The deep mafic magmatic staging chambers of layered mafic intrusions have been conjectured but not imaged. Their existence has long been postulated from geochemical models which require multiple magma injections from staging chambers to account for their multi-scale igneous layering and variations in sources and degrees of crustal contamination. For the Bushveld Complex of southern Africa, the world's largest layered mafic intrusion, seismic receiver functions identify a diffuse crust-mantle transition beneath the Complex that suggests high velocity lower crust and/or uppermost lithospheric mantle. Here we present 3D gravity modelling of the Bushveld Complex that includes dense material at the crust-mantle boundary, imaging for the first time, remnants of magma staging chambers. They underlie the whole Bushveld Complex and extend westwards to the Molopo Farms Complex in Botswana. Feeders to the Bushveld Complex coincide with intersections of major faults like the Thabazimbi-Murchison Lineament and Sugarbush Fault with the staging chamber. This identification of magmatic staging chambers beneath the Bushveld relates to similar geophysically imaged lower crustal features beneath the Duluth and Stillwater Complexes. Comparison of seismic and gravity data with geochemical models from other complexes aid in development of models for the magmatic architecture of layered mafic intrusions in general.

Land use/cover change (LULCC) is an integral part of global environmental change and is influenced by both natural and socioeconomic factors. This study aims to comprehensively analyze land use and land cover (LULC) in Kwazulu-Natal and Mpumalanga provinces in eastern South Africa from 1995 to 2020 and to identify the driving force behind LULCC. Utilizing Landsat series satellite imagery as a data source and based on the Google Earth Engine (GEE) platform and eCognition software 9.0, two different classification methods, pixel-based classification and object-oriented classification, were adopted to gather LULC data every five years. The spatiotemporal characteristics of the data were then analyzed. Using an optimal parameter-based geodetector (OPGD), this study explored the driving factors of LULCC in this region. The results show the following: (1) Of the two classification methods examined, the object-oriented classification had higher accuracy, with an overall accuracy of 80–90%. The pixel-based classification had lower accuracy, with an overall accuracy of 62.33–72.14%. (2) From 1995 to 2020, the area of farmland in the study area showed a fluctuating increase, while the areas of forest and grassland declined annually. The area of constructed land increased annually, whereas the areas of water and unused land fluctuated over time. (3) Socioeconomic factors generally had greater explanatory power than natural factors, with population growth and economic development being the main drivers of LULCC in the region. This study provides a reliable scientific basis for the formulation of sustainable land resource development strategies in the area, as well as for the management and implementation of urban and rural planning, ecological protection, and environmental governance by relevant departments.

Wildfires are an important disturbance factor in forest ecosystems. Assessing the probability of forest wildfires can assist in forest wildfire prevention, control, and supervision. The logistic regression model is widely used to forecast the probability, spatial patterns, and drivers of forest wildfires. This study used logistic regression to establish a spatial prediction model for forest wildfire susceptibility, which was applied to evaluate the risk of forest wildfires in Central Yunnan Province (CYP), China. A forest wildfire risk classification was implemented for CYP using forest burn scar data for 2001 to 2020 and the logistic spatial prediction model for forest wildfire susceptibility. Climate, vegetation, topographical, human activities, and location were selected as forest wildfire prediction variables. The results showed that: (1) The distributions of temperature, vegetation coverage, distance to water bodies, distance to roads, and precipitation were positively correlated with the occurrence of forest wildfires. Elevation, relative humidity, the global vegetation moisture index, wind speed, slope, latitude, and distance to residential areas were negatively correlated with the occurrence of forest wildfires. (2) The results of the logistic spatial prediction model for forest wildfire susceptibility showed a good fit to wildfire data, with an overall simulation probability of 81.6%. The optimal threshold for spatial prediction for forest wildfire susceptibility in CYP was determined to be 0.414. A significance level of a selected model variable of < 0.05 resulted in an area under the receiver operating characteristic curve (AUC) of 0.882–0.890. (3) Forest wildfire prevention efforts should focus on Southwest Yuxi City and southern Qujing City accounted for a high proportion of the areas at high risk of forest wildfires. Other localities should adjust forest wildfire prevention measures according to local conditions and strengthen existing wildfire prevention and emergency resource planning and allocation. (4) Some factors contributing to forest wildfires where different among the different areas. Forest wildfire risk factors had different degrees of impact under different spatial and temporal scales. The spatial relationships between wildfire disasters and influencing factors should be established in areas with heterogeneous environmental conditions for the selection of relevant factors.

