Gönpa Gang—The First Application of Dendrochronological Dating to Study the Traditional Architecture of Upper Mustang (Nepal)

Gönpa Gang is an example of the traditional Buddhist architecture of Upper Mustang. It is also the first monument in Upper Mustang to be studied using the dendrochronological dating method. The gönpa is a two-story building of imposing size, made from simple elements of Tibetan architecture, namely masonry walls, timber posts, and beams. A total of 14 samples were collected from elements on both the ground and the first floor. The limited number of samples results from the cultural and religious character of the object under study. Only the elements consistent with the structure and the space arrangement, interpreted as original features, were examined. Microscopic observation and the analysis of the anatomical features of all 14 samples resulted in the identification of Himalayan pine (blue pine), Pinus wallichiana A.B. Jacks. Intra-annual density fluctuation, false rings, and missing rings were detected. From 14 samples collected in Gönpa Gang, 18 series were worked out. Thus, 15 series from 12 samples were synchronized and used for the development of the mean chronology, UMGG_m, with a total length of 160 rings. The chronology covers the period from 1524 to 1683. Examination of the Gang Gönpa wood resulted in the age determination of 13 elements. The results were compared with architectural stratification by Harrison and historical data from written sources. The timber used in the gönpa comes from the Southern Mustang area. The examined wood demonstrates a correlation with the timber used in the Upper Mustang historical buildings further north.

The use of paleoclimatic simulations to refine the environmental and chronological context of archaeological/paleontological sites

To reconstruct the paleoenvironmental and chronological context of archaeological/paleontological sites is a key step to understand the evolutionary history of past organisms. Commonly used method to infer paleoenvironments rely on varied proxies such as faunal assemblages and isotopes. However, those proxies often show some inconsistencies. Regarding estimated ages of stratigraphic layers, they can vary depending on the dating method used. In this paper, we tested the potential of paleoclimate simulations to address this issue and contribute to the description of the environmental and chronological context of archaeological/paleontological sites. We produced a set of paleoclimate simulations corresponding to the stratigraphy of a Late-Pleistocene Holocene site, El Harhoura 2 (Morocco), and compared the climatic sequence described by these simulations to environmental inferences made from isotopes and faunal assemblages. Our results showed that in the studied site combined US-ESR ages were much more congruent with paleoenvironmental inferences than OSL ages. In addition, climatic variations were found to be more consistent with isotopic studies than faunal assemblages, allowing us to discuss unresolved discrepancies to date. This study illustrates the strong potential of our approach to refine the paleoenvironmental and chronological context of archaeological and paleontological sites.

The international tephra research group ‘Commission on Tephrochronology’ and its activities – the first 60 years

Modern tephra studies per se began almost 100 years ago (in the late 1920s) but the first collective of tephrochronologists, with a common purpose and nascent global outlook, was not formed until 7 September, 1961, in Warsaw, Poland. On that date, the inaugural ‘Commission on Tephrochronology’ (COT) was ratified under the aegis of the International Union for Quaternary Research (INQUA). COT’s formation can be attributed largely to the leadership of Kunio Kobayashi of Japan, the commission’s president for its first 12 years. We were motivated to record COT’s heritage for posterity and also because the discipline of tephrochronology, including the study of cryptotephras, continues to grow globally at a significant rate. This is recognition of tephrochronology as both a unique correlational and age-equivalent dating method, and as a complementary method in other fields, such as volcanology, in which tephra research has been employed to develop eruption histories and hazards and to help understand volcano-climate interactions. In this article, we review the history of COT (which also functioned under other names, abbreviated as COTS, CEV, ICCT, COTAV, SCOTAV, INTAV) under the umbrella of INQUA for 53 of the last 60 years, or under IAVCEI (International Association of Volcanology and Chemistry of the Earth’s Interior) for seven of the last 60 years, including since 2019. We describe the development of the commission and its subsequent activities that include organising nine specialist tephra-field meetings in seven different countries, numerous conference sessions or workshops, and generating tephra-themed issues of journals/books or specialist internet documents or websites. The commission began to prosper after 1987 when key changes occurred, and it has blossomed further, especially in the past decade or so as an entire new cohort of specialists has emerged alongside new analytical and dating techniques to become a vibrant global group today. We name 29 elected officers involved with COT since 1961 and their roles, and 15 honorary life members. We also document the aims of the commission and conclude by evaluating its legacies and current and future work.

