1). incidence angle with secondary splatter and fragments peppering the countryside. A lake of green jade, Time magazine described it in September 1945. The U.S. Department of Energy's Office of Scientific and Technical Information The image to the left is an example of a teardrop-shaped tektite (LTS1) from the Australasian strewn field. ago. The Suspected Eastern Australian Impact one roughly the same as that which excavated the Gulf of Mexico at the Mesozoic-Cenozoic Epeirogenic uplifts seem to correspond spatially with the 2900-km radius rings Meteor, meteroid, asteroid, comet: What's the difference? Found inside Page 646Four strewn fields are currently known: the Australasian, the Ivory Coast, the Central European, and the North whereas for the Australasian strewn field, no suitable source crater has yet been found (Glass, 1990; Koeberl, 1994). Found inside Page 75Microtektites from the North American, Ivory Coast, and Australasian strewn fields have been recovered from deep-sea sediments (see, e.g., Glass 1967, 1968, 1969, 1972; Cassidy et al. 1969). Microtektites are, by definition, Scientists have largely been able to determine the source crater for tektites, with the exception of one -- the Australasian field. our last geomagnetic reversal, and perhaps even, 4) the demise of Peking Man 0.78 Ma) of these large asteroid/cometary impacts on Earth, the location of its Microbiologists; Virologists; Educators; Geographers; Biography; Australia. One of the most fascinating things about the huge Australasian strewn field is the absence of a source crater. The low angle impact, as evidenced by the extremely asymmetrical distribution of tektites (see map below), may not have left a typical rounded crater. Microtektites belonging to the Australasian tektite strewn field have been found in 75 locations so far (Prasad et al. the eastern third of is likely that these events are related. The discovery of these microtektites, and others recovered previously from sites along the Transantarctic Mountains, supports the idea of a stable East Antarctic Ice Sheet over the last ~1 million years. It appears that different regions in the surrounding Australasian tektite field 65th birthday I started focusing on the large-impact scenario of Australia using The Bolaven Plateau volcanic field likely buries the impact crater that produced the tektites of the Australasian strewn field. 35 Microtektites from the Australasian and Ivory Coast strewn fields show low 36 values of the Fe3+/(Fe2++Fe3+) ratios, in fair agreement with tektites from the same 37 strewn field. Australasian tektites are found in most of Southeast Asia, including Vietnam, Thailand, Southern China, Laos and Cambodia. Found inside Page 21The c.800ka Australasian strewn-field, the largest and youngest strewn-field, extends across most of Southeast Asia (Vietnam, Thailand, southern China, Laos, and Cambodia), as well as the Philippines, Indonesia (including Java), glaciated for the first time in the mid-Pleistocene, when the entire tumultuous time that must have been for Earth's creatures, especially those Still, the existence of an impact structure in Tasmania has been neglected and Based on the scientists' calculations, the hidden impact crater that produced the vast Australasian field of strewn tektites is about 13 kilometers (8 Found inside Page 110SOUTHEAST ASIAN AND AUSTRALIAN TEKTITES Often referred to as the Australasian Strewn Field, this area includes Australia and New Zealand, Cambodia, southern China, Laos, Thailand, Vietnam, Java, Malaysia, and the Philippines. Recent estimates suggest it may cover 10%30% of the Earth 's surface. very nicely, but awaits field confirmation. This text commences with the history of tektites, from mediaeval China, through finds in Czechoslovakia in the 18th century and Darwin's description while on the Beagle, to 20th-century finds in South East Asia, the Ivory Coast and the USA. Australasian tektites represent the largest group of tektites on Earth, and their strewn field covers up to one sixth of Earths surface. The Australasian strewn field is characterized by a tri-lobe pattern consisting of a large central distribution lobe, and two smaller side (fig. Global gravity and show morphological and chemical dissimilarity owing to where they're located, The shapes of splash-form tektites (spheres, droplets, teardrops, dumbbells, etc., or fragments thereof) are the result of the solidification of rotating liquids in the air or vacuum. GLASS, B.P. On the day following my The photo above shows four members of the ~788 t.y.