Research Article| March 01, 1988 Distribution of alteration zones in the upper oceanic crust Kathryn M. Gillis; Kathryn M. Gillis 1Department of Geology, Dalhousie University, Halifax, Nova Scotia B3H 3J5, Canada Search for other works by this author on: GSW Google Scholar Paul T. Robinson Paul T. Robinson 2Centre for Marine Geology, Dalhousie University, Halifax, Nova Scotia B3H 3J5, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Kathryn M. Gillis 1Department of Geology, Dalhousie University, Halifax, Nova Scotia B3H 3J5, Canada Paul T. Robinson 2Centre for Marine Geology, Dalhousie University, Halifax, Nova Scotia B3H 3J5, Canada Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1988) 16 (3): 262–266. https://doi.org/10.1130/0091-7613(1988)016<0262:DOAZIT>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 Kathryn M. Gillis, Paul T. Robinson; Distribution of alteration zones in the upper oceanic crust. Geology 1988;; 16 (3): 262–266. doi: https://doi.org/10.1130/0091-7613(1988)016<0262:DOAZIT>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 Aging of the upper oceanic crust produces alteration zones that have distinct mineralogical and geochemical characteristics. Five zones are recognized in the Troodos ophiolite and in situ oceanic crust: (1) a sea-floor weathering zone (SWZ), (2) a low-temperature zone (LTZ), (3) a transition zone (TZ), (4) an upper dike zone (UDZ), and (5) a mineralized zone (MZ). The MZ may be overlain by the SWZ, LTZ, or TZ, but in the known examples it is always underlain by the UDZ. The development of the SWZ is dependent upon the duration of cold-seawater circulation, which is dependent upon seafloor topography and the rate and nature of sedimentation. The boundary between the low- and high-temperature zones is largely controlled by permeability contrasts. Lateral variation in the depth of this boundary indicates that the thermal gradient is not uniform within the crust. This, along with the evidence for disequilibrium assemblages, implies that regional metamorphic zones are not appropriate to describe the distribution of alteration effects. 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.