Northwest Side Research Articles

Gravity field and deep seismogenic environment in the Longmen Shan and adjacent regions, Eastern Tibetan Plateau

In this paper, we adopt the methods of Euler deconvolution, source parameter imaging (SPI), source edge detection (SED), inversion of the Moho interface, and three-dimensional (3-D) visualization of the crust for the inversion of the Bouguer gravity anomaly of the Longmen Shan and adjacent regions, analyse the 3-D structure, deep structure, and deformation characteristics of the crust, and investigate the cause of the deep seismogenic environment and the Wenchuan earthquake. The research indicates that the Longmen Shan fault zone is characterized by a NE-trending large gravity gradient zone with a gradient value that exceeds 3.7 mGal/km. The Euler diagram reveals that there is a low-density anomaly body in the lower crust of the Longmen Shan fault zone that is a NE-trending narrow strip approximately 100 km long, 65 km wide and 35–50 km deep. The Songpan-Garze block on the northwest side does not have the material source and pathway of the lower crustal flow in the Euler diagram. Therefore, the low-density anomaly body is related to the upwelling of the mantle heat flow below it. In comparison with the Songpan-Garze and Chuan-Dian blocks, the strength of the field source of the Sichuan Basin is high (−175 to −96 mGal), indicating that the average density of the crust is high, and the depth of the field source is stable at 15–25 km. The SED map reveals that there has been counter-clockwise rotation of the Sichuan Basin since the Cenozoic. The SPI shows that the Longmen Shan fault zone is narrowly located in the beaded linear “shallow source anomaly” belt and that its two sides are stable areas of deep source anomalies, indicating characteristics of crustal hardness on both sides, so that it is prone to accumulate stress and strain. The Moho depth across the Longmen Shan descends from 41.8 km in the east to 61.6 km in the west. The complex intersection of high-density and low-density anomaly bodies appears in the deep part of the Longmen Shan tectonic belt, and the crustal structure is fragmented. Moreover, there is a strong abrupt change in the Moho topography, and therefore, this region has a deep environment for the genesis of strong earthquakes. The dextral strike-slip movement of the Longmen Shan fault zone is caused by the movement of the Songpan-Garze block and the counter-clockwise rotation of the Sichuan Basin; therefore, the counter-clockwise rotation of the Sichuan Basin is one of the important dynamic backgrounds for the 2008 Wenchuan earthquake.

2-D Coastal Hydrodynamic Model to Evaluate the Performance of the Abu Dhabi Shore Protection System

The main shoreline of the Abu Dhabi City Main Island is facing the Arabian (Persian) Gulf from the north-west side and is exposed to continuous current wave action. Therefore, a shore protection system was developed on this side from the Main Island. The shore protection system consists of onshore and offshore breakwaters, huge volumes of damped sand, and an artificial island known as the Lulu Island. In this study, the performance of the current shore protection system of Abu Dhabi City Main Island was evaluated using the Costal Graphical Wave (CGWAVE) 2D-hydrodynamic model. The model can simulate the characteristics of the waves when they approach the breakwaters or the shoreline. Our study has shown that the breakwaters manage to dissipate most of the wave energy before the waves reach the Lulu Island, whereas this island protects the Abu Dhabi City shoreline by creating an elongated sea area between the island and the shoreline that is devoid of any wave action. The constructed shore protection system was also efficient in controlling beach erosion and flooding by damping the wave energy.

