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Geological setting of Kinmen Island, Taiwan, and the distribution of lightning on 7th May 2018. (A) Simplified geology of Kinmen Island, showing the distribution of the Taiwushan granitic gneiss. The map was created in QGIS version 3.4.14 (https:// qgis. org). Individual CG lightning strikes and their energy are indicated by the location of size of circles. (B) Map view of the fulgurite collected by unmanned aerial vehicle with contours (24°27′51.6" N 118°25′37.9" E). (C) Outcrop photograph of two fulgurites including fresh brown-black glassy crust at the surface (surface fulgurite, part (D)) and within a shallowly-dipping fracture (fracture-related fulgurite; parts (E,F)). (D) Patch of fresh surface fulgurite around 1 m in diameter. (E) Fulgurite surrounding a shallowly-dipping fracture in granitic gneiss that is sub-parallel to the regional gneissic exfoliation joint. (F) Detail of fracture-related fulgurite observed on a subvertical outcrop face, showing a dark crust.
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Cloud-to-ground lightning causes both high-temperature and high-pressure metamorphism of rocks, forming rock fulgurite. We demonstrate that a range of microstructural features indicative of high temperatures and pressures can form in fulgurites at the surface and in fractures up to several meters below the surface. In comparison to a granite refere...
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... occurrence and fulgurite formation on Kinmen Island, Taiwan. Kinmen Island, Tai- wan, is comprised primarily of granitic rocks and their metamorphosed equivalents, mainly granitic gneiss 15 . These are unconformably overlain by Miocene and Pleistocene sedimentary rocks (Fig. 1a). The rock fulgurites described below are found on outcrops of weakly foliated granitic gneiss composed of c. 47% quartz, 43% feldspar (comprising K-feldspar and plagioclase), 7% biotite, and 3% accessory minerals (garnet, zircon, and magnetite; 15 ). The gneissic fabric has a regional strike and dip of c. N4E 20E, and fractures are ...
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... 7th May 2018 more than 3000 lightning events were detected during a storm on Kinmen Island. About 14% of these were cloud-to-ground lightning (circles in Fig. 1a). The strike with the highest current intensity (~ 162 kiloamperes) came to ground on Mt. Taiwushan, the island's highest mountain (253 m). Following the 7 th May storm, we traveled to Mt. Taiwushan in search of fulgurite. One fresh surface occurrence of fulgurite was identified, which occurs as a roughly 1-m diameter patch of ...
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... (~ 162 kiloamperes) came to ground on Mt. Taiwushan, the island's highest mountain (253 m). Following the 7 th May storm, we traveled to Mt. Taiwushan in search of fulgurite. One fresh surface occurrence of fulgurite was identified, which occurs as a roughly 1-m diameter patch of brown-black glassy crust on the surface of granitic gneiss ( Fig. 1b-d; "surface fulgurite" below). A wider examination of the outcrop also revealed a partially moss-covered fulgurite surrounding a shallowly-dipping fracture that intersects both the main sub-horizontal outcrop surface and several sub-vertical rock faces nearby ( Fig. 1e,f; "fracture-related fulgurite" below). The fracture-related ...
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... diameter patch of brown-black glassy crust on the surface of granitic gneiss ( Fig. 1b-d; "surface fulgurite" below). A wider examination of the outcrop also revealed a partially moss-covered fulgurite surrounding a shallowly-dipping fracture that intersects both the main sub-horizontal outcrop surface and several sub-vertical rock faces nearby ( Fig. 1e,f; "fracture-related fulgurite" below). The fracture-related fulgurite lies sub-parallel to the regional gneissic foliation. At its lowest point, the fracture-related fulgurite is c. 2 m below the top surface of the outcrop. It is heterogeneously distributed along the fracture and variable in thickness between a few mm's and a few cm's. ...
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... (sanidine) from the surface fulgurite is ~ 1.57 ± 0.20 GPa, ~ 1.39 ± 0.13 GPa within K-feldspar from fracturerelated fulgurites. The calculated average residual stress in quartz grains, adjacent to the analyzed K-feldspar grains, is ~ 0.50 ± 0.07 GPa and ~ 0.38 ± 0.05 GPa for surface and fracture-related fulgurites, respectively (Supplementary Fig. S1). Because of the abundance of plagioclase grains in the reference sample, the data of Laue diffraction on plagioclase could be set as a representative regional stress at depth. At-depth plagioclase contains ~ 0.38 ± 0.06 GPa from the granitic reference sample (Fig. 7c). In the two fulgurites, the direction of the major residual stress ...
