Geochemistry of lavas from the 2005–2006 eruption at the East Pacific Rise, 9°46′N–9°56′N : implications for ridge crest plumbing and decadal changes in magma chamber compositions
Goss, Adam R.
Perfit, Michael R.
Ridley, W. Ian
Rubin, Kenneth H.
Kamenov, George D.
Soule, Samuel A.
Fornari, Daniel J.
MetadataShow full item record
KeywordMid-ocean ridge basalt; East Pacific Rise; Eruption; Trace elements; Radiogenic isotopes; Fractional crystallization
Detailed mapping, sampling, and geochemical analyses of lava flows erupted from an ∼18 km long section of the northern East Pacific Rise (EPR) from 9°46′N to 9°56′N during 2005–2006 provide unique data pertaining to the short-term thermochemical changes in a mid-ocean ridge magmatic system. The 2005–2006 lavas are typical normal mid-oceanic ridge basalt with strongly depleted incompatible trace element patterns with marked negative Sr and Eu/Eu* anomalies and are slightly more evolved than lavas erupted in 1991–1992 at the same location on the EPR. Spatial geochemical differences show that lavas from the northern and southern limits of the 2005–2006 eruption are more evolved than those erupted in the central portion of the fissure system. Similar spatial patterns observed in 1991–1992 lavas suggest geochemical gradients are preserved over decadal time scales. Products of northern axial and off-axis fissure eruptions are consistent with the eruption of cooler, more fractionated lavas that also record a parental melt component not observed in the main suite of 2005–2006 lavas. Radiogenic isotopic ratios for 2005–2006 lavas fall within larger isotopic fields defined for young axial lavas from 9°N to 10°N EPR, including those from the 1991–1992 eruption. Geochemical data from the 2005–2006 eruption are consistent with an invariable mantle source over the spatial extent of the eruption and petrogenetic processes (e.g., fractional crystallization and magma mixing) operating within the crystal mush zone and axial magma chamber (AMC) before and during the 13 year repose period. Geochemical modeling suggests that the 2005–2006 lavas represent differentiated residual liquids from the 1991–1992 eruption that were modified by melts added from deeper within the crust and that the eruption was not initiated by the injection of hotter, more primitive basalt directly into the AMC. Rather, the eruption was driven by AMC pressurization from persistent or episodic addition of more evolved magma from the crystal mush zone into the overlying subridge AMC during the period between the two eruptions. Heat balance calculations of a hydrothermally cooled AMC support this model and show that continual addition of melt from the mush zone was required to maintain a sizable AMC over this time interval.
Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 11 (2010): Q05T09, doi:10.1029/2009GC002977.
Suggested CitationGeochemistry Geophysics Geosystems 11 (2010): Q05T09
Showing items related by title, author, creator and subject.
Persistent effects of disturbance on larval patterns in the plankton after an eruption on the East Pacific Rise Mills, Susan W.; Mullineaux, Lauren S.; Beaulieu, Stace E.; Adams, Diane K. (2013-07)To predict how benthic communities will respond to disturbance, it is necessary to understand how disturbance affects the planktonic larval supply available to recolonize the area. Deep-sea hydrothermal vent fauna along ...
Segmentation and eruptive activity along the East Pacific Rise at 16°N, in relation with the nearby Mathematician hotspot Le Saout, Morgane; Deschamps, Anne; Soule, Samuel A.; Gente, Pascal (John Wiley & Sons, 2014-11-26)The 16°N segment of the East Pacific Rise is the most overinflated and shallowest of this fast-spreading ridge, in relation with an important magma flux due to the proximity of the Mathematician hotspot. Here, we analyze ...
Hydrothermal vent mussel habitat chemistry, pre- and post-eruption at 9°50′North on the East Pacific Rise Nees, Heather A.; Moore, Tommy S.; Mullaugh, Katherine M.; Holyoke, Rebecca R.; Janzen, Christopher P.; Ma, Shufen; Metzger, Edouard; Waite, Tim J.; Yucel, Mustafa; Lutz, Richard A.; Shank, Timothy M.; Vetriani, Costantino; Nuzzio, Donald B.; Luther, George W. (National Shellfisheries Association, 2008-03)Between October 2005 and March 2006, a seafloor volcanic eruption occurred at 9°50′N East Pacific Rise (EPR), establishing a “time zero” for characterizing newly-formed hydrothermal vent habitats and comparing them to ...