Field Of Geosciences Research Articles

Методы геоинформатики и нечеткой математики в анализе геофизических данных

В настоящей работе приведен обзор базовых математических понятий и конструкций, которые легли в основу методов геоинформатики, развиваемых научной школой академика А.Д. Гвишиани. Важно отметить, что в рамках указанной школы геоинформатика понимается более широко, чем изучение и применение географических информационных систем. Геоинформатика включает в себя исследования по созданию методов и алгоритмов, позволяющих автоматизировать решение задач в области наук о Земле на базе данных исходных наблюдений. Под решением понимается адекватное моделирование логики эксперта, осуществляющего анализ данных и принятие решений вручную. Именно системы наблюдений и регистрируемые данные о процессах, происходящих в недрах Земли и в околоземном пространстве, являются основой фундаментальных исследований как в области геоинформатики, так и других науках о Земле. Так, под руководством академика А.Д. Гвишиани была существенна развита система наблюдений магнитного поля Земли. Настоящая статья в большей мере посвящена математическому аппарату, используемому для анализа данных наблюдений с целью последующего выявления новых закономерностей в процессах Земли и околоземного пространства.

Prediction of uniaxial compressive strength of carbonate rocks from nondestructive tests using multivariate regression and LS-SVM methods

Uniaxial compressive strength (UCS) value of a rock material is one of the most important design parameters in engineering practice and related fields of geosciences. Through this importance, prediction of UCS values of rock materials from nondestructive quicker and simpler tests are widely preferred. The aim of this study is to predict the UCS values of five carbonate rock groups including marble, dolomite, two limestones, and travertine from longitudinal ultrasonic wave velocity (Vp), Schmidt hardness rebound number (SHR), and cubic sample sizes (L). For this aim, a total of 90 cubic samples with 7, 9, and 11 cm edge sizes were prepared. Chemical, petrographical, and basic physical properties of the sample groups were investigated. After Vp and SHR values, UCS values of all samples were determined. By using multivariate regression analyses (MR), different UCS prediction equations from dry unit weight (γd), Vp, SHR, and also L values were proposed. Prediction performances of proposed model in which Vp, SHR, and L are input parameters was also analyzed by least square support vector machines (LS-SVM) method. Prediction performances of the MR and LS-SVM models were analyzed by coefficient of determination (R2), efficiency (E), and root mean square error (RMSE) performance measures. These values were calculated as 0.867, 0.799, and 16.616 respectively for the LS-SVM model and 0.781, 0.749, and 18.561 respectively for the MR model. The LS-SVM method was found to be successful in the prediction of the UCS values from nondestructive test data of carbonate rocks.

The necessity of developing knowledge map of the world in Earth Sciences and mines field studies based on research activities: a case study of Iran

