Volcano-tectonic evolution of the Chyulu Hills and implications for the regional stress field in Kenya

Research Article| February 01, 1995 Volcano-tectonic evolution of the Chyulu Hills and implications for the regional stress field in Kenya Gerald H. Haug; Gerald H. Haug 1Geologisch-Paläontologisches Institut, Universität Kiel, Olshausenstrasse 40, 24098 Kiel, Germany Search for other works by this author on: GSW Google Scholar Manfred R. Strecker Manfred R. Strecker 2Department of Geophysics, Stanford University, Stanford, California 94303 Search for other works by this author on: GSW Google Scholar Author and Article Information Gerald H. Haug 1Geologisch-Paläontologisches Institut, Universität Kiel, Olshausenstrasse 40, 24098 Kiel, Germany Manfred R. Strecker 2Department of Geophysics, Stanford University, Stanford, California 94303 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1995) 23 (2): 165–168. https://doi.org/10.1130/0091-7613(1995)023<0165:VTEOTC>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Gerald H. Haug, Manfred R. Strecker; Volcano-tectonic evolution of the Chyulu Hills and implications for the regional stress field in Kenya. Geology 1995;; 23 (2): 165–168. doi: https://doi.org/10.1130/0091-7613(1995)023<0165:VTEOTC>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The 1.4 Ma to Holocene volcanic eruptive centers and flows in the Chyulu Hills, southeastern Kenya, range in composition between foidites and alkali basalts; they record the relation between linear volcanic chains, preexisting basement structures, geochemical evolution, and the effects of a changing regional tectonic stress field. Pleistocene volcanic centers follow northwest-trending Proterozoic joints and are compatible with the early to middle Pleistocene east-northeast–west-southwest–oriented regional position of the least compressive regional stress (Shmin) documented for the Kenya Rift. Because the angle between the joints and Shmin was high, the ascent of magmas was facilitated by the preexisting basement structures. In contrast, Holocene north-northeast–trending vents and associated normal faults cut older basement structures. The youngest faults and vents are approximately perpendicular to the present regional Shmin position of 135° that has prevailed in Kenya for ∼0.5 m.y. The position of the neotectonic stress field has resulted in a decreased angle between Shmin and the joints and may have led to more difficult magma ascent, longer crustal magma residence, a trend toward more rift-typical volcanic rocks, and finally new alignments of the volcanic fields. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.