Subduction and carbonate platform interactions

Abstract

Plate tectonics, as the unifying theory in Earth sciences, controls the functioning of important planetary processes on geological timescales. Here, we present an open‐source workflow that interrogates community digital plate tectonic reconstructions, primarily in the context of the planetary deep carbon cycle. We present an updated plate tectonic reconstruction covering the last 400 million years of Earth evolution and explore components of the plate–mantle system that is involved in the exchange and storage of carbon. First, the workflow enables us to estimate subduction zone lengths through time, which represent the “tap” of carbon that is released at convergent tectonic margins. Second, we explore the role of Andean‐style versus intra‐oceanic subduction regimes during Pangea assembly and breakup. Third, we provide an improved model for carbonate platform evolution since the Devonian and evaluate the interaction of subduction zones and buried carbonate platforms. Last, we present a new model for estimating oceanic age, carbon content in the upper oceanic crust, and estimated (carbon‐containing) sediment thicknesses through time and present methods to track the subduction of this material through time. These components of the deep carbon cycle are key mechanisms controlling, or at least modulating, atmospheric CO2 on geological timescales and hence strongly influencing long‐term climate. We find that the mid to Late Cretaceous greenhouse climates were likely driven by increased subduction fluxes of volatiles and increased subduction zone interactions with carbonate platforms in the Tethyan tectonic domain. Our work highlights the importance of community digital plate tectonic reconstructions as a framework for studying key systems, such as the deep carbon cycle, that influence the life‐support mechanisms on our planet.

Global Hydrogen Production During High‐Pressure Serpentinization of Subducting Slabs

“…One way to assess the viability of our global estimate is to compare our volumetric fluxes to other similar fluxes within ocean basins, such as gross crustal production rates and H 2 fluxes within different oceanic environments. Gross oceanic fluxes, including subduction flux and mid-ocean ridge flux, have been estimated in previous studies (e.g., East et al, 2019;Jarrard, 2003;Zahirovic et al, 2022). Our calculated volumetric flux of all subducted RAP within subduction zones (1.84 • 10 6 km 3 per Ma) represents ∼10% of the total volume of subducted oceanic crust over the same time range (1.5 • 10 7 km 3 , East et al, 2019).…”

“…Gross oceanic fluxes, including subduction flux and mid‐ocean ridge flux, have been estimated in previous studies (e.g., East et al., 2019; Jarrard, 2003; Zahirovic et al., 2022). Our calculated volumetric flux of all subducted RAP within subduction zones (1.84 • 10 6 km 3 per Ma) represents ∼10% of the total volume of subducted oceanic crust over the same time range (1.5 • 10 7 km 3 , East et al., 2019).…”

The effects of local variations in conditions on carbon storage and release in the continental mantle

“…7a ), which may apply to the formation of continental lithosphere where it originates by assembly during accretionary orogenesis. This may include large tracts of solid, unmelted carbonate that have risen diapirically from subducting slabs and become stored beneath arcs [ 13 ] and later incorporated into the continental lithosphere, especially in periods of the Phanerozoic when carbonate platforms were abundant [ 88 , 89 ]. Carbonate-rich melts may originate during subduction, either when carbonate is a minor component in clastic sediments [ 38 , 39 ] or from melting of altered oceanic crust [ 66 ].…”

Flare-up in Cordilleran arcs controlled by fluxes in subduction water budgets

“…The crustal thickness includes oceanic basement and sediment. Sediment thickness estimates are based on model predictions after Zahirovic et al (2022). Animations of the subduction zone convergence, lithospheric age and sediment thickness are presented in the supplement (S1 & S2).…”

“…In turn, the thickness of the sedimentary cover varies not only in relation to seafloor age, but also latitude, and proximity to prominent deltaic systems (Fig. 1c) (Zahirovic et al, 2022). In combination these all control the capacity to carry and release H 2 O and other fluids (CO 2 , H 2 S, SO 2 ) during subduction.…”