Petrophysical aspects of deep reservoirs in the Absheron and Baku Archipelagos

Many Geological exploration and Geophysical assessments have been conducted recently in Azerbaijan which based on Oil and gas perspective of deeper layers, scientific criterion have been prepared that can be basement for the future exploration. It was noted that main oil and gas deposits are related with South Caspian and Kura basin which exposed to intensive depression during the Mesozoic period. The quantity and numerical expression has not been reflected properly yet, despite the high perceptivity of the central part and deeper layers doesn’t create suspicion in explorers. It is known that exploration, production and assessment of potential of Oil and gas deposits highly depends on the information gathered about the petro-physical characterization of strata encountered in geological profile. In this point of view the process mentioned above should be carried out in the oil and gas regions of Absheron and Baku Arxipelaqo the Mesozoic-Cenozoic deposits are spread widely. In the article different geological-geochemical and physical aspects which affect the gas and collector potentials of oil and gas-condensate deposits encountered in area have been researched. Carried investigations show that, in the Paleo-profiles created along the Kurdakhany-Shahdeniz anticline in the north-west side of the field the Pliocene -Anthropogenic deposits were accumulated in small thickness from 100m to 200 m. The thickness increases in Qum island structure to 3600 m, in Shahdeniz to 6000 m. In the edges of synclines the thickness of named deposits have higher numbers which is in north-west is 3000 m and in Shah deniz around 10000 m. So, without enough knowledge about the collector characteristics of the strata of the field the estimation of hydrocarbon reservoirs and the determination of concrete of production as well as change in exploration direction is impossible. Beside the geological-geophysical investigations carried in the field, the Lithological-petrographic and collector characteristics, for the determination of change in conformity along the field, the carbon contest, porosity, permeability, density, granular content and the velocity of the sonic waves of the above mentioned strata, specially lower parts of it have been investigated. Correspondingly the table has been prepared which reflects the collector characteristics of the field. Also the upper, middle and lower limits of physical characteristics of the field has been identified in the table. At the same time, the dependence of collector characteristics on each-other, on depth and on different physical aspects have been assessed. The research showed that the same named and the same age rocks physical property change at the result of geological- physical process and getting different prices. The collector properties of rocks of productive unit have been learned. The physical properties of rocks of productive unit have been shown in the table. The table and the graphs have been compiled, which showed the petrophysical parameters in the area in time and place and the regularity their spreading in the column of productive unit.

First Records and Descriptions of Early Life Stages of Cephalopods from Rapa Nui (Easter Island) and the Nearby Apolo Seamount

New records of early life stages of cephalopods are presented based on planktonic collections carried out around Easter Island (Rapa Nui; 27°7′S, 109°21′W) and at the nearby Apolo Seamount (located at ∼7 nautical miles southwest from Easter Island) during March and September 2015 and March 2016. A total of 13 individuals were collected, comprising four families (Octopodidae, Ommastrephidae, Chtenopterygidae, and Enoploteuthidae) and five potential genera/types (Octopus sp., Chtenopteryx sp., rhynchoteuthion paralarvae, and two undetermined Enoploteuthid paralarvae). Cephalopod mantle lengths (ML) ranged from 0.8 to 4.5mm, with 65% of them (mainly Octopodidae) corresponding to newly hatched paralarvae of ∼1mm ML, and 35% to rhynchoteuthion and early stages of oceanic squids of around 1.5–4.5mm ML. These results provide the first records on composition and presence of early stages of cephalopods around a remote Chilean Pacific Island, while also providing a morphological and molecular basis to validate the identity of Octopus rapanui (but not Callistoctopus, as currently recorded), Ommastrephes bartramii and Chtenopteryx sp. around Rapa Nui waters. Despite adult Octopodidae and Ommastrephidae having been previously recorded at these latitudes, the current findings provide evidence to suggest that the northwest side of Easter Island, and one of the nearby seamounts, may provide a suitable spawning ground for benthic and pelagic species of cephalopods inhabiting these areas. For Chtenopterygidae and Enoploteuthidae, this is the first record for the Rapa Nui ecoregion.

Klein River Estuary (South Africa): 2D numerical modelling of estuary breaching

2D numerical modelling of the breaching process of the Klein River Estuary in South Africa was carried out. The model was calibrated on field data and performs reasonably well, and is able to simulate the ebb and flood channels that form upstream of the mouth. The focus of the simulations was to determine the effectiveness of flushing of sediments during breaching, by investigating the breaching process at different water levels in the estuary, as well as at two different areas along the berm. Breaching at higher water levels increases the effectiveness of flushing as the discharge through the mouth increases significantly at higher water levels. Flushing towards the middle or south-east side of the berm is much more effective than towards the north-west side.

