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1.
Changes of the susceptibility to lava flow invasion at Mount Etna are quantified by using lava flow simulations on four Digital
Elevation Models documenting the morphostructural modifications of the volcano in the time interval 1986–2007. The probabilistic
code DOWNFLOW is used to derive the areas invaded by several thousands of lava flows obtaining, for each DEM, maps of the
susceptibility to lava flow invasion and of the lava flow hazard. These maps show, for the first time, the evolution of these
surficial properties with time, and render a quantitative image of the effects of topographic changes on the preferential
lava flow drainage paths. The results illustrate how the emplacement of new lava flows and the growth of scoria cones affect
the probability of inundation by lava flows. We conclude that the persistent activity of this volcano requires a frequent
updating of the topography for a reliable lava flow hazard assessment. 相似文献
2.
Long-term thermal consequences of the redistribution of heat-producing elements associated with large-scale granitic complexes 总被引：3，自引：0，他引：3
Crustal thermal regimes are sensitive to both the amount and distribution of heat producing elements (HPEs). Since a significant proportion of the crustal complement of HPEs is contained within granites, granite generation and emplacement should lead to significant long‐term changes in the thermal structure of the crust. Using HPE concentrations appropriate to representative Australian Proterozoic granites we show that granite segregation leads to changes in the temperature field of the crust of up to c. 50 °C, producing long‐term cooling in the source regions and heating at emplacement levels, relative to the pre‐granite conductive thermal regime. Because of the intimate connection between thermal regime and lithospheric strength, granite‐assisted redistribution of HPEs is likely to be fundamental to cratonisation. 相似文献
3.
Lava flow simulations using discharge rates from thermal infrared satellite imagery during the 2006 Etna eruption 总被引：1，自引：0，他引：1
Techniques capable of measuring lava discharge rates during an eruption are important for hazard prediction, warning, and
mitigation. To this end, we developed an automated system that uses thermal infrared satellite MODIS data to estimate time-averaged
discharge rate. MODIS-derived time-varying discharge rates were used to drive lava flow simulations calculated using the MAGFLOW
cellular automata model, allowing us to simulate the discharge rate-dependent spread of lava as a function of time. During
the July 2006 eruption of Mount Etna (Sicily, Italy), discharge rates were estimated at regular intervals (i.e., up to 2 times/day)
using the MODIS data. The eruption lasted 10 days and produced a ~3-km-long lava flow field. Time-averaged discharge rates
extracted from 13 MODIS images were utilized to produce a detailed chronology of lava flow emplacement, demonstrating how
infrared satellite data can be used to drive numerical simulations of lava flow paths during an ongoing eruptive event. The
good agreement between simulated and mapped flow areas indicates that model-based inundation predictions, driven by time-varying
discharge rate data, provide an excellent means for assessing the hazard posed by ongoing effusive eruptions. 相似文献
4.
Litian Hu Peizhen Zhang Tianyao Hao Yuntao Tian Dongli Zhang 《International Geology Review》2020,62(7-8):1081-1093
ABSTRACT The relationships in ocean depth and heat flow with crustal age place valuable constraints on the thermal evolution of the oceanic lithosphere. This work aims to establish the relationships for the V-shaped Southwest Subbasin, the southwestern end of the South China Sea formed during 23.6–16 Ma. Using high-resolution multichannel seismic profiles and heat flow measurements, we calculate sediment-corrected topography and heat flow, which are then plotted against crustal age to establish their relationships. The results show that the post-spreading volcanism in the South China Sea influences less on the present-day heat flow than topography. In addition, the topography data are evidently deeper and heat flow data are much lower in the Southeast Asian marginal seas than other oceans. Previous explanation suggested that the abnormal features resulted from lateral heat loss, which would predict a deeper lithosphere–asthenosphere boundary and a high slope in topography and heat flow with age, contrary to the observations. Possible explanations for the abnormal features of the Southeast Asian marginal seas include (1) lack of long-time upwelling magma at the onset of spreading, and (2) reduced magma supply during the seafloor spreading. 相似文献
5.
