Author: geosciencejournal

Geology (from the Ancient Greek γῆ, gē (“earth”) and -λoγία, -logia, (“study of”, “discourse”) is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also include the study of the solid features of any terrestrial planet or natural satellite such as Mars or the Moon. Modern geology significantly overlaps all other earth sciences, including hydrology and the atmospheric sciences, and so is treated as one major aspect of integrated earth system science and planetary science.Aerial view of Grand Prismatic Spring; Hot Springs, Midway & Lower Geyser Basin, Yellowstone National Park Kinney Lake and Mount Whitehorn near Mount Robson, Canada Geology describes the structure of the Earth on and beneath its surface, and the processes that have shaped that structure. It also provides tools to determine the relative and absolute ages of rocks found in a given location, and also to describe the histories of those rocks.[3] By combining these tools, geologists are able to chronicle the geological history of the Earth as a whole, and also to demonstrate the age of the Earth. Geology provides the primary evidence for plate tectonics, the evolutionary history of life, and the Earth’s past climates.Geologists use a wide variety of methods to understand the Earth’s structure and evolution, including field work, rock description, geophysical techniques, chemical analysis, physical experiments, and numerical modelling. In practical terms, geology is important for mineral and hydrocarbon exploration and exploitation, evaluating water resources, understanding of natural hazards, the remediation of environmental problems, and providing insights into past climate change. Geology is a major academic discipline, and it plays an important role in geotechnical engineering.

For more: http://www.sciaeon.org/geology-and-geoscience/home

For Manuscript submission:  http://www.sciaeon.org/submit-paper

For contact :geology@sciaeonopenaccess.com

The geologic time scale (GTS) is a system of chronological dating that relates geological strata (stratigraphy) to time. It is used by geologists, paleontologists, and other Earth scientists to describe the timing and relationships of events that have occurred during Earth’s history. The table of geologic time spans, presented here, agree with the nomenclature, dates and standard color codes set forth by the International Commission on Stratigraphy (ICS). The primary defined divisions of time are eons, in sequence the Hadean, the Archean, the Proterozoic and the Phanerozoic. The first three of these can be referred to collectively as the Precambrian supereon. Eons are divided into eras, which are in turn divided into periods, epochs and ages.The following four timelines show the geologic time scale. The first shows the entire time from the formation of the Earth to the present, but this gives little space for the most recent eon. Corresponding to eons, eras, periods, epochs and ages, the terms “eonothem”, “erathem”, “system”, “series”, “stage” are used to refer to the layers of rock that belong to these stretches of geologic time in Earth’s history.Geologists qualify these units as “early”, “mid”, and “late” when referring to time, and “lower”, “middle”, and “upper” when referring to the corresponding rocks. For example, the lower Jurassic Series in chronostratigraphy corresponds to the early Jurassic Epoch in geochronology. The adjectives are capitalized when the subdivision is formally recognized, and lower case when not; thus “early Miocene” but “Early Jurassic.” Evidence from radiometric dating indicates that Earth is about 4.54 billion years old. The geology or deep time of Earth’s past has been organized into various units according to events which took place. Different spans of time on the GTS are usually marked by corresponding changes in the composition of strata which indicate major geological or paleontological events, such as mass extinctions. For example, the boundary between the Cretaceous period and the Paleogene period is defined by the Cretaceous–Paleogene extinction event, which marked the demise of the non-avian dinosaurs and many other groups of life. Older time spans, which predate the reliable fossil record (before the Proterozoic eon), are defined by their absolute age.Geologic units from the same time but different parts of the world often look different and contain different fossils, so the same time-span was historically given different names in different locales. For example, in North America, the Lower Cambrian is called the Waucoban series that is then subdivided into zones based on succession of trilobites. In East Asia and Siberia, the same unit is split into Alexian, Atdabanian, and Botomian stages. A key aspect of the work of the International Commission on Stratigraphy is to reconcile this conflicting terminology and define universal horizons that can be used around the world.Some other planets and moons in the Solar System have sufficiently rigid structures to have preserved records of their own histories, for example, Venus, Mars and the Earth’s Moon. Dominantly fluid planets, such as the gas giants, do not preserve their history in a comparable manner. Apart from the Late Heavy Bombardment, events on other planets probably had little direct influence on the Earth, and events on Earth had correspondingly little effect on those planets. Construction of a time scale that links the planets is, therefore, of only limited relevance to the Earth’s time scale, except in a Solar System context. The existence, timing, and terrestrial effects of the Late Heavy Bombardment are still a matter of debate.

