Northwestern Central American Volcanic Arc: Increased contribution of enriched lithosphere to lavas along the volcanic front from Nicaragua to Guatemala and behind the volcanic front.

Heydolph, Ken, Hoernle, Kaj , van den Bogaard, Paul and Hauff, Folkmar (2010) Northwestern Central American Volcanic Arc: Increased contribution of enriched lithosphere to lavas along the volcanic front from Nicaragua to Guatemala and behind the volcanic front. [Talk] In: 88. Jahrestagung der Deutschen Mineralogischen Gesellschaft, DMG, From Dust to Dust. , 19.09.-22.09.2010, Münster . From dust to dust : 88. Jahrestagung der Deutschen Mineralogischen Gesellschaft, DMG ; Abstracts. ; 121, S09-T07 .

[thumbnail of Abstract]
Preview
Text (Abstract)
DMG2010_Abstract_Heydolph.pdf - Published Version

Download (131kB)

Abstract

The Central American Volcanic Arc (CAVA) has been subject of intensive research over the past decades,
leading to a large variety of different models for the origin of CAVA lavas with various source components.
Based on a comprehensive new geochemical data set (i.e. major and trace elements and Sr-Nd-Pb-Hf-O isotope
ratios) of mafic volcanic front (VF), behind the volcanic front (BVF) and back-arc (BA) lava and tephra samples
from NW CAVA (Nicaragua to Guatemala), we present a new model for the NW Central American Volcanic
Arc volcanism. Additional potential source component sample data from subducting Cocos Plate sediments,
igneous oceanic crust and Guatemalan granitic and metamorphic continental basement further contributes to our
new model.
We find systematically increasing Pb isotope ratios and decreasing Nd and Hf isotope ratios along the arc from
NW Nicaragua to Guatemala. BVF lavas generally have more radiogenic Pb and less radiogenic Nd and Hf
isotopic compositions than related VF lavas, similar to what is observed for trace element ratios going
northwards along the VF. Combined isotope and trace element data indicate the presence of three endmembers
for the volcanism in NW Central America: (1) NW Nicaraguan VF samples with very high Ba/(La, Th) and
U/Th, low La/Yb, relatively radiogenic Sr, Nd and Hf but unradiogenic Pb, (2) NW Guatemalan VF and
Guatemalan and Honduran BVF samples with low Ba/(La, Th) and U/Th, high La/Yb, radiogenic Sr and Pb but
unradiogenic Nd and Hf, and elevated d18O, and (3) Honduran and Nicaraguan BVF samples with low Ba/(La,
Th) and U/Th, high La/Yb, unradiogenic Sr but radiogenic Nd, Hf and Pb. We interpret the NW Nicaragua VF
endmember to be dominated by a largely serpentinite-derived fluid flux from the subducting slab, possibly with
small amounts (<1 wt. %) of sediment melts, to a depleted N-MORB type of mantle wedge, resulting in large
degrees of melting of primarily peridotitic material. Based on combined Hf and Nd and Hf and Pb isotope
systematics, the isotopically enriched Guatemala VF and BVF endmember cannot be explained by the addition
of subducted pelagic sediments to the source. Instead this endmember could be derived from pyroxenitic
cumulates in the lithospheric mantle (and possibly lower crust) that were derived from parental magmas for
plutonic rocks in NW Central America, which were melted during the Quaternary subduction-related volcanism.
The isotopically depleted Honduras and Caribbean BA endmember could be derived from melting of young,
recycled, oceanic crust in the asthenosphere upwelling in the back-arc, based on the OIB-like major and trace
element but relatively depleted isotopic compositions of these samples. Mixing between these three endmember
types of magmas can explain the observed systematic geochemical variations along and across the NW Central
American Arc.

Document Type: Conference or Workshop Item (Talk)
Keywords: Mineralogie
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
Open Access Journal?: Yes
Publisher: Westfälische Wilhelms-Universität
Date Deposited: 25 Nov 2010 15:59
Last Modified: 06 Jul 2012 14:59
URI: https://oceanrep.geomar.de/id/eprint/10149

Actions (login required)

View Item View Item