This study focuses on the compound pahoehoe lava flow fields of the 2000 eruption on Mount Cameroon volcano, West Africa and it comprehensively documents their morphology. The 2000 eruption of Mount Cameroon took place at three different sites (sites 1, 2 and 3), on the southwest flank and near the summit that built three different lava flow fields. These lava flow fields were formed during a long‐duration (28th May–mid September) summit and flank eruption involving predominantly pahoehoe flows (sites 2 and 3) and aa flows (site 1). Field observations of flows from a total of four cross‐sections made at the proximal end, midway and at the flow front, have been supplemented with data from satellite imagery (SRTM DEM, Landsat TM and ETM+) and are used to offer some clues into their emplacement. Detailed mapping of these lava flows revealed that site 1 flows were typically channel‐fed simple aa flows that evolved as a single flow unit, while sites 2 and 3 lava flow fields were fed by master tubes within fissures producing principally tube‐fed compound pahoehoe flows. Sites 2 and 3 flows issued from ∼ 33 ephemeral vents along four NE–SW‐trending faults/fissures. Pahoehoe morphologies at sites 2 and 3 include smooth, folded and channelled lobes emplaced via a continuum of different mechanisms with the principal mechanism being inflation. The dominant structural features observed on these flow fields included: fissures/faults, vents, levees, channels, tubes and pressure ridges. Other structural features present were pahoehoe toes/lobes, breakouts and squeeze‐ups. Slabby pahoehoe resulting from slab‐crusted lava was the transitionary lava type from pahoehoe to aa observed at all the sites. Transition zones correspond to slopes of > 10°. Variations in flow morphology and textures across profiles and downstream were repetitive, suggesting a cyclical nature for the responsible processes. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
6.
Ninad R. Bondre Raymond A. Duraiswami Gauri Dole 《Journal of Earth System Science》2004,113(4):809-817
The nature and style of emplacement of Continental Flood Basalt (CFB) lava flows has been a matter of great interest as well
as considerable controversy in the recent past. However, even a cursory review of published literature reveals that the Columbia
River Basalt Group (CRBG) and Hawaiian volcanoes provide most of the data relevant to this topic. It is interesting to note,
however, that the CRBG lava flows and their palaeotopographic control is atypical of other CFB provinces in the world. In
this paper, we first present a short overview of important studies pertaining to the emplacement of flood basalt flows. We
then briefly review the morphology of lava flows from the Deccan Volcanic Province (DVP) and the Columbia-Oregon Plateau flood
basalts. The review underscores the existence of significant variations in lava flow morphology between different provinces,
and even within the same province. It is quite likely that there were more than one way of emplacing the voluminous and extensive
CFB lava flows. We argue that the establishment of general models of emplacement must be based on a comprehensive documentation
of lava flow morphology from all CFB provinces. 相似文献
7.
Valentin R. Troll Alejandro Rodriguez‐Gonzalez Frances M. Deegan Francisco Jos Perez‐Torrado Juan Carlos Carracedo Konstantinos Thomaidis Harri Geiger Fiona C. Meade 《Geology Today》2019,35(2):55-62
Gran Canaria, like most of the Canary Islands, shows evidence for young basaltic volcanism in the form of cinder cones and valley‐hugging lava flows. These landforms were of no particular use to the aboriginal population, nor to the subsequent Spanish settlers, and young lava flows and lava fields are still referred to as ‘malpaís’ (badlands) in the Canary Islands. In north‐west Gran Canaria, one such lava flow fills the bottom of a steep‐sided valley, which reaches the sea at the present day village of Agaete. The lava flow erupted c. 3030 ± 90 yr bp and displays a total length of ～ 11 km. At its distal end, just outside Agaete, it hosts one of Europe’s largest and most important pre‐historic burial sites constructed of volcanic rock: the Maipés necropolis. Over 700 pre‐historic tombs (or tumuli) constructed from the aa‐type clinker materials have been identified on top of the valley‐filling lava flow. The up to soccer‐ball sized vesicular clinker fragments are sufficiently low in density to provide abundant, workable basalt blocks for the construction of the tumuli, allowing the pre‐hispanic aboriginal population to create a large and magnificent ‘sacred ground’ in an otherwise barren landscape. 相似文献
8.
