Heat flow in the central Gulf of California

One hundred and five new heat flow measurements in the Gulf of California support the premise that conductive heat loss is not the only mode by which heat is lost from a sea floor spreading center, even in an area with thick sediment cover. Theoretical estimates suggest that the average heat flow in the Guaymas and Farallon basins should be at least 11 μcal/cm2 s (HFU) (325 mW/m2). Outside a 30-km-wide zone centered on the central troughs, the heat flow values measured are reasonably uniform but average only 4.3±0.2 HFU (180±10 mW/m2). Although the high sedimentation rate may depress the measured heat flow, the effect probably does not exceed 15%. Some heat, particularly in the smaller basins, may be lost to the adjacent cooler continental blocks. The discrepancy between the measured and predicted heat losses, which is at least 30%, may be due to the discharge of thermal waters, through the thinner sediment cover in the central troughs or along active faults

Heat flow at the spreading centers of the Guaymas Basin, Gulf of California

Fifty-four new heat flow measurements in the central troughs of the Guaymas basin support the hypothesis that they are sites of active intrusion. In the northern trough a distinct pattern of hydrothermal cooling is revealed, with venting along the western boundary fault of the trough. In the southern trough an analogous pattern is apparently superimposed upon a conductive cooling anomaly associated with a recent central intrusion. The discharge of thermal waters occurs along the boundary faults and through other faults associated with a possible horst block located in the north central floor of the southern trough. The heat flow patterns suggest that the intrusions are episodic and do not occur simultaneously along the length (15–40 km) of a spreading segment. A review of all available heat flow measurements for the Guaymas basin suggests that most of the recharge for a pervasive regional hydrothermal system is limited to the central depressions, with perhaps some contribution from pore water. The discharge of thermal waters occurs predominantly in the central depressions and possibly along the boundary transform faults and fracture zones. The regions of the basin more than a few kilometers in distance from the spreading axis, although presumably underlain by a hydrothermal system, are probably not the location of numerous vents or recharge zones

\u3csup\u3e40\u3c/sup\u3eAr-\u3csup\u3e39\u3c/sup\u3eAr Age constraints on volcanism and tectonism in the Terror Rift of the Ross Sea, Antarctica

Volcanic sills and dikes inferred from seismic reflection profiles and geophysical studies of the Ross Sea are thought to be related to the rift basins in the region, and their emplacement to be coeval with extension. However, lack of precise geochronology in the Terror Rift of the Ross Sea region has left these inferred relationships poorly constrained and has hindered neotectonic studies, because of the large temporal gaps between seismic reflectors of known ages. New 40Ar/39Ar geochronology presented here for submarine volcanic rocks provides better age constraints for neotectonic interpretations within the Terror Rift. Several samples from seamounts yielded young ages between 156 ± 21 and 122 ± 26 Ka. These ages support interpretations that extension within the Terror Rift was active at least through the Pleistocene. Three evenly spaced samples from the lowermost 100 m of Franklin Island range in age from 3.28 ± 0.04 to 3.73 ± 0.05 Ma. These age determinations demonstrate that construction of a small volcanic edifice such as Franklin Island took at least several hundred thousand years, and therefore that much larger ones in the Erebus Volcanic Province are likely to have taken considerably longer than previously inferred. This warrants caution in applying a limited number of age determinations to define the absolute ages of events in the Ross Sea region

Improved Blast Capacity of Pre-engineered Metal Buildings using Coupled CFD and FEA Modeling

PresentationThe initial CCPS guideline [CCPS, 1996] for estimating lethality for building occupants within petrochemical buildings subjected to blast hazards was based on building construction type and peak overpressure. This method allows for a quick screening of building occupant vulnerability but does not include the effects of the duration of the blast that the buildings are subjected to. Blast hazards within petrochemical facilities include vapor cloud explosions (VCE), BLEVEs, and bursting pressure vessels. VCE’s include both deflagrations having long blast durations and detonations having much shorter durations. Bursting pressure vessels can also be characterized as having relatively short durations. Therefore, the latest CCPS guideline [CCPS, 2012] removed this singular peak overpressure methodology and provided occupant vulnerability as a function of building damage and construction type as a function of peak overpressure and duration. Unfortunately, this improved method on blast characterization did not provide a way to correlate blast loading with building damage. This blast-to-damage correlation is required to conduct quantitative risk assessments. A range of simplified tools are available for assessing the response of structural components and building construction types to blast loads. These tools include Single Degree of Freedom (SDOF) models and Pressure-Impulse (P-I) iso-damage charts. These simplified tools generally do not account for the complex response and failure of real structures or the difference in response to different forms of blast loading that include finite rise times (blast waves). Iso-damage charts may be based upon historical data gathered from a range of sources and are often based upon blast damage caused by High Explosive (HE) detonations. This presentation illustrates the use of multi-degree of freedom structural systems for a pre- engineered metal building (PEMB). PEMBs represent the majority of building construction within petrochemical facilities. Computational Structural Dynamic (CSD) finite element analysis (FEA) and Computational Fluid Dynamic (CFD) approaches are used to show the level of conservatism in estimating the blast capacity of PEMBs compared to more traditional SDOF methods. Fully coupled CFD and FEA modeling that includes the beneficial effect of including the air that is internal to the building is demonstrated

