Rocks and Minerals of the Spanish Landscape: A Geological Overview

Posted on Sep 2, 2024 in Geology

ITEM 1: ROCKS AND MINERALS

1. Introduction

There are many naturally occurring inorganic substances of varying chemical composition and structure: minerals. These minerals are not usually found naturally in isolation. Minerals are usually formed in rocks. The simplest definition of a rock is: material that is composed of the Earth’s crust. One way to classify rocks, which is useful for its simplicity, is to address the processes that gave rise to them. So the source can be separated:

  • Igneous: These are rocks resulting from the crystallization of a melt or magma.
  • Sedimentary: They originate from the accumulation of erosion products as precipitation from aqueous solutions.
  • Metamorphic: They have their origin in the modification of preexisting rocks, due to the effects of temperature and pressure.

Magmatic Rocks: These rocks are divided into:

  • Plutonic: Originated when the magma consolidates in the interior of the earth’s crust, causing rocks like granites.
  • Volcanic: When magma consolidates on the surface. Science is studying the geomorphology of this relief.

Soil is formed slowly over rock deposits and needs thousands of years to reach maturity. Bedrock alters its composition and is broken as a result of rock alteration. Also involved in soil formation is the decomposition of organic matter that falls on the surface. But soil, topsoil and soft, can degrade and disappear.

2. THE ROCKS AND MINERALS OF THE SPANISH LANDSCAPE

2.1 Spanish Rock Relief Core

There are a variety of sedimentary, metamorphic, and magmatic rocks in Spain. Some of these rocks are characterized by the presence of deformation structures caused by two great moments of our history:

  • The Hercynian Orogeny that affected the materials currently located in the NW Iberian Peninsula around 350 MA.
  • The Alpine Orogeny, which began to arise around 140 MA, and generated new ranges at the same time which caused uplift and subsidence in the remains of the former Hercynian mountains, such as the Central System.

This explains the classical division of Spanish territory into four main areas:

2.1.1 Silica Spain

Located on the western peninsula. Mainly constituted by:

  • Magmatic rocks
  • Metamorphic rocks: quartzites and slates.

The Iberian Massif is the geologic unit which is divided into five zones:

  • Cantabrian Zone
  • Zona Centro Ibérica
  • Zona Asturoccidental Leonesa. It covers all Galicia, the northern half of Portugal, parts of Castile and Leon and the province of Caceres.
  • Ossa Morena Zone. Occupies Sierra Morena in Spain and the Sierra de Ossa in Portugal.
  • Zona Sur Portuguesa. Huelva and its continuation in southern Portugal.
2.1.2 Limestone Spain

Located in the eastern half of the peninsula, dominated by calcareous sedimentary rocks. This geological unit includes:

  • The Pyrenees
  • Betic Cordillera
  • Cordillera Ibérica
  • Catalan Coastal Range
2.1.3 Clayey Spain

Predominate in the sedimentary rocks; gravel, sand, and clay. Depressions caused by subsidence, filled by sediments, being now, therefore, mostly horizontal. They are distinguished by their character: marine or continental.

  • Tertiary Continental Basins: On the whole, these are filled by material of lacustrine and fluvial origin. They are the Ebro, Duero, and Tajo.
  • Tertiary Marine Basins: Are those that include materials deposited in a marine environment. Levante basins and the Balearic Islands or the Guadalquivir basin.
2.1.4 Volcanic Spain

Very minority in size, are the volcanic regions of the peninsula. Especially abundant basalts. For example, the Canary Islands. The Canary archipelago is volcanic islands rooted to the ocean floor.

2.2 BASIC MINERALS OF THE SPANISH LANDSCAPE AND ITS ECONOMIC INTEREST

The form of occurrence, abundance, geological significance and their applications allow us to identify two main groups: rock-forming minerals and minerals of economic interest. Among the former, the most common in the earth’s crust, the highlights were silicates and carbonates. In the vast majority of them, it is very difficult to separate its components to obtain, for example, metals of industrial interest. In the case of minerals of economic interest, the reverse occurs. Chemical decomposition of the mineral by appropriate treatment is simple, and they can be easily extracted cations. Some are isolated, they do so with others that are associated with highly variable proportions.

Minerals are classified as:

  • Native: gold, platinum, copper
  • Sulphides: This group includes the salts of sulfide ions, selenide, antimonide, arsenide, and telluride.
  • Halides: We grouped the salts of the halogen elements, namely, fluorides, chlorides, bromides, and iodides.
  • Oxides and hydroxides: for example, quartz (silicon oxide)
  • Carbonates, nitrates, and borates: For example, between the carbonate is calcite (calcium carbonate).
  • Sulfates, tellurates, chromates, molybdates, and tungstate.
  • Phosphates, arsenates, and vanadates.
  • Silicates.

Properties of Minerals:

The need to recognize and differentiate the various minerals led to the development of various analysis techniques. These include:

  • Physical properties: color, hardness, and brightness. Should distinguish between the color of the mineral and the color of your line, you get to scratch a plate of unglazed white material with the sample.
  • X-ray diagram

Economic Interest in Minerals:

Minerals are a good natural resource we need for our supply. The land surface crust and geological resources provided are of great economic importance, which are as given below.

  • Resources: metallic and nonmetallic minerals.
  • Energy resources: coal, oil, natural gas, and radioactive minerals.

2.3 GEOMORPHOLOGY: THE MODELING OF STRESS FACTORS AND THE CONDITIONS

The landforms have been shaped over time by erosive agents. The erosive action of these agents has been and is conditioned by four factors:

  • The dominant rock type.
  • Structures (folds, faults, layers, etc.)
  • Climate. Definable in terms of temperature and precipitation. The climate depends largely on external geological agents.
  • Living beings. The presence or absence of vegetation sets the type of relief and landscape.

Depending on which factor has been considered an object of study, it is spoken of climatic geomorphology, lithologic, or structural.