For more: http://www.sciaeon.org/geology-and-geoscience/home

For Manuscript submission:  http://www.sciaeon.org/submit-paper

For contact :geology@sciaeonopenaccess.com

The diurnal tidal forces can excite a normal mode of the Earth’s core, the free inner core nutation (FICN), which is characterized by a tilt of the rotation axis of the inner core with respect to the rotation axis of the outer core. The differential rotation between the inner core and the outer core induces fluid motions in the outer core and gives rise to Ohmic dissipation in the presence of the Earth’s internal magnetic field. Nutation measurements can reflect such dissipation if it is sufficiently strong and thus can provide insights into the properties and dynamics of the Earth’s core. In this study we perform a set of numerical calculations of the linear perturbations in the outer core induced by the FICN at very low Ekman numbers (as small as 10−11). Our numerical results show that the back-reaction of the magnetic field notably alters the structure and length scale of the perturbations induced by the FICN, and thus influences the Ohmic dissipation resulting from the perturbations. When the Ekman number is sufficiently small, Ohmic dissipation tends to be insensitive to the fluid viscosity and to the magnetic diffusivity, which allows us to estimate the Ohmic dissipation associated with the FICN without relying on an extrapolation. In contrast to the results of Buffett (2010b), the estimated Ohmic dissipation based on our numerical calculations is too weak to account for the observed damping of the FICN mode. This also implies that nutation measurements cannot provide effective constraints on the strength of the magnetic field inside the Earth’s outer core.

For more: http://www.sciaeon.org/geology-and-geoscience/home

For Manuscript submission:  http://www.sciaeon.org/submit-paper

For contact :geology@sciaeonopenaccess.com

A new clean extraction technology for the decomposition of Bayan Obo mixed rare earth concentrate by NaOH roasting is proposed. The process mainly includes NaOH roasting to decompose rare earth concentrate and HCl leaching roasted ore. The effects of roasting temperature, roasting time, NaOH addition amount on the extraction of rare earth and factors such as HCl concentration, liquid-solid ratio, leaching temperature and leaching time on the dissolution kinetics of roasted ore were studied. The experimental results show that when the roasting temperature is 550 °C and the roasting time is 60 min, the mass ratio of NaOH:rare earth concentrate is 0.60:1, the concentration of HCl is 6.0 mol/L, the ratio of liquid to solid was (L/S) 6.0:1.0, and the leaching temperature 90 °C, leaching time 45 min, stirring speed 200 r/min, and the extraction of rare earth could reach 92.5%. The relevant experimental data show that the process of HCl leaching roasted ore conforms to the shrinking core model, but the control mechanism of the chemical reaction process is different when the leaching temperature is different. When the leaching temperature is between 40 and 70 °C, the chemical reaction process is controlled by the diffusion of the product through the residual layer of the inert material. The average surface activation energy of the rare earth element is E_a = 9.96 kJ/mol. When the leaching temperature is 75–90 °C, the chemical reaction process is controlled by the interface transfer across the product layer (product layer interface mass transfer) and diffusion. The average surface activation energy of rare earth elements is E_a = 41.65 kJ/mol. The results of this study have certain significance for the green extraction of mixed rare earth ore. A smelting method for clean extraction of Bayan Obo mixed rare earth concentrate is reported. The reaction process is strengthened by optimizing the reaction mechanism, regulating the phase structure of the product, and increasing the reaction temperature. Therefore, it fundamentally overcomes a series of technical problems such as difficulty in traditional alkali decomposition and filtration, large amount of water washing, and easy occurrence of “splashing” accidents. It has important practical significance and research value for the realization of the clean extraction of rare earth resources and associated elements of Bayan Obo.