-old Australasian strewn field, which covers about 20% of the Earth's surface. Found inside Page 101The former is regarded as unlikely based on available compositional constraints, but the age data do overlap the age of the Australasian strewn field and considerable compositional variation is found across this strewn field (Chapman been. aligned along the ~355. We have examined a combined Seasat/Geos 3 altimeter data set of sea surface heights in the northern portion of the Australasian strewn field for negative gravity anomalies on the continental Since the 1960s, it has been accepted that the strewn field included Hainanin southern China to Australia or about 10% of the Earth's surface. Full colour booklet describing the age, occurrence, composition, shapes and theories of origin of these pebble-sized, naturally occurring glass objects that have long fascinated scientists and explorers. Found inside Page A-135The maximum number of tektites in the Australasian strewn field Luminescence of achondritic forsterite and is estimated to be about 2 x 10 13 on the basis of synthetic diopside their areal density in places where reworking is A mineral After several decades of fruitless quest for a parent crater for Australasian tektites, mostly in the main part of the strewn field in Indochina, the crater remains undiscovered. The Australasian ( biogeographic region that includes Australia and the islands adjacent to it, including New Guinea, New Zealand, Polynesia, and Tasmania) Strewn Field is by far the largest in the world. Indochinite a dark, black Tektite from the Australasian strew field, found in South East Asia. Those have been discovered in Belitung Island which is a part of Australasian strewn field. Google Earth. but this aspect requires much more study. The similar to 790 ka Australasian (micro)tektite strewn field is one of the most recent and best-known examples of impact ejecta emplacement as the result of a large-scale cratering event across a considerable part of Earth's surface (>10% in area). These strewn fields are found on every continent except Antarctica, according to the. needed for Earth to adjust to such an energy flux? The Australasian strewnfield is the youngest and largest of the tektite strewnfields. The minimum absorption of the Thailand tektite (Australasian strewn field) is around 640 nm whereas the Slovokia sample (Moldavite strewn field) is at 582 nm. leaves a lot to be desired. Comparison of Fe What really happened?. The low angle impact, as evidenced by the extremely asymmetrical distribution of tektites (see map below), may not have left a typical rounded crater. What a tektites have been reported. incidence angle with secondary splatter and fragments peppering the countryside. It all seems to correlate The highly polished (2) Moldavites (Tektites of Bohemia) belong'to There seems to be a similar age for all tektites and microtektites in the Australasian strewn field and the 'layered tektites' and 'splash form types' found in Asia suggest an impact occurred in this region with the aerodynamically shaped australites actually being ejected the furthest. Tektites are gravel-sized bodies composed of black, green, brown, or grey natural glass. craters spread over an enormous impact strewn field estimated to be 800,000 years old, One bad period on Earth about 800,000 B.P. Figure 3. All of these events date to within about 12,000 years of 790,000 B.P. Australasian tektite strewn field sourced from newly recognised impact crater in southern Laos. B.P. As can be seen it Table D many of the oxides are characteristic of a strewn field. appreciated. Found insideAustralian Tektite Strewnfield, makes very clear. As for what tektites are, That the Australasian strewn field is swamped with tektites is clear evidence of some Armageddon-style incident having taken place in the past. Does continent. (before the present) considering time-measurement errors! We have examined a combined Seasat/Geos 3 altimeter data set of sea surface heights in the northern portion of the Australasian strewn field for negative gravity anomalies on the continental shelf and slope which might be related to the source crater for these tektites. It is a valuable resource for mineralogists, materials scientists, crystallographers, and earth scientists. This book includes: An introduction to the RRUFF database for structural, spectroscopic, and chemical mineral identification. A given strewn field will contain all tektite types, but most MN-type are known from the Australasian field. There are four major strewn fields, one in North America, the Ivory Coast, Czechoslovakian and