Geochemistry and origin of tektites from Guilin of Guangxi, Guangdong and Hainan

Abstract

Six tektites from Guilin of Guangxi, Hainan, and Guangdong were analyzed for the abundances of major elements and 27 trace elements. All samples are splash-form tektites and have SiO 2 contents ranging from 73.1wt% to 76.0wt% (74.6wt% on average). The chemical compositions, except Cr and Ni, of tektites from different areas, are similar. Guangdong tektite shows enrichments of Ni and Cr contents by a factor of 3, and has slightly higher MgO and FeO than Hainan and Guilin tektites. It indicates that the tektites were formed by mixing several target rocks. The major and trace element concentrations of southern China tektites closely resemble previously reported data for average splash-form and Muong Nong-type indochinites, indicating that they have the same source. (La/Lu) CI (7.99), Zr/Hf (35.45 on average), Ba/Rb (3.59 on average), and the rare earth element (REE) contents of tektites are similar to those of typical post Archean upper crustal rocks. This study suggests that the best fit for the target source of southern China tektites could be a combination of 41% shale, 2% sandstone, 20% greywacke, and 37% quartzite. tektites, southern China, Australasian, source rock, Post-Archean sedimentary rock Citation:Tektites are natural glasses, usually up to a few centimeters in size. At present, tektites occur mainly in four geographically extended strewn fields: the North American ~34.9 Ma [1, 2], Central European ~14.5 Ma [3, 4], Ivory Coast ~1.07 Ma [5] and Australasian strewn fields ~0.77 Ma [6].Tektites in each strewn field are related to one another with respect to their petrographical, physical, and chemical properties as well as their ages.Apart from the microtektites (usually less than 1 mm in diameter) found in deep-sea cores [7,8], tektites on land can be divided into three morphological subgroups: (1) normal or splash-form tektites (spheres, droplets, dumbbells, etc.);(2) aerodynamically ablated tektites (flanged buttons), which result from partial re-melting of the tektite glass during atmospheric re-entry, after the initial melt had been ejected outside the terrestrial atmosphere and solidified through quenching; and (3) Muong Nong-type tektites (layered tektites). Muong Nong-type tektites, named after a locality in Laos [9], are usually chunky and blocky in appearance and inhomogeneous in chemistry [10]; their average major element chemistry and age are identical to those of normal tektites but they have higher abundance of volatile elements (e.g., B, Cu, Zn, Ga, As, Se, Sb and Pb) and water, and contain more bubbles and some relict minerals.

Magnetic Properties of Australasian Tektites From South China

“…They were recognized based on geochemical and morphological investigations in the 1960s (Barnes, 1969; Li, 1963). Their fission track ages (Yan et al., 1979; Zhang et al., 1991), isotopic ages (Hou et al., 2000; Jourdan et al., 2019), and major and trace element concentrations are consistent with those of AASF tektites at other places, indicating that the tektites were formed by a same impact event in a relatively homogeneous target (Ho & Chen, 1996; Lee et al., 2004; Lin et al., 2011). Especially, Muong Nong‐type tektites that are as large as about 10 kg (Futrell & Wasson, 1993; Yuan, 1981) were discovered at Hainan (Figure 1b), which is located at more than 500 km to the northeast of the layered tektites zone at the Indochina Peninsula (Fiske et al., 1999).…”

“…Heterogeneous contamination by ferromagnetic materials from local soils to the samples and/or different contents of magnetic elements (e.g., Fe, Mn, Cr) in the tektites was invoked to explain this observation (Rochette et al., 2019). On the other hand, it is well constrained that AASF tektites at different geographic areas exhibit systematic variations in the geochemistry, and different compositional groups of tektites may occur in a same area (Amare & Koeberl, 2006; Chapman & Scheiber, 1969; Glass & Koeberl, 2006; Koeberl, 1992; Lin et al., 2011; Westgate et al., 2021). For example, most australites (i.e., AASF tektites from Australia) belong to the high‐Na/K group, and they have higher contents of FeO and ferromagnetic elements (e.g., Ni, Co) than indochinites (i.e., the AASF tektites from Indochina Peninsula), indicating that australites may have incorporated more residual iron oxides from the pre‐impact target materials and/or meteoritic components (Amare & Koeberl, 2006; Goderis et al., 2017; Werner & Borradaile, 1998).…”

Quest for the Australasian impact crater: Failings of the candidate location at the Bolaven Plateau, Southern Laos

“…The study by Sieh et al (2020) undoubtedly deserves appreciation for the enormous extent of fieldwork and acquisition of valuable geological and geochemical data. Also, its attempt to perform mixing calculations with real materials from the suggested impact area certainly proceeds a step further than previous mixing calculations with model endmembers such as loess, shale, sandstone or quartzite, greywacke, and soils (e.g., Koeberl, 1992;Lee et al, 2004;Lin et al, 2011). Having found a suspicious structure placed inside the consensus location, with basalts providing a seemingly ingenious solution to a geochemical puzzle, it might be tempting to look for additional supporting evidence and overlook some seemingly minor inconsistencies.…”

Fengshui: Science, Religion, Superstition, or Trade?

“…For instance, Joseph Needham (1900‐1995) classified it as divination, which is among pseudo‐sciences (Needham 2005). Furthermore, Shen Li (1946‐), an influential contemporary Chinese researcher working on traditional Chinese “science” and “religion” (including Confucianism), holds that Fengshui belongs in the category of superstition or magic (Li 2019, 709–14). Although Needham and Li believed that there was “knowledge” similar to natural science in pre‐modern Chinese civilization (tradition), it seems to me that the “knowledge,” arising from traditional China, is different from modern science.…”

“…This claim, that Fengshui is identical or relevant to science, has been convincingly refuted and attacked by Shen Li and another scholar. Li drew the following conclusions from his investigations and analysis: Fengshui is a magic, invented in the Song Dynasty (960–1279); Before the Song Dynasty, “Fengshui” as a phrase did not refer to geomancy, but to edema caused by nephropathy; the author of the Book on Burial was not Pu Guo (276–324, in the Jin Dynasty) because it was written in the Song Dynasty; 10 the theory of Fengshui, based on Book on Burial , was opposed by some Confucians even in the Song Dynasty because it was arrant nonsense, being false and self‐contradictory; thus, Fengshui belongs in superstition as physiognomy and fortune‐telling do (Li 2019, 709–14). No doubt, these conclusions are reasonable and well‐grounded.…”