Analytical Predictions for a Natural Spacing within Dyke Swarms

• Published in: Earth and Planetary Science Letters
• Main Authors: Bunger, Andrew P., Menand, Thierry, Cruden, Alexander, Zhang, Xi, Halls, Henry
• Other Authors: Civil and Environmental Engineering Department Pittsburgh (PITT), University of Pittsburgh (PITT), Pennsylvania Commonwealth System of Higher Education (PCSHE)-Pennsylvania Commonwealth System of Higher Education (PCSHE), CSIRO Earth Science and Resource Engineering Melbourne, Commonwealth Scientific and Industrial Research Organisation Canberra (CSIRO), Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), School of Geosciences, Monash University Clayton, Department of Chemical and Physical Sciences Mississauga, University of Toronto at Mississauga
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: dyke swarms; dyke spacing; fluid-driven cracks; hydraulic fractures; [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology; [SDE.MCG]Environmental Sciences/Global Changes; Canada; Iceland
• Online Access: https://hal.science/hal-00855272; https://hal.science/hal-00855272/document; https://hal.science/hal-00855272/file/Bunger_et_al-2013-1.pdf; https://doi.org/10.1016/j.epsl.2013.05.044

International audience Dykes often grow next to other dykes, evidenced by the widespread occurrence of dyke swarms that comprise many closely-spaced dykes. In giant dyke swarms, dykes are observed to maintain a finite spacing from their neighbors that is tens to hundreds of times smaller than their length. To date, mechanical models have not been able to clarify whether there exists an optimum, or natural spacing between the dykes. And yet, the existence of a natural spacing is at the heart of why dykes grow in swarms in the first place. Here we present and examine a mechanical model for the horizontal propagation of multiple, closely-spaced blade-like dykes in order to find energetically optimal dyke spacings associated with both constant pressure and constant influx magma sources. We show that the constant pressure source leads to an optimal spacing that is equal to the height of the blade-like dykes. We also show that the constant influx source leads to two candidates for an optimal spacing, one which is expected to be around 0.3 times the dyke height and the other which is expected to be around 2.5 times the dyke height. Comparison with measurements from dyke swarms in Iceland and Canada lend initial support to our predictions, and we conclude that dyke swarms are indeed expected to have a natural spacing between first generation dykes and that this spacing scales with, and is on the order of, the height of the blade-like dykes that comprise the swarm.