| Abstract: | Petrographic and chemical data presented and discussed permit the following conclusions regarding the high-latitude Gulf of Alaska (GA) Fe-Mn deposits: 1) thick (10-50 mm) Fe-Mn crusts form on alkali-basalt and volcaniclastic substrates by hydrogenetic processes, contain delta -MnO2 as the principal Mn phase, and have compositions similar to those of seamount crusts from comparable depths in the Hawaiian archipelago. GA crusts have higher Mn/Fe and lower Co contents than crusts from low-altitude, central Pacific seamounts; 2) thin (<10 mm) crusts on tuffaceous conglomerate, sandstone and phosphorite have a high proportion of crystalline Mn oxides and are genetically related to vein deposits; 3) vein deposits of todorokite and cryptomelane form during low-T oxidative diagenesis of volcanogenic sediment. Mn and other transition metals are supplied during the initial palagonitization of basaltic glass. The oxidation of Fe2+ to Fe3+ in palagonite and the dissolution of the diluted microfossil fraction of the sediment lower the Eh of the ambient pore fluid and enhance the solubility of Mn2+. The K released during the formation of palagonite may be redeposited in secondary phyllosilicate minerals, phillipsite, todorokite and cryptomelane; 4) the vein deposits formed soon after the deposition of sediment derived from the erosion and mass wasting of Mill Seamount but before crust deposition. Therefore, the deposition of hydrogenous crusts and the deposition of diagenetic veins are chemically distinct processes in time and space.-J.M.H. |
| Genre: | Article |
| ProdID: | 70014797 |
| Citation Author: | Koski, R. A. |
| Citation Contributing Office: | |
| Citation Datum: | |
| Citation Day: | |
| Citation Edition: | |
| Citation Editor: | |
| Citation End Page: | 133 |
| Citation Issue: | 1 |
| Citation Keywords: | |
| Citation Language: | English |
| Citation Larger Work Title: | Canadian Journal of Earth Sciences |
| Citation LatN: | |
| Citation LatS: | |
| Citation LonE: | |
| Citation LonW: | |
| Citation Month: | |
| Citation No Pagination: | |
| Citation Number Of Pages: | 18 |
| Citation Online Only Flag: | |
| Citation Phsyical Description: | |
| Citation Projection: | |
| Citation Public Comments: | |
| Citation Publisher: | |
| Citation Series: | |
| Citation Series Code: | |
| Citation Series Number: | |
| Citation Search Results Text: | Ferromanganese deposits from the Gulf of Alaska seamount province: mineralogy, chemistry, and origin.; 1988; Article; Journal; Canadian Journal of Earth Sciences; Koski, R. A. |
| Citation Start Page: | 116 |
| Citation Volume: | 25 |
| Citation Year: | 1988 |
| Type: | citation/reference |
| Text: | Ferromanganese deposits from the Gulf of Alaska seamount province: mineralogy, chemistry, and origin.; 1988; Article; Journal; Canadian Journal of Earth Sciences; Koski, R. A. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Fri, 1 Jan 1988 00:00 -0600 |
| Publisher: | |