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... and temperatures greater than 2000 K on the surface of the target rock 17 . To investigate whether or not sufficient electrical energy to form fulgurite can penetrate to a depth of several meters, we use the numerical modeling concept of ref. 12 and develop a simple model that; (1) uses the recently observed lightning currents from Kinmen Island (Fig. 1a) and, (2) contains low electrical resistivity pathways (i.e., simulated fluid-fractures) that are not connected to the surface (Fig. ...
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... is noted that despite the high temperatures required for melting, the quartz grains seem not appear to have undergone any type of recovery that would have subsequently destroyed any shock metamorphic textures ( Supplementary Fig. S1). Theoretical studies suggest that the propagation of shock waves across heterogeneous interfaces may lead to longer duration of the same pressure and higher magnitude of temperature and promotes the kinetics of nucleation of the high-pressure polymorph 28,29 . ...
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... studies suggest that the propagation of shock waves across heterogeneous interfaces may lead to longer duration of the same pressure and higher magnitude of temperature and promotes the kinetics of nucleation of the high-pressure polymorph 28,29 . As a result, the high pressure-temperature phase transitions in alkali feldspar can be sensitive to attribute to shock-induced phase transitions, which quartz grains are only brecciated, consistent with the observed low residual stresses (Supplementary Fig. S1). We therefore suggest that lightning strikes can give rise to a range of temperature-and pressure-dependent crystallographic reactions involving feldspars, although the specific nature of such reactions will require additional natural and experimental data to be collected and quantified. ...
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... database of sanidine (AMCSD 0000312) and oligoclase (AMCSD 0010721) is used to calculate the strain tensor for fulgurites and the reference granite sample, respectively. After the index and calculation, six strain tensor components (ε11, ε22, ε33, τ12, τ13, τ23,) give the quantity and direction of principle and shear strain in the crystal. Negative values refer to compressive force, and positive values pertaining to tensile force. ...
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... occurrence and fulgurite formation on Kinmen Island, Taiwan. Kinmen Island, Tai- wan, is comprised primarily of granitic rocks and their metamorphosed equivalents, mainly granitic gneiss 15 . These are unconformably overlain by Miocene and Pleistocene sedimentary rocks (Fig. 1a). The rock fulgurites described below are found on outcrops of weakly foliated granitic gneiss composed of c. 47% quartz, 43% feldspar (comprising K-feldspar and plagioclase), 7% biotite, and 3% accessory minerals (garnet, zircon, and magnetite; 15 ). The gneissic fabric has a regional strike and dip of c. N4E 20E, and fractures are ...
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... 7th May 2018 more than 3000 lightning events were detected during a storm on Kinmen Island. About 14% of these were cloud-to-ground lightning (circles in Fig. 1a). The strike with the highest current intensity (~ 162 kiloamperes) came to ground on Mt. Taiwushan, the island's highest mountain (253 m). Following the 7 th May storm, we traveled to Mt. Taiwushan in search of fulgurite. One fresh surface occurrence of fulgurite was identified, which occurs as a roughly 1-m diameter patch of ...
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... (~ 162 kiloamperes) came to ground on Mt. Taiwushan, the island's highest mountain (253 m). Following the 7 th May storm, we traveled to Mt. Taiwushan in search of fulgurite. One fresh surface occurrence of fulgurite was identified, which occurs as a roughly 1-m diameter patch of brown-black glassy crust on the surface of granitic gneiss ( Fig. 1b-d; "surface fulgurite" below). A wider examination of the outcrop also revealed a partially moss-covered fulgurite surrounding a shallowly-dipping fracture that intersects both the main sub-horizontal outcrop surface and several sub-vertical rock faces nearby ( Fig. 1e,f; "fracture-related fulgurite" below). The fracture-related ...