For more: http://www.sciaeon.org/geology-and-geoscience/home

For Manuscript submission:  http://www.sciaeon.org/submit-paper

For contact :geology@sciaeonopenaccess.com

A fossil fuel is a fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms, containing energy originating in ancient photosynthesis.Such organisms and their resulting fossil fuels typically have an age of millions of years, and sometimes more than 650 million years. Fossil fuels contain high percentages of carbon and include petroleum, coal, and natural gas.Commonly used derivatives of fossil fuels include kerosene and propane. Fossil fuels range from volatile materials with low carbon-to-hydrogen ratios (like methane), to liquids (like petroleum), to nonvolatile materials composed of almost pure carbon, like anthracite coal. Methane can be found in hydrocarbon fields either alone, associated with oil, or in the form of methane clathrates.The theory that fossil fuels formed from the fossilized remains of dead plants by exposure to heat and pressure in the Earth’s crust over millions of years was first introduced by Andreas Libavius “in his 1597 Alchemia [Alchymia]” and later by Mikhail Lomonosov “as early as 1757 and certainly by 1763”.The first use of the term “fossil fuel” occurs in the work of the German chemist Caspar Neumann, in English translation in 1759.The Oxford English Dictionary notes that in the phrase “fossil fuel” the adjective “fossil” means “[o]btained by digging; found buried in the earth”, which dates to at least 1652[6] – before the English noun “fossil” came to refer primarily to long-dead organisms in the early 18th century.As of 2017 the world’s primary energy sources consisted of petroleum (34%), coal (28%), natural gas (23%), amounting to an 85% share for fossil fuels in primary energy-consumption in the world.Non-fossil sources as of 2006 included nuclear (8.5%), hydroelectric (6.3%), and others (geothermal, solar, tidal, wind, wood, waste) amounting to 0.9%.World energy-consumption was growing[when?] at about 2.3% per year. As of 2015 about 18% of worldwide consumption came from renewable sources.Although natural processes continually form fossil fuels, such fuels are generally classified as non-renewable resources because they take millions of years to form and the known viable reserves are being depleted much faster than new ones are being made. The use of fossil fuels raises serious environmental concerns. The burning of fossil fuels produces around 21.3 billion tonnes (21.3 gigatonnes) of carbon dioxide (CO2) per year. It is estimated that natural processes can only absorb about half of that amount, so there is a net increase of 10.65 billion tonnes of atmospheric carbon dioxide per year. Carbon dioxide is a greenhouse gas that increases radiative forcing and contributes to global warming. A global movement towards the generation of low-carbon renewable energy is underway to help reduce global greenhouse-gas emissions.