火山"熔岩流气泡古高度计"及其在云南腾冲火山区的应用 总被引：6，自引：5，他引：1
通过对火山熔岩流及其气泡特征的研究能够确定熔岩流喷发时的古高度,本文将这一方法称为火山“熔岩流气泡古高度计”.“熔岩流气泡古高度计”是在实地测量熔岩流厚度和实验室对熔岩流顶底气泡体积精确测定的基础上,利用流体力学原理和气体状态方程,通过计算古大气压强,最终获得火山喷发时的古高度.由于火山岩是开展同位素测年的理想材料,并且利用熔岩流计算古高度所需的参数(熔岩流厚度和气泡体积)不受古气候等因素(温度、降雨量等)影响,因此,这一方法以其可靠的年龄和独立的计算参数明显区别于其它古高度计.“熔岩流气泡古高度计”核心技术包括:(1)熔岩流的挑选与厚度测量;(2)熔岩流底部和顶部气泡体积的计算.中等规模、具简单冷凝历史,并且厚度稳定的偏基性熔岩流,是开展古高度计算的理想对象.熔岩流气泡体积的测试手段包括注胶、岩石抛光-扫描、体视学转换和三维CT扫描4种方法.“熔岩流气泡古高度计”最终计算结果误差为400m左右.本文利用“熔岩流气泡古高度计”计算了腾冲火山区熔岩流的古高度,研究结果显示:“熔岩流气泡古高度计”计算的黑空山熔岩流高程与目前的实际高程相吻合.开展“熔岩流气泡古高度计”研究的前提是研究区必须出露保存完好的熔岩流.我国青藏高原的隆升历史一直是国际学术界争论的热点课题,那里出露大面积熔岩流.可以预见,“熔岩流气泡古高度计”将会逐渐成为研究青藏高原隆升历史的有效手段之一. 相似文献
9.
Effects of pore water pressure dissipation on rate dependency of shear strength in localised failure of soils 
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下载免费PDF全文 The paper presents analytical solutions for the evolution of excess pore pressures in the vicinity of a shear band in a rate‐dependent, strain‐softening permeable soil, with the aim to explore, both qualitatively and quantitatively, the potential variation of failure shear stress in the shear band. The solutions encompass both dissipation of a pre‐existing pore pressure regime within the main soil domain, and the effects of generation of additional pore pressure within the shear band itself. The simplified analytical solutions were checked by numerical inversion of exact solutions in Laplace transform space, confirming their high accuracy. The solutions show that it is possible for the failure shear stress to rise initially because of short‐term dissipation of the pre‐existing excess pore pressure at a faster rate than generation of new excess pore pressure within the shear band. This apparent strain hardening in a strain‐softening soil can be misleading in that it can temporarily slow down the sliding mass and create a false sense of stabilization of the slope. It can also result in additional temporary shear resistance for sliding foundations or pipelines on the seabed. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
10.
《Sedimentology》2018,65(4):1246-1276
Submarine mass‐transport deposits represent important stratigraphic heterogeneities within slope and basinal sedimentary successions. A poor understanding of how their distribution and internal architecture affect the fluid flow migration pathway may lead to unexpected compartmentalization issues in reservoir analysis. Studies of modern carbonate mass‐transport deposits mainly focus on large seismic‐scale slope failures; however, the near‐platform basinal depositional environment often hosts mass‐transport deposits of various dimensions. The small‐scale and meso‐scale (metres to several tens of metres) carbonate mass‐transport deposits play a considerable role in distribution of sediment and therefore have an impact on the heterogeneity of the succession. In order to further constrain the geometry and internal architecture of mass‐transport deposits developed in near‐slope basinal carbonates, a structural and sedimentological analysis of sub‐seismic‐scale mass‐transport deposits has been undertaken on the eastern margin of the Apulian carbonate platform in the Gargano Promontory, south‐east Italy. These mass‐transport deposits, that locally comprise a large proportion (50 to 60%) of the base of slope to basinal sediments of the Cretaceous Maiolica Formation, typically display a vertically bipartite character, including debrites and slump deposits of varying volume ratios. A range of brittle and ductile deformation styles developed within distinct bed packages, together with the presence of both chert clasts, folded chert layers and spherical chert nodules, suggest that sediments were at different stages of lithification prior to downslope movement associated with mass‐transport deposits. This study helps elucidate the emplacement processes, frequency and character of subseismic‐scale mass‐transport deposits within the basinal carbonate environment, and thereby reduces the uncertainties in the characterization of subsurface carbonate geofluid reservoirs. 相似文献
11.