Journal- Based Reflection in Undergraduate Service Learning and the University Therapeutic Riding Center

Principles of Therapeutic Riding, Animal Science 3309, is a service- based learning course that gives undergraduates the opportunity to participate in hippotherapy sessions. This course first offered in 1998, has been held for 12 semesters. A total of 233 students from over 15 majors have been trained in this discipline. Advanced Therapeutic Riding, Animal Science 4001, is a continuation of the Principles class that allows students to participate in the sessions and serve in leadership roles. This class has been active for 8 semesters and has included 51 students

Agricultural Safety Education: Formative Assessment of a Curriculum Integration Strategy

The purpose of this study was to assess an agricultural tractor and machinery safety curriculum for teacher training that focused on hands-on integration activities to assist with training youth in machinery safety skills. Teachers attended a single ten-hour summer training seminar hosted in Montana, South Dakota, or Utah during 2017. Teachers completed the National Tractor and Machinery Safe Operation (NSTMOP) exam to measure their existing knowledge prior to beginning the training. Upon seminar completion, teachers took an NSTMOP post-test to measure their knowledge gain of agricultural safety practices and hazard recognition associated with machinery and tractors. A total of 116 teachers completed the training. Fifty-three participants (45.7%) identified as female, and 63 (54.3%) identified as male. The average participant was 35 years old (SD = 11.3) and had 9.5 years of teaching experience (SD = 9.2). The average NSTMOP pre-test score was 35.2 out of 48 (SD = 3.3), and the average NSTMOP post-test score was 40.3 out of 48 (SD = 4.1). Participants‘ scores increased by ten percentage points. A paired-samples t-test was used to determine statistical significance. The difference between pre-test and post-test was significant (t(109) = 11.9, p \u3c 0.001). Open responses indicated continuation of hands-on activities that focused on “how to teach” skills training that is relevant to the students. Teachers suggested developing new activities each year with a rotation of topics for upcoming seminars. Research is needed to determine the training‘s influence on the behaviors of young workers in agriculture

Youth Voice: Developing Future Leaders

The purpose of this study was to examine youths’ perceptions regarding their involvement on youth advisory boards in Cooperative Extension. A stratified, random sample of counties with active youth advisory boards was selected to ensure representation from all Extension districts in the state. A copy of the Involvement and Interaction Rating Scale was mailed to all participants. The findings indicate that Youth feel good about their level of participation on their youth advisory board and that adult members of the board allow them to have an active voice in the activities of the board

Effect of the Deepening of the Tasman Gateway on the Global Ocean

We examine the effect of the deepening of the Tasman Seaway at the end of the Eocene in a climate model with realistic late Eocene bathymetry and winds. For this, we have constructed an Eocene numerical model based on the University of Victoria climate model with wind forcing derived from a fully coupled Eocene simulation. The model climate state is characterized by an oceanic meridional overturning circulation (MOC) involving Southern Hemisphere sinking and a northward atmospheric moisture transport across the equator. The deepening of the Tasman Seaway in the presence of an open Drake Passage and the associated establishment of the Antarctic Circumpolar Current (ACC) have a limited climatic impact on Antarctica. Nonetheless, the Antarctic deep sinking regions cool sufficiently to lead to a global deep ocean cooling of 3°C. No initiation of Northern Component Water is found, indicating that this may require the development of a more mature ACC. Previous studies suggest that the Ross Sea gyre cools the east coast of Australia, and expected the deepening of the Tasman Seaway to lead to a warming east of Australia due to the introduction of warmer water from the Australo-Antarctic Gulf. We here find that this warming is limited to close to the Australian coast, and that widespread cooling prevails further off shore