The establishment of a standard and unified evaluation system model and its application to a cross-regional eco-environmental quality evaluation and analysis are required for identifying patterns of change in eco-environmental quality in different regions and the driving factors. This knowledge is important for achieving sustainable development. This study used remote sensing (RS) data and geographic information science (GIS) to construct a unified eco-environmental quality evaluation index system based on the Driving Forces, Pressure, State, Impact and Response (DPSIR) framework and the Analytic Hierarchy Process (AHP), the Entropy method, and Grey Relational Analysis (GRA). The index system was applied to evaluate the eco-environmental quality of central Yunnan Province (CYP) and eastern South Africa (ESA) at the county scale and to identify driving factors. The results showed that: (1) The mean ecological quality index of all counties (districts/cities) in the ESA in 2019 was 0.3696, which was slightly higher than that of 0.3449 in the CYP, indicating similar total ecological quality between the CYP and ESA. (2) The Moran's I value of eco-environmental quality in the CYP and ESA both exceeded 0, with significant spatial agglomerations. (3) The strongest correlations were between state class indicators and eco-environmental quality in both study areas. The grey relational coefficients exceeded 0.9, representing state indicators (such as vegetation coverage, habitat quality index, remote-sensed vegetation water supply index, vegetation net primary productivity, and annual mean precipitation) as the main driving forces of eco-environmental quality.

Wildland fires dramatically affect forest ecosystems, altering the loss of their biodiversity and their sustainability. In addition, they have a strong impact on the global carbon balance and, ultimately, on climate change. This review attempts to provide a comprehensive meta-analysis of studies on remotely sensed methods and data used for estimation of forest burnt area, burn severity, post-fire effects, and forest recovery patterns at the global level by using the PRISMA framework. In the study, we discuss the results of the analysis based on 329 selected papers on the main aspects of the study area published in 48 journals within the past two decades (2000–2020). In the first part of this review, we analyse characteristics of the papers, including journals, spatial extent, geographic distribution, types of remote sensing sensors, ecological zoning, tree species, spectral indices, and accuracy metrics used in the studies. The second part of this review discusses the main tendencies, challenges, and increasing added value of different remote sensing techniques in forest burnt area, burn severity, and post-fire recovery assessments. Finally, it identifies potential opportunities for future research with the use of the new generation of remote sensing systems, classification and cloud performing techniques, and emerging processes platforms for regional and large-scale applications in the field of study.

Оперативный, точный и регулярный мониторинг засухи на основе спутниковых данных представляется важной составляющей при оценке состояния и продуктивности лесных насаждений.В работе проведён пространственно-временной анализ влияния засухи на лесные экосистемы Среднего Поволжья России за период с 2000 по 2020 г. на основе оценки временных рядов данных MODIS разностного индекса вегетации (NDVI), индекса состояния растительности (VCI), стандартизированного индекса осадков (SPI) и их стандартизованных аномалий.Растровые карты пространственного распределения трендов исследуемых индексов на площади лесного покрова были получены методом геостатистической интерполяции «Кригинг».Исследование выявило, что два метеорологических показателя (температура и осадки), полученные по спутниковым данным, оказываются наиболее приемлемыми для оценки NDVI в засушливые годы.Возможности использования аномальных значений изучаемых индексов ограничены в силу особенностей отклика на негативные последствия влияния засушливого сезона на лесной покров.При мониторинге засух на территории крупных лесных массивов необходимо учитывать локальные пространственно-временные тренды исследуемых индексов, что позволит оценить ситуацию в целом.Индекс VCI на примере отдельного региона (Республика Марий Эл) позволил провести более точную оценку влияния интенсивности засухи на состояние и продуктивность лесных насаждений, чем для всего исследуемого региона

