Although a complete section of oceanic crust has not yet been drilled, geologists have several pieces of evidence that help them understand the ocean floor. For example, continents are composed of igneous, sedimentary, and metamorphic rocks. Bureau Gravimetrique International (BGI), Paris, Boudier F, Nicolas A, Mainprice D (2005) Does anisotropy of thermal contraction control hydrothermal circulation at the Moho level below fast spreading oceanic ridges? J Geophys Res: Solid Earth 99:3081–3095. J Geophys Res. The models run until a steady state is obtained and melt fraction does not change with time. https://doi.org/10.1029/92GL00161, Chen YJ (2000) Dependence of crustal accretion and ridge-axis topography on spreading rate, mantle temperature, and hydrothermal cooling. See Fig. In: Ahrens TJ (ed) Rock physics and phase relations, 3rd edn. https://doi.org/10.1190/1.1440444, Parker RL (1972) Rapid calcultion of potential anomalies. 1992). 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The melt fraction is defined as: where \(X_{{H_{{_{2} }} O}}^{{}}\) is the weight fraction of water dissolved in the melt, \(X_{{H_{{_{2} }} O}}^{bulk}\) the total weight fraction of water, \(T_{cpx - out}^{{}}\) the temperature when clinopyroxene (cpx) is totally dissolved, \(T_{solidus}^{{}}\) the solidus temperature of mantle, \(T_{liquidus}^{{}}\) the liquidus temperature of mantle, \(T_{liquidus}^{lherz}\) the liquidus temperature of lherzolite (lerhz), \(\Delta T(X_{{H_{{_{2} }} O}}^{{}} )\) the temperature variation due to the bulk water, \(F_{cpx - out}^{{}}\) the weight fraction of F when cpx is totally dissolved, \(\gamma_{1}\) and \(\gamma_{2}\) the exponents of melt function. Sci Rep 4:6342. https://doi.org/10.1038/srep06342. Our observed melt volume at a mid-ocean ridge (MOR) is an upper bound on the volume of crust, as it assumes 100% melt extraction. In: Davis EE, Elderfield H (eds) Hydrogeology of the oceanic lithosphere. These trends correspond to increasing Curie point depth (from 12 to 14 km, Fig. The mantle transition zone to the NW of Tristan da Cunha is thickened and cool. The simplest model shows an oceanic-like crust, slightly thickened to 9 km. Mar Geophys Res 41, 14 (2020). J Geophys Res: Solid Earth. Geology. Nature 423:962–965. Thus, a decreasing near-ridge temperature probably contributes to crustal thinning from slow to fast-spreading centers. Heat flux is zero on the lateral walls. https://doi.org/10.1029/JB092iB08p08089, Langmuir CH, Forsyth DW (2007) Mantle melting beneath mid-ocean ridges. https://doi.org/10.1016/j.lithos.2015.10.020, Cannat M, Cann J, Maclennan J (2004) Some hard rock constraints on the supply of heat to mid-ocean ridges. The initial temperatures are 0 °C at the surface and 1607 °C at the bottom (660 km depth) based on a potential temperature of 1277 ºC and an adiabatic gradient of 0.5 °C/km. J Petrol 51:1913–1940. Nature 508:508–512. https://doi.org/10.1093/petrology/25.3.713, Morgan JP, Chen YJ (1993) The genesis of oceanic crust: magma injection, hydrothermal circulation, and crustal flow. Texas A&M University, College Station, TX, Dick HJB, Lin J, Schouten H (2003) An ultraslow-spreading class of ocean ridge. Geochem Geophys Geosyst. Furthermore, we imaged the mantle transition zone discontinuities by analysing receiver functions at the permanent seismological station TRIS and surrounding OBS stations. This research is funded by National Natural Science Foundation of China (Grant No. The initial temperature corresponds to a half-space cooling model (Afonso et al. Inferred low melt volume anomalies beneath fast-spreading centers are consistent with a 20 °C temperature drop in the near-ridge mantle, likely caused by efficient hydrothermal cooling. Nature 355:815–817. Cambridge University Press, Cambridge, pp 59–107, Chen YJ (1992) Ocean crustal thickness versus spreading rate. Mar Geophys Res 5:165–172. 3 for a detailed interpretation. Earth Planet Phys 2:1–15. 10). 7) due to low melt production (< 100 km3/Ma/km, Fig. It is made of mainly basalt, grabbo and diabise. 8a, b). 2004; Katsura et al. In: Morgan JP, Blackman DK, Sinton JM (eds) Mantle flow and melt generation at mid-ocean ridges. The dashed line marks the area shown in Fig. Nature 421:252–256. https://doi.org/10.1016/j.cageo.2008.02.018, Gómez-Ortiz D, Agarwal BNP (2005) 3DINVER.M: a MATLAB program to invert the gravity anomaly over a 3D horizontal density interface by Parker–Oldenburg's algorithm. Nature 385:326–329. Data processing and mapping are supported by MATLAB and GMT (Wessel and Smith 1995). Crustal thickness (H) variation with half spreading rate (Sr) within 5 Ma isochrons. Here melt volume is computed using a numerical model. https://doi.org/10.1016/j.tecto.2013.06.020, Reid I, Jackson HR (1981) Oceanic spreading rate and crustal thickness. https://doi.org/10.1016/j.epsl.2006.04.011, Wolery TJ, Sleep NH (1976) Hydrothermal circulation and geochemical flux at mid-ocean ridges. Earth Planet Sci Lett 25:305–312. Earth Planet Sci Lett 311:386–395. As the name implies, oceanic crust is the floor of the oceans. https://doi.org/10.1016/j.pepi.2003.11.012, Hasenclever J, Theissen-Krah S, Rupke LH, Morgan JP, Iyer K, Petersen S, Devey CW (2014) Hybrid shallow on-axis and deep off-axis hydrothermal circulation at fast-spreading ridges. Blue and red dotted lines with corresponding circles are simulated volumes with different Tlab. J Geophys Res: Solid Earth 122:3934–3952. Elsevier, Amsterdam, pp 497–541. In: Lagabrielle WRBP (ed) Faulting and magmatism at mid-ocean ridges, vol 106. 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