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Topic Review
Geochemical Characteristics of Oceanic Carbonatites
The occurrence of carbonatites in oceanic settings is very rare if compared with their continental counterpart, having been reported only in Cape Verde and Canary Islands. This entry provides an overview of the main geochemical characteristics of oceanic carbonatites, around which many debates still exist regarding their petrogenesis.
  • 823
  • 26 Mar 2021
Topic Review
Last Deglaciation Rainfall Changes
Three drier periods (lower rainfall) (i.e., before ~17, ~1513.5, and 7–3 ka BP) and three wetter periods (higher rainfall) (i.e., ~17–15, ~13.5–7, and after ~3 ka BP) were detected on Southern Indonesia (off southwest Sumba) based on geochemical element (terrigenous input) proxies (ln Ti/Ca and K/Ca). During the Last Deglaciation, AISM rainfall responded to high latitude climatic events related to the latitudinal shifts of the austral summer ITCZ. Sea level rise, solar activity, and orbitally-induced insolation were most likely the primary driver of AISM rainfall changes during the Holocene, but the driving mechanisms behind the latitudinal shifts of the austral summer ITCZ during this period are not yet understood.
  • 822
  • 27 Jan 2022
Topic Review
Gas Emissions from Arctic Permafrost
The active emission of gas (mainly methane) from terrestrial and subsea permafrost in the Russian Arctic has been confirmed by ample evidence. A generalization and some systematization of gas manifestations recorded in the Russian Arctic is carried out. The published data on most typical gas emission cases have been summarized in a table and illustrated by a map. All events of onshore and shelf gas release are divided into natural and man-caused and the natural ones are further classified as venting from lakes or explosive emissions in dryland conditions that produce craters on the surface. a description of the observed man-caused gas manifestations associated with the drilling of geotechnical and production wells in the Arctic region is given.
  • 805
  • 29 Oct 2020
Topic Review Peer Reviewed
Physical-Chemical Properties of Nano-Sized Phyllosilicates: Recent Environmental and Industrial Advancements
Phyllosilicates are common minerals that include the most widely known micas and clay minerals. These minerals are found in several natural environments and have unique physical-chemical features, such as cation exchange capacity (CEC) and surface charge properties. When phyllosilicates are nano-sized, their physical-chemical properties are enhanced from those of the micro-sized counterpart. Because of their unique crystal chemical and physical-chemical features, kinetics, and particle size, nano-sized clay minerals (i.e., kaolinite, montmorillonite/illite) and micas (i.e., muscovite) are of great interest in several fields spanning from environmental applications to engineered materials. This paper aims to overview the recent developments of environmental protection and technological applications employing nano-sized natural micas and clay minerals. Emphasis is given to the role that the unique physical-chemical properties of montmorillonite, vermiculite, kaolinite, and muscovite play in nanoparticle formulations, manufacture, and technical performance.
  • 803
  • 06 Dec 2023
Topic Review
Microorganisms in the Nucleation of Carbonates
Microbially induced carbonate precipitation (MICP) is an important process in the synthesis of carbonate minerals, and thus, it is widely explored as a novel approach with potential for many technological applications. The processes and mechanisms involved in carbonate mineral formation in the presence of microbes are not yet fully understood. This research covers the current knowledge regarding the role of microbial cells and metabolic products (e.g., extracellular polymeric substances, proteins and amino acids) on the adsorption of divalent metals, adsorption of ionic species and as templates for crystal nucleation. Moreover, they can play a role in the mineral precipitation, size, morphology and lattice. By understanding how microbes and their metabolic products promote suitable physicochemical conditions (pH, Mg/Ca ratio and free carbonate ions) to induce carbonate nucleation and precipitation, the manipulation of the final mineral precipitates could be a reality for (geo)biotechnological approaches. The applications and implications of biogenic carbonates in areas such as geology and engineering are presented and discussed in this research, with a major focus on biotechnology.
  • 795
  • 03 Jan 2023
Topic Review
Geology and Geomorphology of Mare Fecunditatis
Mare Fecunditatis is a ~310,000 km2 flat basalt plain located in the low-latitude area of the Moon. Mare Fecunditatis basin was formed in the pre-Nectarian period, followed by the mare basalts eruption in the Imbrian period, and the volcanic activity continued until the early Eratosthenian period. There is no mass concentration in the center of Mare Fecunditatis, while there are positive Bouguer anomalies on the east and west sides of the basin. A diversity of geological features is found in Mare Fecunditatis.
