Sign Up

Sign up to join our community!

Sign In

Forgot Password

Lost your password? Please enter your email address. You will receive a link and will create a new password via email.

You must login to ask a question.

GEOLOGY HUB Latest Questions

How are extrusive and intrusive rocks formed?

How are extrusive and intrusive rocks formed?

How igneous rocks formed?

5 Answers

  1. When the molten lava comes on the earth's surface, it rapidly cools down and becomes solid. Rocks formed in this way on the crust are extrusive igneous rocks. Sometimes the molten magma cools down deep inside the earth's crust. Solid rocks so formed are the intrusive igneous rocks.

    When the molten lava comes on the earth’s surface, it rapidly cools down and becomes solid. Rocks formed in this way on the crust are extrusive igneous rocks.

    Sometimes the molten magma cools down deep inside the earth’s crust. Solid rocks so formed are the intrusive igneous rocks.

    See less
  2. When the molten lava comes on the earth's surface, it rapidly cools down and becomes solid. Rocks formed in this way on the crust are extrusive igneous rocks. Sometimes the molten magma cools down deep inside the earth's crust. Solid rocks so formed are the intrusive igneous rocks.

    When the molten lava comes on the earth’s surface, it rapidly cools down and becomes solid. Rocks formed in this way on the crust are extrusive igneous rocks.

    Sometimes the molten magma cools down deep inside the earth’s crust. Solid rocks so formed are the intrusive igneous rocks.

    See less
  3. Intrusive Igneous Rocks Intrusive igneous rocks cool underground. Deep in the crust, magma cools slowly. Slow cooling gives crystals a chance to grow. Intrusive igneous rocks have relatively large crystals that are easy to see. Intrusive igneous rocks are also called plutonic. A pluton is an igneousRead more

    Intrusive Igneous Rocks

    Intrusive igneous rocks cool underground. Deep in the crust, magma cools slowly. Slow cooling gives crystals a chance to grow. Intrusive igneous rocks have relatively large crystals that are easy to see. Intrusive igneous rocks are also called plutonic. A pluton is an igneous rock body that forms within the crust.

     

    Granite is the most common intrusive igneous rock. Pictured below are four types of intrusive rocks.

    Extrusive Igneous Rocks

    Extrusive igneous rocks form above the surface. The lava cools quickly as it pours out onto the surface (Figure below). Extrusive igneous rocks cool much more rapidly than intrusive rocks. The rapid cooling time does not allow time for large crystals to form. So igneous extrusive rocks have smaller crystals than igneous intrusive rocks. Extrusive igneous rocks are also called volcanic rocks.

    See less
  4. Intrusive Igneous Rocks Intrusive igneous rocks cool underground. Deep in the crust, magma cools slowly. Slow cooling gives crystals a chance to grow. Intrusive igneous rocks have relatively large crystals that are easy to see. Intrusive igneous rocks are also called plutonic. A pluton is an igneousRead more

    Intrusive Igneous Rocks

    Intrusive igneous rocks cool underground. Deep in the crust, magma cools slowly. Slow cooling gives crystals a chance to grow. Intrusive igneous rocks have relatively large crystals that are easy to see. Intrusive igneous rocks are also called plutonic. A pluton is an igneous rock body that forms within the crust.

     

    Granite is the most common intrusive igneous rock. Pictured below are four types of intrusive rocks.

    Extrusive Igneous Rocks

    Extrusive igneous rocks form above the surface. The lava cools quickly as it pours out onto the surface (Figure below). Extrusive igneous rocks cool much more rapidly than intrusive rocks. The rapid cooling time does not allow time for large crystals to form. So igneous extrusive rocks have smaller crystals than igneous intrusive rocks. Extrusive igneous rocks are also called volcanic rocks.

    See less
  5. Intrusive Rocks   Igneous rocks which form by the crystallization of magma at a depth within the Earth are called intrusive rocks. Intrusive rocks are characterized by large crystal sizes, i.e., their visual appearance shows individual crystals interlocked together to form the rock mass. The coRead more

    Intrusive Rocks

     

    Igneous rocks which form by the crystallization of magma at a depth within the Earth are called intrusive rocks. Intrusive rocks are characterized by large crystal sizes, i.e., their visual appearance shows individual crystals interlocked together to form the rock mass. The cooling of magma deep in the Earth is typically much slower than the cooling process at the surface, so larger crystals can grow. Rocks with visible crystals of roughly the same size are said to have a phaneritic texture.

     

    A body of intrusive igneous rock that crystallizes from cooling magmas beneath the Earth’s surface is called a “pluton”. If the pluton is large, it may be called a batholith or a stock. Minor plutons include dikes and sills. If a penetrating intrusion cuts across the geological layers it is called a dike. If it runs parallel to the layers, it is called a sill. If an intrusion causes the rocks above to rise and form a dome, it is called a laccolith.

     

    Extrusive Rocks

     

    Igneous rocks which form by the crystallization of magma at the surface of the Earth are called extrusive rocks. They are characterized by fine-grained textures because their rapid cooling at or near the surface did not provide enough time for large crystals to grow. Rocks with this fine-grained texture are called aphanitic rocks. The most common extrusive rock is basalt.

