In this study, we investigate the potential of rock surfaces to provide luminescence burial ages for boulders from moraine deposits. We sampled four boulders from a terminal moraine at the Malta ...Valley, Austria, all deposited ∼2 m below the present ground surface, and measured the IRSL signal as a function of depth into the boulder surfaces. It is clear from these profiles that all four boulders were exposed to at least some daylight prior to final deposition, and in one boulder, there is evidence for multiple exposure/burial events. The profiles show that the luminescence signal at the surface of two boulders must have been completely zeroed before burial. The burial doses derived from these two well-reset surfaces can thus be safely used to calculate burial ages, which may be the same as the depositional age of the terminal moraine. The IRSL signals from both boulders seem to suffer from anomalous fading with g-values of up to 15% decade−1. The younger fading-corrected age of ∼14 ka is in agreement with the deposition of the terminal moraine and coincides with the assumed Gschnitz stadial, while the older age of ∼39 ka most likely represents an earlier event during which this boulder was exposed to light.
Our results suggest that there is a high probability of sampling light-exposed and even well-bleached boulders from moraine deposits. We thus conclude that rock surface luminescence dating offers the possibility of obtaining reliable ages for moraine deposition. Even boulders which are partially bleached and thus not suitable for dating can provide insight into transportation pathways as well as depositional processes in glacial environments leading to a better understanding of the dynamics of glaciers.
•First luminescence depth profiles from alpine glacial boulders.•Records of several burial and exposure events are identified in moraine boulders.•Identifying glacial transport mechanisms through rock surface luminescence depth profiles.
This article explores gendered patterns of online dating and their implications for heterosexual union formation. Using 6 months of online dating data from a midsized Southwestern city (N = 8,259 ...men, 6,274 women), the authors found that men and women tend to send messages to the most socially desirable alters in the dating market regardless of their own desirability levels. They also found that male initiators connect with more desirable partners than men who wait to be contacted, but female initiators connect with equally desirable partners as women who wait to be contacted. Female-initiated contacts are also more than twice as likely as male-initiated contacts to result in a connection, but women send 4 times fewer messages than men. Finally, the authors compared partner desirability levels over repeated exchanges and concluded that couple similarities are more likely to result from relationship termination (i.e., nonreciprocity) than initial homophilous preferences.
The formation of Carlin-type gold deposits is poorly constrained, mainly due to the lack of accurate ages for gold mineralization. The Youjiang basin, SW China, represents the world’s second-largest ...Carlin-type gold province after NV, USA. In this paper, we use hydrothermal apatite U–Th–Pb dating to systemically determine the mineralization ages of five Carlin-type gold deposits, namely, Shuiyindong, Jinfeng, Zimudang, Linwang, and Jinya, in the Youjiang basin. The hydrothermal apatite is characterized by intimate intergrowth with gold-bearing sulfides, presence of primary fluid inclusions, irregular morphology and cathodoluminescence zoning, and MREE-enriched composition patterns, indicating that it is clearly associated and coeval with gold mineralization. The concentrations of lattice-bound U and Th in the apatite are highly variable, making it suitable for in situ secondary ion mass spectrometry (SIMS) U–Th–Pb dating. The dating results of hydrothermal apatite from the five deposits show that they formed at ca. 150–140 Ma, contemporary with the widespread felsic magmatism and associated W–Sn mineralization to the east of the Youjiang basin, probably in response to slab breakup of the Paleo-Pacific oceanic plate beneath the South China continental plate. Our case story suggests that hydrothermal apatite could be a robust chronometer for age dating of sedimentary rock-hosted gold mineralization worldwide.