Contingency planning for fire protection in built environment: Risk analysis in campus area

Urban and Regional Planning Department, Institut Teknologi Sepuluh Nopember has experienced small fire incident in Computer Laboratory, in the middle of 2015. This incident is caused by short circuiting and electricity used in high activities. In addition, the buildings have not yet equipped with evacuation paths strategies nor fire protection system. This article aims to describe the contingency plan formulation process of fire incident in campus building concerning the hazard, vulnerability, and risk level of fire. The method used is based on disaster risk management process, included identify the hazard, measure the vulnerability, analyse the risk level of fire, then analyse the assembly point and evacuation routes to formulate the contingency plan. The finding shows that the fire risk level is categorised into high, medium, and low fire risk. Then, based on scoring analysis, we found the best route to assembly point in the Northwest side of the building. The results are then combined with the stakeholders perception consists of Department’s managers, employees, head of the laboratory and students to formulate contingency plans as an improvement over a fire preparedness. Contingency plan consists of scenarios, policies and strategies according to the fire prevention sectors.

Research on Potential Evaluation and Sustainable Development of Rural Biomass Energy in Gansu Province of China

The development and utilization of renewable energy is an important way to solve the environmental dilemma. Biomass energy is a kind of renewable energy and one of the most widely distributed and easily accessible energy forms. It has currently become a main direction of renewable energy development. This paper took Gansu Province of China as the research object to calculate its theoretical reserves of biomass energy resources and then evaluate its potential of biomass energy development by using TOPSIS method under different agricultural development and geographical environmental conditions. Spatial autocorrelation analysis was also performed to reveal the spatial distribution and temporal evolution of the potential of biomass energy development in Gansu Province. The results show that: (1) The total reserves of biomass energy resources from agricultural wastes in Gansu Province reach 7.28 × 107 t/year, with equivalent biogas production of about 1.95 × 1010 m3/year. (2) In most counties of Gansu Province, the Ci value is smaller than 0.5000, indicating that the potential of biomass energy development is relatively low in Gansu Province. (3) The spatial agglomeration of biomass energy development potential occurs mainly in the Hexi area, the Gannan area and the Loess Plateau area of East Gansu Province. (4) There is an area with obvious high-low (H-L) agglomeration of biomass energy development potential to the north-west side of the Gannan area with low-low (L-L) agglomeration of biomass energy development potential. It is a key zone to help drive biomass energy development in the Gannan area. (5) The spatial range of positive correlation (high-high and low-low agglomeration) areas shrunk during the evaluation period.

Erosion and ponding of Thunder Horse deepwater turbidites by mass transport complexes in Mississippi Canyon based on image log sedimentology

Abstract Mass transport complexes are often associated with deepwater turbidite reservoirs, but typical subsurface data sets are of insufficient resolution or coverage to determine if and how the mass transport complexes have an impact on reservoir architecture. We present a case study of integrated, high resolution data (core, image logs, and seismic) from Thunder Horse, one of the largest deepwater oil and gas discoveries in the Gulf of Mexico, to illustrate how mass transport complexes can both compartmentalize and pond reservoirs. The key data type enabling these conclusions are image logs, which reveal erosive mass transport complexes whose emplacement removed the upper portion of one of the Thunder Horse sandstone reservoirs on the northwest side of the asset and resedimented the sand as multiple smaller compartments. Stacked seafloor landslide deposits interbedded with turbidite sandstone reservoirs are herein characterized in detail from image logs at Thunder Horse, located in lower Mississippi Canyon. Dips from bedding boundaries on image logs in the sandstone reservoirs show little variation in structural tilt ( Unconformable bedding contacts at the tops of the sandstone reservoirs in northern Thunder Horse suggest scouring and erosion, whereas basal sandstone contacts are in conformance with overall structural dip, suggesting amalgamation. On seismic data, the mass transport complexes stack and mound together, forming a paleo-topographic high with at least 30 m of relief. Core acquired in this mudrock-dominated deposit reveals convoluted and folded bedding capped by 0.5 m of highly bioturbated marl that is interpreted as a Glossifungites hiatal surface. The implication is that the mass transport complexes formed a topographic obstacle that diverted subsequent debris and turbidite flows, and later created localized ponding and thickening of the overlying reservoir. Thus, mass transport complexes were found to both erode and augment sandstone reservoirs. Biostratigraphic dating of the two reservoirs brackets their deposition as occurring in As a case study this type of integrated, high resolution data has wide applicability to other deepwater, sub-salt reservoirs, as improved structural and depositional interpretations inform reservoir performance and impact future well plans. Further, recognition of mass transport complexes as agents of reservoir compartmentalization and sandstone ponding allows for more accurate reserves estimation.