Australia. The landscape was incredibly scarred, and in many place, melted by the nuclear explosion., The Smithsonian Magazine provides these words: No one commented on the glass at the timeits creation was the least of the Gadgets spectacular effectsbut visitors to the site after the war noticed the unusual scattering of glassy mineral that surrounded the shallow bomb crater and began collecting pieces as souvenirs. The most famous variety of Tektite is the green Moldavite, which hails from the Czech Republic. Also applied to the area covered by tektites, which are produced by large meteorite impacts. temporal coincidence between the four enigmatic circumstances noted above in Any help with that would be Darwin glass, an impact glass occurring in South West Tasmania, has been found at least since human beings reached Tasmania ca. enigmatic Australasian tektite field (figs. The Bolaven Plateau volcanic field likely buries the impact crater that produced the tektites of the Australasian strewn field. This is the most recent strewn field, the largest and is unique due to the very low angle impact, which resulted in the formation of highly oriented forms typified by the much sought after flanged Australite buttons. While the Australasian strewn field (ASF) is the most recent (ca. Tektites fell over 16-18 percent of the Earth's surface. Tektite and especially micro-tektite strewn fields come with an inherent advantage of being distributed over vast geographic areas as demonstrated in three of the four strewn fields (Koeberl 1994; Glass 1990). ensuing lithospheric flexure and changed mantle dynamics needed to reconfigure A photograph showing mid-Pleistocene Australasian strewn field. The large A secondary objective of the present study was to At only 790,000 years old, the Australasian tektite strewn field (Fig. In contrast to tektites, microtektites are sub-millimetre in size and are found almost exclusively in deep-sea cores. Aerodynamically shaped tektites are known mainly from the Australasian strewn field where they occur as flanged-button australites. The largest component of the collection is from the Australasian strewn field, but there are also representative samples of other major global strewn fields. show morphological and chemical dissimilarity owing to where they're located, When asked through correspondence, he told me that the photograph was taken at Von Koenigswald divides it into three zones: a northern zone comprising that part of southern China where tektites occur, the Indochinese The U.S. Department of Energy's Office of Scientific and Technical Information It is the only adequately large and thick postimpact deposit on the Khorat Plateau, the largest region of plausible target rocks. Found inside Page 786Tektites of the Australasian strewn field (AA) include australites, thailandites, indochinites, philippinites, and javanites and spread from the southeastern region of Asia down to Australia (Fig. 22.10). It covers most of Australia and Southeast Asia and a large portion of the Indian Ocean. The photo above shows four members of the ~788 t.y.-old Australasian strewn field, which covers about 20% of the Earth's surface. It is also the only This field is huge, estimated to cover almost 20 million square miles! Figure 5 is a photograph posted on line in Wikipedia commons that was taken by Indochinite tektite from the Pleistocene of southeastern Asia. 40 k.y. The c. 790,000-year-old strewnfield (Schneider, 1992) includes most of Southeast Asia (Thailand, Laos, Vietnam, Cambodia, and Southern China). time boundary (Chicxulub ~ 66 Ma). (2004) described a rhyolitic volcanic ash layer, occurring just above the Australasian microtektite layer, which they propose is from an early supereruption of the Toba caldera complex in northern Sumatra. heading and appears to be of low- to moderate incidence (estimated to be less Of the four known strewn fields, the Australasian Strewn Field is both the youngest (0.77-0.78 Ma {million years old}), and the largest strewn field covering a 10th the surface area of the Earth. The Main Strewn Fields Of the seven known strewn fields, the largest is the Australasian Strewn Field. Found inside Page 247they suggested may be from a previously unidentified strewn field (or strewn fields). However, the locations are all within or very close to the boundary of the Australasian strewn field as defined by Glass (I982), and the composition Although there is a preponderance of evidence that tektites were formed by asteroid impacts on the Earth, no source crater has been found for the largest and youngest of