    See less

Leave an answer

You must login to add an answer.

Related Questions

Latest Geology Articles

GEOLOGY HUB Latest Articles

The Importance of Gossans in Mineral Exploration

1. Introduction to Gossans Definition:Gossans are iron-rich, weathered outcrops formed by the oxidation and chemical weathering of sulfide-bearing mineral deposits. They appear as rusty, reddish-brown to yellow zones on the Earth’s surface and are critical indicators of potential subsurface mineralization. Formation:Gossans develop through the supergene alteration of sulfide ores (e.g., pyrite, chalcopyrite) in the near-surface […] Table of Contents Toggle 1. Introduction to Gossans2. Characteristics of Gossans

Porphyry Copper Deposits: Formation Processes and Economic Significance

Porphyry copper deposits are among the most significant sources of copper globally, accounting for over 60% of the world’s copper production . 1. Geological Overview a) Geological Background Porphyry copper deposits are typically associated with magmatic arcs related to subduction zones, where an oceanic plate subducts beneath a continental or another oceanic plate. This tectonic […] Table of Contents Toggle 1. Geological Overviewa) Geological Background

Ore-Bearing Hydrothermal Fluids: Key Drivers in Mineral Deposit Formation

Introduction Ore-bearing hydrothermal fluids are one of the most important agents in the formation of mineral deposits. These fluids, which originate from various geological processes, have the ability to dissolve, transport, and deposit metals in economic concentrations. The study of hydrothermal fluids is crucial for understanding ore genesis and guiding mineral exploration. This article provides […] Table of Contents Toggle Introduction1. Sources of Hydrothermal Fluids

How to Identify Gold-Bearing Rocks in the Field: A Geologist’s Guide

Gold has been one of the most sought-after minerals for centuries due to its value and rarity. Prospectors, geologists, and even hobbyists often search for gold-bearing rocks in the field. But how do you identify rocks that contain gold? This guide will provide an in-depth look at the geological features, rock types, and mineral indicators […] Table of Contents Toggle 1. Understanding the Geological Settings of Gold2. Key Rocks Associated with ...

Alteration in Geology: Types, Processes, and Significance

Introduction Alteration in geology refers to mineralogical, textural, and chemical changes in rocks due to interactions with fluids, temperature variations, and pressure changes. This process occurs in diverse geological settings, including hydrothermal systems, weathering environments, and metamorphic terrains. Understanding alteration is essential in mineral exploration, petrology, geotechnical engineering, and environmental studies. This article explores the […] Table of Contents Toggle IntroductionTypes and Processes of Alteration

Induced Polarization Method in Sulfide Ore Exploration

Introduction The Induced Polarization (IP) method is one of the most effective geophysical techniques used in the exploration of sulfide ore deposits. This method is particularly useful for identifying disseminated sulfide minerals, which are commonly associated with copper (Cu), gold (Au), silver (Ag), zinc (Zn), and lead (Pb) deposits. This article provides a detailed overview […] Table of Contents Toggle Introduction1. Understanding the Induced Polarization (IP) Method

Pathfinders for Gold Deposits

Introduction Gold exploration is a complex process that requires a combination of geological knowledge, geochemistry, and geophysical techniques. One of the most effective methods for locating gold deposits is the identification of pathfinder elements and minerals. Pathfinder elements and minerals are geochemical indicators that suggest the presence of gold nearby, even if the gold itself […] Table of Contents Toggle IntroductionWhat Are Pathfinders for Gold Deposits?

The Crucial Role of Structural Control in Hydrothermal Gold Deposits

Introduction Structural control is one of the most significant factors influencing the formation and distribution of hydrothermal gold deposits. Structural geology determines the pathways for mineralizing fluids, the locations of ore deposition, and the overall geometry of gold-bearing zones. Understanding these structural controls is essential for exploration geologists seeking new gold deposits and for mining […] Table of Contents Toggle IntroductionStructural Controls in Hydrothermal Gold Deposits

What is Geology? Defination, Importance, Branches and Facts

Introduction to Geology Geology, derived from the Greek words geo (Earth) and logos (study), is the scientific discipline dedicated to understanding the Earth’s composition, structure, processes, and history. It seeks to answer fundamental questions: How did mountains form? Why do volcanoes erupt? What clues do rocks hold about ancient life? From the atomic structure of […] Table of Contents Toggle Introduction to GeologyThe Scope of Geology: What Do Geologists Study?

Engineering Geological Tests: Purpose, Types, and Applications

Engineering geological tests are critical for assessing the physical, mechanical, and chemical properties of rocks and soils to ensure safe and cost-effective design of infrastructure (e.g., dams, tunnels, foundations). These tests help determine material strength, stability, permeability, and susceptibility to hazards like landslides or subsidence. Below are key tests categorized by their application: 1. Field […] Table of Contents Toggle 1. Field Tests (In-Situ)2. Laboratory Tests

All Geology Articles