Episodic nature of continental arc activity since 750 Ma: A global compilation

Abstract

Continental arcs have been recently hypothesized to outflux large amounts of CO 2 compared to island arcs so that global flare-ups in continental arc magmatism might drive long-term greenhouse events. Quantitative testing of this hypothesis, however, has been limited by the lack of detailed studies on the spatial distribution of continental arcs through time. Here, we compile a worldwide database of geological maps and associated literature to delineate the surface exposure of granitoid plutons, allowing reconstruction of how the surface area addition rate of granitoids and the length of continental arcs have varied since 750 Ma. These results were integrated into an ArcGIS framework and plate reconstruction models. We find that the spatial extent of continental arcs is episodic with time and broadly matches the detrital zircon age record. Most vigorous arc magmatism occurred during the 670-480 Ma and the 250-50 Ma when major greenhouse events are recognized. Low continental arc activity characterized most of the Cryogenian, middle-late Paleozoic, and Cenozoic when climate was cold. Our results indicate that plate tectonics is not steady, with fluctuations in the nature of subduction zones possibly related in time to the assembly and dispersal of continents. Our results corroborate the hypothesis that variations in continental arc activity may play a first order role in driving long-term climate change. The dataset presented here provides a quantitative basis for upscaling continental arc processes to explore their effects on mountain building, climate, and crustal growth on a global scale.

True Polar Wander: A Key Indicator for Plate Configuration and Mantle Convection During the Late Neoproterozoic

“…This comparison shows that the global detrital zircon age frequency is a powerful proxy for estimating not only continental arc activity as proposed by McKenzie et al (2016) and Cao et al (2017) but the total subduction activity in the past. This comparison shows that the global detrital zircon age frequency is a powerful proxy for estimating not only continental arc activity as proposed by McKenzie et al (2016) and Cao et al (2017) but the total subduction activity in the past.…”

“…(3) Around 635 Ma, the girdle of subduction restarts and produces the pair of TPW episodes during the Ediacaran. Cao et al (2017) show that the global detrital zircon age frequency is correlated with the estimated length of continental arcs for the last 750 Ma suggesting it may be a good proxy for continental arc activity through time. Nevertheless, there are no paleomagnetic constraints on these blocks during that period to estimate the size of the oceanic basin and the potential impact of subducted material on inertia.…”

“…According to their results, the convective system during a supercontinental phase is thus mainly modulated by the location and velocity of slabs pertaining to the girdle of subduction. McKenzie et al (2016) and Cao et al (2017) suggest that large subduction changes from the Cryogenian to the Ediacaran may have played a major role in driving the Neoproterozoic global-scale glaciations. Surrounding subductions would produce a widespread extensional stress field inside the girdle (Bott, 1992;Greff-Lefftz et al, 2017).…”

Spatial and Depth‐Dependent Variations in Magma Volume Addition and Addition Rates to Continental Arcs: Application to Global CO2 Fluxes since 750 Ma

“…The Cascades Core, however, shows unusual high MARs and MMA, reasons for this are discussed in section 6. We use these width estimates in combination with the continental arc lengths of Cao et al (2017) to calculate areas of continental arcs since 750 Ma. Thus, when doing these calculations, the variability of arc widths and the episodic behavior of continental arc magmatism needs to be considered.…”

“…The release of CO 2 to the atmosphere through arc volcanoes plays a major role in the global carbon cycle (e.g., Kelemen & Manning, 2015), and its influence on modulating climate variability throughout Earth's history has been documented (e.g., McKenzie et al, 2016). We further calculate global estimates of CO 2 outgassing through time by upscaling individual MARs from the investigated arcs to global values based on the record of changing global continental arc lengths since 750 Ma from Cao et al (2017). Plutonic footprints of arc systems are volumetrically enormous in comparison to volcanic caps, with plutonic to volcanic ratios ranging from 10:1 to 30:1 (Lipman & Bachmann, 2015;Tierney et al, 2016;Ward et al, 2017;Zandt et al, 2003).…”