A full three-dimensional (3D) potential field model of the central and southern Bushveld Complex reveals information about the Complex in areas obscured by younger geological cover. Previously, two-dimensional gravity models and a few magnetic models limited to certain sections of the Bushveld Complex have been used to propose geometries for the Rustenburg Layered Suite, especially in the western and eastern lobes. These models were often used to support different emplacement models. Although these models provided valuable information, two-and-a-half-dimensional (2.5D) potential field modelling is not well suited to modelling complex 3D geology. Also, in most cases, only the magnetic or gravity data were modelled, but jointly modelling both data sets better constrains the results, as was shown recently for a 3D model of the northern lobe. Joint 3D modelling of regional gravity and magnetic data combined with published crustal thickness models derived from broadband seismic tomography studies and constrained by density and susceptibility data, geologic mapping, boreholes and seismic reflection data were used to create a 3D model of the central and southeastern sections of the Bushveld Complex, as well as the southern part of the northern lobe. The model shows a complex geometry with thick continuous Rustenburg Layered Suite S in most of the western and southeastern lobes, but less continuous Rustenburg Layered Suite in the eastern lobe. Large domes or thick granites and granophyre in the latter interrupt the continuity of the Rustenburg Layered Suite and the western and eastern lobes are strictly speaking only partially connected in places. However, they are not separate intrusions, but one disconnected by pre-existing and synmagmatic updoming. Three possible feeders were modelled in the northern, western, and south-eastern lobes.

Exploration for mineral resources using geophysical methods generally focuses on depths of less than 2 km, because the cost of exploring and mining below that depth is prohibitive. However, this strategy neglects the added value of a broader context, possibly resulting in missed opportunities for the discovery of significant deposits and their large-scale extensions. Larger-scale geophysical methodologies, such as considering the entire crust and upper mantle in the conceptual model, offer great potential for the recognition and exploitation of new, potentially large, ore deposits and their extensions. The Bushveld Complex from South Africa provides a rich lesson in how changing concepts resulted in new exploration strategies.

The Namaqua sector of the Namaqua-Natal Province consists of large tectonostratigraphic terranes, some of which includes Paleoproterozoic fragments inherited from the supercontinent Columbia. Most of the terranes became part of Rodinia during the Mesoproterozoic Namaqua Orogeny (1.3-1.0 Ga, Grenvillian). The terranes in the western foreland of the Kaapvaal Craton (Kheis Subprovince) form a thin-skin fold and thrust belt (5-15 km depth to sole thrust). Westerly directed thrusting towards the hinterland is reminiscent of thick-skin tectonics, associated with the exhumation of high grade facies terranes, such as the granulitic and migmatitic Griinau Terrane. Upper amphibolite Upington Terrane was thrusted from the west onto thrust sheets contiguous to Kaapvaal Craton, in turn over-ridden near Prieska by the Griinau Terrane. Severity of the ductile deformation is illustrated by regional shear zones, ubiquitous recumbent isoclinal folds and allochthonous mega sheath folds in the Griinau Terrane. Vergence reversal of fold and thrust structures along a narrow (10-20 km) northwesterly trending zone (Vergence Inversion Zone, VIZ), represents a crustal scale pop-up structure coincident with the Namaqua Front, a paired low-high gravity anomaly linked to a mega-scale anticline-syncline pair caused by deep-seated thrusting of the Columbian Moho.Late Columbian extension (1.6-1.3 Ga, diachronous with early Rodinian events) produced parautochthonous basins with volcano-sedimentary sequences, deformed during the Namaqua Orogeny. Early to mid-Columbian (2.3-1.9 Ga) rocks form basement to the mobile belt, with Steinkopf Terrane as type outcrop area (probably time-equivalent with the Grunau and Pofadder Terranes, Sperrgebiet Domain, Rehoboth structural Province and part of the Congo Craton). The western boundary of the Kaapvaal Craton (and composite Kalahari Craton) exhibits structural wedge edges of Archaean Kaapvaal basement and Ventersdorp-Vaalian basins. Columbia-Kaapvaal Detachment (COLKAD), a decollement between Kaapvaal and Columbia cratons (footwall) and Olifantshoek and other Namaqua terranes (hanging wall) extends for > 600 km westwards.Namaqua crust was thickened (20-25 km) by both structural stacking and sheeted intrusions (Namaqua tectogenesis) with clockwise PTt-paths in the west-central Namaqua sector (Olifantshoek, Griinau, Pofadder, Bladgrond Terranes). In the western part (Okiep/Garies Terrane), crust was dominantly thickened by massive sheetlike granitoid intrusions resulting in granulite grade and anti-clockwise PTt-paths. COLKAD-rooted inter/intra-terrane thrusts are subhorizontal except where rotated by subvertical (discrete) shear zones (e.g. Tantalite Valley and Brakbos-Doringberg-Dabep). Crustal thickening and granulite-uplift stimulated temperature rise with anatexis-palingenesis of early Columbian/supracrustal rocks. Kilometer-scale granitoid bodies, derived from predominantly Columbian crust (according to isotopic source rock models) that are emplaced along shear zones, caused a rise in the brittle to ductile transition zone (i.e. mid-crustal conditions) and low-pressure granulite facies.