As Robert Merton believes, as Science is a social construct, researchers in a certain research community have to share their findings. However, one of the main activities of knowledge management is the sharing knowledge through formal channels, including theses and dissertations, books, articles, conferences, etc., because it has a significant impact on the advancement of sciences and will improve the quality of R&D activities, organizational performance, and the achievement of researchers to competitive advantage. Current global databases such as Scopus, web of science, Google Scholar, as well as academic social network sites (SNS) such as Researchgate and Academia.edu are not successful in demonstrating the dynamics of knowledge In order to understand the dynamics of science, scientific collaboration, industrialization of the countries, we analyze and draw a strategic map in Earth Sciences and Mines of Iran's to help science and technology policy-makers, based on reviewing of the research activities of researchers in different dimensions of geology and mining field study. Through a scientometrics approach, 8431 publications including thesis (1967 to 2015) and papers (1991 to 2016) in two special fields of geology and mining were analyzed. According to the findings, a total of 127 universities in the 80 field study and 294 disciplines in the field of geosciences, 52 universities, and 13 disciplines in the field of geology and 36 universities and 26 disciplines in the field of mining and geophysics have been involved in the production of theses. Among them, the largest amount of publications in the field of geosciences includes fields of geology, mining engineering, civil engineering, natural geography, natural resources engineering respectively. There is an incremental growth of scientific activities in the mineral sector of Iran but unacceptable trend in relation to the number of minerals deposits, mines as well as the total number of mines in Iran. According to the International Standard Industrial Classification (ISIC), researchers in this area are more interested and performed the most scientific activity in metal (7), non-metallic and decorative (8), and oil and gas (5) section and (3), (5), (2) categories respectively. Also developing the statistical and GIS Mapping of research activities show low index of relationship between industrial needs and university research activities, lowest to medium (dispersive) overlap and duplicates, and insufficient research activities in various fields of the earth's sciences and subsequently lowest growth of quantity of the publications in this field so far for geosciences education of Iran despite the advances in the field of geosciences over the past 50 years. These findings improved our knowledge and helped us to know about our deficiencies/potential so that we suggest to develop a new generation of freely geosciences research activities databases based on web-GIS and scientometrics for researches/ers in the world in the 3rd millennium. In fact, understanding of these and drawing the universal research activities strategic map in the geosciences field study will help us to make an appropriate policies and decisions, improving initiatives and creativity, shed light on developing multi-dimensions of geosciences.

Achieving Inclusive Field-based Education: Results and Recommendations from an Accessible Geoscience Field Trip

Learners with disabilities are often denied field-based learning experiences in naturalistic disciplines. Geology can present substantial barriers due to rugged terrain in difficult-to-reach locations. In 2014, a field trip was executed with the dual purpose of 1) designing inclusion in field learning and 2) demonstrating to college faculty an accessible field experience. Direct observations of participants on the trip, as well as pre- and post-trip focus groups, illuminate the student and faculty field learning experience. Geoscience faculty have little guidance or support in understanding what disability is, how to reconcile accommodation with field-geology learning goals, and they cited instances where disability service providers acted as gatekeepers. The net effect of these ontologies is to reduce faculty empathy with, and thus their ability to be inclusive of, students with disabilities in field settings. Recommendations for teachers include taking campus disability-services administrators on field trips, opening and maintaining communications with disability service providers, and designing pedagogically sound field trips that align as much as possible to principles of universal design. An advocacy approach is described, which focuses on the students and the educational process, instead of on institutional compliance. Finally, geoscience faculty should conceptualize disability service providers as accessibility service providers.

Valuing and representing exogeodiversity: From scientific imagery to artistic imagination

Geodiversity –i.e., the abiotic equivalent of biodiversity– has gained international recognition and usage for more than two decades in the field of geosciences. It now has the theoretical foundations and practical applications of a new paradigm underlying strategies of geoconservation. However, geodiversity has rarely been considered in the context of extraterrestrial environments despite the great geological and geomorphological diversities of celestial bodies revealed by planetary science missions for at least a mid-century. In this paper, we propose to introduce the term “exogeodiversity” to encompass the variety of geological, geomorphological, regolith and hydrological features on all extraterrestrial rocky bodies. Like its terrestrial counterpart, exogeodiversity is endowed with a range of societal values, including cultural, historic, artistic, aesthetic, functional, scientific and educational ones. Given the threats associated with the many projects of human exploration of planetary surfaces, an objective assessment of these values is more than ever required. In the absence of direct (in situ) observations with the notable exception of the Moon, the only (indirect) way for a valuation of exogeodiversity is provided by an analysis of the scientific and artistic representations whose historical trajectories are intimately cross-cut. Finally, we stress the potential of the images to promote exogeodiversity in the era of digital technologies, for instance by imagining new forms of virtual exogeotourism.

