TY - JOUR
T1 - 40Ar/39Ar geochronology of the Neogene-Quaternary Harrat Al-Madinah intercontinental volcanic field, Saudi Arabia
T2 - Implications for duration and migration of volcanic activity
AU - Moufti, M. R.
AU - Moghazi, A. M.
AU - Ali, K. A.
N1 - Funding Information:
This paper is a part of the research project ARP-26-79 funded by King Abdulaziz City for Science and Technology (KACST). We thank the staff of the KACST who made every effort to streamline the research. Thanks are also due to the President and geologists of the Saudi Geological Survey (SGS) for help during field work. Our thanks are also extended to John Haurd (Orogen State University, USA) for doing the 40 Ar/ 39 Ar age determinations and Dr. Jan Lindsay (University of Auckland, New Zealand) for constructive comments on the first draft. Dr. Peter Johnson, Prof. Boris Natalin and Dr. M. Khalifa are gratefully acknowledged for their comments and suggestions that greatly helped to improve the manuscript. We thank Editor-in-Chief Prof. Bor-ming Jahn for his insightful comments.
PY - 2013/1/30
Y1 - 2013/1/30
N2 - New 40Ar/39Ar ages, based on incremental heating techniques for groundmass separates of 25 samples, are presented for the Harrat Al-Madinah volcanic field, part of Harrat Rahat in the north western part of the Arabian plate. This area is an active volcanic field characterized by the occurrence of two historical eruptions approximately in 641 and 1256AD. Field investigations of the main volcanic landforms indicate dominantly monogenetic strombolian eruptions, in addition to local more explosive eruptions. The lavas consist mainly of olivine basalt and hawaiite flows with minor evolved rocks of mugearite, benmoreite, and trachyte that occur mainly as domes, tuff cones and occasionally as lava flows. Previous K/Ar dating shows that the Harrat Al-Madinah lava flows and associated domes comprise seven units spanning an age range of ca. 1.7Ma-Recent. The new 40Ar/39Ar age determinations confirm, to a great extent, the previously obtained K/Ar ages in the sense that no major systematic biases were found in the general stratigraphy of the different flow units. However, the 40Ar/39Ar plateau ages show that volcanism in this area began in the Neogene (∼10Ma) and continued to Recent, with the most voluminous eruptions occurring in the Quaternary. Neogene volcanism occurred in at least three pulses around 10, 5 and 2Ma, whereas Quaternary volcanism produced at least seven units reflecting lava flow emplacement in the time period of 1.90Ma-Recent. Thus, the whole duration of volcanic activity in the Harrat Al-Madinah (10Ma-Recent) appears much longer than that previously identified. The longevity of volcanism in the same part of the moving Arabian plate and absence of evidence for uni-directional migration of volcanic activity indicate that there is no fixed plume beneath this region. The NNW-trending distribution of the volcanic vents is parallel to the Red Sea, and suggests their origin is related to periodic extensional episodes along the reactivated Red Sea fault system.
AB - New 40Ar/39Ar ages, based on incremental heating techniques for groundmass separates of 25 samples, are presented for the Harrat Al-Madinah volcanic field, part of Harrat Rahat in the north western part of the Arabian plate. This area is an active volcanic field characterized by the occurrence of two historical eruptions approximately in 641 and 1256AD. Field investigations of the main volcanic landforms indicate dominantly monogenetic strombolian eruptions, in addition to local more explosive eruptions. The lavas consist mainly of olivine basalt and hawaiite flows with minor evolved rocks of mugearite, benmoreite, and trachyte that occur mainly as domes, tuff cones and occasionally as lava flows. Previous K/Ar dating shows that the Harrat Al-Madinah lava flows and associated domes comprise seven units spanning an age range of ca. 1.7Ma-Recent. The new 40Ar/39Ar age determinations confirm, to a great extent, the previously obtained K/Ar ages in the sense that no major systematic biases were found in the general stratigraphy of the different flow units. However, the 40Ar/39Ar plateau ages show that volcanism in this area began in the Neogene (∼10Ma) and continued to Recent, with the most voluminous eruptions occurring in the Quaternary. Neogene volcanism occurred in at least three pulses around 10, 5 and 2Ma, whereas Quaternary volcanism produced at least seven units reflecting lava flow emplacement in the time period of 1.90Ma-Recent. Thus, the whole duration of volcanic activity in the Harrat Al-Madinah (10Ma-Recent) appears much longer than that previously identified. The longevity of volcanism in the same part of the moving Arabian plate and absence of evidence for uni-directional migration of volcanic activity indicate that there is no fixed plume beneath this region. The NNW-trending distribution of the volcanic vents is parallel to the Red Sea, and suggests their origin is related to periodic extensional episodes along the reactivated Red Sea fault system.
KW - Al-Madinah
KW - Ar/Ar geochronology
KW - Harrat Rahat
KW - Intraplate volcanism
KW - Quaternary flood basalts
KW - Saudi Arabia
UR - http://www.scopus.com/inward/record.url?scp=84872805490&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84872805490&partnerID=8YFLogxK
U2 - 10.1016/j.jseaes.2012.09.027
DO - 10.1016/j.jseaes.2012.09.027
M3 - Article
AN - SCOPUS:84872805490
SN - 1367-9120
VL - 62
SP - 253
EP - 268
JO - Journal of Asian Earth Sciences
JF - Journal of Asian Earth Sciences
ER -