Geology Today最新文献

{"title":"Geodigest","authors":"","doi":"10.1111/gto.12392","DOIUrl":"10.1111/gto.12392","url":null,"abstract":"","PeriodicalId":100581,"journal":{"name":"Geology Today","volume":"38 3","pages":"82-93"},"PeriodicalIF":0.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90465702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geohazards explained 10","authors":"Ugur Ozturk","doi":"10.1111/gto.12391","DOIUrl":"10.1111/gto.12391","url":null,"abstract":"<p>On the eve of the new year, 2021, a single landslide claimed 70 souls in Ask, a village in Norway. This tragic event highlighted, once again, the need to understand whether research efforts to map landslide susceptible areas could help save lives and if these identified landslide-prone regions change with time. A landslide is a downslope gravitational mass wasting of earth materials. Hence, a classification model could estimate the likelihood of a landslide occurring under certain terrain conditions studying the landslide predisposing factors, such as hillslope inclination and land cover, of old landslides. Projecting these likelihoods in a landscape would be a landslide susceptibility map, which highlights areas that could potentially generate a landslide without any implication of an occurrence time. However, landslide predisposing factors change over time, resetting those susceptibility estimates—they are not static as traditionally assumed by most models. These changes could be evident, such as artificial alterations in land cover, or disguised, such as accumulated damage on hillslopes in the form of subsurface cracks due to a large earthquake. In times referred to as legacy effects, those latter hidden effects could be assessed by studying the spatial distribution of those landslides triggered by the same event. This perspective lists several potential biases of the time-invariant landslide susceptibility approach and offers hints to overcome these challenges using a more dynamic model that evolves.</p>","PeriodicalId":100581,"journal":{"name":"Geology Today","volume":"38 3","pages":"117-120"},"PeriodicalIF":0.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89213156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Classic localities explained 25","authors":"Michael J. Simms","doi":"10.1111/gto.12385","DOIUrl":"10.1111/gto.12385","url":null,"abstract":"<p>Britain's geology is perhaps more diverse than any equivalent area in the world, spans almost 3 billion years, and has been studied for more than two centuries yet, for too long, it seemed that we could find no evidence here for one of the most spectacular events on the Earth—a giant meteorite impact. Perhaps, the only evidence might be localized and easily overlooked, like the thin layer of millimetre-scale microtektites, once molten beads of rock blasted out by an impact, found near Bristol in 2001. Alas, these proved actually to have originated more than a thousand kilometres from Britain, in the 100 km Manicouagan Crater in eastern Canada. However, just a few years later, a spectacular discovery revealed that a world-class impact deposit, metres thick and extending for tens of kilometres, had been hiding in plain sight at a location visited by countless geology students and their teachers. For decades, the Assynt region in northwest Scotland has been a training ground for geologists, drawn by the immensely old Lewisian Gneiss, the spectacular hills of Torridon sandstone that overlie it, and the structural complexity of the Moine Thrust Zone. How could this remarkable impact deposit have gone unnoticed for so long?</p>","PeriodicalId":100581,"journal":{"name":"Geology Today","volume":"38 2","pages":"75-79"},"PeriodicalIF":0.0,"publicationDate":"2022-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86248016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geodigest","authors":"","doi":"10.1111/gto.12381","DOIUrl":"10.1111/gto.12381","url":null,"abstract":"The Matterhorn appears to be a massive, immovable mountain towering over the landscape near Zermatt, Switzerland, for millennia (Fig. 1). However, new research led by the WSL Institute for Snow and Avalanche Research SLF in Switzerland shows that this impression is wrong and that the Matterhorn is in fact constantly in motion, swaying gently back and forth approximately every 2 seconds (Andrei Ionescu, Earth.com, 23 December 2021). This subtle vibration with imperceptible amplitudes is caused by seismic energy in the Earth originated from oceans, earthquakes and human activity. Each object, including mountains, high-rise buildings, or bridges, vibrates at certain frequencies when affected by seismic energy. These natural frequencies depend on the geometry and material properties of the object. ‘We wanted to know whether such resonant vibrations can also be detected on a large mountain like the Matterhorn’, said the study lead author Samuel Weber, a researcher at the WSL Institute. Weber and his colleagues installed several seismometers on the Matterhorn, including one just below the summit, at 14 665 feet above sea level, and recorded all movements of the mountain at a high resolution in order to derive the frequency and