Source and Magmatic Plumbing Systems

**Chapter 2**

**Abstract**

alkaline basalt

**1. Introduction**

**21**

Modeling of Olivine and

A Case Study from the

Clinopyroxene Fractionation in

Carpathian-Pannonian Region

*Tamás Sági, Szabolcs Harangi and Theodoros Ntaflos*

VF and from the Lucaret-Sanoviţa (Lukácskő-Sziklás) volcano.

Intracontinental Alkaline Basalts:

Besides mantle peridotites primary basaltic melts are the best tool to investigate upper mantle petrology and geochemistry. However, de facto primitive melts are hard to found, as basaltic melts usually go through a fractionation process during their ascent towards the surface. Most primary melt calculators are based on the major or trace element compositions of olivine-phyric ocean island basalts and peridotites and are less accurate if clinopyroxene fractionation occurred. In this chapter a new fractionation modeling method of alkaline basalts will be introduced, which has been published earlier only in Hungarian. Olivine clinopyroxene fractionation of four basaltic volcanoes have been modeled from different Miocene-Quaternary volcanic fields from the Carpathian-Pannonian Region (Stiavnica (Selmec) VF, Novohrad-Gemer (Nógrád-Gömör) VF, Perşani Mts. (Persányi Mts.)

**Keywords:** olivine, clinopyroxene, fractionation, intracontinental, monogenetic,

Intracontinental monogenetic alkaline basaltic volcanic fields consist of various types of small-scale volcanoes (e.g. scoria cones, tuff rings, maars, diatremes and related lava flows) [1]. However, the size of the volcanic edifices is usually smaller than 1 km<sup>3</sup> and they are short-lived volcanoes, the total magma output rate of a monogenetic volcanic field can be compared with a polygenetic volcano [1]. The lifespan of the volcanic field can last for several millions of years (e.g. [2, 3]). Based on the geochemical and petrographic characteristics of the individual volcanoes, monogenetic basaltic volcanic fields could be very diverse both spatially and temporally (e.g. [4]). This diversity depends on several factors. Basaltic melt could be

generated in the asthenosphere or in the lithosphere. Partial melting of the asthenosphere could be caused by a mantle plume (e.g. [5–7]), or mantle flows related to active rifting, collision or lithospheric delamination (e.g. [8–10]). Melt generation in the lithospheric mantle is often related to metasomatized peridotites
