Search results for " palaeoclimate"
showing 6 items of 6 documents
The influence of decision-making in tree ring-based climate reconstructions.
2021
Tree-ring chronologies underpin the majority of annually-resolved reconstructions of Common Era climate. However, they are derived using different datasets and techniques, the ramifications of which have hitherto been little explored. Here, we report the results of a double-blind experiment that yielded 15 Northern Hemisphere summer temperature reconstructions from a common network of regional tree-ring width datasets. Taken together as an ensemble, the Common Era reconstruction mean correlates with instrumental temperatures from 1794–2016 CE at 0.79 (p < 0.001), reveals summer cooling in the years following large volcanic eruptions, and exhibits strong warming since the 1980s. Differing in…
Osmium and lithium isotope evidence for weathering feedbacks linked to orbitally paced organic carbon burial and Silurian glaciations
2022
Abstract The Ordovician (∼487 to 443 Ma) ended with the formation of extensive Southern Hemisphere ice sheets, known as the Hirnantian glaciation, and the second largest mass extinction in Earth History. It was followed by the Silurian (∼443 to 419 Ma), one of the most climatically unstable periods of the Phanerozoic as evidenced by several large scale ( > 5 ‰ ) carbon isotope (δ13C) perturbations associated with further extinction events. Despite several decades of research, the cause of these environmental instabilities remains enigmatic. Here, we provide osmium (187Os/188Os) and lithium (δ7Li) isotope measurements of marine sedimentary rocks that cover four Silurian δ13C excursions. Osmi…
Reconstruction of the internal structure of the pore system of a complex dinosaur eggshell (Megaloolithus siruguei)
2013
Despite the many reconstructions of fossil material that have recently appeared in the literature, dinosaur eggshells have never been reconstructed using computing techniques. Using the EMAC 3-D modelling methodology, we reconstruct a section of the Late Cretaceous Megaloolithus siruguei eggshell, which has a particularly complex pore system, exhibiting an intricate network of vertical, oblique, and horizontal pores.
Geological context and micromammal fauna characterisation from the karstic infilling of La Pedrera (Albaida, Valencia, E Spain)
2020
La Pedrera is a new palaeontological site located south of the province of Valencia, between the Betic and Iberian Ranges, in a cavity filled with sediments inside a tufa formation. Roughly 260 fossil remains, corresponding to 14 taxa, have been recovered and studied from Unit III. Six rodents (Microtus sp., M. sp. gr. M. (Terricola) duodecimcostatus-lusitanicus, Microtus sp. gr. M. brecciensis-cabrerae, Arvicola sapidus, Eliomys quercinus, and Apodemus sp. gr. sylvaticusfl avicollis), one lagomorph (Oryctolagus cf. cuniculus), three insectivores (Soricinae indet., Crocidura sp., and Talpa cf. europaea) and four bats (Myotis blythii, Rhinolophus cf. ferrumequinum, Myotis bechsteinii, and Rh…
The small mammals (insectivores, bats and rodents) from the Holocene site of Vallone Inferno (Scillato, Sicily)
2013
The Vallone Inferno rock-shelter is an archeological site located at 770 m a.s.l. in the Madonie massif in Sicily. This massif is modeled into the Triassic and Oligocene sedimentary rocks of the Imerese Basin. Thearchaeological excavations conducted since 2008 have provided a long prehistoric and historic sequence from the Neolithic to the medieval period. From the four sedimentary complexes identified, only levels 3.4 to 3.1 from complex 3 and 4.2 from complex 4 have yielded small-mammal material. Level 4.2 is poor in remains and as yet without cultural ascription, though it has a radiocarbon age of 9450±50 years BP. Level 3.4 has yielded fragments of ceramic characteristic of the Middle N…
Evaporite karst in Italy: A review
2017
none 16 si Although outcropping rarely in Italy, evaporite (gypsum and anhydrite) karst has been described in detail since the early 20th century. Gypsum caves are now known from almost all Italian regions, but are mainly localised along the northern border of the Apennine chain (Emilia Romagna and Marche), Calabria, and Sicily, where the major outcrops occur. Recently, important caves have also been discovered in the underground gypsum mines in Piedmont. During the late 80s and 90s several multidisciplinary studies were carried out in many gypsum areas, resulting in a comprehensive overview, promoting further research in these special karst regions. More recent and detailed studies focused…