Geophysical models image the 3D geometry of the mafic portion of the Bushveld Complex north of the Thabazimbi-Murchison Lineament (TML), critical for understanding the origin of the world's largest layered mafic intrusion and platinum group element deposits. The combination of the gravity and magnetic data with recent seismic, MT, borehole and rock property measurements powerfully constrains the models. The intrusion north of the TML is generally shallowly buried (generally <1500 m) with a modeled area of similar to 160 km x similar to 125 km. The modeled thicknesses are not well constrained but vary from similar to<1000 to >12,000 m, averaging similar to 4000 m. A feeder, suggested by a large modeled thickness (>10,000 m) and funnel shape, for Lower Zone magmas could have originated near the intersection of NS and NE trending TML faults under Mokopane. The TML has been thought to be the feeder zone for the entire Bushveld Complex but the identification of local feeders and/or dikes in the TML in the models is complicated by uncertainties on the syn- and post-Bushveld deformation history. However, modeled moderately thick high density material near the intersection of faults within the central and western TML may represent feeders for parts of the Bushveld Complex if deformation was minimal. The correspondence of flat, high resistivity and density regions reflect the sill-like geometry of the Bushveld Complex without evidence for feeders north of Mokopane. Magnetotelluric models indicate that the Transvaal sedimentary basin underlies much of the Bushveld Complex north of the TML, further than previously thought and important because the degree of reaction and assimilation of the Transvaal rocks with the mafic magmas resulted in a variety of mineralization zones. Published by Elsevier B.V.

Expansive soils are some of the most widely distributed and costly of geological hazards. This study examined ASTER satellite data, combined with standard remote sensing techniques, namely band ratios, in identifying these soils. Ratios designed to detect various clay minerals were calculated and possible expansive soils were detected, especially in the pans. It was also possible to delineate the mudrock that may act as a source for expansive soils. Moisture content clearly affected the ratios and it shows that remote sensing can detect where wetness leads to the development of problem soils. The fact that the area has relatively dry climatic conditions may explain why large areas of the mudrock have not yet weathered to clays. Because the ratios are not unique, results can be ambiguous, so care must be taken in the interpretation phase.

Sixteen tectonic terranes of the Namaqua-Natal metamorphic complex are distinguished (the Aggeneys, Agulhas, Bladgrond, Gamka, Grootdrink, Grunau, Fraserburg, Upington, Margate, Mossel, Mzumbe, Okiep, Olifantshoek, Steinkopf, Pofadder, and Tugela terranes). Evidence obtained from field investigations in the outcrop regions of Namaqualand and Natal are correlated with the geophysical data, enabling recognition of terrane suboutcrops in the regions covered by Phanerozoic deposits in the south. This is illustrated by nine selected profiles over the western and southern parts of the metamorphic complex. Four terranes that have not been observed in outcrop are postulated (Agulhas, Fraserburg, Gamka and Mossel terranes) and may represent extensions of some of the Natal terranes (Mzumbe and Margate terranes). The depth to Moho is generally about 40 km, diminishing dramatically at the present continental edge to as little as 15 km. Listric thrust ramps may originate on rises of the gently undulating topography of the Moho zone. Zones of thrusting and later shearing often exploit older structures and fabrics. The terranes that participated in the Grenvillian Namaqua-Natal Orogeny exhibit a dichotomy of vergences regionally. Those that moved to the northeast and north accreted onto the Archaean Kaapvaal Craton before becoming part of the Kalahari Craton. Terranes with vergences to the south and southwest were amalgamated onto other Archaean cratons. All of the composite cratons took part in the assembly of Rodinia. (C) 2014 Elsevier Ltd. All rights reserved.

