Activité hydrothermale dans la fosse Atlantis II (mer Rouge) : composition isotopique et chimique des eaux prélevées en mai 1985 L'activité hydrothermale est enregistrée isotopiquement et chimiquement dans l'eau profonde de la mer Rouge, au-dessus de la saumure supérieure de la fosse Atlantis II. Contrairement aux travaux antérieurs, les signatures chimiques isotopiques obtenues suggèrent que la résurgence des fluides hydrothermaux était probablement située sur le flanc du bassin SW en mai 1985, au-dessus de la limite supérieure des saumures. La comparaison des compositions isotopiques en hydrogène, oxygène et strontium avec celles des autres fluides de la mer Rouge et de ses marges suggère que l'eau de la fosse Atlantis II correspond à un mélange avec des paléo-eaux de mer du dernier optimum climatique, des eaux interstitielles des sédiments évaporitiques miocènes et des fluides hydrothermaux.
Research Article| July 01, 1988 Geochemical study of an early Paleozoic island-arc-back-arc basin system. Part 2: Eastern Klamath, early to middle Paleozoic island-arc volcanic rocks (northern California) MARC BROUXEL; MARC BROUXEL 1Centre de Recherches Pétrographiques et Géochimiques, BP 20, 54501 Vandoeuvre-les-Nancy cedex, France2Laboratoire de Pétrologie, U.A. 735, Université de Nancy 1, BP 239, 54506 Vandceuvre-les-Nancy cedex, France Search for other works by this author on: GSW Google Scholar HENRIETTE LAPIERRE; HENRIETTE LAPIERRE 2Laboratoire de Pétrologie, U.A. 735, Université de Nancy 1, BP 239, 54506 Vandceuvre-les-Nancy cedex, France3Département des Sciences de la Terre, Université d'Orléans, 45046 Orléans cedex, France Search for other works by this author on: GSW Google Scholar ANNIE MICHARD; ANNIE MICHARD 1Centre de Recherches Pétrographiques et Géochimiques, BP 20, 54501 Vandoeuvre-les-Nancy cedex, France Search for other works by this author on: GSW Google Scholar FRANCIS ALBARÉDE FRANCIS ALBARÉDE 1Centre de Recherches Pétrographiques et Géochimiques, BP 20, 54501 Vandoeuvre-les-Nancy cedex, France4Ecole Nationale Supérieure de Géologie, 94 Avenue de-Lattre-de-Tassigny, BP 452, 54001 Nancy cedex, France Search for other works by this author on: GSW Google Scholar GSA Bulletin (1988) 100 (7): 1120–1130. https://doi.org/10.1130/0016-7606(1988)100<1120:GSOAEP>2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation MARC BROUXEL, HENRIETTE LAPIERRE, ANNIE MICHARD, FRANCIS ALBARÉDE; Geochemical study of an early Paleozoic island-arc-back-arc basin system. Part 2: Eastern Klamath, early to middle Paleozoic island-arc volcanic rocks (northern California). GSA Bulletin 1988;; 100 (7): 1120–1130. doi: https://doi.org/10.1130/0016-7606(1988)100<1120:GSOAEP>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 SocietyGSA Bulletin Search Advanced Search Abstract A systematic mineralogical, REE and Sr-Nd isotopic study of the eastern Klamath Mountains pre- to Early Devonian volcanism (Copley tholeiites, Lovers Leap volcanic rocks, Trinity ophiolitic basalts) show that all of the rocks belong to a low-K, island-arc, tholelitic suite, with the exception of the Late Ordovician Lovers Leap Butte calc-alkalic volcanic rocks. All of the latter have low ϵNd values (ϵNd(T)= 3.9), suggesting that they suffered crustal contamination.The Copley and Lovers Leap low-K tholeiites exhibit variable LREE enrichment or depletion and variable ϵNd values (ϵNd(T)range mostly between 5 and 8), suggesting that variable partial melting degree and/or contamination by sediments occur(s). The isotopic features of the Copley high-Mg andesites (boninitic affinities, ϵNd(T) range between 6.2 and 7.9) show that they were derived from the same source as the low-K tholeiites. The Trinity ophiolitic basalts, along with the LREE-depleted Copley and Lovers Leap tholeiites, show similar geochemical and isotopic features (ϵNd(T) = 7.3 and 7.4), suggesting that they belong to the same island-arc-back-arc basin system. 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.
Abstract The Nador lagoon is the largest one in Morocco and along the Mediterranean. It is located on the northeastern coast near the Rif chain (North Morocco), and it is surrounded by volcanic and sedimentary rocks of various lithofacies. The watershed has an area of about 2200 km2 and is drained by a dense river network. The lagoon dimension is of 115 km2 (25 x 7.5 km) with a depth not exceeding 8 m. The island barrier is 25 km in length and 350 m in average width. The carbonate fraction is the dominant component of the present-day sedimentation in the Nador lagoon. It represents 13 to 48 % of total sediments. Its distribution within the lagoon reflects the nature of marine and continental watershed. The carbonate fraction is composed, in decreasing order of importance, of calcite, magnesium calcite, dolomite and aragonite. The Sr isotopic signatures of lagoonal carbonates sediments show that they are dominated by marine biogenic sediments deposited, and by chemical precipitation. In addition, other carbonates of external origin and less radiogenic Sr isotopic are also present, coming from aerosols and ancient carbonates and transported by streams and rivers. From northwest to southeast, the Sr concentration of these lagoon carbonates increases, showing a slow renewal of waters in the southeastern zone because of its remoteness from communication with sea.