A new type of micro-X-ray diffractometer focused by polycapillary optics

Micro-X-ray diffraction (μ-XRD) plays a significant role in measuring the phase structures of small samples or micro areas of larger samples. In this article, we propose a new type of desktop micro-X-ray diffractometer named μ-Hawk focused by polycapillary optics. It consists mainly of a microfocus X-ray tube, polycapillary optics, receiving slits, a silicon drift diode (SDD) X-ray detector integrated with single/multi-channel pulse analyzer, independently rotating <i>θ</i>-<i>θ</i> goniometer, high precision <i>XYZ</i> sample stage, computer programs developed by LabVIEW codes, etc. The main interface of the program has micro-X-ray diffraction analysis mode and micro energy dispersive X-ray fluorescence analysis mode. In addition, the monochromatization of X-ray, the angular resolution and the accuracy of the results of μ-Hawk are discussed. In order to demonstrate the feasibility of the instrument, the phase of micro area in the middle of the first stroke on the Chinese character “Jiao” from a 5-Jiao coin (Chinese currency) is measured by the μ-Hawk, and the phase of a copper wire 140 μm in diameter is also detected by it. After that, the phase of 1.0 mm × 0.6 mm area on the welding joint of the motherboard from an iPhone is two-dimensionally scanned by μ-Hawk. The <i>θ</i>-<i>θ</i> scanning is performed at each detected point inside the two-dimensional area. Four motors drive the <i>X</i> and <i>Y</i> axis of the sample stage as well as the <i>θ</i><sub>1</sub> and <i>θ</i><sub>2</sub> axis of the goniometer to accomplish the above functions. The results show that the micro energy dispersive X-ray fluorescence analysis mode of μ-Hawk can provide elementary reference information for the analysis of phase structure. Compared with conventional X-ray diffractometer, the μ-Hawk can detect the same diffraction peaks on the coin with lower background. Furthermore, the accurate diffraction peaks can be measured with a lower power and shorter time. The measured results can better reflect the true phase structure of the micro area. Six diffraction peaks and their phases can be clearly identified from the diffraction pattern of the copper wire. For the welding joint, the phase mapping of SnO<sub>2 </sub>(3 1 2) is acquired through data processing. Therefore, the μ-Hawk can adapt to the micro-X-ray diffraction analysis of small samples or micro areas of samples as well as the two-dimensional scanning analysis of phase mapping. The μ-Hawk exhibits the unique advantages of accomplishing accurate micro-X-ray diffraction analysis, convenient software, low working power, time saving, and small in size. It indicates a wide application prospect in the fields of materials, geosciences and heritage protection.

Downscaling Census Data for Gridded Population Mapping With Geographically Weighted Area-to-Point Regression Kriging

Understanding human population distribution on the earth at fine scales is an increasingly need to a broad range of geoscience fields, including resource allocation, transport and city planning, infectious disease assessment, disaster risk response, and climate change. Many approaches have been developed to spatially downscale census data to gridded population distribution datasets, which are preferable to integration with natural and socio-economic variables. We present a novel population downscaling approach that geographically weighted area-to-point regression kriging technique is used to downscale census data to gridded population distribution datasets with multisource geospatial and social sensing data. As a case study in Nanjing city, China we evaluated the effectiveness of the proposed population downscaling approach. The experimental results demonstrated that the proposed approach generated more accurate details of population distribution and higher accuracy than existing widely-used gridded population distribution products. Hence, the proposed population downscaling approach is a valuable option in producing gridded population distribution maps.

Motivation and Connection to Earth on Geology Field Trips in New Zealand: Comparing American Study Abroad Students with Local Undergraduates

Field education is a critical and enriching component of the undergraduate geoscience curriculum, enhanced when combined with a study abroad program. The affective domain – defined in geoscience as emotion, motivation, and connection to Earth – is an integral part of the field experience. Using questionnaire data collected at the start of two geoscience field trips, this study compares motivation and connection to Earth of study abroad students from the United States with local New Zealand students. Results show that study abroad students have more expert-like motivations and ecological worldviews, and are more attached to and see more positive and diverse meanings in the field area. To take advantage of this and improve student outcomes, we recommend that this study abroad module be adapted to be more applied, environmentally-focused, and place-based. Findings highlight the importance of teaching and learning to specific study abroad students, rather than applying unchanged curricula from local institutions.