direction of resonance. They found that the Matterhorn oscillates in a north–south direction at a frequency of 0.42 Hz, and in an east–west direction at a similar frequency. Compared to the reference station at the foot of the mountain, the measured movements on the summit were up to 14 times stronger. This phenomenon is due to the fact that the summit moves freely, while the base of the mountain is fixed, like a tree swaying in the wind. The researchers warn that such movements can intensify during earthquakes and potentially cause damage. ‘Areas of the mountain experiencing amplified ground motion are likely to be more prone to landslides, rockfall and rock damage when shaken by a strong earthquake’, said study co-author Jeffrey Moore, an assistant professor of Geology and Geophysics at the University of Utah. Such vibrations are not a peculiarity of this specific mountain. Other peaks, such as the Grosse Mythen, which is significantly smaller than the Matterhorn, vibrate in a similar manner. In fact, since it is smaller, the Grosse Mythen vibrates at a frequency four times higher than the Matterhorn. The Matterhorn is the largest mountain shown to vibrate. ‘It was exciting to see that our simulation approach also works for a large mountain like the Matterhorn and that the results were confirmed by measurement data’, concluded Moore.","PeriodicalId":100581,"journal":{"name":"Geology Today","volume":"38 2","pages":"42-57"},"PeriodicalIF":0.0,"publicationDate":"2022-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83906992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vertebrate lies? Arthropods were the first land animals!","authors":"Michael E. Brookfield,&nbsp;Elizabeth J. Catlos,&nbsp;Stephanie E. Suarez","doi":"10.1111/gto.12383","DOIUrl":"10.1111/gto.12383","url":null,"abstract":"<p>\u0000 <b>In contrast to the ‘propaganda’ of the currently dominant vertebrates (i.e. us), arthropods not amphibians were the first land animals. And like many another great advance, they first appeared in Scotland. The first land animals were ‘millipedes’, which evolved with the first true land plants at the edges of Scottish mountain lakes about 425 Ma. From then on, more elaborate and complex plant-arthropod land communities evolved incredibly rapidly, and spread to lowland marshes, taking only 40 Myr to reach complex forest grade communities by 385 Ma. We recently dated some of the sediments enclosing these fossils to give a more precise age for the communities, a study still in progress, which indicates that the oldest land animal is a ‘millipede’ from Kerrera, Oban, Scotland.</b>\u0000 </p>","PeriodicalId":100581,"journal":{"name":"Geology Today","volume":"38 2","pages":"65-68"},"PeriodicalIF":0.0,"publicationDate":"2022-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84130642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From alchemy to modern mineralogy: dating mineral collections via chemical notation","authors":"J. C. Cooke,&nbsp;A. J. Jeffery","doi":"10.1111/gto.12382","DOIUrl":"10.1111/gto.12382","url":null,"abstract":"<p>Mineral specimens found in historical collections often include specimen labels, which may provide vital information on the nature, chemistry and origin of the material. However, the evolution of chemical notation, particularly during the eighteenth and nineteenth centuries, led to a wide range of ways in which a given sample could be adequately documented, many of which may still be found in collections in the present day. Prior to the advent of modern mineralogy, samples were labelled using a complex and sometimes baffling language of alchemical symbols with little meaning to modern scientists. The efforts of notable chemists and mineralogists, such as Torbern Bergman, Antoine Lavoisier, John Dalton and Jöns Jacob Berzelius, began to reform and unify chemical nomenclature, providing a number of new terms, symbols and approaches to the description of materials. With the advent of atomic theory in the nineteenth century, new classification schemes based on quantitatively describing the atomic arrangement and composition of minerals were proposed, representing a significant step towards modern mineralogy. Understanding the development of chemical notation over time not only facilitates the identification of mineral specimens but may also provide clues as to the date that the sample was documented, and potentially even the location.</p>","PeriodicalId":100581,"journal":{"name":"Geology Today","volume":"38 2","pages":"58-64"},"PeriodicalIF":0.0,"publicationDate":"2022-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81520791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Choosing between a dichotomy of methods in stratigraphy","authors":"Peter Lunt,&nbsp;Xiwu Luan","doi":"10.1111/gto.12384","DOIUrl":"10.1111/gto.12384","url":null,"abstract":"<p>An overview of stratigraphical methods here focusses on the tectonically active basins of Southeast Asia, where studies over the past three decades have tried to adopt global methods. Unfortunately, these attempts inevitably moved towards a hybrid method that is argued to be neither satisfactory or even scientific. It is proposed that, in order to understand a complex area controlled by tectonism, a paradigm shift to a fully inductive, or evidence-based methodology is required. Initial attempts to do this are improving our understanding of the sedimentary geology, as well as enhancing plate tectonic reconstructions and mechanisms.