308 research outputs found
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Magmatic Intrusions into the Sulfur-Rich Carmel Formation on the Colorado Plateau, USA: Implications for the Mars 2020 Mission
We report on basaltic dikes in the Colorado Plateau, which crosscut sulfate bearing sediments and compare this to Martian basalts and basaltic sediments in contact with sulfate mineralizations
Hot Rocks! Near-Infrared Reflectances (and Emissivities) or Rocks at Venus Surface Temperatures
Venus surface can be viewed in emission through a few near-infrared (NIR) spectral windows (1 m) in its relatively opaque atmosphere [1]. Venus surface shows NIR emissivities that correlate with surface geology [2-4], and these emissivity variations are interpreted as differences in surface rock type (mafic vs. silicic) and/or extent of weathering (Fe2+ silicates vs. Fe3+-oxide-coated). To understand and quantify the observed variations in NIR emissivity, high-temperature (T) emissivity can be measured directly [5,6]. For example, emissivities of basalts in the wavelength range 0.85 1.2 m are ~0.95 [5-8]. This can be tested by measureing reflectance, because Kirchoffs Law holds that emissivity (e) = 1 reflectance (r). The r of basalt in the NIR is ~0.05 [o] consistent with a NIR e of ~0.95 [5-8]. High-T NIR es of silicic igneous rocks (granitic, rhyolite) have been reported to be 0.8-0.9 [5,6], which is inconsistent with r values of 0.3-0.8 of such rocks at 25C [9,10]. However, these measurements have been updated [7,8] and are consistent with the results here (see below and Fig. 3)
TANGGUNG JAWAB HUKUM TERHADAP PENYEDIA BARANG DAN JASA DALAM PELAKSANAAN JASA KONSTRUKSI BERDASARKAN UNDANG-UNDANG NOMOR 2 TAHUN 2017 TENTANG JASA KONSTRUKSI
Penelitian ini dilakukan dengan tujuan untuk mengetahui bagaimana Tanggung jawab Hukum penyedia barang dan jasa secara administratif dan bagaimana Tanggung jawab Hukum penyedia barang dan jasa dilaksanakan secara fisik konstruktif. Dwengan menggunakan metode penelitian yuridis normatif, disimpulkan: 1. Pelaksanaan jasa konstruksi, penyedia jasa harus memiliki standart hukum/peraturan yang berlaku secara administratif dalam menyediakan barang dan jasa, karena mempunyai peran yang penting dalam pencapaian pembangunan nasional. Administratif yang dimaksud adalah mulai dari tahap pelelangan sampai dengan tahap pelaksanaan, meliputi kelengkapan dokumen sesuai standart peraturan yang berlaku. Persyaratan kelengkapan dokumen tersebut adalah bagian dari tanggung jawab serta bukti hukum pelaksanaan kegiatan. 2. Pelakasanaan kontrak khususnya pembangunan proyek, tanggung jawab pihak penyedia jasa atau kontraktor adalah melaksanakan pekerjaan konstruksi sesuai dengan instruksi dari pihak pemberi tugas atau dalam kontrak ini disebut dengan Pejabat Pembuat Komitmen (PPK). Pihak kontraktor bertanggung jawab untuk melaksanakan pekerjaan tersebut sesuuai dengan kontrak atau syarat-syarat yang telah ditetapkan berdasarkan hasil negosiasi awal yang telah disepakati. Karena dilapangan seringkali ditemukan perjanjian antara pihak pengguna jasa dan penyedia jasa/kontraktor yang tidak sesuai dan hal ini perlu dihindari.Kata kunci: Tanggung Jawab Hukum, Penyedia Barang dan Jasa, Konstruks
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Alteration and Oxidiation of an Olivine Lamprophyre Dike from Southern Utah, USA: An Analog for Mars
We report on oxidized basaltic dike intrusions on the Colorado Plateau as analog for Martian basalt oxidation
Phase Equilibria Modeling of Low-grade Metamorphic Martian Rocks
Hydrous phases have been identified to be a significant component of martian mineralogy. Particularly prehnite, zeolites, and serpentine are evidence for low‐grade metamorphic reactions at elevated temperatures in mafic and ultramafic protoliths. Their presence suggests that at least part of the martian crust is sufficiently hydrated for low‐grade metamorphic reactions to occur. A detailed analysis of changes in mineralogy with variations in fluid content and composition along possible martian geotherms can contribute to determine the conditions required for subsurface hydrous alteration, fluid availability and rock properties in the martian crust. In this study, we use phase equilibria models to explore low‐grade metamorphic reactions covering a pressure‐temperature range of 0‐0.5 GPa and 150‐450 °C for several martian protolith compositions and varying fluid content. Our models replicate the detected low‐grade metamorphic/hydrothermal mineral phases like prehnite, chlorite, analcime, unspecified zeolites, and serpentine. Our results also suggest that actinolite should be a part of lower‐grade metamorphic assemblages, but actinolite may not be detected in reflectance spectra for several reasons. By gradually increasing the water content in the modeled whole rock composition, we can estimate the amount of water required to precipitate low‐grade metamorphic phases. Mineralogical constraints do not necessarily require an elevated geothermal gradient for the formation of prehnite. However, restricted crater excavation depths even for large impact craters are not likely sampling prehnite along colder gradients, either suggesting a geotherm of ~ 20 °C/km in the Noachian or an additional heat source such as hydrothermal or magmatic activity
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Crystallization history of gabbroic shergottite NWA 6963 as revealed by pyroxene zoning
NorthWest Africa (NWA) 6963 is an intriguing new coarse grained Martian meteorite that further extends our sample collection both compositionally and texturally. It was originally documented as a basaltic shergottite because the pyroxene compositions and modal abundances are similar to Shergotty. However, recent work reclassified NWA 6963 as an intrusive, gabbroic Martian meteorite because of the large oriented pyroxene crystals. This investigation will focus on NWA 6963 pyroxene zoning profiles and interpreting igneous processes related to its crystallization history.
