**1.5 Conclusion**

The geostatistic and geographical mapping model of volcanic bulk rock chemistry in the Chichinautzion Volcanic Field (CVF) served as a methodological approach. Improve the comprehension of the spatial distribution of the magma heterogeneities inside a typical monogenetic volcanic field. The major methodological outcomes and geological explanations for such geochemical variations are resumed as follows:

1.The method presented here showed incertitude particularly for interpreting alkalis and Sr/Y lineation on the final models (**Figures 2, 3**). Limitations were encountered for assigning geographical coordinates, to control arbitrary parameters for spatial interpolation, to integrate physical environment parameters and to consider all strategical sampling objectives that may influence sample rock positions cumulated since 1948. The Moran Index (I) and the parameter Prob1Pnt helped to determine sample dispersion, which become mandatory to determine if some sectors inside a monogenetic field as CVF should be pre-

**207**

*Spatial Visualization of Geochemical Data: Application to the Chichinautzin Volcanic Field…*

the Inverse Distance Weight (IDW) and Linear Decrease (LD).

ferred for kriging, IDW or LD. It is consequently recommended to segment the area of study from monogenetic field and use the kriging method where a preferential sample orientation for high sample density cover is observed (satellite cones on the same flank from a polygenetic system, unidirectional topographic gradient, sampling along a lava flow or a structural lineation). Sectors where sample orientation is random and distribution is homogeneous should consider

2.The tectonic significance of high Ba/Nb geomarker is particularly of interest to indicate contribution of fluids derived from the subducted plate. This occurs in addition to the highly depleted mantle signature in the region of stratovolcanoes [21, 28, 29, 44]. One consideration is the presence of such anomalies related to amphibole fractioning [7] and even garnet from a deep source (~400 km; [27]). Another consideration is that such magmas are deeply sourced where hydrated fluids are produced by a metasomatized mantle source (from the slab, for example supported by [23, 29]). Despite of this association, such anomalies are geographically restricted to polygenetic systems. In addition, the Sr/Y ratio or alkalis geomarkers as Ba/Nb itself do not correlate with literature observations of the continental thickness [10, 11, 16, 18] nor the contact geometry of the subducted slab vs. lower continental crust [8, 20, 46]. Consequently, below CVF, rather than the slab influence [45], it is suggested that the role of lithospheric mantle–crust interaction is crucial to modify geochemical signature on the mag-

3.Shallow depth rigid continental crust (thickness and fractures) does not allow sufficient time and space for magmas to record subduction signature, therefore, the fast magma ascent feeding typical monogenetic systems do not easily record high Ba/Nb ratios [1]. In some cases, those magma could rather come from a fertile mantle, some with OIB signature, some hybrid depleted mantles [7, 9, 15, 21]. If this inference is correct, obstacles in the continental crust could be slowing down the frequent injection of new batches of magma feeding new minor eruptive vents around Iztaccihuatl-Popocatepetl, and Nevado de Toluca volcanic complexes. The plumbing system architecture of those stratovolcanoes already channel volumetric magmas derivated from a contrasting mantle-

The persons especially thanked for the technical support are Isaac Abimelec Farraz Montes (technician), Osvaldo Franco Ramos (student at Instituto de geografia, UNAM), and Laura Luna (technical secretary at Instituto de Geologia, UNAM). Dolores Ferres and Marie-Noël Guilbaud from Instituto de Geofisica (UNAM) reviewed datasets and gave important opinions about the methodology and the

This work was supported by the Fonds de Recherche du Québec Nature et technologies (FRQNT) (Concours B1, Comité B4 (Maîtrise) who helped to support the Master program between 2010 and 2013 at Instituto de Geología, Universidad Nacional Autónoma de México (UNAM). The submission work process is supported by Conicyt Fondecyt Fondo Nacional de Desarrollo Científico y Tecnológico, with Project Code 11190846 attributed to Dr. Philippe Robidoux from Centro de Excelencia en Geotermia de los Andes (CEGA) and Departamento de Geología,

Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile.

*DOI: http://dx.doi.org/10.5772/intechopen.93798*

mas feeding minor eruptive vents.

crust source.

**Acknowledgements**

volcanological aspects of the work.

*Spatial Visualization of Geochemical Data: Application to the Chichinautzin Volcanic Field… DOI: http://dx.doi.org/10.5772/intechopen.93798*

ferred for kriging, IDW or LD. It is consequently recommended to segment the area of study from monogenetic field and use the kriging method where a preferential sample orientation for high sample density cover is observed (satellite cones on the same flank from a polygenetic system, unidirectional topographic gradient, sampling along a lava flow or a structural lineation). Sectors where sample orientation is random and distribution is homogeneous should consider the Inverse Distance Weight (IDW) and Linear Decrease (LD).