  • 783
  • 07 Mar 2022
Topic Review
List of Minerals Approved by IMA (E)
This list includes those recognised minerals beginning with the letter E. The International Mineralogical Association is the international group that recognises new minerals and new mineral names, however minerals discovered before 1959 did not go through the official naming procedure, although some minerals published previously have been either confirmed or discredited since that date. This list contains a mixture of mineral names that have been approved since 1959 and those mineral names believed to still refer to valid mineral species (these are called "grandfathered" species). The list is divided into groups: The data was exported from mindat.org on 29 April 2005; updated up to 'IMA2018'. The minerals are sorted by name, followed by the structural group (rruff.info/ima and ima-cnmnc by mineralienatlas.de, mainly) or chemical class (mindat.org and basics), the year of publication (if it's before of an IMA approval procedure), the IMA approval and the Nickel–Strunz code. The first link is to mindat.org, the second link is to webmineral.com, and the third is to the Handbook of Mineralogy (Mineralogical Society of America).
  • 764
  • 20 Oct 2022
Topic Review
Porphyry Mo Deposits
Porphyry Mo deposits are the most important type of Mo resource. They result from a high oxygen fugacity of the parent magma, which acts as an effective indicator for evaluating the mineralization. In the ore-forming system of porphyry Mo deposits, sulfur exists mainly as sulfate in highly oxidized magma but as sulfide in ores. What triggers the reduction in the mineralization system that leads to sulfide precipitation has not yet been determined. 
  • 763
  • 28 Jul 2023
Topic Review
Mineralogy and Geochemistry of Ferromanganese Crusts
Late Pleistocene–Holocene rocks from the western part of Cocos-Nazca Spreading Centre (C-NSC) include ferromanganese crusts that elucidate the geochemistry and mineralogy of a deep-sea geological setting. Geochemical, mineralogical and petrological signatures indicate complex formation influenced by mild hydrothermal processes. These crusts consist mostly of mixed birnessite, todorokite-buserite, and Mn-(Fe) vernadite with traces of diagenetic manganates (asbolane), Fe-oxides and oxyhydroxides or hydrothermally associated and relatively pure Mn-oxyhydroxides (manganite). The average Mn/Fe ratio is 2.7, which suggests predominant mixed hydrogenous-early diagenetic crusts with hydrothermal influences. The mean concentrations of three prospective metals (Ni, Cu and Co) are low: 0.17, 0.08 and 0.025 wt %, respectively. The total content of ΣREY is also low, and ranges from 81 to 741 mg/kg (mean 339 mg/kg).
  • 761
  • 27 May 2022
Topic Review
Global Isotopic Hydrograph Separation
Isotopic Hydrograph Separation (IHS) is a novel research field that has shown a great shift in separating runoff into pre-event and event water throughout its production lifetime.
  • 759
  • 24 Sep 2021
Topic Review
Uturunku
Uturunku (Quechua for jaguar, Hispanicized spellings Uturunco, Uturuncu) is a dormant volcano in the Cordillera de Lípez in Potosí Department, Bolivia. It is located in the Sur Lípez Province, San Pablo de Lípez Municipality. It is in the Central Volcanic Zone of the Andes, and its highest summit is 6,008 metres (19,711 ft) above sea level. The volcano has two summits, with a fumarole field between them. The volcano's landforms include lava domes and lava flows. The volcano was sporadically active during the Pleistocene, with the most recent eruption dated at 271,000 years ago. Since then, Uturunku has displayed fumarolic activity. Starting in 1992, satellite observations have indicated a large area of regional uplift centered on Uturunku, which has been interpreted as an indication of large-scale magma intrusion under the volcano. This might be a prelude to large-scale volcanic activity, including "supervolcanic" activity and caldera formation.
  • 750
  • 29 Sep 2022
Topic Review
Adelaide Superbasin
The Adelaide Superbasin is a series of geologically related rift to passive margin sedimentary basins formed during the Neoproterozoic to Cambrian. They are located at the south-eastern margin of Proterozoic Australia.
  • 736
  • 18 Apr 2022
Topic Review
Geological Structure and Tectonic Complexity of Northern Thessaly
Knowing the rich presence of active faults in northern Thessaly and the lack of any significant seismic activity since at least the mid-1940s, the 2021 seismic sequence did not surprise people. What did surprise people was the fact that (i) despite the great knowledge of the neotectonic faults in the area, the causative faults were unknown, or almost unknown; (ii) the direction of the 2021 faulting was different than the expected, and given that the focal mechanisms showed almost pure normal dip-slip motion, the extensional main axis was also different than the one known for this area; and (iii) besides the co-seismic ruptures that occurred within the Domeniko-Amouri basin and along the Titarissios River valley, there is evidence of rupturing in the alpine basement of Zarkos mountains. 