Introduction to the China-Vietnam Cooperation Project: A Comparative Study of the Holocene Sedimentary Evolution of the Yangtze and Red River Deltas

Both China and Vietnam confront the challenges of natural geohazards and environmental changes in their deltas and coastal zones due to rapid urbanization, economic development, and the impacts of global climate change. China and Vietnam initiated a comparative study of the Holocene sedimentary evolution of the Yangtze River Delta (YRD) and Red River Delta (RRD) for the period 2015–2018 in order to improve the understanding of the two delta evolution histories in the Holocene. Previous investigative data of the two rivers, onshore delta plains, and offshore subaqueous deltas have been explored and reinterpreted. New data gleaned from boreholes, piston cores, shallow seismic and hydrodynamic sources have been collected from the offshore YRD and the East China Sea inner shelf, and surface sediments and short cores have been collected from the RRD near-shore areas. Six focal areas of the joint project have been defined for comparative studies of the two deltas, including morphological development, sequential stratigraphy, coastline shifting, sedimentary characteristics, sedimentary dynamics, and correlation with anthropogenic global climate change. The results of these study areas are presented herein. The joint project also includes cooperative capacity building; exchanges of young scientists have been organized during the project period, and hands-on training in laboratory geochemical analysis, numerical modeling, and seismic data processing and interpretation have been provided by China and its Vietnamese geoscientist partners. Joint field excursions were organized to the upstream of the Yangtze and Red Rivers in Yunan Province, China, all the way downstream along the Vietnamese portion of the Red River. These joint studies have, over the past three years, improved understanding of the evolutionary history of these two major rivers and their mechanisms of source to sink. Joint project results of these two major deltas are not limited to the geosciences; the cooperative mechanical and operational experiences have been helpful for future cooperation in the field of marine geoscience between China and Vietnam, as well for cooperative activities with other ASEAN member countries.

The ISC-GEM Earthquake Catalogue (1904–2014): status after the Extension Project

Abstract. We outline the work done to extend and improve the ISC-GEM Global Instrumental Earthquake Catalogue, a dataset which was first released in 2013 (Storchak et al., 2013, 2015). In its first version (V1) the catalogue included global earthquakes selected according to time-dependent cut-off magnitudes: 7.5 and above between 1900 and 1918 (plus significant continental earthquakes 6.5 and above); 6.25 between 1918 and 1959; 5.5 between 1960 and 2009. Such selection criteria were dictated by time and resource limitations. With the Extension Project we added both pre-1960 events below the original cut-off magnitudes (if enough station data were available to perform relocation and magnitude recomputation) and added events with magnitude 5.5 and above from 2010 to 2014. The project ran over a 4-year period during which a new version of the ISC-GEM Catalogue was released each year via the ISC website (http://http://www.isc.ac.uk/iscgem/, last access: 10 October 2018). For each year, not only have we added new events to the catalogue for a given time range but also revised events already in V1 if additional data became available or location and/or magnitude reassessments were required. Here we recall the general background behind the production of the ISC-GEM Catalogue and describe the features of the different periods in which the catalogue has been extended. Compared to the 2013 release, we eliminated earthquakes during the first 4 years (1900–1903) of the catalogue (due to lack of reliable station data), added approximately 12 000 and 2500 earthquakes before 1960 and between 2010 and 2014, respectively, and improved the solution for approximately 2000 earthquakes already listed in previous versions. We expect the ISC-GEM Catalogue to continue to be one of the most useful datasets for studies of the Earth's global seismicity and an important benchmark for seismic hazard analyses, and, ultimately, an asset for the seismological community as well as other geoscience fields, education and outreach activities. The ISC-GEM Catalogue is freely available at https://doi.org/10.31905/D808B825.

