Sebastian Schaller, Bennet Schuster, Sarah Beraus
et al.
Abstract In the context of a project of the International Continental Scientific Drilling Program (ICDP) (DOVE; Drilling Overdeepened Alpine Valleys), a series of boreholes were drilled into buried overdeepened glacial troughs in the central and eastern part of the northern Alpine foreland. The sedimentary records of these overdeepenings, reaching back to the Middle Pleistocene, are essential archives for paleoclimate and a key to better understanding past glaciations and landscape evolution. As part of the project, an over 250 m long succession of unconsolidated Quaternary sediments was recovered from the Basadingen Trough (ICDP 5068_2, NE Switzerland), belonging to the NW part of the former Rhine Glacier’s foreland lobe. The drill site is positioned on a high-resolution 2D seismic line, serving as the basis for a sequence and facies analysis. Acoustic wire-line logging data (vertical seismic profile—VSP) directly links the sediment succession with the seismic data, allowing the establishment of a detailed and unifying seismic- and core-based glacial sequence stratigraphy dividing the strata into chronostratigraphically distinct sedimentary units. Based on this stratigraphy, the overdeepened valley fill could be grouped into three overdeepened glacial sequences, reflecting three pulses of glacial advance and retreat. Furthermore, a 3D model of a segment of the Basadingen Trough was created by combining the 2D seismic lines with the local geological information (i.e., geological maps, existing bedrock models, and drill-logs from core and flush drillings), visualizing the shape of the initial bedrock incision, the multiphase trough-infill architecture, and the overlying non-overdeepened cover. A generic model for a glacio-seismic sequence is developed that underlines the benefits of combining complementary geological and geophysical data in these highly complex depositional settings. The close link of these sequences to glacial advance-retreat cycles contributes to the development of a local glaciation model, as shown for the Basadingen Trough. This approach can be applied to other similar settings in formerly glaciated areas.
Abstract Silurian strata are well-developed in the northwest margin of Yangtze Platform. A total of 117 densely spaced argillaceous samples were taken from the Shenxuanyi Member, upper Ningqiang Formation to the lowermost Chejiaba Formation of the Majia section in northern Sichuan Province. The main aim of this study is to obtain chitinozoans to test whether Wenlock deposits are preserved here. A highly diverse and abundant chitinozoan assemblage is documented, including 21 species from six genera. This assemblage was then compared to contemporaneous chitinozoan assemblages reported from adjacent areas. This study proposes that Eisenackitina venusta (corresponds to the Pterospathodus celloni conodont Biozone) is of chronostratigraphical significance for discussing the Telychian of the Yangtze region. It is suggested that the Silurian upper red bed (lower part of the Shenxuanyi Member) in the study area is younger than the Xiushan Formation and can be correlated with the Huixingshao Formation of the Central Yangtze Platform. There are no index chitinozoan species near the Llandovery–Wenlock boundary that have been found in the upper part of the Shenxuanyi Member, and the updated chronostratigraphic framework suggests that it is Telychian-aged deposits.
The Pleistocene Epoch, marked by significant climatic fluctuations and glaciations, profoundly impacted plant populations. However, our understanding of the influences of last glaciations on tropical-subtropical flora and vegetation remains limited due to insufficient data. Here, we present mummified wood of Magnolia insignis (Wall.) Bl. from the Upper Pleistocene (33–30 ka cal. BP) of Maoming, South China, providing direct evidence of a broader historical range for this species during the period prior to the LGM in the last glaciation. Combining these findings with results from MaxEnt modeling, we demonstrate an expanded range of M. insignis into lower latitudes during last glaciation with subsequent interglacial contraction. This represents the second documented case of such a scenario for a cold-tolerant high-elevation plant species at low latitudes. The results of MaxEnt modeling and a comparison of climatic data across different time periods indicate that the contraction of M. insignis from the Maoming and other low latitude regions of East Asia was driven by the increase in summer temperatures during Holocene. This study not only sheds light on the responses of cold-adapted mountainous species at low latitudes of East Asia to last glaciation, but also justifies the importance of their protection in the view of nowadays and future climate changes.
Abstract Beetles have a remote evolutionary history dating back to the Carboniferous, with Mesozoic fossils playing a pivotal role in elucidating the early evolution of extant families. Despite their exceptional preservation in amber, deciphering the systematic positions of Mesozoic trogossitid‐like beetles remains challenging. Here, we describe and illustrate a new trogossitid‐like lineage from mid‐Cretaceous Kachin amber, Foveapeltis rutai Li, Kolibáč, Liu & Cai, gen. et sp. nov. Foveapeltis stands out within the Cleroidea due to the presence of a significant large cavity on each hypomeron. While the exact phylogenetic placement of Foveapeltis remains uncertain, we offer a discussion on its potential affinity based on our constrained phylogenetic analyses.
Floian, Early Ordovician trilobites are systematically described and revised based on new material from the middle part
of the Duoquanshan Formation of the Shihuigou area, northern Qinghai Province, northwest China. The fauna that lived
on the shallow-water carbonate platform comprises three species belonging to two families, i.e., Tsaidamaspis diarmatus,
Zhiyia tsinghaiensis, and Liexiaspis sp. indeterminate. It exhibits a strong endemicity to the Olongbluk terrane. The new
isoteline genus Zhiyia is established on the basis of the material from the Olongbluk terrane and South China palaeoplate,
and is characterized by its: (i) almost obsolete cephalic and pygidial axial furrows; (ii) flattened anterior border
and narrow (sag., exsag.) occipital ring; (iii) bilobed hypostome with a shallow median notch and a small triangular
median projection; (iv) subsemicircular pygidium with wide pygidial axis and border. Faunal evidence indicates that the
palaeogeographic position of the Olongbluk terrane may have been situated closer to the South China palaeoplate rather
than the North China palaeoplate during the Floian.