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... diameter patch of brown-black glassy crust on the surface of granitic gneiss ( Fig. 1b-d; "surface fulgurite" below). A wider examination of the outcrop also revealed a partially moss-covered fulgurite surrounding a shallowly-dipping fracture that intersects both the main sub-horizontal outcrop surface and several sub-vertical rock faces nearby ( Fig. 1e,f; "fracture-related fulgurite" below). The fracture-related fulgurite lies sub-parallel to the regional gneissic foliation. At its lowest point, the fracture-related fulgurite is c. 2 m below the top surface of the outcrop. It is heterogeneously distributed along the fracture and variable in thickness between a few mm's and a few cm's. ...
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... (sanidine) from the surface fulgurite is ~ 1.57 ± 0.20 GPa, ~ 1.39 ± 0.13 GPa within K-feldspar from fracturerelated fulgurites. The calculated average residual stress in quartz grains, adjacent to the analyzed K-feldspar grains, is ~ 0.50 ± 0.07 GPa and ~ 0.38 ± 0.05 GPa for surface and fracture-related fulgurites, respectively (Supplementary Fig. S1). Because of the abundance of plagioclase grains in the reference sample, the data of Laue diffraction on plagioclase could be set as a representative regional stress at depth. At-depth plagioclase contains ~ 0.38 ± 0.06 GPa from the granitic reference sample (Fig. 7c). In the two fulgurites, the direction of the major residual stress ...
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... and temperatures greater than 2000 K on the surface of the target rock 17 . To investigate whether or not sufficient electrical energy to form fulgurite can penetrate to a depth of several meters, we use the numerical modeling concept of ref. 12 and develop a simple model that; (1) uses the recently observed lightning currents from Kinmen Island (Fig. 1a) and, (2) contains low electrical resistivity pathways (i.e., simulated fluid-fractures) that are not connected to the surface (Fig. ...
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... is noted that despite the high temperatures required for melting, the quartz grains seem not appear to have undergone any type of recovery that would have subsequently destroyed any shock metamorphic textures ( Supplementary Fig. S1). Theoretical studies suggest that the propagation of shock waves across heterogeneous interfaces may lead to longer duration of the same pressure and higher magnitude of temperature and promotes the kinetics of nucleation of the high-pressure polymorph 28,29 . ...
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... studies suggest that the propagation of shock waves across heterogeneous interfaces may lead to longer duration of the same pressure and higher magnitude of temperature and promotes the kinetics of nucleation of the high-pressure polymorph 28,29 . As a result, the high pressure-temperature phase transitions in alkali feldspar can be sensitive to attribute to shock-induced phase transitions, which quartz grains are only brecciated, consistent with the observed low residual stresses (Supplementary Fig. S1). We therefore suggest that lightning strikes can give rise to a range of temperature-and pressure-dependent crystallographic reactions involving feldspars, although the specific nature of such reactions will require additional natural and experimental data to be collected and quantified. ...
Context 18
... database of sanidine (AMCSD 0000312) and oligoclase (AMCSD 0010721) is used to calculate the strain tensor for fulgurites and the reference granite sample, respectively. After the index and calculation, six strain tensor components (ε11, ε22, ε33, τ12, τ13, τ23,) give the quantity and direction of principle and shear strain in the crystal. Negative values refer to compressive force, and positive values pertaining to tensile force. ...
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To unravel fault zone properties, high-resolution imaging and probing are pivotal. Here we present a comprehensive study utilizing Distributed Dynamic Strain Sensing of a 3D array of optical fiber with a surface-to-depth installation, traversing an active fault zone at depth, combined with a geological analysis of drilled cores. We identify an asymmetric fault zone with a narrow fault core, exhibiting a notable amplification in strain rate across a broad-band frequency range, which is attributed to the presence of weak gouge material within a much stronger host rock. This feature heightens responsiveness of the weak fault zone with low rigidity to ground motion, and intensifies strain from both nearby and remote seismic events. We demonstrate that optical fiber facilitates long-term monitoring of ground motion amplification with high spatial resolution, thus indicating where strain and deformation accumulate through repeating ruptures. This progress is pivotal to the understanding of the role of low rigidity and changes thereof within fault gouge material.
