New detrital zircon U-Pb ages and Lu-Hf isotopic data from metasedimentary rocks along the western boundary of the composite Avalon terrane in the southeastern New England Appalachians

ABSTRACT West Avalonia is a composite terrane that rifted from the supercontinent Gondwana in the Ordovician and accreted to Laurentia during the latest Silurian to Devonian Acadian orogeny. The nature and extent of West Avalonia are well constrained in Nova Scotia, New Brunswick, and Newfoundland, Canada, by U-Pb detrital zircon data and/ or isotope geochemistry of (meta)sedimentary and igneous rocks. The southeastern New England Avalon terrane in eastern Massachusetts, Connecticut, and Rhode Island has generally been interpreted as an along-strike continuance of West Avalonia in Canada, but the ages and origins of metasedimentary units along the western boundary of the Avalon terrane in Massachusetts and Connecticut remain poorly constrained. In this study, new detrital zircon U-Pb and Lu-Hf laser-ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) data from three samples of metasedimentary units along the western boundary of the southeastern New England Avalon terrane in Connecticut and Massachusetts were compared with existing data to test whether these metasedimentary units can be correlated along strike. The data were also compared with existing detrital zircon U-Pb and εHf data in New England and Canada in order to constrain the extent and provenance of West Avalonia. The maximum depositional age of two of the three detrital zircon samples analyzed in this study, based on the youngest single grain in each sample (600 ± 28 Ma, n = 1; 617 ± 28 Ma, n = 1) and consistency with existing analyses elsewhere in the southeastern New England Avalon terrane, is Ediacaran, while that of the third sample is Tonian (959 ± 40 Ma, n = 4). Detrital zircon analyses of all three samples from this study showed similar substantial Mesoproterozoic and lesser Paleoproterozoic and Archean populations. Other existing detrital zircon U-Pb data from quartzites in the southeastern New England Avalon terrane show similar Tonian populations with or without Ediacaran grains or populations. Most published detrital zircon U-Pb data from (meta)sedimentary rocks in West Avalonia in Canada yielded Ediacaran youngest detrital zircon age populations, except for a quartzite unit within the Gamble Brook Formation in the Cobequid Highlands of Nova Scotia, which showed a Tonian maximum depositional age, and otherwise a nearly identical detrital zircon signature with rocks from the southeastern New England Avalon terrane. All samples compiled from the southeastern New England Avalon terrane and West Avalonia in Canada show main age populations between ca. 2.0 Ga and ca. 1.0 Ga, with major peaks at ca. 1.95, ca. 1.50, ca. 1.20, and ca. 1.00 Ga, and minor ca. 3.1–3.0 Ga and ca. 2.8–2.6 Ga populations. The εHf(t) values from the three samples yielded similar results to those from West Avalonia in Canada, suggesting that both regions were derived from the same cratonic sources. The εHf(t) values of all West Avalonian samples overlap with both Amazonia and Baltica, suggesting that there is a mixed signature between cratonic sources, possibly as a result of previous collision and transfer of basement fragments between these cratons during the formation of supercontinent Rodinia, or during subsequent arc collisions.

Toward an alternative community-driven restorative model of school discipline

Introduction -- Education is concomitantly a path for self-actualization and personal growth, a mechanism of social mobility, a crucial factor of labour market outcomes and lifetime earnings, a social determinant of health and quality of life, a fundamental institution in a democratic society, and a human right. Because education is so consequential at the individual and societal levels, barriers to it are a cause of great concern for various stakeholders, including parents, students, and community advocates. As a case in point, several advocates have identified issues pertaining to school discipline processes and outcomes in Nova Scotia (Barjun Consultants, 2001; Black Learners Advisory Committee, 1994; Nunn, 2006). Recently, we learned that Black learners in Nova Scotia are more likely to be subjected to out-of-school suspensions than other students across the province (Woodbury, 2016). Yet, scholarly literature indicates that punitive school discipline, such as out-of-school suspensions, are ineffective, worsen problematic behaviour, alienate students from school, and keep students away from formal learning opportunities (Fenning et al., 2004; Gregory et al., 2010; Jean-Pierre & Parris-Drummond, 2018; Mayer, 2001; Noguera, 2003). <div><br></div><div>This report is based on the main findings of a qualitative study that aimed to address school discipline racial disproportionality in Nova Scotia, conceive an alternative model of school discipline, and promote the academic success of Black learners. A research project was conducted with African Nova Scotian and Black immigrant youth, parents, and community members across the province between 2018 and 2019 in both English and French. Through nine focus groups and 17 interviews, 60 members of the community provided their perspectives and insights to inform the conception of an alternative model of school discipline. A community forum subsequently took place in March 2020 to discuss the findings and main recommendations with community members. Based on the research project and scholarly literature, this report presents key findings and recommendations that can foreground future school discipline policy and interventions to further Black learners’ academic success in Nova Scotia. Overall, the key themes derived from participants’ narratives emphasize the need to adopt alternative non-punitive responses to misconduct—primarily a restorative model—while simultaneously enhancing inclusive curricular and pedagogical practices to foster Black students’ academic success.</div>