New disk discovered with VLT/SPHERE around the M star GSC 07396−00759

Debris disks are usually detected through the infrared excess over the photospheric level of their host star. The most favorable stars for disk detection are those with spectral types between A and K, while the statistics for debris disks detected around low-mass M-type stars is very low, either because they are rare or because they are more difficult to detect. Terrestrial planets, on the other hand, may be common around M-type stars. Here, we report on the discovery of an extended (likely) debris disk around the M-dwarf GSC 07396−00759. The star is a wide companion of the close accreting binary V4046 Sgr. The system probably is a member of the β Pictoris Moving Group. We resolve the disk in scattered light, exploiting high-contrast, high-resolution imagery with the two near-infrared subsystems of the VLT/SPHERE instrument, operating in the Y J bands and the H2H3 doublet. The disk is clearly detected up to 1.5′′ (~110 au) from the star and appears as a ring, with an inclination i ~ 83°, and a peak density position at ~70 au. The spatial extension of the disk suggests that the dust dynamics is affected by a strong stellar wind, showing similarities with the AU Mic system that has also been resolved with SPHERE. The images show faint asymmetric structures at the widest separation in the northwest side. We also set an upper limit for the presence of giant planets to 2 MJ. Finally, we note that the 2 resolved disks around M-type stars of 30 such stars observed with SPHERE are viewed close to edge-on, suggesting that a significant population of debris disks around M dwarfs could remain undetected because of an unfavorable orientation.

Influence of the Northeast Cold Vortex on Flooding in Northeast China in Summer 2013

Severe flooding occurred in Northeast China (NEC) in summer 2013. Compared with the rainfall climatology of the region, the rainy season began earlier in 2013 and two main rainy periods occurred from late June to early July and from mid July to early August, respectively. During the summer season of 2013, the western Pacific subtropical high (WPSH) was located farther westward, which strengthened the southerly winds on its west side in the lower troposphere. Under this circulation pattern, more water vapor was transported to North China and NEC. Another moisture transport pathway to NEC was traced to the cross-equatorial flow over the Bay of Bengal. In mid–high latitudes in summer 2013, the Northeast Cold Vortex (NECV) was much stronger and remained stable over NEC. Thus, the cold air flow from its northwest side frequently met with the warm and wet air from the south to form stronger moisture convergence at lower levels in the troposphere, resulting in increased precipitation over the region. Correlation analysis indicated that the NECV played a more direct role than the WPSH. Synoptic analyses of the two heaviest flood cases on 2 and 16 July confirmed this conclusion. The four wettest summers in NEC before 2000 were also analyzed and the results were consistent with the conclusion that both the WPSH and the NECV led to the intense rainfall in NEC, but the NECV had a more direct role.

Identification of the Paleocene–Eocene boundary in coastal strata in the Otway Basin, Victoria, Australia