</p>","PeriodicalId":100581,"journal":{"name":"Geology Today","volume":"38 2","pages":"69-74"},"PeriodicalIF":0.0,"publicationDate":"2022-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76491829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geology Today Index 2021","authors":"","doi":"10.1111/gto.12387","DOIUrl":"10.1111/gto.12387","url":null,"abstract":"","PeriodicalId":100581,"journal":{"name":"Geology Today","volume":"38 2","pages":"i-viii"},"PeriodicalIF":0.0,"publicationDate":"2022-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91378892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geodigest","authors":"","doi":"10.1111/gto.12378","DOIUrl":"10.1111/gto.12378","url":null,"abstract":"Calcium silicate perovskite (CaSiO3) is arguably the most geochemically important phase in Earth’s lower mantle, because it concentrates elements that are incompatible in the upper mantle. No one has ever successfully retrieved this high-pressure compound from the lower mantle before. This is because CaSiO3perovskite is ‘unquenchable’, meaning that it cannot retain its structure after being removed from its highpressure environment. In a new study, US geologists have finally found the first calcium silicate perovskite from Earth’s lower mantle in a diamond from the Orapa kimberlite pipe in Botswana (sci-news.com, 17 November 2021). ‘Calcium silicate perovskite is among the most geochemically important minerals in the lower mantle, largely because it concentrates elements that are incompatible in the upper mantle, including rareearth elements and radioactive isotopes that make an important contribution to the heat of Earth’s mantle’, said lead author Oliver Tschauner from the Department of Geoscience at the University of Nevada, Las Vegas, and his colleagues. ‘Although theorized for decades, to date, no one has ever successfully retrieved a high-pressure phase silicate from Earth’s lower mantle, largely because they cannot retain their mineralogical structure after being removed from a high-pressure, high-temperature environment. The only other highpressure phase silicate mineral confirmed in nature, bidgmanite, was found inside a highly shocked meteorite.’ In the new study, the researchers identified and characterized an inclusion of the high-pressure CaSiO3-perovskite within a deep-earth diamond using synchrotron X-ray diffraction. The unique diamond was unearthed from Botswana’s Orapa mine—the world’s largest diamond mine by area—in the 1980s (Fig. 1). A gem dealer sold the diamond in 1987 to a mineralogist at the California Institute of Technology. ‘For jewellers and buyers, the size, colour, and clarity of a diamond all matter, and inclusions—those black specks that annoy the jeweller—for us, they're a gift. I think we were very surprised. We didn't expect this’, Tschauner said. The crystalline compound the researchers found was named davemaoite in honor of the prominent experimental high-pressure geophysicist Ho-kwang (Dave) Mao and confirmed as a new mineral by the Commission of New Minerals, Nomenclature, and Classification of the International Mineralogical association. ‘This honour is a fitting tribute given the profound impact Dave’s work has had throughout the geosciences,’ said Richard Carlson, director of Earth and Planets Laboratory at the Carnegie Institution for Science. ‘His contributions have shaped our understanding of our world and now a piece of the world will forever bear his name’. The structural and chemical analysis of davemaoite showed that it is able to host a wide variety of elements in its structure, including potassium, thorium and uranium—three of the major heat-producing elements. The findings support the existence","PeriodicalId":100581,"journal":{"name":"Geology Today","volume":"38 1","pages":"2-12"},"PeriodicalIF":0.0,"publicationDate":"2022-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gto.12378","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81212388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Minerals explained 61: Melilites","authors":"Kent Brooks","doi":"10.1111/gto.12380","DOIUrl":"10.1111/gto.12380","url":null,"abstract":"<p>The melilites are a group of little-known silicate minerals. In nature, the commonest are rock-forming minerals found in the igneous rocks characterized by a low silica content (undersaturated rocks), in contact metamorphic rocks formed where igneous rocks invade impure limestones. They are also found in artificial slags and primitive meteorites, where they are an important component of the oldest material in the Solar System.</p>","PeriodicalId":100581,"journal":{"name":"Geology Today","volume":"38 1","pages":"32-36"},"PeriodicalIF":0.0,"publicationDate":"2022-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gto.12380","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88704685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}