Mean MORB and Bulk Mantle compositions

The Mean MORB compositions were calculated from ~5000 glass analyses downloaded from the PetDB data base (thanks to K. Lehnert for her help). Oxides in percent and traces in ppm. The data are first corrected to 8 percent MgO by plotting log C_i vs [MgO]. I provide an arithmetic mean (normal distribution), a geometric mean (log-normal distribution) and a mode (most frequent value) for each histogram. 2s stands for the relative uncertainty on the geometric mean at the 95 percent confidence level.

Element^1	data #	rMgO^2	arith.	geom.	2s (rel)^5	Mode ^6	HOF88^7	SUN89^8
			mean^3	mean^4
				recom.
SiO2	4838	-0.51	50.89	50.89	0.001	51.04	50.45
TiO2	4832	-0.76	1.73	1.73	0.017	1.84	1.615
Al2O3	4832	0.53	14.47	14.47	0.004	14.69	15.255
FeOT	4143	-0.69	10.8	10.8	0.007	10.14	10.426
MgO	4876		8	8		8	7.576
CaO	4832	0.7	10.95	10.95	0.005	11.41	11.303
Na2O	4828	-0.55	2.78	2.78	0.007	2.91	2.526
K2O	4793	-0.56	0.16	0.16	0.047	0.17
87Sr/86Sr	540	0.01	0.70279	0.70279	0.00006	0.70303
143Nd/144Nd	424	0.01	0.51307	0.51307	0.00002	0.51323
eps(Nd)			8.5	8.4		11.5
206Pb/204Pb	421	-0.16	18.458	18.459	0.002	18.38
207Pb/204Pb	421	-0.1	15.518	15.518	0.0003	15.496
208Pb/204Pb	421	-0.11	38.092	38.093	0.001	38.187
(3He/4He)A	180	0.2	8.1	8.1	0.047	7.7
U	538	-0.39	0.333	0.138	0.112	0.233	0.0711
Rb	661	-0.43	3.9	2.83	0.116	2.98	1.262	0.56
K	4798	-0.56	1465	1328	0.026	1375	883.7
Th	615	-0.44	0.508	0.383	0.115	0.363	0.1871	0.12
Pb	406	-0.26	2.57	0.657	0.075	0.662	0.489	0.3
Ba	925	-0.37	42.7	25.9	0.093	14.4	13.87	6.3
Sr	1218	-0.13	133	126	0.017	115	113.2	90
La	826	-0.57	5.87	5.35	0.065	4.09	3.895	2.5
Ce	816	-0.77	15.9	15.6	0.056	12.8	12	7.5
Nd	840	-0.82	12.3	12.3	0.042	10.8	11.18	7.3
Sm	987	-0.8	3.9	3.94	0.031	3.67	3.752	2.63
Eu	805	-0.86	1.39	1.42	0.028	1.35	1.335	1.02
Gd	563	-0.8	5.07	4.99	0.029	4.73	5.08	3.68
Dy	595	-0.8	5.84	5.7	0.031	5.18	6.304	4.55
Y	1049	-0.69	35.7	36.1	0.023	32.6	35.82	28
Er	590	-0.74	3.6	3.46	0.032	3.14	4.143	2.97
Yb	795	-0.71	3.53	3.44	0.028	3.13	3.9	3.05
Lu	378	-0.78	0.552	0.556	0.05	0.495	0.589	0.46
P	4533	-0.68	753	783	0.016	860		510
Zr	1182	-0.77	116	118	0.031	119	104.24	74
Hf	298	-0.84	3.41	3.54	0.086	2.88	2.974	2.05
Ta	478	-0.53	0.428	0.368	0.113	0.277	0.192	0.13
Nb	778	-0.52	6	4.89	0.088	6.98	3.507	2.33
Co	353	0.24	43.2	42.2	0.01	43.8	47.07
Cr	799	0.78	253	191	0.07	255
Cu	517	0.38	73.7	68	0.016	66.8	74.4
Ni	945	0.83	91.8	74.8	0.04	77.4	149.5
Sc	841	0.12	40.6	40	0.007	41.4	41.37
Zn	522	-0.55	92.1	93.1	0.025	89.7
1 major elements in percent, trace elements in ppm
2 correlation coefficient between concentration or ratio and ln [MgO]
3 arithmetic mean (normal density)
4 geometric mean (log-normal density)
5 2 standard deviation / (geom. mean sqrt(n))
6 2^nd derivative of the 4th-degree best-fit polynomial through the cumulated distribution between 10 and 90 percent is set to zero
7 N-MORB Hofmann (1988) EPSL 90, 297-314.
8 N-MORB Sun and McDonough (1989) Geol. Soc. Spec. Pub. 42, 313-345

The Bulk Mantle concentrations (ppm) are calculated by subtracting Continental Crust from the Bulk Silicate Earth. Continental Crust compositions from Rudnick and Fountain (1995) and from Taylor and McLennan (1995). Bulk Silicate Earth composition from Sun and McDonough (1989).

Element	mean mantle composition
(ppm)	RF^a	TM ^b
U	0.00988	0.0137
Rb	0.174	0.367
K	125	174
Th	0.0385	0.0541
Pb	0.0576	0.0917
Ba	3.75	4.79
Sr	17.6	18.1
La	0.519	0.534
Ce	1.38	1.44
Nd	1.11	1.14
Sm	0.38	0.383
Eu	0.146	0.147
Gd	0.521	0.524
Dy	0.653	0.652
Y	4.19	4.19
Er	0.425	0.425
Yb	0.429	0.427
Lu	0.0656	0.0658
P	84.2
Zr	9.63	9.8
Hf	0.258	0.263
Ta	0.0293	0.0301
Nb	0.573	0.581
Co	106	106
Cr	2644	2643
Cu	30	29.7
Ni	1974	1974
Sc	16.2	16.1
Zn	54.9	54.8
Continental crust composition from
(a) Rudnick and Fountain (1995) Rev. Geophys., 33, 267-309.
(b) Taylor and McLennan (1995) Rev. Geophys., 33, 241-265.

Details and histograms in:

Albarède, F. (2005). The survival of mantle geochemical heterogeneities. In Earth's Deep Mantle: Structure, Composition, and Evolution. Geophys. Monogr. R. D. van der Hilst, J. Bass, J. Matas and J. Trampert. Washington D.C., Amer. Geophys. Union. 160, pp 27-46.