Emplacement of small‐volume (<0·1 km3) pyroclastic flows is significantly influenced by topography. The Arico ignimbrite on Tenerife (Canary Islands) is a characteristic small‐volume pyroclastic flow deposit emplaced on high relief topography. The pyroclastic flow flowed down pre‐existing valleys on the southern slopes of the island. In proximal areas deep (up to 100 m) valleys acted as efficient conduits for the pyroclastic flow, which was mostly channelled; in this particular area the ignimbrite corresponds to a homogeneous, moderately welded deposit, consisting of flattened pumices in an abundant ashy matrix with a relatively low lithic fragment content. In intermediate zones significant changes occur in the steepness of the slope and, although still channelled, here the pyroclastic flow was influenced by hydraulic jumps. In this area, two different units can be clearly distinguished in the ignimbrite: the lower unit is composed of a lithic‐rich ground‐layer deposit that formed at the turbulent, highly concentrated head of the flow; the upper unit consists of a well welded pumice‐rich deposit that occasionally reveals a basal layer formed by shearing with the lower part. This division into two units is maintained as far as distal areas near the present‐day coastline, where the slope is very gentle or null and the ignimbrite is not channelled. The ground layer is not found in distal areas. The ignimbrite here only consists of the upper unit, which is occasionally repeated due to a surging process provoked by the lower flow speed, as the pyroclastic flow spread out of the channelled zone. A theoretical model on how topography controlled the deposition of the Arico ignimbrite is derived by interpreting the observed lithological and sedimentological variations in terms of changes in topography and bedrock morphology. This new model is of general applicability and will help to explain other deposits of similar characteristics. 相似文献
12.
Komatiites I: Eruption and Flow 总被引：2，自引：1，他引：2
Because of their high eruption temperatures and ultrabasic composition,komatiite lavas had low viscosities, which typically rangedfrom 0-1 to 10 Pa s. A major consequence of this low viscosityis that most lavas erupted as turbulent flows. An analysis oftheir ascent through the lithosphere suggests ascent velocitiesin the range of 1 to over 10ms–1 and Reynolds numbersmuch greater than the critical value of 2000. The lavas wouldhave remained turbulent for most or all of their subsequentflow and emplacement. Typical horizontal flow rates are estimatedto range from 0?5 to 100 m2 s–1 per unit width of flow.Such turbulent lava flows would have lost their heat by convectionto the surroundings, at rates which are orders of magnitudegreater than the rates for laminar flows, which cool by conduction.A quantitative analysis of the cooling of komatiites indicatescooling rates from over 1000 ?C hr–1 to a few ?C hr–1,while the flows remained turbulent. These rates are in an appropriaterange to cause phenomena such as high nucleation rates, strongsupersaturation of the lava, delayed nucleation of olivine,and skeletal or dendritic crystal morphologies. Komatiites often flowed over ground composed of rocks with lowermelting temperatures. It is proposed that the turbulent lavasmelted the ground to form deep thermal erosion channels. Meltingrates at the lava source are calculated at several metres perday, and deep troughs with depths of several metres to hundredsof metres and lengths of several kilometres probably formed.Laboratory experiments performed to simulate thermal erosionshow qualitative agreement with the theory with channel depthdecreasing downstream. The experiments also revealed that thechannel margins become undercut during thermal erosion to formoverhanging sides of the channel. Some sinuous rilles observedin the mare regions of the Moon are thought to have formed bythermal erosion (Hulme, 1973). They provide analogues of thechannels postulated to form in komatiite eruptions, where conditionswere in fact more favourable for thermal erosion. An assessmentof the role of olivine crystals, precipitated in the cooling,turbulent flows, indicates that they will remain in suspensionuntil the lava has come to rest. Contamination of komatiite lava by underlying rock can be asmuch as 10 per cent. Some illustrative calculations show howthe major element and trace element compositions of residualmelts can be significantly modified by combined assimilationand fractional crystallization in a moving flow. Assimilationof tholeiitic basalt into a komatiite can cause incompatibletrace element ratios, such as Ti/Zr and Y/Zr, and the rare earthpatterns of derivative lavas, to vary substantially. Some ofthe variations in such geochemical parameters, which are oftenascribed to mantle heterogeneity, also could have resulted fromassimilation of the ground. Assimilation could have modifiedthe isotope geochemistry of lava suites and led to apparentages which differ from the true eruption age. The thermal erosionmodel also provides an explanation of the formation of somenickel sulphide ores found at the bottom of thick komatiiteflows. It is proposed that ores can form by assimilation ofsulphur-rich sediment, which combines with Ni from the komatiiteto form an immiscible liquid. 相似文献
13.
14.