Gravity models reveal the 3-D extent of the mafic component of the Bushveld Complex, critical for understanding the origin of the world's largest layered mafic intrusion and largest source of platinum-group elements (PGEs). New density information, broadband seismic data, borehole data and geological discoveries have improved the constraints on the gravity modelling. Furthermore, all of the models published up to now have been done in two or 2.5 dimensions which is not well suited to modelling the complex geometry of the Bushveld intrusion. Constrained three dimensional modelling takes into account effects of variations in geometry and geophysical properties of lithologies, providing better fits to the shape and amplitude of calculated fields. Gravity data reveal subsurface density contrasts to great depths and the significant density contrast between the mafic rocks of the Bushveld Complex and the surrounding granites and sediments, as well as contrasts across the crust mantle boundary, make gravity modelling ideal for constraining the 3D geometry of the Bushveld Complex.The aim of this paper is to demonstrate the effect of the new constraints and use of full three dimensional modelling on gravity models of the Bushveld intrusion. We remodel previously published models using full three dimensional potential field modelling software to test the existing conceptual models in an equally conceptual way. Including the measured thicker crust underneath the Bushveld Complex necessitates the presence of dense material in the central area between the eastern and western lobes. The simplest way to achieve this is to model the Rustenburg Layered Suite as a single connected intrusion. This is similar to the first geometries suggested for the Bushveld Complex. In addition to these findings, variations in the lower crust and mantle densities also contribute to models of this scale and have to be considered. (C) 2014 Elsevier Ltd. All rights reserved.

Aeromagnetic data clearly delineate the mafic rocks of the economically significant Bushveld Igneous Complex. This is mainly due to the abundance of magnetite in the Upper Zone of the Rustenburg Layered Suite of the Bushveld, but strongly remanently magnetised rocks in the Main Zone also contribute significantly in places. In addition to delineating the extent of the magnetic rocks in the complex, the magnetic anomalies also provide information about the dip and depth of these units. The presence of varying degrees of remanent magnetisation in most of the magnetic lithologies of the Rustenburg Layered Suite complicates the interpretation of the data. The combination of available regional and high resolution airborne magnetic data with published palaeomagnetic data reveals characteristic magnetic signatures associated with the different magnetic lithologies in the Rustenburg Layered Suite. As expected, the ferrogabbros of the Upper Zone cause the highest amplitude magnetic anomalies, but in places subtle features within the Main Zone can also be detected. A marker with strong remanent magnetisation located in the Main Zone close to the contact with the Upper Zone is responsible for very high amplitude negative anomalies in the southern parts of both the eastern and western lobes of the Bushveld Complex. Prominent anomalies are not necessarily related to a specific lithology, but can result from the interaction between anomalies caused by differently magnetised bodies.The magnetic data provided substantial information at different levels of detail, ranging from contacts between zones, and layering within zones, to magnetite pipes dykes and faults that can have an impact on mine planning. Finally, simple modelling of the magnetic data supports the concept of continuous mafic rocks between the western and eastern lobes. (C) 2013 Elsevier B.V. All rights reserved.

The 1915 +/- 6 Ma Trompsburg Complex is a large layered mafic intrusion, measuring approximately 2500 km(2) in area. Seven boreholes were drilled in the 1940s to constrain a strong gravimetric and magnetic anomaly. These approximately 2 kin deep boreholes intersected up to 760 in of gabbro-troctolite-anorthosite containing up to 19 massive magnetite layers. Physical property analyses including density, magnetic susceptibility, intensity of magnetization, electrical resistivity and induced polarization were performed on specimens from these cores. Gridded aeromagnetic and Bouguer gravity data, combined with the available borehole information were used to construct a three dimensional polygonal model of the Trompsburg Complex. This was then used to calculate a forward three dimensional gravity and magnetic model using an algorithm that computes the gravity and magnetic fields for polyhedrons. Unfortunately the boreholes were confined to the northwestern part of the Complex and as a result the rest of the model is not as well constrained as in this area. The model is saucer-shaped at the top, with a large feeder to the south-cast. The extremely high values of the Bouguer gravity anomaly reaching a maximum of almost 93 mGal with respect to the regional suggests a substantial thickness of more than 6000 in for the Complex reaching up to 16,000 in at the feeder. (c) 2005 Elsevier Ltd. All rights reserved.