Search for: All records

Although many sources of atmospheric CO2 have been identified, the major sinks are best understood in a deep-time context. Here, we focus on two Large Igneous Provinces (LIPs), the Central Atlantic Magmatic Province (CAMP) situated in the low latitude humid zone ~201.6 Ma and the Karoo-Ferrar located at high southern latitudes ~183 Ma. We use soil carbonate, lithologic, δD of n-alkanes, Sr data, and modeling to examine how these eruptions, hydrological cycling, and weathering impacted global atmospheric CO2, carbon cycling, and biotic extinction at the ETE and T-OAE hyperthermals. CAMP largely erupted in the tropics, doubled atmospheric CO2 from ~2,500 – 5,000 ppm at the ETE (observed in soil carbonates with an onset <1000 and a duration of <~20 ky) and rapidly sequestered CO2 (< 2,500 ppm) as recorded in Newark Supergroup basins (eastern US). These same strata preserve variations in the lake level expression of the climatic precession cycle based on lithology and δD. High cyclicity variance tracked high pCO2 (>~4000 ppm) and drove insolation-paced increases in precipitation. Leaf wax δD shows significant variability, reflecting an enhanced hydrological cycle at the ETE with repeated sudden shifts in relative evaporation for ~1 Myr. In marine strata, 87Sr/86Sr and 187Os/188Os values track changes in pCO2, suggesting a terrestrial/marine linkage through continental weathering, CO2, and runoff. Despite the northward movement of these basins into the arid belt, our data suggest lower evaporation relative to precipitation driven by lower temperatures, consistent with lower pCO2 due to CAMP weathering, which modeling estimates to have increased 6 to 10-fold for >1.6 Myr after the eruptive phase. Release of CO2 from the Karoo-Ferrar LIP similarly enhanced the hydrological cycle as evidenced from sedimentary observations (e.g., fine-scale turbidites and debris flow deposits) in Yorkshire (UK). The onset of the carbon isotope excursion at the T-OAE lasts 0.5 Myr with a 1.5 Myr duration modulated by astronomical pacing. Our leaf wax δD from the same strata show a transient enhancement in the hydrological cycle. Although the Karoo-Ferrar has a limited drawdown potential when compared with CAMP‐type basalts because of its higher latitude location, Toarcian weathering rates may have increased 2 to 5-fold, acting as a net sink 1–2 Myr after eruptions ceased. 

The COVID-19 pandemic has extensively changed the state of psychological science from what research questions psychologists can ask to which methodologies psychologists can use to investigate them. In this article, we offer a perspective on how to optimize new research in the pandemic’s wake. Because this pandemic is inherently a social phenomenon—an event that hinges on human-to-human contact—we focus on socially relevant subfields of psychology. We highlight specific psychological phenomena that have likely shifted as a result of the pandemic and discuss theoretical, methodological, and practical considerations of conducting research on these phenomena. After this discussion, we evaluate metascientific issues that have been amplified by the pandemic. We aim to demonstrate how theoretically grounded views on the COVID-19 pandemic can help make psychological science stronger—not weaker—in its wake. 

We present a gravitational lensing and X-ray analysis of a massive galaxy cluster and its surroundings. The core of MACS J0717.5+3745 ($M(R\lt 1\, {\rm Mpc})\sim$ $2 \times 10^{15}\, \, {\rm M}_{\odot }$, $z$ = 0.54) is already known to contain four merging components. We show that this is surrounded by at least seven additional substructures with masses ranging $3.8{-}6.5\times 10^{13}\, \, {\rm M}_{\odot }$, at projected radii 1.6–4.9 Mpc. We compare MACS J0717 to mock lensing and X-ray observations of similarly rich clusters in cosmological simulations. The low gas fraction of substructures predicted by simulations turns out to match our observed values of 1–$4{{\ \rm per\ cent}}$. Comparing our data to three similar simulated haloes, we infer a typical growth rate and substructure infall velocity. That suggests MACS J0717 could evolve into a system similar to, but more massive than, Abell 2744 by $z$ = 0.31, and into a ∼ $10^{16}\, \, {\rm M}_{\odot }$ supercluster by $z$ = 0. The radial distribution of infalling substructure suggests that merger events are strongly episodic; however, we find that the smooth accretion of surrounding material remains the main source of mass growth even for such massive clusters.