Abstract. Detailed, stratigraphically well-constrained environmental reconstructions are available for Paleocene and Eocene strata at a range of sites in the southwest Pacific Ocean (New Zealand and East Tasman Plateau; ETP) and Integrated Ocean Discovery Program (IODP) Site U1356 in the south of the Australo-Antarctic Gulf (AAG). These reconstructions have revealed a large discrepancy between temperature proxy data and climate models in this region, suggesting a crucial error in model, proxy data or both. To resolve the origin of this discrepancy, detailed reconstructions are needed from both sides of the Tasmanian Gateway. Paleocene–Eocene sedimentary archives from the west of the Tasmanian Gateway have unfortunately remained scarce (only IODP Site U1356), and no well-dated successions are available for the northern sector of the AAG. Here we present new stratigraphic data for upper Paleocene and lower Eocene strata from the Otway Basin, southeast Australia, on the (north)west side of the Tasmanian Gateway. We analyzed sediments recovered from exploration drilling (Latrobe-1 drill core) and outcrop sampling (Point Margaret) and performed high-resolution carbon isotope geochemistry of bulk organic matter and dinoflagellate cyst (dinocyst) and pollen biostratigraphy on sediments from the regional lithostratigraphic units, including the Pebble Point Formation, Pember Mudstone and Dilwyn Formation. Pollen and dinocyst assemblages are assigned to previously established Australian pollen and dinocyst zonations and tied to available zonations for the SW Pacific. Based on our dinocyst stratigraphy and previously published planktic foraminifer biostratigraphy, the Pebble Point Formation at Point Margaret is dated to the latest Paleocene. The globally synchronous negative carbon isotope excursion that marks the Paleocene–Eocene boundary is identified within the top part of the Pember Mudstone in the Latrobe-1 borehole and at Point Margaret. However, the high abundances of the dinocyst Apectodinium prior to this negative carbon isotope excursion prohibit a direct correlation of this regional bio-event with the quasi-global Apectodinium acme at the Paleocene–Eocene Thermal Maximum (PETM; 56 Ma). Therefore, the first occurrence of the pollen species Spinizonocolpites prominatus and the dinocyst species Florentinia reichartii are here designated as regional markers for the PETM. In the Latrobe-1 drill core, dinocyst biostratigraphy further indicates that the early Eocene (∼ 56–51 Ma) sediments are truncated by a ∼ 10 Myr long hiatus overlain by middle Eocene (∼ 40 Ma) strata. These sedimentary archives from southeast Australia may prove key in resolving the model–data discrepancy in this region, and the new stratigraphic data presented here allow for detailed comparisons between paleoclimate records on both sides of the Tasmanian Gateway.

Optical Coronagraphic Spectroscopy of AU Mic: Evidence of Time Variable Colors?

Abstract We present coronagraphic long slit spectra of AU Mic’s debris disk taken with the STIS instrument aboard the Hubble Space Telescope. Our spectra are the first spatially-resolved, scattered light spectra of the system’s disk, which we detect at projected distances between approximately 10 and 45 au. Our spectra cover a wavelength range between 5200 and 10200 Å. We find that the color of AU Mic’s debris disk is bluest at small (12–17 au) projected separations. These results both confirm and quantify the findings qualitatively noted by Krist et al. and are different than IR observations that suggested a uniform blue or gray color as a function of projected separation in this region of the disk. Unlike previous literature, which reported that the color of AU Mic’s disk became increasingly more blue as a function of projected separation beyond ∼30 au, we find the disk’s optical color between 35 and 45 au to be uniformly blue on the southeast side of the disk and decreasingly blue on the northwest side. We note that this apparent change in disk color at larger projected separations coincides with several fast, outward moving “features” that are passing through this region of the southeast side of the disk. We speculate that these phenomenon might be related and that the fast moving features could be changing the localized distribution of sub-micron-sized grains as they pass by, thereby reducing the blue color of the disk in the process. We encourage follow-up optical spectroscopic observations of AU Mic to both confirm this result and search for further modifications of the disk color caused by additional fast moving features propagating through the disk.

