Table 1.

He content and isotopic ratios of MORB or MM and “primordial” or “plume” material (PM)

	MM	PM	Ref(s).
3He/4He	6 to 10 Ra	2 to 31 Ra	28, 32
	(definition)
3He/36Ar	2	1†	32
3He/130Xe	4.5	1†	32
3He/22Ne	4	1†	32
	1.6	1†	45
He/Sr	7	1†	8, 31
3He/CO2 (×10−10)	1.3 to 10	0.5 to 5	37
4He/CO2 (×10−5)	1 to 20	0.3 to 2	37
He, μcc/g	1 to 80	0.03 to 4.5	33, 34, 43
			46, 47, 53
3He, ncc/g	0.01 to 1	10−4 to 0.04	33, 34, 43
			46, 47
3He/238U (atomic ratio)	10−4	4.5 × 10−4	32
4He*/21Ne* (107)	>4	>3	4, 5, 42, 45
4He*/40Ar* (107)	>1	>3	4, 5, 42
			43, 46

^*Radiogenic or nucleoogenic component. 

^†Reference value.