In situ stress heterogeneity in a highly developed strike-slip fault zone and its effect on the distribution of tight gases: A 3D finite element simulation study

Abstract Strike-slip fault zones are an important type of structure formed during continental orogenic events. Exploring the influence of strike-slip faults on the distribution of natural gas by using the 3D finite element method (FEM) is a frontier in the field of geoscience. In this paper, the effects of strike-slip faults on the heterogeneity of in situ stress and reservoir quality were systematically studied in a shallow commercial coalbed methane reservoir in the Shanxi Formation in the southern Qinshui Basin. Systematic 3D FEM modeling and in situ stress evaluation of a highly developed strike-slip fault zone were conducted. The results indicate that the simulated in situ stress distributions of σH, σh and σv in the target layer present ranges of 10–55 MPa, 3–23 MPa and 5–30 MPa, respectively, which are consistent with acoustic emission and hydraulic fracturing measurements. Along the strike-slip faults, the distribution of horizontal in situ stress is mainly affected by the fault length and vertical throw. The stress magnitude differs greatly between the two sides of a given strike-slip fault, affecting the compaction degree and petrophysical properties of the gas-bearing reservoir on both sides of the fault. Along the strike of a given strike-slip fault, the minimum horizontal in situ stress exhibits distinct segmentation characteristics, which affect the distribution of wells with a higher and lower yields. For the 2 s-order faults (the Sitou and Houchengyao faults), wells with a higher gas production capacity are typically located on the northwestern side of the faults. In the middle and southern sections of the Sitou-Houchengyao strike-slip fault zone, both highly concentrated faults and large-scale opening faults (basement and surface faults) produce greater stress concentrations, and the gas production capacity of the gas wells in these areas is poor. When the main strike direction of the faults is consistent with the loading direction of the boundary stress, the stress concentration is relatively low; whereas, the stress concentration increases as the angle between the main fault strike and the loading direction increases. The shear stress of the target layer is characterized by clockwise rotation, which is an important control on the stress heterogeneity of the strike-slip faults in the study area.

Pressure-induced structural modulations in coesite

Silica phases, $\mathrm{Si}{\mathrm{O}}_{2}$, have attracted significant attention as important phases in the fields of condensed-matter physics, materials science, and (in view of their abundance in the Earth's crust) geoscience. Here, we experimentally and theoretically demonstrate that coesite undergoes structural modulations under high pressure. Coesite transforms to a distorted modulated structure, coesite-II, at 22--25 GPa with modulation wave vector $q=0.5{b}^{*}$. Coesite-II displays further commensurate modulation along the $y$ axis at 36--40 GPa and the long-range ordered crystalline structure collapses beyond $\ensuremath{\sim}40\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$ and starts amorphizing. First-principles calculations illuminate the nature of the modulated phase transitions of coesite and elucidate the modulated structures of coesite caused by modulations along the $y$-axis direction. The structural modulations are demonstrated to result from phonon instability, preceding pressured-induced amorphization. The recovered sample after decompression develops a rim of crystalline coesite structure, but its interior remains low crystalline or partially amorphous. Our results not only clarify that the pressure-induced reversible phase transitions and amorphization in coesite originate from structural modulations along the $y$-axis direction, but also shed light on the densification mechanism of silica under high pressure.

Broadband Seismic Inversion for Low-Frequency Component of the Model Parameter

Seismic inversion is an important approach in parameters estimation in the fields of geosciences. The low-frequency component of the model parameter plays an important role in seismic inversion. The emergence of broadband seismic data acquisition and processing technologies is pushing the attention of the low frequency to a new level. With the review of the research status of the estimation of the low-frequency models in history and the low-frequency component contained in the complex frequency domain, a novel broadband seismic Bayesian inversion approach in the complex frequency domain is proposed to implement the estimation of the low-frequency component of the model parameter. The proposed approach makes full use of the advantage of broadband seismic data and the low-frequency component of the damped wave fields in the complex frequency domain. The kernel function of the proposed inversion approach is built with Bayesian inference. Synthetic examples demonstrate the feasibility and robustness of the proposed inversion approach in the estimation of the low-frequency component of the model parameter. A field data example verifies the feasibility and reasonability of the proposed inversion approach in application. Finally, the estimated low-frequency component of the model parameter is utilized as the initial model for the suggested seismic Bayesian inversion method in time domain. Model and field data examples further verify the effectiveness and superiority of the proposed inversion method in the final estimation of the model parameter by comparing with the conventional inversion approach.

