Carling Paul A, Tada Toshihiro, Tada Ryuji, Songtham Wickanet, Cresswell Alan J, Sanderson David C W, Porat Naomi, Duangkrayom Jaroon, Darby Stephen E, Chansom Praphas
School of Geography & Environmental Science, University of Southampton, Southampton, SO19 1BJ UK.
State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu, 610059 Sichuan China.
Prog Earth Planet Sci. 2024;11(1):58. doi: 10.1186/s40645-024-00660-9. Epub 2024 Nov 20.
Aspects of the Quaternary sedimentary geology of South-East Asia have proven problematic in terms of interpretation as to the origins and relationships of the surface sediment layers. The MIS 20 large meteorite impact (., 788 to 785 ka) occurred within mainland South-East Asia, evident from the well-researched 'Australasian Tektite Strewn Field' which extends over at least one tenth of the surface of the Earth. Key questions include: 1) whether the sedimentary impact signature is preserved in the Quaternary sediment cover of the region and 2) whether stratigraphic indicators and dating methods can discriminate meteorite impact-related associations of sedimentary strata, despite subsequent reworking and diagenesis. The importance of the questions raised relate to the search for the impact site, which has not been located conclusively. Moreover, the sedimentary signatures of meteorite impacts are not well known and the descriptions in this study should aid the recognition of impact signatures elsewhere in the world. An hypothesis was developed: Surface Quaternary sediments across a wide area of mainland South-East Asia represent the effects of a regionally significant meteorite impact. Over one hundred sedimentary sections were logged across five countries in mainland South-East Asia. Methods used, defining the stratigraphy and sedimentology, include computed tomography and X-ray scanning, geochemistry, magnetic susceptibility, and environmental luminescence as well as conventional grain size analyses. Luminescence analyses were applied to samples from key strata to provide age constraints and indications of reworking through dose distributional analysis of quartz fractions. The results of the investigation explain the nature of the stratigraphy and relate it specifically to the meteorite impact. In this manner, the strata and sedimentary signatures of the ejecta from a large cosmic impact are defined across a broad region, rather than being described at singular and isolated sections. The novelty is the spatial scale of the investigation which nevertheless remains detailed. A summary model of impact stratigraphy is presented that applies to the regional ejecta blanket covering at least 300,000 km. Tektites were co-deposited with the ejecta and not introduced by surface processes reworking the deposits. Similar models may be applicable outside of mainland South-East Asia, wherever other large impacts are suspected to have occurred.
The online version contains supplementary material available at 10.1186/s40645-024-00660-9.
东南亚第四纪沉积地质学的某些方面在解释地表沉积层的起源和关系方面已被证明存在问题。末次间冰期第20阶段的大型陨石撞击（约78.8至78.5万年前）发生在东南亚大陆内部，从经过充分研究的“澳大拉西亚玻陨石散落场”可以明显看出，该散落场覆盖了地球表面至少十分之一的区域。关键问题包括：1）该地区第四纪沉积物覆盖层中是否保留了沉积撞击特征；2）尽管随后经过了再加工和成岩作用，地层指标和年代测定方法能否区分与陨石撞击相关的沉积地层组合。所提出问题的重要性与寻找撞击地点有关，目前尚未最终确定撞击地点。此外，陨石撞击的沉积特征尚不为人所知，本研究中的描述应有助于识别世界其他地方的撞击特征。由此形成了一个假设：东南亚大陆广大地区的地表第四纪沉积物代表了一次具有区域重要性的陨石撞击的影响。在东南亚大陆的五个国家中记录了一百多个沉积剖面。所使用的确定地层学和沉积学的方法包括计算机断层扫描和X射线扫描、地球化学、磁化率、环境发光以及传统的粒度分析。对关键地层的样本进行发光分析，通过对石英组分的剂量分布分析来提供年龄限制和再加工迹象。调查结果解释了地层的性质，并将其具体与陨石撞击联系起来。通过这种方式，在一个广阔区域内定义了一次大型宇宙撞击喷出物的地层和沉积特征，而不是在单个孤立的剖面中进行描述。新颖之处在于调查的空间尺度，不过仍然很详细。提出了一个适用于至少覆盖30万平方公里区域喷出物覆盖层的撞击地层学总结模型。玻陨石与喷出物同时沉积，而不是由对沉积物进行再加工的地表过程引入的。类似的模型可能适用于东南亚大陆以外其他怀疑发生过其他大型撞击的地方。
在线版本包含可在10.1186/s40645 - 024 - 00660 - 9获取的补充材料。