  • 726
  • 15 Nov 2022
Topic Review
Soil in Atsbi Wenberta
The soils of the Atsbi Wenberta woreda (district) in Tigray (Ethiopia) reflect its longstanding agricultural history, highly seasonal rainfall regime and relatively low temperatures. The northern part of the district is on the high uplifted Atsbi Horst (with metamorphic rock and consolidated Palaeozoic fluvio-glacial deposits) , whereas the southern part is dominated by the Des’a forest on Antalo Limestone. In between there is the fluvial landscape of Hayqi Meshal. Particularities in the southern part of the district are soil catenas on intervening plains behind tufa dams and in a polje.
  • 684
  • 30 Sep 2022
Topic Review
Volcanism and Submarine Sedimentation around Alps during Eo-Oligocene
Different magmatic systems developed during the Eo-Oligocene on and around the Alpine Belt, favouring the accumulation of thick volcanogenic submarine sedimentary sequences in the coveal foreland and foredeep basins. 
  • 683
  • 22 Nov 2021
Topic Review
Gender Equality in Tanzanite Mine-to-Market
In the mining industry, the contemporary concept of mapping artisanal and small-scale mining to the UN Sustainable Development Goals is a newer aspect of sustainability. SDG 5 aims to achieve gender equality and empower all women and girls. However, while there have been initiatives to support gemstone mining in Tanzania and East Africa, to date, the role of women in the lucrative tanzanite mine-to-market (M2M) supply chain has been less visible and a missed opportunity. This is a concern, as in 2019, pre-COVID-19 pandemic, gemstone and precious metals accounted for an incredible 33.2% of Tanzania’s total exports. In contrast, in leading mining countries such as Australia and Canada, the participation of women continues to steadily advance, economically empowering the women involved.
  • 661
  • 02 Apr 2022
Topic Review
Loess in Xinjiang, China
The loess in the arid area of Xinjiang is located at the eastern end of the Central Asia Loess Belt, and paleoclimate research about it is of great importance for understanding the mechanism of interaction of the Eurasian Westerly monsoon system and the aridity of Central Asia. Loess sediments have been mainly distributed on the river terraces and windward piedmont of the Tianshan Mountains and the Kunlun Mountains since the late Pliocene (mainly late Pleistocene). Grain size and age data show that Xinjiang loess deposits at some locations are rapid and discontinuous or sedimentary hiatus. The Siberian High system largely controlled dust mobilization and loess accumulation in northern Xinjiang but not southern Xinjiang. In southern Central Asia, the intensity of dust activity may be determined by the Caspian Sea–Hindu Kush Index (CasHKI) and local circulation. 
  • 637
  • 01 Nov 2022
Topic Review
Geoethics and Education for Sustainability
The United Nations 2030 Agenda is a plan designed to encourage prosperity that is respectful of the planet and its inhabitants. The Agenda will help introduce the concept of education for sustainability (EfS) to a wider population in order to promote inter- and trans-disciplinary knowledge about sustainability. Connecting Earth Sciences (ES) with sustainability allows us to deal with the ethical dimensions and the social implications of this field. Geoethics is defined as the “research and reflection on the values which underpin appropriate behaviors and practices, wherever human activities interact with the Earth system” by the International Association for Promoting Geoethics (IAPG).
  • 604
  • 06 Jul 2022
Biography
Brian Harold Mason
Brian Harold Mason (18 April 1917 – 3 December 2009) was a New Zealand geochemist and mineralogist who was one of the pioneers in the study of meteorites.[1] He played a leading part in understanding the nature of the solar system through his studies of meteorites and lunar rocks. He also examined and classified thousands of meteorites collected from Antarctica.[2][3] Mason was born in Port
  • 601
  • 26 Dec 2022
Topic Review
Lake-Level Fluctuations
Recent decades of warmer climate have brought drying wetlands and falling lake levels to southern Alaska. These recent changes can be placed into a longer-term context of postglacial lake-level fluctuations that include low stands that were as much as 7 m lower than present at eight lakes on the Kenai Lowland. Closed-basin lakes on the Kenai Lowland are typically ringed with old shorelines, usually as wave-cut scarps, cut several meters above modern lake levels; the scarps formed during deglaciation at 25–19 ka in a kettle moraine topography on the western Kenai Lowland. These high-water stands were followed by millennia of low stands, when closed-basin lake levels were drawn down by 5–10 m or more. Peat cores from satellite fens near or adjoining the eight closed-basin lakes show that a regional lake level rise was underway by at least 13.4 ka. At Jigsaw Lake, a detailed study of 23 pairs of overlapping sediment cores, seismic profiling, macrofossil analysis, and 58 AMS radiocarbon dates reveal rapidly rising water levels at 9–8 ka that caused large slabs of peat to slough off and sink to the lake bottom.
  • 593
  • 25 Apr 2022
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