Lithopetrographic and geochemical features of the Saalian tills in the Szczerców outcrop (Poland) in various deformation settings

This paper presents the results of new studies of Saalian tills, from the Ławki and Rogowiec formations, filling the Kleszczów Graben. The study area is located in the Szczerców outcrop, Bełchatów Lignite Opencast Mine, central Poland. Laboratory studies included macrofossil analysis of the deposits, as well as petrographic and geochemical (neodymium isotope ratio) measurements. The studies were carried out in 2014–2016 and resulted in both establishing the sedimentary Saalian complex and constructing geological cross-sections and a synthetic lithostratigraphic profile. Development of sediments in this part of the Kleszczów Graben in the Pleistocene was largely influenced by tectonic factors (Chabielice fault, Dębina Salt Dome) and glacitectonic processes (Wartanian Glaciation). The Saalian tills (T4 – Ławki and T7 – Rogowiec lithotypes) are between the Holsteinian sand with macroremnants of trees and the Eemian gyttja and peat. Petrographic coefficients for lithotype T4 (Ławki Formation) are 1.33–1.06–1.01 and 0.12 and for lithotype T7 (Rogowiec Formation) are 1.29–1.23–1.04 and 0.12. Investigations of the Nd isotopic compositions of the studied samples reinforce our interpretations of till deformation and tentative lithostratigraphic correlations. Neodymium isotope ratios “P” (−14.4 ± 0.7) and “D” (−12.4 ± 0.3) ε Nd values (2σ) correspond to mean signatures of Saalian glacigenic moraine sediment. This proves that ε Nd values less than −12.4 reflect the southern Fennoscandian Ice Sheet sediment provenance, but ε Nd values greater than −12.4 indicate the western European origin.

A millennial-scale reconstruction of spruce budworm abundance in Saguenay, Quéebec, Canada

A high-resolution macrofossil analysis was conducted to reconstruct spruce budworm abundance in an 8600-year-old mire in Saguenay, Québec, Canada. Abundant spruce budworm (Choristoneura fumiferana [Clem.]) faeces recovered in the peat profile suggested endemic and epidemic presence of the insect in the study site since 8240 cal. BP. Important variations in the abundance of faeces were observed, and two exceptional periods of insect activity were delineated, from 6815 to 6480 cal. BP and during the twentieth century. Lepidoptera head capsules were also found in the Lac des Îlets peat profile. They were less abundant and more altered than spruce budworm faeces, but they offered complementary information on insect activity. The long-term perspective achieved with this macrofossil analysis strongly suggests that intense periods of spruce budworm activity were rare events during the Holocene.