the strewn fieldsthe Australasian strewn field. Ages around 10,000-20,000 years were usually quoted. Papers related to other strewn fields may be of equal general importance. And what about the climate-frequency change? Found inside Page 375Except for the Australasian strewn field, the crater sizes used here are those reported by the Earth Impact Database (2018) and are the best estimate for the collapsed transient crater diameter (rim-to-rim dimension). Even more so because of the small This much older event has its crater buried below the Yucatan and is further marked by widespread biological extinctions. strewn field (EASF). Yet, despite the geological recency of the event and despite much geological surveying, no convincing crater has been discoveredThe mystery deepens when one realizes that whatever cataclysm sent the Australian The two Australasian coesite-bearing quartz ejecta studied in this work are silica shocked particles, < 65th birthday I started focusing on the large-impact scenario of Australia using The Australasian strewn field is deemed the largest of the four known strewn fields across the globe. aligned along the ~355o heading and most likely stem from a low Figure 3 details the locations of three of the bigger, (CNN)One of the largest known meteorites to hit Earth struck nearly 800,000 years ago, but the exact spot where it smashed into our planet has been a mystery -- until now. Read Insurance Business 10.05 by Key Media on Issuu and browse thousands of other publications on our platform. Evidence of an Ancient Impact. about 12,000 later. Microtektites belonging to the Australasian strewn field have been found in more than 40 deep-sea cores throughout much of the Indian wake. Newark, Ohio; Cincinnati rock and mineral show. The Los Alamos National Laboratory state the following on all of this: Trinitite has also been referred to as atomsite or Alamogordo glass (after a nearby city). Stay tuned. the age of the associated tektites Tektite research spans over a Darwin Crater was recognized about 30 years ago. The Australasian strewn field has tektites in Australia, southern China, the Philippines, Thailand and Indonesia. Australasian (AA) tektites are distal ejecta of a cosmic impact into terrestrial sediments 788.1 2.8 ka. Many Earth-systems were disrupted in it's These are distributed approximately 18 to 19 percent of the world (Mccall, 2005). There are four major strewn fields, one in North America, the Ivory Coast, Czechoslovakian and Australia. 41,000 year cycles before to 100,000-year-ones afterwards. Their results show that microtektites range to considerably lower silica values than cooccurring tektites, that for the two groups the other chemical components generally show similar trends with silica, and that there are This was later extended by fin The largest, suspected crater Scientists believe tektites formed from Earth material that melted upon meteorite impact and were thrown into our atmosphere, before falling back to the ground. suspected craters, although there seem to be many more. The distribution of the Australasian tektite field 3 and 4). Although only 800,00 old (yesterday, geologically), it is the only one not paired with an astroblem. Based on the scientists' calculations, the hidden impact crater that produced the vast Australasian field of strewn tektites is about 13 kilometers (8 miles) wide and 17 kilometers (11 miles) long. A pertinent question thus arises: is 12,000 years he time Meteoritics and Planetary Science said: Early workers, including such astute observers as Charles Fenner, George Baker, and Edward Gill, who picked up pristine tektites on the arid and ancient surface of Australia, became convinced that this shower of glass had arrived very recently. Insets (left to right) show (1) Found inside Page 28Four known tektite strewn fields such as the North American (35 Ma), Central European (14 Ma), Ivory Coast (1.1 Ma), The largest and youngest is the Australasian strewn field, which blankets nearly 10% of the Earth's surface, Lao. Found insideAustralasian strewn-field tektites From time to time the Earth collides with showers of small meterorites, called tektites. If the area of impact (the strewnfield) is widespread, and if the tektites are physically or chemically The impact that formed Australasian tek-tites is conspicuously young relative to those that formed other strewn fields, occurring only ~790 Age: Papers that mainly discuss the age of the Australasian strewn field using different dating techniques. Australasian tektites are found in most of Southeast Asia, including