Visible, near-infrared, and mid-infrared spectral characterization of Hawaiian fumarolic alteration near Kilauea's December 1974 flow: Implications for spectral discrimination of alteration environments on Mars

The December 1974 flow in the SW rift zone at Kilauea Volcano, Hawaii, has been established as a Mars analog due to its physical, chemical, and morphological properties, as well as its interaction with the outgassing plume from the primary Kilauea caldera. We focus on a solfatara site that consists of hydrothermally altered basalt and alteration products deposited in and around a passively degassing volcanic vent situated directly adjacent to the December 1974 flow on its northwest side. Reflectance spectra are acquired in the visible/near-infrared (VNIR) region and emission spectra in the mid-infrared (MIR) range to better understand the spectral properties of hydrothermally altered materials. The VNIR signatures are consistent with silica, Fe-oxides, and sulfates (Ca, Fe). Primarily silica-dominated spectral signatures are observed in the MIR and changes in spectral features between samples appear to be driven by grain size effects in this wavelength range. The nature of the sample coating and the thermal emission signatures exhibit variations that may be correlated with distance from the vent. Chemical analyses indicate that most surfaces are characterized by silica-rich material, Fe-oxides, and sulfates (Ca, Fe). The silica and Fe-oxide-dominated MIR/VNIR spectral signatures exhibited by the hydrothermally altered material in this study are distinct from the sulfate-dominated spectral signatures exhibited by previously studied low-temperature aqueous acid-sulfate weathered basaltic glass. This likely reflects a difference in open vs. closed system weathering, where mobile cations are removed from the altered surfaces in the fumarolic setting. This work provides a unique infrared spectral library that includes martian analog materials that were altered in an active terrestrial solfatara (hydrothermal) setting. Hydrothermal environments are of particular interest as they potentially indicate habitable conditions. Key constraints on the habitability and astrobiological potential of ancient aqueous environments are provided through detection and interpretation of secondary mineral assemblages; thus, spectral detection of fumarolic alteration assemblages observed from this study on Mars would suggest a region that could have hosted a habitable environment.

The effect of local hydrodynamics on the spatial extent and morphology of cold-water coral habitats at Tisler Reef, Norway

This study demonstrates how cold-water coral morphology and habitat distribution are shaped by local hydrodynamics, using high-definition video from Tisler Reef, an inshore reef in Norway. A total of 334 video frames collected on the north-west (NW) and south-east (SE) side of the reef were investigated for Lophelia pertusa coral cover and morphology and for the cover of the associated sponges Mycale lingua and Geodia sp. Our results showed that the SE side was a better habitat for L. pertusa (including live and dead colonies). Low cover of Geodia sp. was found on both sides of Tisler Reef. In contrast, Mycale lingua had higher percentage cover, especially on the NW side of the reef. Bush-shaped colonies of L. pertusa with elongated branches were the most abundant coral morphology on Tisler Reef. The highest abundance and density of this morphology were found on the SE side of the reef, while a higher proportion of cauliflower-shaped corals with short branches were found on the NW side. The proportion of very small L. pertusa colonies was also significantly higher on the SE side of the reef. The patterns in coral spatial distribution and morphology were related to local hydrodynamics—there were more frequent periods of downwelling currents on the SE side—and to the availability of suitable settling substrates. These factors make the SE region of Tisler Reef more suitable for coral growth. Understanding the impact of local hydrodynamics on the spatial extent and morphology of coral, and their relation to associated organisms such as sponges, is key to understanding the past and future development of the reef.

Expelled grains from an unseen parent body around AU Microscopii

Context. Recent observations of the edge-on debris disk of AU Mic have revealed asymmetric, fast outward-moving arch-like structures above the disk midplane. Although asymmetries are frequent in debris disks, no model can readily explain the characteristics of these features. Aims. We present a model aiming to reproduce the dynamics of these structures, more specifically their high projected speeds and their apparent position. We test the hypothesis of dust emitted by a point source and then expelled from the system by the strong stellar wind of this young M-type star. In this model we make the assumption that the dust grains follow the same dynamics as the structures, i.e., they are not local density enhancements. Methods. We perform numerical simulations of test particle trajectories to explore the available parameter space, in particular the radial location R0 of the dust producing parent body and the size of the dust grains as parameterized by the value of β (ratio of stellar wind and radiation pressure forces over gravitation). We consider the cases of a static and of an orbiting parent body. Results. We find that for all considered scenarios (static or moving parent body), there is always a set of (R0,β) parameters able to fit the observed features. The common characteristics of these solutions is that they all require a high value of β, of around 6. This means that the star is probably very active, and the grains composing the structures are submicronic in order for observable grains to reach such high β values. We find that the location of the hypothetical parent body is closer in than the planetesimal belt, around 8 ± 2 au (orbiting case) or 28 ± 7 au (static case). A nearly periodic process of dust emission appears, of 2 yr in the orbiting scenarios and 7 yr in the static case. Conclusions. We show that the scenario of sequential dust releases by an unseen point-source parent body is able to explain the radial behavior of the observed structures. We predict the evolution of the structures to help future observations discriminate between the different parent body configurations that have been considered. In the orbiting parent body scenario, we expect new structures to appear on the northwest side of the disk in the coming years.

