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| Titel |
What caused Mongolian Mesozoic Magmatism: was it crustal or mantle driven? |
| VerfasserIn |
Thomas Sheldrick, Tiffany Barry, Andy Saunders |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250090333
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| Publikation (Nr.) |
 EGU/EGU2014-4561.pdf |
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| Zusammenfassung |
| The Mesozoic was a time of anomalous widespread extension [1]across southern and eastern
Mongolia producing Basin-and-Range type topography in eastern Mongolia and China [2].
This extension occurred after a major collisional event associated with the closure of the
Mongol-Okhotsk ocean. Accompanying this phase of extension are large abundances of
basin-infilling basalts which have had a number of models proposed to explain
their genesis. The diversity of these models include: (1) a mantle plume [3]; (2)
delamination [4]; (3) post-orogenic collapse [5]; (4) back-arc extension due to the
collapse of a subducted slab and (5) mantle upwelling initiated by mantle avalanches
[6].
This study aims to assess the plausibility of these models by constraining the
mechanisms for magma genesis by combining geochemical evidence with field and age
relations. Then, using these constraints, we will test local and regional tectonic
syntheses.
To date, we have collected a large suite of samples from the western limit of volcanism,
the Gobi, Mongolia. Samples have been analysed for major, trace and REE elements (XRF &
ICP-MS) and Sr-Nd-Pb isotope data, with results showing the basalts are LREE enriched
(high La/Ti) and slightly HREE depleted. The chemistry and limited isotope data suggests
fractionation and crustal contamination processes likely played a role in the formation
of these lavas. Furthermore, modelling has been done to constrain the amount of
partial melting and to help explain the HREE depletion. It is hoped that further
sampling and modelling will help to constrain the processes responsible for melt
generation.
[1] Lister and Davis 1989. Struct. Geol. 11, 65-94. [2] Graham et al., 2012. Phanerozoic
Rift Basins and Sedimentary Basins. 17, 443-461. [3] Yarmolyuk and Koalenko 2001.
Tectonics, magmatism and metallogeny of Mongolia, London. [4] Tomurtugoo et al., 2005.
Jour Geol Soc 162, 125-134. [5] Fan et al., 2005. Geo Res. 121, 115-135. [5] Bat Ulzii et al.,
2013. Gondwana Research |
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