Compositional zoning of pyroxene crystals in basaltic shergottites have previously been interpreted for petrology and degrees of undercooling. In addition, cooling rates of Martian magmas have been determined experimentally to constrain volcanic processes based on both pyroxene and olivine zoning. These studies interpret crystallization histories of basaltic shergottites and provide valuble insight of volcanic flows on Mars. However, igneous conditions below the Martian surface can now be constrained with instrusive shergottite NWA 6963. The crystallization history of a gabbroic shergottite is expected to differ from basaltic Martian meteorites due to the nature of instrusive and extrusive igneous conditions. Determining rates of cooling from pyroxene zoning will further constrain the petrogenetic history of NWA 6963. This will provide new information on the nature of instrusive igneous processes within the shallow Martian subsurface
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Magmatic intrusions into sulfur-rich sediments on the Colorado Plateau: an analog for Mars exploration
Mafic magmatism is a prevalent geologic process on Earth, and is a principal source of subsurface geologic change and energy influx on postNoachian Mars. While rare on Earth, the intrusion of mafic magmas into sulfur-rich soils and rocks is expected on Mars due to the observation of widespread high sulfur concentrations in Martian soils. On Mars, soils have been found to be rich in sulfur. Respectively, soil samples from Gusev Crater and Gale Crater contain between 4-8 weight percent, and 4-7 weight percent SO3, though ammounts[sic] as high as 31 weight percent have been measured in Gusev crater. With widespread sulfur-rich sediments and evidence of magmatism both ancient and young, mafic intrusions into rocks and sediments bearing significant quantities of sulfur species is expected on Mars. Processes associated with the magmatic intrusion of a sulfur-rich host, including degassing and alteration, may provide the requisite energy and nutrients for biological activity.On Earth, well exposed mafic dikes intrude the sulfur-rich sedimentary formations of the Jurassic San Rafael Group. Approximately 200 dikes, sills, and breccias can be found in proximity to the San Rafael Swell in Utah, and represent an Earth analog for a scenario of mafic magma intruding sulfur-rich sediments. Here we will investigate such an analog; a mafic dike intruding the sulfur-rich Jurassic Carmel Formation of the San Rafael Group
An original application of image recognition based location in complex indoor environments
This paper describes the first results of an image recognition based location (IRBL) for a mobile application focusing on the procedure to generate a database of range images (RGB-D). In an indoor environment, to estimate the camera position and orientation, a prior spatial knowledge of the surroundings is needed. To achieve this objective, a complete 3D survey of two different environments (Bangbae metro station of Seoul and the Electronic and Telecommunications Research Institute (ETRI) building in Daejeon, Republic of Korea) was performed using a LiDAR (Light Detection and Ranging) instrument, and the obtained scans were processed to obtain a spatial model of the environments. From this, two databases of reference images were generated using specific software realised by the Geomatics group of Politecnico di Torino (ScanToRGBDImage). This tool allows us to generate synthetically different RGB-D images centred in each scan position in the environment. Later, the external parameters (X, Y, Z, ω, ϕ, and κ) and the range information extracted from the retrieved database images are used as reference information for pose estimation of a set of acquired mobile pictures in the IRBL procedure. In this paper, the survey operations, the approach for generating the RGB-D images, and the IRB strategy are reported. Finally, the analysis of the results and the validation test are described
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Mineral Surface and Fluid Chemistry in Nakhlite Analog Water-Rock Reactions
We report on experiments with Mars analog materials under diagenetic conditions and find characteristic chemical surface changes in correspondence with the fluid conditions
A review of volatiles in the Martian interior
Multiple observations from missions to Mars have revealed compelling evidence for a volatile-rich Martian crust. A leading theory contends that eruption of basaltic magmas was the ultimate mechanism of transfer of volatiles from the mantle toward the surface after an initial outgassing related to the crystallization of a magma ocean. However, the concentrations of volatile species in ascending magmas and in their mantle source regions are highly uncertain. This work and this special issue of Meteoritics & Planetary Science summarize the key findings of the workshop on Volatiles in the Martian Interior (Nov. 3–4, 2014), the primary open questions related to volatiles in Martian magmas and their source regions, and the suggestions of the community at the workshop to address these open questions
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