History of oceanic front development in the New Zealand sector of the Southern Ocean during the Cenozoic--a synthesis

The New Zealand sector of the Southern Ocean (NZSSO) has opened about the Indian-Pacific spreading ridge throughout the Cenozoic. Today the NZSSO is characterised by broad zonal belts of antarctic (cold), subantarctic (cool), and subtropical (warm) surface-water masses separated by prominent oceanic fronts: the Subtropical Front (STF) c. 43deg.S, Subantarctic Front (SAF) c. 50deg.S, and Antarctic Polar Front (AAPF) c. 60deg.S. Despite a meagre database, the broad pattern of Cenozoic evolution of these fronts is reviewed from the results of Deep Sea Drilling Project-based studies of sediment facies, microfossil assemblages and diversity, and stable isotope records, as well as from evidence in onland New Zealand Cenozoic sequences. Results are depicted schematically on seven paleogeographic maps covering the NZSSO at 10 m.y. intervals through the Cenozoic. During the Paleocene and most of the Eocene (65-35 Ma), the entire NZSSO was under the influence of warm to cool subtropical waters, with no detectable oceanic fronts. In the latest Eocene (c. 35 Ma), a proto-STF is shown separating subantarctic and subtropical waters offshore from Antarctica, near 65deg.S paleolatitude. During the earliest Oligocene, this front was displaced northwards by development of an AAPF following major global cooling and biotic turnover associated with ice sheet expansion to sea level on East Antarctica. Early Oligocene full opening (c. 31 Ma) of the Tasmanian gateway initiated vigorous proto-circum-Antarctic flow of cold/cool waters, possibly through a West Antarctic seaway linking the southern Pacific and Atlantic Oceans, including detached northwards "jetting" onto the New Zealand plateau where condensation and unconformity development was widespread in cool-water carbonate facies. Since this time, a broad tripartite division of antarctic, subantarctic, and subtropical waters has existed in the NZSSO, including possible development of a proto-SAF within the subantarctic belt. In the Early-early Middle Miocene (25-15 Ma), warm subtropical waters expanded southwards into the northern NZSSO, possibly associated with reduced ice volume on East Antarctica but particularly with restriction of the Indonesian gateway and redirection of intensified warm surface flows southwards into the Tasman Sea, as well as complete opening of the Drake gateway by 23 Ma allowing more complete decoupling of cool circum-Antarctic flow from the subtropical waters. During the late Middle-Late Miocene (15-5 Ma), both the STF and SAF proper were established in their present relative positions across and about the Campbell Plateau, respectively, accompanying renewed ice buildup on East Antarctica and formation of a permanent ice sheet on West Antarctica, as well as generally more expansive and intensified circum-Antarctic flow. The ultimate control on the history of oceanic front development in the NZSSO has been plate tectonics through its influence on the paleogeographic changes of the Australian-New Zealand-Antarctic continents and their intervening oceanic basins, the timing of opening and closing of critical seaways, the potential for submarine ridges and plateaus to exert some bathymetric control on the location of fronts, and the evolving ice budget on the Antarctic continent. The broad trends of the Cenozoic climate curve for New Zealand deduced from fossil evidence in the uplifted marine sedimentary record correspond well to the principal paleoceanographic events controlling the evolution and migration of the oceanic fronts in the NZSSO

A new US polar research vessel for the twenty-first century

Author Posting. © The Oceanography Society, 2012. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 25, no. 3 (2012): 204-207, doi:10.5670/oceanog.2012.96.Scientific and political interests at the poles are significant and rapidly increasing, driven in part by the effects of climate change and emerging geopolitical realities. The polar regions provide important services to global ecosystems and humankind, ranging from food and energy to freshwater and biodiversity. Yet the poles are experiencing changes at rates that far outpace the rest of the planet. Coastal Arctic communities are impacted by climate change through coastal erosion, sea level rise, ice loss, and altered marine food webs, threatening the future of their subsistence lifestyle. Climate change has dramatically increased the melt rate of ice sheets and glaciers at both poles and has the potential to significantly raise sea level worldwide. Oil and gas drilling as well as transportation in the Arctic have reached all-time high levels, in part because of reduced sea ice cover. Tourism is a growing industry at both poles, bringing more than 20,000 tourists each year to the western Antarctic Peninsula alone. The collateral effects of human activities include the potential for pollution of the marine environment, particularly through spills of hydrocarbons. Our ability to understand the effects of such activities and mishaps is limited, particularly in ice-covered areas during winter