The lithologic types

The map of lithological groups of Catalonia 1:250,000

The map of lithological groups of Catalonia 1:250,000 provides petrological, mineralogical and basic geochemistry information of the rocks and of the non-consolidated (drift) deposits that crop out in Catalonia.

This map has been obtained from the treatment of the database associated to the Mapa Geològic de Catalunya 1:250,000 (BGC250M). For its formation new attributes have been incorporated into each one of the cartographic units of the BGC250M. These attributes refer to the essential lithology, mineralogy and geochemistry of the materials, to their origin and to other characteristics, like the grain size of the detrital rocks or the degree of consolidation of recent sediments. The joint treatment of this data has allowed us to group the cartographic units of the BGC250M in a series of lithologic groups.

A lithologic group is defined in the lithological Data Base of Catalonia 1:250,000 (BLC250M) as a cartographic unit with a predominant lithology or a constant lithological association covering the whole map area. Each lithologic group is characterized by the presence of determined minerals or mineral groups, disregarding the age of the rocks.

But not all the lithologic groups represented in the map are comparable with regard to their lithological constitution. There are homolithic lithological groups, which are characterized for presenting very uniform lithologies in all of its outcrop area, while the heterolithic lithological groups are formed cartographically by inseparable lithological associations. For those cases in which the cartographic units of the BGC250M are formed by lithological groups that can be separated on a more detailed scale, the plurilithic units that constitute special lithological groups have been defined.

Thirty-eight lithologic groups have been defined, each of them represented by a colour on the map and in the legend. Each lithological group is identified by a code with two fields that make reference, in first place, to the lithological characteristics or to their origin and in the second place, to the most important chemical and/or mineralogical components.

The abbreviations that have been used in the formulation of the codes that identify the lithological groups are the following (in catalan):

 

Origin or lithologic types

• E: Evaporitic
• C: Carbonated
• D: Detrital
  • Dg: Large-grained detrital
  • Dh: Hetero-granular detrital
  • Dm: Medium-grained detrital
  • Df: Fine-grained detrital
• O: Organic or plant organogenous
• Nc: Non consolidated
• P: Plutonic
• V: Volcanic
• M: Metamorphic
• G: Ortogneissic

Chemistry and/or mineralogy

• Q: Siliceous
• Si: Silicates
• Mx: Siliceous /Silicates /Carbonates
• Ca: Calcareous
• Do: Dolomitic
• Su: Sulphates
• Cl: Chlorides
• Mo: Plant organic material
• Pl: Plurilithic units

Map of lithological groups of Catalonia 1: 250,000 (Download 6 MB)
Institut Geològic de Catalunya, Institut Cartogràfic de Catalunya (2006)

 

In order to illustrate the great variety of lithologic types that crop out in Catalonia, a series of pictures of the main types of rocks are presented in the following pages. In these pages the rocks are placed in order keeping in mind the classical genetic criteria and following, to a great extent, the classification established in the Mapa de grups litològics de Catalunya 1:250,000.

For each genetic group a brief definition has been included, focusing on the aspects that facilitate their identification from the direct observation of the rocky outcrops and of the hand specimens. With these descriptions and the pictures that accompany them the lithologic diversity of the geological record in Catalonia is obvious.