Global Continental Arc Flare-ups and Their Relation to Long-Term Greenhouse Conditions

The rise and fall of continental arcs: Interplays between magmatism, uplift, weathering, and climate

“…This is because much of the carbonate subducted may just come back out through the volcanoes, or as recently suggested, some of the carbonate subducted may bypass the volcanic front, given modern thermal states of subducting slabs (Dasgupta, 2013;Kerrick and Connolly, 2001). It is in continental arcs where the effect of upper plate carbonates may be most pronounced because continental margins serve as long-lived storage sites for sedimentary carbonate accumulated over a continent's history (Lee and Lackey, 2015;Lee et al, 2013). Magmatic interaction with stored upper plate carbonates can serve to enhance the magmatic flux of CO 2 (Chadwick et al, 2007;Deegan et al, 2010;Toutain et al, 2009) such that changes in the global ratio of continental to island arcs might be expected to lead to variations in global CO 2 inputs to the exogenic system.…”

“…Such may be the case for volcanic arcs. Volcanic arcs are a large source of CO 2 , which derives from background mantle CO 2 , decarbonation of subducted carbonates, and magmatically induced thermal metamorphism of carbonates in the upper plate (Burton et al, 2013;Dasgupta and Hirschmann, 2010;Hilton et al, 2002;Lee and Lackey, 2015;Lee et al, 2013;Marty and Tolstikhin, 1998). Averaged over 10-50 My, intra-oceanic arcs may not be as important as continental arcs in terms of net CO 2 inputs into the exogenic system (arc flux minus subduction flux).…”

Arc volcanism, carbonate platform evolution and palaeo-atmospheric CO<sub>2</sub>: Components and interactions in the deep carbon cycle

“…Ancient carbonate platforms are known to persist to present-day in surface reservoirs, and can be reconstructed from the geological record as they either outcrop, are sampled by drilling or are interpreted from seismic reflection studies (Kiessling et al, 2003). Some crustal carbonate is inevitably eroded or subducted into the deep mantle, however it is improbable that most reservoirs have been destroyed in the way as most carbonate platforms accumulate on continental margins and are not likely to subduct (Lee and Lackey, 2015). Given limited erosion on 5 passive continental margins, except in the cases of major uplift and deformation through mountainbuilding, it is far more likely that carbonate platform expansion has exceeded their depletion by erosion through time (Ridgewell and Zeebe, 2005).…”

“…Simultaneously, CO2 is emitted 15 during arc volcanism and at mid-ocean ridges (MORs) where new oceanic crust is being created (Burton et al, 2013). Despite the proposal that silicate weathering has, at some stages, been a dominating control of atmospheric CO2 levels (Kump, 2000;Kent and Muttoni, 2013), arc magmatism at icehousegreenhouse transitions is thought to be the first-order control on climate fluctuations while silicate weathering acts to modulate atmospheric CO2 as a secondary regulative process (Ridgwell and Zeebe,20 2005; Lee and Lackey, 2015;McKenzie et al, 2016). Recent studies have found support for links between global arc activity and icehouse-greenhouse transitions using detrital zircon ages, modelling and experimental techniques, particularly as drivers of greenhouse conditions in the Cambrian (McKenzie et al, 2016;Cao et al, 2017), Jurassic-Cretaceous (McKenzie et al, 2016) and early Paleogene (Lee et al, 2013;Carter and Dasgupta, 2015;Cao et al, 2017).…”

“…At different points in Earth's history, emissions from continental, carbonate-intersecting arcs (CIAs) may have dominated global volcanic carbon flux, such as during the Cretaceous (144-65 Ma) where continental arcs are hypothesised to have been longer than modern day lengths and where a greenhouse climate prevailed (Lee et al, 2013;van der Meer et al, 2014;Cao et al, 10 2017). It is plausible that crustally-derived carbon at other points in Earth's history has played a significant role in affecting global climate (Lee and Lackey, 2015), yet it is difficult to test this hypothesis, especially due to preservation bias in the geological record (Berner, 2004).…”