For more: http://www.sciaeon.org/geology-and-geoscience/home

For Manuscript submission:  http://www.sciaeon.org/submit-paper

For contact :geology@sciaeonopenaccess.com

Geologic history of Earth, evolution of the continents, oceans, atmosphere, and biosphere. The layers of rock at Earth’s surface contain evidence of the evolutionary processes undergone by these components of the terrestrial environment during the times at which each layer was formed. By studying this rock record from the very beginning, it is thus possible to trace their development and the resultant changes through time. The Pregeologic Period:From the point at which the planet first began to form, the history of Earth spans approximately 4.6 billion years. The oldest known rocks—the faux amphibolites of the Nuvvuagittuq greenstone belt in Quebec, Canada—however, have an isotopic age of 4.28 billion years. There is in effect a stretch of approximately 300 million years for which no geologic record for rocks exists, and the evolution of this pregeologic period of time is, not surprisingly, the subject of much speculation. To understand this little-known period, the following factors have to be considered: the age of formation at 4.6 billion years ago, the processes in operation until 4.3 billion years ago, the bombardment of Earth by meteorites, and the earliest zircon crystals.It is widely accepted by both geologists and astronomers that Earth is roughly 4.6 billion years old. This age has been obtained from the isotopic analysis of many meteorites as well as of soil and rock samples from the Moon by such dating methods as rubidium–strontium and uranium–lead. It is taken to be the time when these bodies formed and, by inference, the time at which a significant part of the solar system developed. When the evolution of the isotopes of lead-207 and lead-206 is studied from several lead deposits of different age on Earth, including oceanic sediments that represent a homogenized sample of Earth’s lead, the growth curve of terrestrial lead can be calculated, and, when this is extrapolated back in time, it is found to coincide with the age of about 4.6 billion years measured on lead isotopes in meteorites. Earth and the meteorites thus have had similar lead isotope histories, and so it is concluded that over a period of about 30 million years they condensed or accreted as solid bodies from a primeval cloud of interstellar gas and dust—the so-called solar nebula from which the entire solar system is thought to have formed—at about the same time. Models developed from the comparison of lead isotopes in meteorites and the decay of hafnium-182 to tungsten-182 in Earth’s mantle, however, suggest that approximately 100 million years elapsed between the beginning of the solar system and the conclusion of the accretion process that formed Earth. These models place Earth’s age at approximately 4.5 billion years old.

For more: http://www.sciaeon.org/geology-and-geoscience/home

For Manuscript submission:  http://www.sciaeon.org/submit-paper

For contact :geology@sciaeonopenaccess.com

To improve the resolution of seismic events, one often designs a Wiener inverse filter that optimally (in the least‐squares sense) transforms a measured source signature into a spike. When this filter is applied to seismic data, the bandwidth of any noise which is present increases along with the bandwidth of the signal. Thus the signal‐to‐noise ratio is degraded. To reduce signal ambiguity it is common practice to prewhiten the Wiener filter. Prewhitening the filter improves the output signal‐to‐ambient noise ratio, but at the same time it reduces resolution. The ability to resolve the temporal separation between events is determined by the resolution time constant which we define as the ratio of signal energy to peak signal power from the filter. For unfiltered wavelets the resolution time constant becomes the reciprocal of resolving power recently described by Widess (1982). For matched filter signals the resolution time constant can be regarded as the inverse of the frequency span of the signal. Although it is satisfying that the resolution time constant definition agrees with other measures of resolution, this more general definition has two major advantages. First, it incorporates the effect of filtering; second, it is easily generalized to incorporate the effects of noise by assuming that the filter is a Wiener filter. For a given amount of noise the Wiener filter is a generalization of the matched filter. Marine seismic wavelets demonstrate how reducing the noise level improves the resolution of a Wiener filter relative to a matched filter. For these wavelets a point of diminishing return is reached, such that, to realize a further small increase in resolution, a large increase in input signal‐to‐noise ratio is required to maintain interpretable information at the output.