Background and Aims Silvopastoral management of tree plantations is becoming popular in Brazil. The impact of this practice on carbon dynamics of these soils is unknown, and predicting it is ...difficult because historical land-use records of the region do not exist. The objective of the study was to quantify the relative soil organic carbon (SOC) contributions of C3 and C4 plants in different land-use system. Methods We evaluated total δ13C, the contribution of C4 and C3-derived soil organic C in three fraction-size classes of soils in six land-use systems (Eucalyptus hybrid plantations established in 1985 and 2005; a native forest; silvopasture stands of Brachiaria brizantha under eucalyptus established in 1994 and 2004; and an open pasture), and undertook carbon dating (14C) for three of those systems, an Oxisol in Minas Gérais, Brazil. From each system, soil samples were collected from four depths (0–10, 10–20, 20–50, and 50–100 cm); samples were fractionated into 250–2000, 53–250, and <53 μm size classes, and their δ13C determined. Carbon dating (14C analysis) was done for whole soil samples from 0 to 10 cm and 50–100 cm depth classes of three land-use systems. Results The δ13C values increased (showing increase in C contribution by C4 plants, i.e., grasses) with soil depth at all sites and all size-classes. The older systems showed a higher contribution of C4-derived SOC at all depths. Carbon dating indicated that the area had been cleared about 300 years ago. Conclusions Silvopastoral and pasture systems can be considered as good carbon sinks. We infer that the study site was grassland with high proportion of C4 plants in the past, not a forest as it is today.
Mobile dating applications (MDAs), such as Momo and Tinder, allow mobile phone owners to meet potential mates through social media, thus contributing to the radicalization of Chinese attitudes toward ...sex. Although these applications may gratify the needs of users for love and sex, the potential of risk is often overlooked. However, it should be considered in their decision regarding whether to meet a stranger or not. This study investigated the motivations and risks involved in the use of MDAs to meet strangers and the outcomes of using this technology. The results showed that sexuality was the only predictor of the reasons that people use MDAs to meet people offline for dates and casual sex. Among the perceived risks of mobile dating, only the fear of self-exposure to friends, professional networks, and the community significantly explained why users would not meet people offline for casual sex.
Whether tectonic strain from the early stage India‐Asia collision has synchronously affected the far‐field margin of the Tibetan Plateau is crucial for understanding plateau deformation and growth ...processes. However, direct evidence for early far‐field deformation remains scarce. Utilizing illite K‐Ar dating of three fault gouge samples, we established the faulting history of the Leibo fault zone (LFZ) at the southeastern margin of the Tibetan Plateau (SEMTP). Consistent authigenic illite ages of 52 ± 2, 54 ± 12 and 55 ± 6 Ma suggest the reactivated thrust faulting of the LFZ in the Early Cenozoic. Positioned ∼700 km east of the collisional boundary and at the intersection of three blocks with distinct lithospheric rheology in strength/viscosity, this event suggests a quasi‐synchronous far‐field tectonic response in the SEMTP to the India‐Asia collision.
Plain Language Summary
Understanding how tectonic strain resulting from the collision between the Indian and Eurasian plates in the Early Cenozoic can spread to the edges of the Tibetan Plateau is crucial for comprehending the plateau's tectonic development. To investigate this question, we used fault gouge, which resulted from the sliding of brittle faults, to directly reveal faulting information. By conducting illite K‐Ar dating on three samples from the Leibo fault zone (LFZ) at the southeastern margin of the Tibetan Plateau (SEMTP), we found consistent ages of newly formed illite, 52 ± 2, 54 ± 12, and 55 ± 6 million years ago. Since this type of minerals form simultaneously with faulting, these ages reveal a reactivated thrust faulting event of the LFZ, suggesting a nearly simultaneous response of faulting in the SEMTP to the early stage of the India‐Asia collision.
Key Points
Fault gouge illite K‐Ar dating is used to establish the faulting history of the Leibo fault zone, SE margin of the Tibetan Plateau
Three consistent authigenic illite ages of ∼55, ∼54, and ∼52 Ma suggest a reactivated thrust faulting event of the Leibo fault zone
This event indicates a quasi‐synchronous far‐field response of the SE margin of the Tibetan Plateau to the India‐Asia collision
Komatiites are presented as direct evidence for higher mantle temperatures during the Archean. In the North China Craton, komatiites with spinifex structure have been identified only at one locality, ...i.e. the Sujiagou area, western Shandong. They were considered as formed during the early Neoarchean mainly based on their association with supracrustal rocks considered to be that age. This study carried out SHRIMP U‐Pb zircon dating on metamorphosed trondhjemitic and monzogranitic dykes intruding the Sujiagou komatiites, and they have magmatic zircon ages of 2592 ± 12 Ma and 2586 ± 13 Ma respectively. This provides direct evidence that the komatiites formed during the early Neoarchean.