Estimating critical path analysis on digital topology of the connectivity of pore media

The relationship between pore media microstructure and permeability has been a hot topic in the field of geosciences. However, there are still significant technical challenges in accurately estimating permeability, especially in spatially complex pore media. Here we introduce morphological of porous media, expressed by Euler-Poincare Characteristic (Euler Number) which is a key parameter in the digital topology that describes the connectivity of pore media. In this short communication, the connectivity function of porous media is established by Euler number and used to determine the critical pore size in the theory of percolation. Then the critical path analysis (CPA) and percolation theory are combined to study the relationship between the Euler number and the permeability of porous media. Using twelve digital core samples, the empirical formula and the theoretical estimations of CPA-based model (Friedman and Seaton, 1998) are compared respectively with the experimental measurement data. The results show that the permeability estimation under the Euler number factor model is more accurate than the CPA-based model. Some possible sources of uncertainty are also discussed. The relationship between permeability and morphological (Euler Number) of porous media makes it possible to predict permeability of porous media accurately and reasonably.

Random forest as a generic framework for predictive modeling of spatial and spatio-temporal variables.

Random forest and similar Machine Learning techniques are already used to generate spatial predictions, but spatial location of points (geography) is often ignored in the modeling process. Spatial auto-correlation, especially if still existent in the cross-validation residuals, indicates that the predictions are maybe biased, and this is suboptimal. This paper presents a random forest for spatial predictions framework (RFsp) where buffer distances from observation points are used as explanatory variables, thus incorporating geographical proximity effects into the prediction process. The RFsp framework is illustrated with examples that use textbook datasets and apply spatial and spatio-temporal prediction to numeric, binary, categorical, multivariate and spatiotemporal variables. Performance of the RFsp framework is compared with the state-of-the-art kriging techniques using fivefold cross-validation with refitting. The results show that RFsp can obtain equally accurate and unbiased predictions as different versions of kriging. Advantages of using RFsp over kriging are that it needs no rigid statistical assumptions about the distribution and stationarity of the target variable, it is more flexible towards incorporating, combining and extending covariates of different types, and it possibly yields more informative maps characterizing the prediction error. RFsp appears to be especially attractive for building multivariate spatial prediction models that can be used as “knowledge engines” in various geoscience fields. Some disadvantages of RFsp are the exponentially growing computational intensity with increase of calibration data and covariates and the high sensitivity of predictions to input data quality. The key to the success of the RFsp framework might be the training data quality—especially quality of spatial sampling (to minimize extrapolation problems and any type of bias in data), and quality of model validation (to ensure that accuracy is not effected by overfitting). For many data sets, especially those with lower number of points and covariates and close-to-linear relationships, model-based geostatistics can still lead to more accurate predictions than RFsp.

Gravity measurements below 10\u22129g with a transportable absolute quantum gravimeter

Gravimetry is a well-established technique for the determination of sub-surface mass distribution needed in several fields of geoscience, and various types of gravimeters have been developed over the last 50 years. Among them, quantum gravimeters based on atom interferometry have shown top-level performance in terms of sensitivity, long-term stability and accuracy. Nevertheless, they have remained confined to laboratories due to their complex operation and high sensitivity to the external environment. Here we report on a novel, transportable, quantum gravimeter that can be operated under real world conditions by non-specialists, and measure the absolute gravitational acceleration continuously with a long-term stability below 10 nm.s−2 (1 μGal). It features several technological innovations that allow for high-precision gravity measurements, while keeping the instrument light and small enough for field measurements. The instrument was characterized in detail and its stability was evaluated during a month-long measurement campaign.