Historical reports from the 17th Century document two destructive tsunamis with run‐ups exceeding 5 m, affecting proximal basins of Lake Lucerne (Switzerland). One event in ad 1601 is coeval with a strong nearby earthquake (MW ca 5·9) which caused extensive slope failures in many parts of the lake. The second event in ad 1687 is associated with an apparently spontaneous partial collapse of the Muota river delta. This study combines high‐resolution bathymetry, reflection seismic and lithological data to document the sedimentary and morphological signatures of the two subaqueous mass movements that probably generated the observed tsunamis. Such mass movements are significant as a common sedimentation process and as a natural hazard in fjord‐type lakes and similar environments. The deposits, covering large parts of the basins with thicknesses reaching >10 m, consist of two subunits: A lower ‘massflow deposit’ contains variably deformed sediments from the source areas. Its emplacement affected pre‐existing sediments, incorporating thin sediment slices into the deposit and increasing its volume. Deep‐reaching deformation near basin margins is expressed as bulges on the lake floor. An overlying ‘megaturbidite’, featuring a graded, sandy base and a thick homogeneous muddy part, was deposited from suspended particles. The source area for the ad 1601 event, gently dipping lateral slopes with an unconsolidated hemipelagic sediment cover, hosts a pronounced slide scar with sharp escarpments and sliding surfaces. The source area for the ad 1687 event on an active delta slope has been overprinted by continued sedimentation and does not show an unambiguous scar. The case studies are exemplary for end‐member types of source areas (lateral versus delta slopes) and trigger mechanisms (seismic versus aseismic); they show that morphological mapping and reconstructions of past events are key components of a hazard assessment for mass movement‐generated tsunamis. 相似文献
15.
16.
R. A. F. Cas 《Australian Journal of Earth Sciences》2013,60(7-8):381-401
The Merrions Tuff is the structural‐stratigraphic marker of the flysch‐like fill of the Hill End Trough, a Siluro‐Devonian basin lying in central‐western New South Wales and bounded to the east and west by coeval, linear, meridional, shoalwater accumulations of limestones and volcanics. The Merrions Tuff is grossly tabular in form and consists of sheet‐like to lobate horizons of dacitic lavas and volcaniclastics. Internal vertical and lateral heterogeneities allow subdivision into members. Although some members are regionally extensive, others are not, so leading to a complex internal stratigraphy. Identification of regionally extensive time planes and analysis of the time‐stratigraphy shows that the base of the Merrions Tuff is diachronous. Although mesoscopic sedimentary structures such as sole structures are rare or not exposed, analysis of the parameters (spatial distribution of members, variation of and within members of their shape, thickness, grainsize, sand‐to‐shale ratios, numbers of sedimentation units, and distribution of vitriclasts), demonstrates that the Merrions Tuff was not derived from a single source and a single eruptive phase, but from several sources which were variously active at different times. Furthermore, through time there appears to have been a shift in the direction of dominant influx of basin fill, from the west through to the south, to the southeast and finally the east. Depositional patterns were controlled by a changing basin‐floor topography which was particularly influenced by the emplacement of the very thick member B lava. The effect of this flow was to displace the northwesterly‐trending basin axis existing at the beginning of the history of the Merrions Tuff to the east. 相似文献
17.
R. Gertisser S.J. Charbonnier V.R. Troll J. Keller K. Preece J.P. Chadwick J. Barclay R.A. Herd 《Geology Today》2011,27(2):57-62
Merapi is Indonesia's most dangerous volcano with a history of deadly eruptions. Over the past two centuries, the volcanic activity has been dominated by prolonged periods of lava dome growth and intermittent gravitational or explosive dome failures to produce pyroclastic flows every few years. Explosive eruptions, such as in 2010, have occurred occasionally during this period, but were more common in pre‐historical time, during which a collapse of the western sector of the volcano occurred at least once. Variations in magma supply from depth, magma ascent rates and the degassing behaviour during ascent are thought to be important factors that control whether Merapi erupts effusively or explosively. A combination of sub‐surface processes operating at relatively shallow depth inside the volcano, including complex conduit processes and the release of carbon dioxide into the magmatic system through assimilation of carbonate crustal rocks, may result in unpredictable explosive behaviour during periods of dome growth. Pyroclastic flows generated by gravitational or explosive lava dome collapses and subsequent lahars remain the most likely immediate hazards near the volcano, although the possibility of more violent eruptions that affect areas farther away from the volcano cannot be fully discounted. In order to improve hazard assessment during future volcanic crises at Merapi, we consider it crucial to improve our understanding of the processes operating in the volcano's plumbing system and their surface manifestations, to generate accurate hazard zonation maps that make use of numerical mass flow models on a realistic digital terrain model, and to utilize probabilistic information on eruption recurrence and inundation areas. 相似文献
18.