... Furthermore, most rock fulgurites are dark in color (Appel et al. 2006;Castro et al. 2020;Daly et al. 1993;Elmi et al. 2017;Gieré et al. 2015;Grapes and Müller-Sigmund 2010;Roberts et al. 2019;Kuo et al. 2021) and are typically thin glassy layers from tens (Gieré et al. 2015) to hundreds of micrometers (Appel et al. 2006). Due to weathering, some low cohesive host rocks (e.g., sandstone, tuff, and igneous rocks) may form rock fulgurite in troughs or tubular shapes. ...
... The lightning strikes on consolidated rocks would burn the lichens (Appel et al. 2006;Elmi et al. 2017), and cause cracked quartz crystals . The rock fulgurite can be distributed from several hundreds of square centimeters Gieré et al. 2015) to around ten square meters (Kuo et al. 2021). ...
... It has been suggested that fulgurite is one of the most suitable substances for the study of the effect of transient high-temperature events on rocks and soils because of both the accessibility of their host rocks and the absence of extraterrestrial contamination (Sheffer 2007). Evidence of reduction-oxidation reaction and high pressure on rocks and minerals has been described from fulgurite, indicating that thermodynamic and mechanical processes are activated in geological materials by lightning Elmi et al. 2017;Gieré et al. 2015;Kenny and Pasek 2021;Kuo et al. 2021;Roberts et al. 2019). Furthermore, the analysis of gas composition trapped in bubbles found in fulgurite glass can provide data that can help reconstruct the paleoecology of an area (Navarro-González et al. 2007). ...
Cloud-to-ground lightning can cause high-temperature and high-pressure deformation features in rock at the strike point, forming fulgurite. Although cloud-to-ground lightning is a frequent phenomenon, rock fulgurites are rarely reported. Here, we present field, optical microscope, X-ray fluorescence, scanning and transmission electron microscope, in situ synchrotron projection X-ray microscopy and X-ray diffraction, and Raman data to investigate the formation and preservation of a recently formed rock fulgurite from Kinmen Island, Taiwan. In the field, the fulgurite is asymmetrically distributed on the surface over an ~ 12 m² area. In detail, the fulgurite contains an opaque glassy layer comprised of quartz and feldspar clasts, voids, iron-rich spheres, and barite aggregates that overlies fractured quartz grains and feldspar grains with planar features. Secondary minerals found locally adhering to the glassy layer as greenish patches are mainly jarosite group minerals, which commonly form as a secondary hydrothermal alteration product. We interpret the jarosite to have formed during the solidification of melt in the presence of raindrops, suggesting the rapid alteration of glass and short preservation potential of rock fulgurite. Finally, we estimate the production ratio of fulgurite by calculating the energy required for fulgurite formation and that released to the ground by the lightning event. A calculated energy ratio of 0.026% is within the range of 10–2 to 10–4 of the lightning total energy delivered to the strike point. We suggest that the scarcity of rock fulgurite in the geological record may be due to both the low production possibility and rapid alteration.
Knjiga „Ni na nebu ni u zemlji. Procesi stjecanja znanja o dalekoj prošlosti“ bavi se dugotrajnim procesima koji su doveli do formiranja arheologije kao znanstvene discipline. Iako arheologija kao znanstvena samostalna disciplina postoji od 19. stoljeća, interes za prošlost je inherentan čovjeku pa možemo reći da interes za prošlost postoji otkada postoji svijest. Prošlost se percipirala, upotrebljavala, bilježila i prenosila na mnogo načina dio kojih se pokušalo ocrtati u ovoj knjizi. To su procesi spoznaje, zabluda, maštanja, zaborava, pričanja, prepričavanja, zapisivanja, prepisivanja, preobličivanja. Istaknula sam procese, koji često izostaju iz uobičajenih pregleda povijesti discipline, a imali su važnu ulogu u oblikovanju društvene zbilje, odnosa prema prošlosti i selekcije predmeta i događaja iz prošlosti koji su nam poznati i danas. Namjera ove knjige nije donijeti cjelovit prikaz razvoja pojedinog razdoblja ili arheologije nego na primjerima upozoriti na ključne aspekte i događaje, istaknuti da razvoj arheologije traje koliko i cijela čovjekova (pisana) povijest, uputiti na opsežnije publikacije i problematizirati neke teme koje, po autoričinom mišljenju, najbolje opisuju okolnosti i promjene u kojima neki istraživački interes nastaje, raste i gubi se.