Die Burg Warbeck (Kastre)

Die Burg Warbeck (Kastre)

Variation of copper isotopes in chalcopyrite from Dabu porphyry Cu-Mo deposit in Tibet and implications for mineral exploration

The study presents copper (Cu) isotope data of mineral separates of chalcopyrite from four drill core samples in the Miocene Dabu porphyry Cu-Mo deposit formed in a post-collisional setting in the Gangdese porphyry copper belt, southern Tibet. Copper isotope values in hypogene chalcopyrite range from –1.48‰ to +1.12‰, displaying a large variation of up to 2.60‰, which demonstrates Cu isotope fractionation at high-temperature during hydrothermal evolution. The majority of measured chalcopyrite isotopic compositions show a gradual increasing trend from –1.48‰ to +1.12‰ with the increase of drilling depth from 130m to 483m, as the alteration assemblages change from potassic to phyllic. Similarly, the other δ65Cu values (δ65Cu=((65Cu/63Cu)sample/(65Cu/63Cu)standard−1)×1000) of the chalcopyrite show a gradual increasing trend from −1.48‰ to +0.59‰ with the decrease of drilling depth from 130m to 57m, as the alteration assemblages change from potassic, phyllic, through argillic to relatively fresh. These observations suggest a genetic link between Cu isotope variation and silicate alteration assemblages formed at different temperatures, indicative of a Rayleigh precipitation process resulting in the large variation of δ65Cu values at Dabu. In general, samples closest to the center of hydrothermal system dominated by high-temperature potassic alteration are isotopically lighter, whereas samples dominated by low-temperature phyllic alteration peripheral to the center are isotopically heavier. The predicted flow pathways of hydrothermal fluids are from No. 0 to No. 3 exploration line, and the lightest δ65Cu values are the most proximal to the hydrothermal source. Finally, we propose that the northwest side of the No. 0 exploration line has high potential for hosting undiscovered orebodies. The pattern of Cu isotope variation in conjunction with the features of silicate alteration in porphyry system can be used to trace the hydrothermal flow direction and to guide mineral exploration.

Comparison of long-term total ozone observations from space- and ground-based methods at Zhongshan Station, Antarctica