Dating archaeological materials is essential to understand time and rate of changes in different civilizations. For this purpose, different dating methods are used in several materials, including ...organic remains, sediments, and ceramics. Archaeomagnetic dating is a developing dating tool that has been improving rapidly due to the advances in geomagnetic model curves. The premise of this method is to compare the inclination, declination, and intensity of the geomagnetic field recorded by burnt archaeological materials (i.e., bricks, kilns, burned floors, pit ovens, soils, ceramics, slags), with mathematical models that describe the evolution of the Earth's magnetic field. Different regional geomagnetic models have been built based on local data that allow the application of this dating method, whereas for regions where regional models are lacking, global geomagnetic models are used. In any case, it is essential to assess the intrinsic uncertainties of geomagnetic models to properly evaluate the feasibility of the archaeomagnetic dating. In this context, this work evaluated global geomagnetic models for South America over the last 2000 years, to select the most appropriate statistically for dating purposes. Based on Casas and Tema (2019), a thorough assessment of the age uncertainties of the models was carried out. The statistical analyses of the magnetic parameters of the selected models regarding high-quality data were integrated to the intersection analyses of different magnetic parameters. From this result, this study suggests a geomagnetic multi-model approach as the best configuration for archaeomagnetic dating for South America.
•Feasibility of the archaeomagnetic dating tool for South America was tested.•Global magnetic models can be used for archaeomagnetic dating in South America.•Geomagnetic multi-model approach is the best configuration for this case.
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•In-situ U–Pb dating of garnet apatite and scheelite indicates the timing of mineralization of the Qiaomaishan deposit as 139 Ma.•In-situ U–Pb dating of scheelite can provide a ...reliable and accurate ages of mineralization.•The scheelite with high U content is more suitable for in-situ dating and the oxygen fugacity is one of the main factors controlling the U content in scheelite.
Determining the precise timing of mineralization and mineralizing events is crucial to understanding regional mineralizing and other geological events and processes. However, there are a number of mineralogical and analytical limitations to the approaches developed for the absolute dating of mineralizing systems, such as molybdenite Re–Os and zircon and garnet U–Pb, among others. This means that the precise and accurate dating of mineralizing systems that may not contain minerals suitable for dating using existing approaches requires the development of new (and ideally in situ) approaches to absolute dating. This study outlines a new in situ analytical approach that has the potential to rapidly and accurately evaluate the timing of ore formation. Our study employs a novel application of in situ scheelite U–Pb dating analysis using laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) and samples from the Qiaomaishan deposit, a representative example of skarn mineralization within the Xuancheng ore district of eastern China. Our approach to scheelite dating of the deposit is verified by cross-comparison to dating of cogenetic garnet and apatite, proving the effectiveness of this approach. Our new approach to dating of scheelite-bearing geological systems is rapid, cheap, requires little sample preparation, and is undertaken in situ, allowing crucial geological and mineralogical context to be retained during analysis. The approaches outlined here not only allow the determination of the absolute timing of formation of the Qiaomaishan deposit through the U–Pb dating of scheelite 138.6 ± 3.2 Ma, N = 39, mean square weighted deviation (MSWD) = 1.17, garnet (138.4 ± 1.0 Ma, N = 40, MSWD = 1.3), and apatite (139.6 ± 3.3 Ma, N = 35, MSWD = 0.72), but also further supports the theoretical genetic links between this mineralization and the emplacement of a proximal porphyritic granodiorite intrusion (zircon U–Pb age: 139.5 ± 1.2 Ma, N = 23, MSWD = 0.3). Moreover, our research indicates that the higher the concentrations of U within scheelite, the more suitable that scheelite is for U–Pb dating, with the main factor controlling the U content of scheelite seemingly being variations in oxygen fugacity conditions. This novel approach provides a potentially powerful tool, not just for the dating of skarn systems but also with potential applications in orogenic and intrusion-related gold, porphyry W–Mo, and greisen mineralizing systems as well as other scheelite-bearing geological bodies or geological systems.
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