The establishment of metadatabase: The program Euromarsin for the marin sediments samples

The project EUMARSIN (European MARine Sediment Information Network), is an international scientific project financed by the European Community and its aim has been the development of an internet retrievable metadatabase containing the marine sediment samples collected from the European Seas. The project, with duration of two years, started on November 1998 and ended on October 2000. This paper elucidates the concerted activities of the partners participating in the project and represent the Marine Geology Departments of the Eurogeosurveys (ERG) now called Geological Survey Organizations (GSOs) of the European Union maritime countries, with the additional participation of a private company specialized on marine data management. The metadata can be accessed on the EU-SEASED Website through both an alphanumeric search and retrieval interface and by a geographical interface which allows the user to define an area of interest on a scrollable map showing the distribution of the seafloor sample/core locations. The EUMARSIN metadatabase now contains approximately 180.000 seabed samples collected by the Geological Surveys and other research organizations, universities, hydrographie offices and commercial companies in Europe. The metadatabase will be regularly updated by the partners on an on-line data entry system which will allow other organizations to contribute their metadata either retrospectively or as new data. The outcome of the EUMARSIN project, will be the successful establishment of the http://www.eu-seased.net marine sediment metadatabase and the development of analogous databases in each Geological Institute with the same specifications. This constitutes the first pan-European metadatabase in the marine geoscience field.

Application of China satellite data in geological hazards survey and evaluation: taking Baoji loess area as example

The development of domestic satellites has injected new vitality into the application of satellite technology in the geoscience field, and showing good application results, especially the development of high resolution satellites. This paper by using the image data of research area in 2013 and 2014 two annual Ziyuan III satellite (ZY-3), have extracted hazard-formative factors such as topography, active faults, water systems, vegetation, attempts to carry out geological hazards survey. Combined with the data of engineering geological petrofabric and rainfall in research area, to carry out susceptibility and risk assessment of the geological hazards by using the information model. It provides a demonstration for geological hazards survey, monitoring and evaluation in the loess landslide area by using domestical high resolution satellites.

Supercontinents: myths, mysteries, and milestones

Abstract There is an emerging consensus that Earth's landmasses amalgamate quasi-periodically into supercontinents, interpreted to be rigid super-plates essentially lacking tectonically active inner boundaries and showing little internal lithosphere–mantle interactions. The formation and disruption of supercontinents have been linked to changes in sea-level, biogeochemical cycles, global climate change, continental margin sedimentation, large igneous provinces, deep mantle circulation, outer core dynamics and Earth's magnetic field. If these hypotheses are correct, long-term mantle dynamics and much of the geological record, including the distribution of natural resources, may be largely controlled by these cycles. Despite their potential importance, however, many of these proposed links are, to date, permissive rather than proven. Sufficient data are not yet available to verify or fully understand the implications of the supercontinent cycle. Recent advances in many fields of geoscience provide clear directions for investigating the supercontinent cycle hypothesis and its corollaries but they need to be vigorously pursued if these far-reaching ideas are to be substantiated.

Review of smartphone applications for geoscience: current status, limitations, and future perspectives

Smartphones can be utilized in the field of geosciences for various purposes due to their multifaceted abilities that combine both hard- and software features. The unique abilities of smartphones allow new methodologies for the collection and visualization of data that rarely become available in traditional computing platforms. In this study, commercially available smartphone applications (apps) that have been released in geoscience (e.g., geology/soil, minerals and rocks, petroleum and gas) so far were investigated. The apps were categorized based on the extent of smartphone feature usage into (a) basic, standard-feature apps; (b) calculator and referencing apps; and (c) sensing and communication apps. Furthermore, each of these categories was divided into several app groups based on specific features. Representative apps of each specific app group were selected and their characteristics and applicability were examined. Lastly, major limitations regarding smartphone app development and implementation in geoscience and implications for future improvements were discussed.