Assessment of prospective geological hazards in Torrevieja-La Mata coast (western Mediterranean) based on Pleistocene and Holocene events

The coastal zone in which the lagoons of La Mata and Torrevieja (Eastern Spain) developed can be described as a compilation of geo-hazards typical of the Mediterranean realm. This study has focused mainly on those linked to recent tectonics. Extensive use of the amino acid racemization dating method allowed us to establish the evolution of all the geomorphological units differentiated in the area, the most striking manifestation being at the La Mata Lagoon Bar, where MIS 5 deposits settled on MIS 7 sediments along a marked erosive unconformity, thereby attesting coastal uplift between these two stages. In addition, recent uplift processes were reflected on stepped abrasion platforms and, in some cases, enormous boulders were transported over these platforms by extreme surge waves. Furthermore, we obtained feasible evidence that, during the end of MIS 5, an earthquake with an offshore epicenter linked to Torrevieja Fault, Bajo Segura Fault or the set of faults linked to the former, was responsible for tsunami surge deposits represented in accumulations of randomly arranged and well-preserved Glycymeris and Acanthocardia shells. Recent catastrophic effects linked to the earthquakes were also detected. In this regard, comparison of the paleontological and taphonomic analyses allowed us to discern between wave and tsunami surge deposits. Therefore, evidence of these hazards undoubtedly points to important future (and present) erosive and/or catastrophic processes, which are enhanced by the presence of tourist resorts and salt-mining industry. Thus, these sites are also threatened by future increases in sea level in the context of warmer episodes, attested by raised marine fossil deposits. At the north of Cervera Cape, beaches will be eroded, without any possibility of sediment input from the starved Segura River delta. At the south of this cape, waves (and tsunamis) will erode the soft rocks that built up the cliff, creating deep basal notches.

Hydrothermal Fluids and Cold Meteoric Waters along Tectonic-Controlled Open Spaces in Upper Cretaceous Carbonate Rocks, NE-Iraq: Scanning Data from In Situ U-Pb Geochronology and Microthermometry

The Upper Cretaceous carbonates along the Zagros thrust-fold belt “Harir-Safin anticlines” experienced extensive hot brine fluids that produced several phases of hydrothermal cements, including saddle dolomites. Detailed fluid inclusion microthermometry data show that saddle dolomites precipitated from hydrothermal (83–160 °C) and saline fluids (up to 25 eq. wt.% NaCl; i.e., seven times higher than the seawater salinity). The fluids interacted with brine/rocks during their circulation before invading the Upper Cretaceous carbonates. Two entrapment episodes (early and late) of FIs from the hydrothermal “HT” cements are recognized. The early episode is linked to fault-related fractures and was contemporaneous with the precipitation of the HT cements. The fluid inclusions leaked and were refilled during a later diagenetic phase. The late episode is consistent with low saline fluids (0.18 and 2.57 eq. wt.% NaCl) which had a meteoric origin. Utilizing the laser ablation U-Pb age dating method, two numerical absolute ages of ~70 Ma and 3.8 Ma are identified from calcrete levels in the Upper Cretaceous carbonates. These two ages obtained in the same level of calcrete indicate that this unit was twice exposed to subaerial conditions. The earlier exposure was associated with alveolar and other diagenetic features, such as dissolution, micritization, cementation, while the second calcrete level is associated with laminae, pisolitic, and microstromatolite features which formed during the regional uplifting of the area in Pliocene times. In conclusion, the hydrothermal-saddle dolomites were precipitated from high temperature saline fluids, while calcrete levels entrapped large monophase with very low salinity fluid inclusions, indicative for a low temperature precipitation from water with a meteoric origin.