Total ozone errors for satellite observations at Zhongshan Station in Antarctica are characterized using their relative difference (RD) from ground-based Brewer observations during 1993–2015. All satellite total ozone observations slightly overestimated ground-based ones (with RD less than 4%). This is in contrast to conclusions drawn from global-scale validation studies, where main ground-based reference stations are located in middle latitudes. Given multiple total ozone data per day at Zhongshan Station, observed by a sun synchronous orbit satellite, measurements at the lowest solar zenith angle (SZA) show greatest consistency with Brewer ones, having an overall RD of −0.02–1.15%. Algorithm-retrieved total ozone data from the Total Ozone Mapping Spectrometer (TOMS), including Solar Backscatter Ultra Violet (SBUV), TOMS-Earth Probe (EP), Ozone Monitoring Instrument (OMI)-TOMS, show best agreement with ground-based values; followed by the Global Ozone Measurement Experiment-type Direct Fitting (GOD-FIT) algorithm for the GOME-2A, and finally the Differential Optical Absorption Spectroscopy (DOAS) —Algorithm retrieved products for satellites-detectors of Global Ozone Measurement Experiment (GOME), Scanning Imaging Absorption spectroMetr for Atmospheric CHartographY (SCIAMACHY), and OMI. Satellite total ozone RD presents some statistical characteristics, but no specific trends. DOAS and GOME-2A algorithms have values that significantly increase, when the SZA is above 60°–70°, whereas values for GOME-2A decrease, when the SZA is 80–85°. Satellite total ozone RD is a minimum, when the Brewer total ozone is 300–350 DU, with an obvious increase in RD values for DOAS- and GOME-2A, when the Brewer total ozone is 150–300 DU. Satellite total ozone RD obviously increases, as the time difference between satellite overpasses and Brewer measurements grows. Specifically, RD rises as the absolute time difference increases to more than 4 h, yielding an OMI-TOMS RD of more than 10% as this difference increases to 8 h. The DOAS- RD may be up to 15%, while GOME-2A RD does not exceed 10%. The satellite total ozone RD may reach −5%, as the distance between the satellite overpass pixel and the station become more than 100 km. Possibly because of the discrepancy in surface albedo, the TOMS-algorithm retrieved total ozone produced underestimation, when the pixel on the south-east side of the station (the Antarctica continent) is used, but overestimation on the north-west side of the station (the Indian Ocean). Consistency between space and ground-based total ozone data is least for the “ozone hole”. Typically, the RD of TOMS-algorithm retrieved total ozone is within 1%/10 yr. Thus, the SBUV and Brewer monthly averaged total ozone anomalies from 1996 to 2015 were 1%/10 yr and 0.9%/10 yr, respectively. Both indicate slight, but consistent, ozone layer recovery.

Effect of asymmetrical street canyons on pedestrian thermal comfort in warm-humid climate of Cuba

Walkability and livability in cities can be enhanced by creating comfortable environments in the streets. The profile of an urban street canyon has a substantial impact on outdoor thermal conditions at pedestrian level. This paper deals with the effect of asymmetrical street canyon profiles, common in the historical centre of Camaguey, Cuba, on outdoor thermal comfort. Temporal-spatial analyses are conducted using the Heliodon2 and the RayMan model, which enable the generation of accurate predictions about solar radiation and thermal conditions of urban spaces, respectively. On these models, urban settings are represented by asymmetrical street canyons with five different height-to-width ratios and four street axis orientations (N-S, NE-SW, E-W, SE-NW). Results are evaluated for daytime hours across the street canyon, by means of the physiologically equivalent temperature (PET index) which allows the evaluation of the bioclimatic conditions of outdoor environments. Our findings revealed that high profiles (facades) located on the east-facing side of N-S streets, on the southeast-facing side of NE-SW streets, on the south-facing side of E-W street, and on the southwest-facing side of SE-NW streets, are recommended to reduce the total number of hours under thermal stress. E-W street canyons are the most thermally stressed ones, with extreme PET values around 36 °C. Deviating from this orientation ameliorates the heat stress with reductions of up to 4 h in summer. For all analysed E-W orientations, only about one fifth of the street can be comfortable, especially for high aspect ratios (H/W > 3). Optimal subzones in the street are next to the north side of the E-W street, northwest side of the NE-SW street, and southwest side of the SE-NW street. Besides, when the highest profile is located on the east side of N-S streets, then the subzone next to the east-facing facade is recommendable for pedestrians. The proposed urban guidelines enable urban planners to create and renovate urban spaces which are more efficient in diminishing pedestrian thermal stress.

Crime, housing tenure, and economic deprivation: Evidence from Milwaukee, Wisconsin

ABSTRACTThis study examines the determinants of 6 types of crime in Milwaukee, a Rust Belt city that has experienced significant deindustrialization in recent decades. Inner-city areas, as well as a unique low-density area on the city’s northwest side with many rental units, might lack the social control necessary to reduce crime. Creating an index of deprivation at the block group level for 2014, we find it to be high in the central city and on the northwest side and correlated with crime, income, and other socioeconomic variables. Crime hot spots, with a few notable exceptions, are located in 2 central-city areas that are poorer and less White than other block groups. A spatial lag regression model shows that deprivation primarily drives arson and assaults, and the share of renters is shown to increase thefts and robberies in low-income areas but not high-income areas.