For more: http://www.sciaeon.org/geology-and-geoscience/home

For Manuscript submission:  http://www.sciaeon.org/submit-paper

For contact :geology@sciaeonopenaccess.com

Different types of the most common coherent and random noise components encountered in marine seismic data are introduced. These include operational noise, air gun bubble, multiple reflections, swell noise, bird’s noise, tail buoy noise, mechanical cable noise, direct wave, refracted wave, diffractions, guided waves, seismic interference and other types of noise such as harmonic noise, spikes, side-sweep and noise from marine mammals. Analysis of noise records and formation mechanisms of different noise types are discussed, and several specific examples for each noise type are provided. Spectral analysis of the noise components in terms of amplitude spectrum, f-k and f-x spectra are also included.Despite significant advances in marine streamer design, seismic data are often plagued by coherent noise having approximately linear moveout across stacked sections. With an understanding of the characteristics that distinguish such noise from signal, we can decide which noise‐suppression techniques to use and at what stages to apply them in acquisition and processing. Three general mechanisms that might produce such noise patterns on stacked sections are examined: direct and trapped waves that propagate outward from the seismic source, cable motion caused by the tugging action of the boat and tail buoy, and scattered energy from irregularities in the water bottom and sub‐bottom. Depending upon the mechanism, entirely different noise patterns can be observed on shot profiles and common‐midpoint (CMP) gathers; these patterns can be diagnostic of the dominant mechanism in a given set of data. Field data from Canada and Alaska suggest that the dominant noise is from waves scattered within the shallow sub‐buttom. This type of noise, while not obvious on the shot records, is actually enhanced by CMP stacking. Moreover, this noise is not confined to marine data; it can be as strong as surface wave noise on stacked land seismic data as well. Of the many processing tools available, moveout filtering is best for suppressing the noise while preserving signal. Since the scattered noise does not exhibit a linear moveout pattern on CMP‐sorted gathers, moveout filtering must be applied either to traces within shot records and common‐receiver gathers or to stacked traces. Our data example demonstrates that although it is more costly, moveout filtering of the unstacked data is particularly effective because it conditions the data for the critical data‐dependent processing steps of predictive deconvolution and velocity analysis.

For more: http://www.sciaeon.org/geology-and-geoscience/home

For Manuscript submission:  http://www.sciaeon.org/submit-paper

For contact :geology@sciaeonopenaccess.com

Based on a critical literature review, the article argues that transformative learning (TL) that fosters a shift in consciousness towards a more ecological approach is an inherently place-based phenomenon. In this article we build a place-based approach to TL based on a literature review. Our theoretical framework is grounded in three key themes which emerge from the literature: (re-) connection, (self-)compassion and creativity. (Re-)connection involves all processes that evoke an experience of the interconnected nature of all life. (Self-)compassion, acting to alleviate suffering or doing the least harm, naturally follows a sense of interconnection. Creativity is the materialisation of a sense of interconnection and compassion or the means through which these can be experienced. This theoretical framework can be used empirically to research the extent to which people involved in place-based sustainability initiatives develop an ecological consciousness. Empirical research can then be used to further develop and anchor this framework, and seek the kind of practices that can evoke experiences of connection, cultivate the human ability for compassion and give space for creative living.

For more: http://www.sciaeon.org/geology-and-geoscience/home

For Manuscript submission:  http://www.sciaeon.org/submit-paper

For contact :geology@sciaeonopenaccess.com

A combination of Geological mapping and two-dimensional electrical resistivity (2D-ER) surveys was applied to study the Unilorin Dam and its environment. The purpose of the study was to investigate the dam for structural anomalies that may compromise the purpose and safety of the dam. Field equipment for the study comprised a SuperSting R8/IP Multi-Electrodes Resistivity Meter, 84 metallic electrodes and the accessories, compass clinometer, and portable GPS equipment. Geological data were processed and plotted to obtain a Geological Map and Rosette Diagram that were used for structural interpretations. The structures interpreted include an asymmetric fold and a strike-slip fault. The 2D resistivity data were processed and tomographically inverted to obtain the resistivity models of the subsurface around the dam. Interpretations of 2D resistivity models showed that the dam reservoir floor is underlain by competent basement rocks, however, the basement rock is weathered in some places. Patches of low resistivities structures interpreted as seepages, fractures and water-saturated cavity were delineated in different sections of the dam. The surface structural elements from geological study support the subsurface structures interpreted in the 2D resistivity models. Weathered structures, fractures, and seepage in the reservoir floor constitute areas of excessive water loss in the dam. The cavity delineated in the dam foundation is a potential threat to the dam’s safety. The dam section with cavity has been referred to structural engineers for detailed study.

For more: http://www.sciaeon.org/geology-and-geoscience/home

For Manuscript submission:  http://www.sciaeon.org/submit-paper

For contact :geology@sciaeonopenaccess.com