Toward an alternative community-driven restorative model of school discipline

Introduction -- Education is concomitantly a path for self-actualization and personal growth, a mechanism of social mobility, a crucial factor of labour market outcomes and lifetime earnings, a social determinant of health and quality of life, a fundamental institution in a democratic society, and a human right. Because education is so consequential at the individual and societal levels, barriers to it are a cause of great concern for various stakeholders, including parents, students, and community advocates. As a case in point, several advocates have identified issues pertaining to school discipline processes and outcomes in Nova Scotia (Barjun Consultants, 2001; Black Learners Advisory Committee, 1994; Nunn, 2006). Recently, we learned that Black learners in Nova Scotia are more likely to be subjected to out-of-school suspensions than other students across the province (Woodbury, 2016). Yet, scholarly literature indicates that punitive school discipline, such as out-of-school suspensions, are ineffective, worsen problematic behaviour, alienate students from school, and keep students away from formal learning opportunities (Fenning et al., 2004; Gregory et al., 2010; Jean-Pierre & Parris-Drummond, 2018; Mayer, 2001; Noguera, 2003). <div><br></div><div>This report is based on the main findings of a qualitative study that aimed to address school discipline racial disproportionality in Nova Scotia, conceive an alternative model of school discipline, and promote the academic success of Black learners. A research project was conducted with African Nova Scotian and Black immigrant youth, parents, and community members across the province between 2018 and 2019 in both English and French. Through nine focus groups and 17 interviews, 60 members of the community provided their perspectives and insights to inform the conception of an alternative model of school discipline. A community forum subsequently took place in March 2020 to discuss the findings and main recommendations with community members. Based on the research project and scholarly literature, this report presents key findings and recommendations that can foreground future school discipline policy and interventions to further Black learners’ academic success in Nova Scotia. Overall, the key themes derived from participants’ narratives emphasize the need to adopt alternative non-punitive responses to misconduct—primarily a restorative model—while simultaneously enhancing inclusive curricular and pedagogical practices to foster Black students’ academic success.</div>

Spatial and Temporal Differences in Fecundity of Atlantic Herring (Clupea harengus) off Nova Scotia and Consequences for Biological Reference Points

The relationships between fecundity and size of Atlantic herring (Clupea harengus) were estimated within five different spawning areas off the coast of Nova Scotia in 2019 and 2020. Statistically significant differences in fecundity relative to body weight were observed among spawning areas and between years. Fecundity-at-length on the German Bank spawning ground was 29-36% and 22-28% lower than estimates from 2001 and 1970, respectively. Temporal changes in weight- and relative fecundity- at-age resulted in a decrease in the number of eggs-per-recruit (in an equilibrium unfished state) by 50% and a decrease of 27% in the egg production per tonne of spawning stock biomass (SSB) in 2020 relative to 1970. Decreases in SSB-per-recruit and eggs-per-recruit over time resulted in proportional decreases in equilibrium SSB at maximum sustainable yield (MSY); however, the fishing mortality rate (F) at MSY remained relatively stable over time. Total egg production was shown to be disproportional to SSB. Equilibrium SSB at MSY was greater (and F at MSY lower) when estimated using eggs-per-recruit compared to SSB-per-recruit. Failing to account for fecundity and assuming that egg production is proportional to SSB resulted in an overestimate of stock status

Petrographic Record and Conditions of Expansive Hydration of Anhydrite in the Recent Weathering Zone at the Abandoned Dingwall Gypsum Quarry, Nova Scotia, Canada

In the Dingwall gypsum quarry in Nova Scotia, Canada, operating in 1933–1955, the bedrock anhydrite deposits of the Carboniferous Windsor Group have been uncovered from beneath the secondary gypsum beds of the extracted raw material. The anhydrite has been subjected to weathering undergoing hydration (gypsification), transforming into secondary gypsum due to contact with water of meteoric derivation. The ongoing gypsification is associated with a volume increase and deformation of the quarry bottom. The surface layer of the rocks is locally split from the substrate and raised, forming spectacular hydration relief. It shows numerous domes, ridges and tepee structures with empty internal chambers, some of which represent unique hydration caves (swelling caves, Quellungshöhlen). The petrographic structure of the weathering zone has been revealed by macro- and microscopic observations. It was recognized that gypsification commonly starts from a developing network of tiny fractures penetrating massive anhydrite. The gypsification advances from the fractures towards the interior of the anhydrite rocks, which are subdivided into blocks or nodules similar to corestones. Characteristic zones can be recognized at the contact of the anhydrite and the secondary gypsum: (1) massive and/or microporous anhydrite, (2) anhydrite penetrated by tiny gypsum veinlets separating the disturbed crystals and their fragments (commonly along cleavage planes), (3) gypsum with scattered anhydrite relics, and (4) secondary gypsum. The secondary gypsum crystals grow both by replacement and displacement, and also as cement. Displacive growth, evidenced by abundant deformation of the fragmented anhydrite crystals, is the direct cause of the volume increase. Crystallization pressure exerted by gypsum growth is thought to be the main factor generating volume increase and, consequently, also the formation of new fractures allowing water access to “fresh” massive anhydrite and thus accelerating its further hydration. The expansive hydration is taking place within temperature range from 0 to ~30 °C in which the solubility of gypsum is lower than that of anhydrite. In such conditions, dissolving anhydrite yields a solution supersaturated with gypsum and the dissolution of anhydrite is simultaneous with in situ replacive gypsum crystallization. Accompanying displacive growth leads to volume increase in the poorly confined environment of the weathering zone that is susceptible to upward expansion.