Vietnam, Thailand, Southern China, Laos and Cambodia. Recognized types of tektites, grouped according to their known strewn fields, their associated craters, and ages are: Australasian strewnfield (The impact crater was located in 2019 after a falling over an area reflective of such dynamics. The Bolaven Plateau volcanic field likely buries the impact crater that produced the tektites of the Australasian strewn field. It is the only adequately large and thick postimpact deposit on the Khorat Plateau, the largest region of plausible target rocks. north of Tasmania (fig. Tektites are small (up to a few centimetres), natural glass nodules, shaped as ovoids, spheres and dumbbells. Earth's magnetic armature? Google Earth. But alas, this may Spatial comparison of the Australasian This May be related to the chemistry of one or more of the elements making up the tektite. Australasian strewn field. At only 790,000 years old, the Australasian tektite strewn field is both the youngest and the largest known. event of probable Mid-Pleistocene age that covers the eastern third of the The search to locate it represents something akin to a holy grail in impact cratering studies. This book explores the scientific evidence that supports the popular belief that the Earth was visited in prehistory, but it goes even further-concluding that there is also compelling evidence of alien involvement with the human genome. The Australasian Strewn-Field This strewn-field, which includes the northeastern part of Thailand, is the largest of all tektite strewn-fields. figure 1 and the apparent, common link to the EASF. In contrast, microtektites from the North American strewn fields show a 38 wide range of Fe3+/(Fe2++Fe3+) ratios from 0.02 to ca. In contrast, the Australasian-tektite event is not only minus an obvious crater but seems to have had scant effect on the earths cargo of sensitive life forms. require more robust modeling reflecting atmospheric transport. magnetic potential-field anomalies show that the event happened along a ~355o Significance. (~4.4 centimeters across at its widest) Large and small impacts have affected Earth since its formation 4.55 billion years ago. than 45o) based on it's elongate, tapered geometric nature. 6, Center for Meteorite Studies, Arizona State University. Whilst a number of tektite strewn fields exist, the focus of this website is on the Australasian strewn field. The glass takes strange shapeslopsided marbles, knobbly sheets a quarter-inch thick, broken, thin-walled bubbles, green, wormlike forms. Ultimately, it is a glasslike substance that was created from the sand and other materials at the Site during the intense heat of that first atomic test. These three are 2) Geologic mapping and. long-term oscillatory cycles of hot versus cold extremes transitioned from Despite the largest size and youngest age of the strewn field, the Australasian strewn field indicate a likely impact site somewhere in southern Laos, northern Cambodia or eastern Thailand, but the location of the impact site has not yet been discovered. Moldavite (Czech: vltavn) is a forest green, olive green or blue greenish vitreous silica projectile rock formed by a meteorite impact probably in southern Germany (Nrdlinger Ries Crater) that occurred about 15 million years ago. The Australasian strewn field is the largest of those in aerial distribution (China to Madagascar to Antarctica), and estimated tektite mass (~60 billion tons). This photo includes samples of the This event likely ties together 1) the Australasian Tektite field, 2) Each of these fields, which extend over hundreds to thousands of kilometers, is associated with a meteorite impact craterexcept one, the biggest of them all, the Australasian strewn field. suspected craters, although there seem to be many more. 1) has butterfly wings and a down-range lobe (and rays) extending southeastwards sug- The material from the impact stretches across the ocean to include the Philippines, Indonesia, Malaysia, and Java. There is also Libyan Irgiz, and Aouelloul, depending on what you read. Photo by James St. John, Ohio State University, Lee et al. "This volume contains a sizable suite of contributions dealing with regional impact records (Australia, Sweden), impact craters and impactites, early Archean impacts and geophysical characteristics of impact structures, shock metamorphic The distribution map of the Australasian strewn field (Fig. The Australasian strewn field is the youngest with an age of 770 ka and appears to be somehow special compared to the others. The density of spontaneous fission tracks in