of aseptic processing facilities. Occasional isolated alert level excursions may occur even if the process remains in a state of control. However, repeated alert level excursions occurring at a rate &gt;2.5% indicate the process is changing and the system is drifting from normal operating conditions. An adverse trend of alert level excursions should be investigated for root cause. It is critical to determine if an alert level excursion, at its onset, indicates an adverse trend. A total of 24 rules at various sample sizes were tested for their ability to detect an adverse trend at the onset of an excursion using data obtained over a period of 1 year. The rationale for choosing these rules is described.