Growth rates for freshwater ferromanganese concretions indicate regional climate change in eastern Canada at the Northgrippian-Meghalayan boundary

Abstract

The existence of freshwater ferromanganese concretions has been known for decades, but we are not aware of a generally accepted explanation for their formation, and there has been little research into their potential use as records of Holocene climate and paleohydrology. A conceptual model is presented to describe the environmental and geochemical processes which result in the formation and growth of freshwater ferromanganese concretions. In order to evaluate their potential as historical geochemical records, a concretion from Magaguadavic Lake, New Brunswick, Canada is the focus of a detailed geochronological and geochemical investigation. The radiocarbon data provide a coherent growth curve and a maximum age for the concretion of 8448 ± 43 years, consistent with the establishment of Magaguadavic Lake as a stable post-glacial lacustrine system. The data suggest accretion rates of 1.5 and 3.4 mm per 1000 years during the Northgrippian and Meghalayan stages of the Holocene, respectively. The abrupt change in growth rate observed at the stage boundary may be an indicator of Holocene climate change. These features are consistent with inferences from previous research that warmer climate in the Northgrippian led to eutrophication in some lakes in eastern North America. The results confirm that freshwater Fe–Mn concretions may yield important information about past climatic and environmental conditions.

Overview of the Morphology and Chemistry of Diagenetic Features in the Clay‐Rich Glen Torridon Unit of Gale Crater, Mars

“…On Earth, such concretions are observed to contain mostly crystalline silicates and a FeO T and MnO‐rich amorphous fraction. Repeated wetting and drying resulting in redox cycling of sediments rich in Fe and Mn oxides near the surface (either subaqueously or subaerially, in deep sea or in shallow freshwater lakes) is one mechanism to produce concretions (e.g., Hayles et al., 2021; Liu et al., 2002; Müller et al., 2002; Schwertmann & Fanning, 1976; Szymański et al., 2014). The FeO and MnO cements in concretions are typically very poorly crystallized and difficult to characterize (Cornu et al., 2005; Zhang & Karathanasis, 1997).…”

Early evidence for beer drinking in a 9000-year-old platform mound in southern China

“…In contrast, collecting other resources, such as shellfish, yam, or bamboo roots, would take only about two to three hours. During the Shangshan period, rice was in the early stage of domestication; its acquisition and production probably involved high labor costs [ 17 , 22 ].…”

“…Carmel, Israel, as well as Göbekli Tepe in southeastern Turkey, a monumental sanctuary erected by hunter-gatherer groups [ 5 , 6 , 70 ]. The discovery of rice beer at Qiaotou provided supporting evidence for the “beer hypothesis.” It is important to note that, however, rice domestication had been ongoing for about a millennium before Qiaotou was constructed [ 17 , 22 ]. Beer drinking may have been one of many contributing factors in the protracted process of rice domestication.…”

“…BP) [ 16 – 21 ] ( Fig 1 ). Shangshan was the earliest Neolithic culture in the region, capturing the onset of rice domestication and sedentism [ 16 , 17 , 20 , 22 ]. Recent archaeological investigations have discovered 18 Shangshan culture sites in the Jinqu Basin.…”