CO2 content beneath northern Iceland and the variability of mantle carbon ...

• Main Authors: Hauri, EH, Maclennan, JC, McKenzie, D, Gronvold, K, Oskarsson, N, Shimizu, N
• Format: Article in Journal/Newspaper
• Language: English
• Published: Geological Society of America 2018
• Subjects: 37 Earth Sciences; 3703 Geochemistry; 3705 Geology; 3706 Geophysics; Borgarhraun; Pacific; Iceland
• Online Access: https://dx.doi.org/10.17863/cam.20620; https://www.repository.cam.ac.uk/handle/1810/273547

Primitive basalt melt inclusions from Borgarhraun, northern Iceland, display large correlated variations in CO2 and non-volatile incompatible trace elements (ITEs) such as Nb, Th, Rb, and Ba. The average CO2/ITE ratios of the Borgarhraun melt inclusion population are precisely determined (e.g., CO2/Nb = 391 ± 16; 2M, n = 161). These data, along with published data on five other populations of undegassed MORB glasses and melt inclusions, demonstrate that upper mantle CO2/Ba and CO2/Rb are nearly homogenous, while CO2/Nb and CO2/Th are broadly correlated with long-term indices of mantle heterogeneity reflected in Nd isotopes (143Nd/144Nd) in five out of the six regions of the upper mantle examined thus far. Our results suggest that heterogeneous carbon contents of the upper mantle are long-lived features, and that average carbon abundances of the mantle sources of Atlantic mid-ocean ridge basalts (MORB) are higher by a factor of two than those of Pacific MORB. This observation is correlated with a similar ...