Influences of Source Heterogeneity and Potential Temperature on the Generation of Basalts from the North Atlantic Large Igneous Province
Abstract
Source heterogeneity and mantle potential temperature are important factors affecting the mantle melting process and must be adequately accounted for to interpret the compositions of mantle-derived melts derived from a variety of tectonomagmatic settings. Several previous studies have attempted to simplify the problem by modeling the melting of a homogeneous source, or by creating 1-D melting models of a heterogeneous source (i.e. solid-solid source mixing). The results of these studies are limited as the latter approach places no constraints on pressures and extents of melting while the former approach does not account for the role of non- peridotite lithologies in the source. We have begun investigating 2-D models using a modified version of the REEBOX polybaric melting model of [1] in an attempt to gain insight into melt compositions related to the effects of the melting process (related to potential temperature) while simultaneously identifying the chemical effects of source heterogeneity. This new model incorporates experimentally - determined melt productivity functions, melting reactions and solidus pressures for eclogite and peridotite source lithologies. At a given potential temperature, model outputs produce grids in trace element and isotope space that reflect variable mixing of melts derived from eclogite and peridotite source lithologies at different segregation pressures from the melting column. Consequently, we are able to qualitatively assess relative pressures and extents of melting within the melting column for comparison with basalt compositions. To better understand the influences of source heterogeneity and potential temperature within the North Atlantic Large Igneous Province, we apply this model to volcanic products from the Paleocene rifted margin of Greenland and the modern ridge system. In the case of the east Greenland flood basalts, variations in contributions from a source involving highly depleted peridotite and eclogite and changes in potential temperatures can be distinguished. These insights are useful in constraining the nature of the chemical and thermal anomaly associated with the ancestral Iceland plume. (1) Fram and Lesher, 1993, Nature, v 363, p 712-714
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AGUFM.V33B1384B
- Keywords:
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- 1040 Radiogenic isotope geochemistry;
- 1065 Major and trace element geochemistry;
- 3610 Geochemical modeling (1009;
- 8410);
- 3619 Magma genesis and partial melting (1037);
- 3621 Mantle processes (1038)