Igneous intrusions and extrusions occur in many coal-bearing deposits throughout the world. Dikes, sills, volcanic flows, and tuffs are the most common igneous units associated with coal deposits exploited for coal and CBM.
Igneous intrusions, such as dikes and sills, interrupt the continuity of coal seams and, occasionally, can limit mine development. They also can create barriers to the migration of methane and, therefore, restrict the size of coal reservoirs. Dikes are steeply-dipping, tabular, discordant igneous units, whereas sills are concordant with bedding (Pictures 1, 2, 3, 4, and 5).
Figures & Tables
This volume of the “Atlas of Coal Geology” provides 393 images on various subject matters related to coal deposits and coal resource utilization. The supporting text provides an introductory overview of coal exploration, mining, and coalbed methane (CBM) development, followed by discussions on various megascopic aspects of coal geology (microscopic aspects are covered in Volume 2). Because of the vast subject matter, many generalities had to be made in the text. References are included to guide those interested to more detailed discussions. All citations within the document are linked to the detailed reference list for this volume. The overriding theme for this publication is that a picture is worth a thousand words.