Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Long, M. D., Wagner, L. S., King, S. D., Evans, R. L., Mazza, S. E., Byrnes, J. S., Johnson, E. A., Kirby, E., Bezada, M. J., Gazel, E., Miller, S. R., Aragon, J. C., & Liu, S. Evaluating models for lithospheric loss and intraplate volcanism beneath the Central Appalachian Mountains. Journal of Geophysical Research: Solid Earth, 126(10), (2021): e2021JB022571, https://doi.org/10.1029/2021JB022571.

Description: The eastern margin of North America has been shaped by a series of tectonic events including the Paleozoic Appalachian Orogeny and the breakup of Pangea during the Mesozoic. For the past ∼200 Ma, eastern North America has been a passive continental margin; however, there is evidence in the Central Appalachian Mountains for post-rifting modification of lithospheric structure. This evidence includes two co-located pulses of magmatism that post-date the rifting event (at 152 and 47 Ma) along with low seismic velocities, high seismic attenuation, and high electrical conductivity in the upper mantle. Here, we synthesize and evaluate constraints on the lithospheric evolution of the Central Appalachian Mountains. These include tomographic imaging of seismic velocities, seismic and electrical conductivity imaging along the Mid-Atlantic Geophysical Integrative Collaboration array, gravity and heat flow measurements, geochemical and petrological examination of Jurassic and Eocene magmatic rocks, and estimates of erosion rates from geomorphological data. We discuss and evaluate a set of possible mechanisms for lithospheric loss and intraplate volcanism beneath the region. Taken together, recent observations provide compelling evidence for lithospheric loss beneath the Central Appalachians; while they cannot uniquely identify the processes associated with this loss, they narrow the range of plausible models, with important implications for our understanding of intraplate volcanism and the evolution of continental lithosphere. Our preferred models invoke a combination of (perhaps episodic) lithospheric loss via Rayleigh-Taylor instabilities and subsequent small-scale mantle flow in combination with shear-driven upwelling that maintains the region of thin lithosphere and causes partial melting in the asthenosphere.

Description: The authors acknowledge support from the U.S. National Science Foundation EarthScope and GeoPRISMS programs via grants EAR-1460257 (R. L. Evans), EAR-1249412 (E. Gazel), EAR-1249438 (E. A. Johnson), EAR-1250988 (S. D. King), EAR-1251538 (E. Kirby), and EAR-1251515 (M. D. Long). The collection and dissemination of most of the geophysical data and models discussed in this study were facilitated by the Incorporated Research Institutions for Seismology (IRIS). The facilities of the IRIS Consortium are supported by the United States National Science Foundation under Cooperative Agreement EAR-1261681.

Description: We present spatio-temporal mass balance trends for the Antarctic Ice Sheet from a statistical inversion of satellite altimetry, gravimetry, and elastic-corrected GPS data for the period 2003–2013. Our method simultaneously determines annual trends in ice dynamics, surface mass balance anomalies, and a time invariant solution for glacio-isostatic adjustment, while remaining largely independent of forward models. We establish that over the period 2003–2013, Antarctica has been losing mass at a rate of −84± 22 Gt yr −1 , with a sustained negative mean trend of dynamic imbalance of −111 ±13 Gt yr −1 . West Antarctica is the largest contributor with −112 ±10 Gt yr −1 , mainly triggered by high thinning rates of glaciers draining into the Amundsen Sea Embayment. The Antarctic Peninsula has experienced a dramatic increase in mass loss in the last decade, with a mean rate of −28 ±7 Gt yr −1 , and significantly higher values for the most recent years following the destabilization of the Southern Antarctic Peninsula around 2010. The total mass loss is partly compensated by a significant mass gain of 56 ± 18 Gt yr −1 in East Antarctica due to a positive trend of surface mass balance anomalies.