Integrative geochronology calibrates the Middle and Late Stone Ages of Ethiopia’s Afar Rift

The Halibee member of the Upper Dawaitoli Formation of Ethiopia’s Middle Awash study area features a wealth of Middle and Later Stone Age (MSA and LSA) paleoanthropological resources in a succession of Pleistocene sediments. We introduce these artifacts and fossils, and determine their chronostratigraphic placement via a combination of established radioisotopic methods and a recently developed dating method applied to ostrich eggshell (OES). We apply the recently developed 230Th/U burial dating of OES to bridge the temporal gap between radiocarbon (14C) and 40Ar/39Ar ages for the MSA and provide 14C ages to constrain the younger LSA archaeology and fauna to ∼24 to 21.4 ka. Paired 14C and 230Th/U burial ages of OES agree at ∼31 ka for an older LSA locality, validating the newer method, and in turn supporting its application to stratigraphically underlying MSA occurrences previously constrained only by a maximum 40Ar/39Ar age. Associated fauna, flora, and Homo sapiens fossils are thereby now fixed between 106 ± 20 ka and 96.4 ± 1.6 ka (all errors 2σ). Additional 40Ar/39 results on an underlying tuff refine its age to 158.1 ± 11.0 ka, providing a more precise minimum age for MSA lithic artifacts, fauna, and H. sapiens fossils recovered ∼9 m below it. These results demonstrate how chronological control can be obtained in tectonically active and stratigraphically complex settings to precisely calibrate crucial evidence of technological, environmental, and evolutionary changes during the African Middle and Late Pleistocene.

EVIDENCE OF MASS MORTALITY OF THE LONG-LIVED BIVALVE MERCENARIA STIMPSONI CAUSED BY A CATASTROPHIC TSUNAMI

ABSTRACT Tsunamis are huge disasters that can significantly damage benthic organisms and the sea-bottom environment in coastal areas. It is of great ecological importance to understand how benthic ecosystems respond to such destructive forces and how individual species are affected. Investigating the effect of such disasters on animals that are seldom caught alive is particularly difficult. Bivalve mollusks are especially suitable for investigating how a tsunami affects coastal benthic species because they preserve an environmental record in their shells that can be extended back in time by crossdating the records of multiple individuals. Here we studied dead shells of Mercenaria stimpsoni, a long-lived clam, and precisely determined the time of death by using nuclear bomb–induced radiocarbon (bomb-14C) and by counting annual growth increments. First, a quasi-continuous, regional bomb-14C record was created by analyzing the shells of 6 live-caught M. stimpsoni individuals. Then 27 dead shells collected from the seafloor of Funakoshi Bay were 14C-dated and analyzed. The results showed that the huge tsunami that struck northeastern Japan on 11 March 2011 caused mass mortality of this bivalve in Funakoshi Bay. Nine of the 27 clams died during the March 2011 tsunami, probably by starvation after burial by tsunami deposits or exposure above the seafloor as a result of sediment liquefaction during the earthquake. The dating method used in this study can help us understand how long-lived marine organisms with low population density are affected by huge natural disasters such as a tsunami.

Supplemental Material: Evaluating preservation bias in the continental growth record against the monazite archive

Table S1 (global compilation of monazite ages); Table S2 (compilation of whole rock geochemistry of monazite-bearing rocks); data sources for the zircon ages from the Himalayan orogen and Figure S1 (comparison of monazite and zircon age histograms and cross-correlation results based on the monazite dating method).<br>

Supplemental Material: Evaluating preservation bias in the continental growth record against the monazite archive

Table S1 (global compilation of monazite ages); Table S2 (compilation of whole rock geochemistry of monazite-bearing rocks); data sources for the zircon ages from the Himalayan orogen and Figure S1 (comparison of monazite and zircon age histograms and cross-correlation results based on the monazite dating method).<br>