A possible mechanism for spontaneous cyclic back-arc spreading

Progress in Earth and Planetary Science

Table 1 Physical properties of rocks

	Reference density^*1	Reference temperature^*1	Reference pressure^*1	Thermal expansion^*2	Compressibility ^*3	Thermal conductivity ^*2	Radioactive heating^*4
	ρ₀	T₀	P₀	α	β	k	H_r
	kg/m³	K	MPa	10^–5/K	10^–11/Pa	W/m/K	μW/m³
Continental upper crust	2700	273	0.1	2.6	1	2.5	1.3
Continental lower crust	2900	273	0.1	2.6	1	2.5	0.27
Oceanic crust	3000–3300^*5	273	0.1	2.6	1	2.5	0.27
Mantle wedge	3512	1740	13,500	3.0	0.7	3.1	0
Upper mantle	3532	1740	13,500	3.0	0.7	3.1^*6	0
Upper mantle for SP^*7	3532	1740	13,500	3.0	0.7	3.1	0
Transition zone	3650	1740	13,500	2.3	0.45	4.0	0
Lower mantle	3984	1850	23,000	2.0	0.25	6.0	0

*1 Modified from Faccenda and Dal Zilio (2017) according to density distribution of the present model
*2 Tosi et al. (2013)
*3 Turcotte and Schubert (2002)
*4 Peacock and Wang (1999)
*5 Linearly increase with the depth of 15–60 km to incorporate the effect of eclogitization
*6 Eq. 6 is applied for z > 20 km to incorporate the effect of heat transport due to fluid and/or melt migration
^*7 Upper mantle for subducting plate (purple in Fig. 1b and 2)