M. Carracedo Sánchez F. Sarrionandia T. Juteau J. I. Gil Ibarguchi 《International Journal of Earth Sciences》2012,101(8):2201-2214
Distal pillows occur associated with a sheet flow and megapillows in the me?akoz outcrops of the Basque–Cantabrian Basin (N Spain). Basaltic volcanic rocks are interbedded with Turonian sediments and depict typical features of shallow submarine emissions. An exceptional basaltic flow displays four types of morphology: (1) sheet lava with columnar jointing, (2) welded columnar breccia, (3) megapillows, and (4) pillow lavas with sparse megapillows. The field data from me?akoz combined with experimental and field data from the literature for similar volcanic facies can be integrated into a new propagation model for the transition from sheet flows to pillow lavas in underwater environments. At near vent high emission rates, lava flows develop a thin crust immediately after its emplacement and break at the front under the magma pressure allowing for the massive propagation of lava as a sheet flow. Increased cooling promotes thickening of the lava outer crust far from the vent while continuous supply of fresh magma increases the pressure onto the thick crust until its rupture. The lava emitted in small volumes from the flow front promotes the formation of megapillows and pillow lavas that are later on covered by the advancing sheet flow. The lava flow freezes progressively toward more distal parts, gradually increasing its viscosity until it stops. The crust temporarily holds the residual melt pressure increasing the volume of the flow distal section by inflation. Finally, the internal magma pressure breaks the crust and liberates lava at moderate-to-low flow rates producing pillows, while lava drainage inside the inflated sheet flow produces lava tunnels and gravitational collapse of the roofs by hydrostatic pressure to form breccias nurtured by columnar lava fragments. 相似文献
19.
《Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy》1999,24(11-12):949-952
The formation of compound lava fields is a common feature of basaltic volcanic areas such as Mount Etna and Hawaii. It is generally promoted by a breakin-slope which results into a decrease of the mean flow velocity and the rapid adjustment to new rheological conditions. In fact, on a steep slope the flow is generally focused into long-lived lava tubes or channels. On the contrary, in correspondence of a flat ground the propagation of a lava field is guaranteed by the continuos opening of new ephemeral vents, and by the overlapping of lava lobes or tongues the length of which is order of 10−1−102 m. At Mount Etna these flow units show a complex structure which reflects the existence of a central plug zone and lateral shear zones, and an internal structure characterized by a succession of lava layers separated by gas-rich layers which occur in correspondence of vesicle alignments. Such internal structure insulates the active moving core and preserves high lava temperatures, favoring the advancement of the flow units. The evolution of a compound lava field may be thus envisaged as a spatial and temporal succession of lava tubes. An example of this situation may be found in the 1983 and 1991–93 Etnean eruptions, where the propagation of long-lived compound lava fields through a great number of small subarterial flow units gave origin to a source of natural hazards for some of the communities living on the flanks of the volcano. The detailed study of the structure of the described lava flows helps understand their emplacement dynamics and evaluate the associated volcanic, hazard. 相似文献
20.
The Rupnica locality became the first protected geosite in Croatia in 1948 owing to a well‐exposed phenomenon of columnar jointing developed in albite rhyolite. According to the geochemical signature, melt that originated at mid‐crustal depths (10–15 km) reached a shallow emplacement level as a high‐temperature lava. Non‐destructive statistical analysis conducted at the geosite revealed that relatively narrow (29.4 ± 6.3 cm) predominantly four‐ and five‐sided columns, tightly packed striae (4.8 ± 2.1 cm) and small‐amplitude wavy sets of columns (wavelength of 32.5 ± 6.7 cm) dominate the exposed part of the Rupnica. A number of features quantified through this statistical approach, together with petrography, geochemistry and the geology of the geosite's surroundings, suggest the rapid cooling of a (sub)surface acidic lava body and the behaviour of the evolving volcanic system, developing columnar jointing under the combined influence of large‐scale constitutional supercooling and thermal contraction processes. 相似文献