Open Access
Subduction Fluxes of Water, Carbon Dioxide, Chlorine, and Potassium
Richard D. Jarrard
- Vol. 2002
TLDR
In this paper, the authors estimate that half to two thirds of subducted crustal water is later refluxed at the prism toe; most of the remaining water escapes at subarc depths, triggering partial melting.Abstract:
[1] The alteration of upper oceanic crust entails growth of hydrous minerals and loss of macroporosity, with associated large-scale fluxes of H2O, CO2, Cl−, and K2O between seawater and crust. This age-dependent alteration can be quantified by combining a conceptual alteration model with observed age-dependent changes in crustal geophysical properties at DSDP/ODP sites, permitting estimation of crustal concentrations of H2O, CO2, Cl−, and K2O, given crustal age. Surprisingly, low-temperature alteration causes no net change in total water; pore water loss is nearly identical to bound water gain. Net change in total crustal K2O is also smaller than expected; the obvious low-temperature enrichment is partly offset by earlier high-temperature depletion, and most crustal K2O is primary rather than secondary. I calculate crustal concentrations of H2O, CO2, Cl−, and K2O for 41 modern subduction zones, thereby determining their modern mass fluxes both for individual subduction zones and globally. This data set is complemented by published flux determinations for subducting sediments at 26 of these subduction zones. Global mass fluxes among oceans, oceanic crust, continental crust, and mantle are calculated for H2O, Cl−, and K2O. Except for the present major imbalance between sedimentation and sediment subduction, most fluxes appear to be at or near steady state. I estimate that half to two thirds of subducted crustal water is later refluxed at the prism toe; most of the remaining water escapes at subarc depths, triggering partial melting. The flux of subducted volatiles, however, does not appear to correlate with either rate of arc magma generation or magnitude of interplate earthquakes.read more
Citations
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Journal ArticleDOI
The deep carbon cycle and melting in Earth's interior
TL;DR: Carbon geochemistry of mantle-derived samples suggests that the fluxes and reservoir sizes associated with deep cycle are in the order of 1012−13−g−C/yr and 1022−23−g C, respectively.
Journal ArticleDOI
Subduction factory: 4. Depth-dependent flux of H2O from subducting slabs worldwide
TL;DR: In this article, a global compilation of the thermal structure of subduction zones is used to predict the metamorphic facies and H 2 O content of downgoing slabs.
Journal ArticleDOI
The chemistry of subduction-zone fluids
TL;DR: In this paper, it was shown that H2O-rich, Cl-poor, alkali-aluminosilicate-bearing fluid is fundamental to element transport in the mantle wedge.
Journal ArticleDOI
Reevaluating carbon fluxes in subduction zones, what goes down, mostly comes up.
TL;DR: Carbon fluxes in subduction zones can be better constrained by including new estimates of carbon concentration in subducting mantle peridotites, consideration of carbonate solubility in aqueous fluid along subduction geotherms, and diapirism of carbon-bearing metasediments.
Journal ArticleDOI
Metamorphic chemical geodynamics in continental subduction zones
TL;DR: In this paper, a review of the geochemical properties of UHP terranes is presented, focusing on the following issues in continental subduction zones: the time and duration of uHP metamorphism, the origin and action of metamorphic fluid/melt inside UHP slices, the element and isotope mobilities under HP to UHP conditions during continental collision, the origins of premetamorphic protoliths and its bearing on continental collision types, and the crustal detachment and crust mantle interaction in subduction channels.
References
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Journal ArticleDOI
Derivation of some modern arc magmas by melting of young subducted lithosphere
Marc J. Defant,Mark S. Drummond +1 more
TL;DR: In this paper, the trace-element geochemical properties of the adakites (termed "adakites") of modern island and continental arcs are shown to be consistent with a derivation by partial melting of the subducted slab, and in particular that subducting lithosphere younger than 25 Myr seems to be required for slab melting to occur.
Journal ArticleDOI
World-Wide Delivery of River Sediment to the Oceans
John D. Milliman,Robert H. Meade +1 more
TL;DR: The authors showed that rivers with large sediment loads (annual discharges greater than about $15 \times 10^{6}$ tons) contribute about $7 −times 10 −9$ tons of suspended sediment to the ocean yearly.
Journal ArticleDOI
Effect of recent revisions to the geomagnetic reversal time scale on estimates of current plate motions
TL;DR: In this article, the optimal recalibration of NUVEL-1 is proposed to multiply the angular velocities by a constant, α, of 0.9562, which is a compromise among slightly different calibrations appropriate for slow, medium, and fast rates of seafloor spreading.
Current plate motions
TL;DR: In this paper, a new global model (NUVEL-1) was proposed to describe the geologically current motion between 12 assumed-rigid plates by inverting plate motion data.
Journal ArticleDOI
Geomorphic/Tectonic Control of Sediment Discharge to the Ocean: The Importance of Small Mountainous Rivers
TL;DR: In this paper, data from 280 rivers discharging to the ocean indicates that sediment loads/yields are a log-linear function of basin area and maximum elevation of the river basin.