microtektites is relatively low (of the order of 100 per square centi-meter). Again, what a tumultuous period that must have The Australasian strewn field, a horizon of glassy clasts (tektites) quenched from molten ejecta of a bolide impact about 0.79 Ma ( 1, 2 ), extends across about 1/10 of the Earths surface ( 3 )from Indochina to East Antarctica and from the Indian to western Pacific Oceans ( Australasian tektites vary suspected craters are mapped as part an enormous impact strewn field covering These three are aligned along the ~355 o heading and most likely stem from a low incidence angle with secondary splatter and fragments peppering the countryside. Yet, despite the geological recency of the event and despite much geological surveying, no convincing crater has been discoveredThe mystery deepens when one realizes that whatever cataclysm sent the Australian tektites aloft may have been comparable in magnitude to the impact that extinguished the dinosaurs (and other fauna) some 65 million years ago. The Australasian strewn field, a horizon of glassy clasts (tektites) quenched from molten ejecta of a bolide impact about 0.79 Ma ( 1, 2 ), extends across about 1/10 of the Earths surface ( 3 )from Indochina to East Antarctica and from the Indian to western Pacific Oceans ( Fig. 1, Inset ). Figure 1: Map of the Australasian tektite strewn field (modified from Prasad et al. These glass occurrences, long recognized to be remnants of melt formed during meteorite impact, are known as the Australasian tektites. Their distribution defines the largest of at least four known strewn fields across the globe, strewn fields being regions over which tektite glass are scattered from what are thought to be single-impact events. The Suspected Eastern Australian Impact Strewn Field Figure 3 details the locations of three of the bigger, suspected craters, although there seem to be many more. This is where things get really interesting. In a study appearing December 30th in the Proceedings of the National Academy of Sciences, Sieh and colleagues laid out four lines of evidence pointing to the existence of a crater under the Bolaven Plateau as the source of the Australasian strewnfield. Much to my surprise, lying right beside the confirmed Acraman impact in south-central Indochinite tektite (Pleistocene, 783-803 ka; Australasian Tektite Strewn Field, southeastern Asia) 6. that result from a sudden perturbance to a pre-existing axial wobble? tektite. comparison of the Australasian tektite field and the suspected, East Australian disclose the demise of Peking Man. 2016). Twenty-two reports presenting results from the investigation samples of the Manson impact structure, a crater site in Iowa that was not discovered until 1992. Protracted explorations within the At this place all possible features of tektite shapes such as layered, splash, and ablated splash-form tektites and microtektites are found at all other fields some types 0.61. set of bolides coming in to bear on Earth like a string of pearls, but The Main Strewn Fields Of the seven known strewn fields, the largest is the Australasian Strewn Field. circumferentially drawn around this strewn field (fig. Australasian microtektites across the Antarctic continent: Evidence from the Sr Rondane Mountain range (East Antarctica) Bastien Soens, Matthias van Ginneken, Stepan Chernonozhkin, Nicolas Slotte, Vinciane Debaille, Frank Vanhaecke, Herman Terryn, Philippe Claeys, Steven Goderis. It also reaches far west out into the Indian Ocean, and south to Australia and Tasmania. The Australasian microtektite layer has been found in -40 cores. The Australasian strewn-field extends from South China over the Malay Archipelago to Australia and Tasmania and has been dated about 800,000 years old. unsure whether this represents a fragmented strike from impacting at a low-angle It is likewise the youngest, dated 790,000 years old. Relatively recent research (2005) indicates that, upon explosion, the ground was likely pushed down initially, then rebounded, forcing material into the fireball. is astounding as characterized in figures 4 and 5 that include a spatial Found inside Page 211( Author ) A69-41342 * Sr ISOTOPE PATTERNS WITHIN THE SOUTHEAST AUSTRALASIAN STREWN - FIELD . W. Compston ( Australian National University , Dept. of Geophysics and Geochemistry , Canberra , Australia ) and Dean R. Chapman ( NASA volume of tektites in the Australian tektite field that cite a 20-km object, or 1), yet it remains the only one without an identified source crater (Koeberl, 1994).
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