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| Format: | Dataset Open Access |
| Langue: | en |
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PANGAEA
1997
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| Accès en ligne: | https://doi.org/10.1594/PANGAEA.712032 |
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| _version_ | 1867170890296328192 |
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| author | Keller, Randall A Fisk, Martin R Duncan, Robert A White, William M |
| author_facet | Keller, Randall A Fisk, Martin R Duncan, Robert A White, William M |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | Age-progressive, linear seamount chains in the northeast Pacific appear to have formed as the Pacific plate passed over a set of stationary hotspots; however, some anomalously young ages and the lack of an "enriched" isotopic signature in basalts from the seamounts do not fit the standard hotspot model. For example, published ages (28-30 Ma) for basalts dredged from the Patton-Murray seamount platform in the Gulf of Alaska are 2-4 m.y. younger than the time when the platform was above the Cobb hotspot. However, the lowermost basalt recovered by ocean drilling on Patton-Murray yielded a 40Ar-39Ar age of 33 Ma. This age exactly coincides with the time when the seamount platform was above the Cobb hotspot, consistent with a stationary, long-lived mantle plume. A 27 Ma alkalic basalt flow recovered 8 m above the 33 Ma basalt is similar in age and composition to the previously dredged basalts, and may be the alkalic capping phase typical of many hotspot volcanoes. A 17 Ma tholeiitic basalt sill recovered 5 m above the 27 Ma basalt was emplaced long after the seamount platform moved away from the hotspot, and may be associated with a period of intraplate extension. Anomalously young phases of volcanism on this and other hotspot seamounts suggest that they can be volcanically rejuvenated by nonhotspot causes, but this rejuvenation does not rule out the hotspot model as an explanation for the initial creation of the seamount platform. The lack of an "enriched" isotopic signature in any of these basalts shows that enriched compositions are not necessary characteristics of plume-related basalts. The isotopic compositions of the lower basalts are slightly more depleted than the 0-9 Ma products of the Cobb hotspot, despite the fact that the hotspot was closer to a spreading ridge at 0-9 Ma. It appears that this hotspot, like several others, has become more enriched with time. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_712032 |
| institution | PANGAEA |
| language | en |
| publishDate | 1997 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | (Table 1) Trace element and isotopic data for ODP Hole 145-887D basalts Keller, Randall A Fisk, Martin R Duncan, Robert A White, William M 145-887D; Barium; Caesium; Calculated; Cerium; Depth, bottom/max; Depth, top/min; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Dysprosium; Erbium; Europium; Gadolinium; Hafnium; Holmium; Inductively coupled plasma - mass spectrometry (ICP-MS); Isotope ratio mass spectrometry; Joides Resolution; Lanthanum; Lead; Lead-206/Lead-204 ratio; Lead-207/Lead-204 ratio; Lead-208/Lead-204 ratio; Leg145; Lithologic unit/sequence; Lutetium; Neodymium; Neodymium-143/Neodymium-144 ratio; Niobium; North Pacific Ocean; Ocean Drilling Program; ODP; Praseodymium; Rubidium; Samarium; Sample code/label; Strontium; Strontium-87/Strontium-86 ratio; Tantalum; Terbium; Thorium; Thulium; Uranium; Ytterbium; Yttrium; Zirconium Age-progressive, linear seamount chains in the northeast Pacific appear to have formed as the Pacific plate passed over a set of stationary hotspots; however, some anomalously young ages and the lack of an "enriched" isotopic signature in basalts from the seamounts do not fit the standard hotspot model. For example, published ages (28-30 Ma) for basalts dredged from the Patton-Murray seamount platform in the Gulf of Alaska are 2-4 m.y. younger than the time when the platform was above the Cobb hotspot. However, the lowermost basalt recovered by ocean drilling on Patton-Murray yielded a 40Ar-39Ar age of 33 Ma. This age exactly coincides with the time when the seamount platform was above the Cobb hotspot, consistent with a stationary, long-lived mantle plume. A 27 Ma alkalic basalt flow recovered 8 m above the 33 Ma basalt is similar in age and composition to the previously dredged basalts, and may be the alkalic capping phase typical of many hotspot volcanoes. A 17 Ma tholeiitic basalt sill recovered 5 m above the 27 Ma basalt was emplaced long after the seamount platform moved away from the hotspot, and may be associated with a period of intraplate extension. Anomalously young phases of volcanism on this and other hotspot seamounts suggest that they can be volcanically rejuvenated by nonhotspot causes, but this rejuvenation does not rule out the hotspot model as an explanation for the initial creation of the seamount platform. The lack of an "enriched" isotopic signature in any of these basalts shows that enriched compositions are not necessary characteristics of plume-related basalts. The isotopic compositions of the lower basalts are slightly more depleted than the 0-9 Ma products of the Cobb hotspot, despite the fact that the hotspot was closer to a spreading ridge at 0-9 Ma. It appears that this hotspot, like several others, has become more enriched with time. |
| title | (Table 1) Trace element and isotopic data for ODP Hole 145-887D basalts |
| topic | 145-887D; Barium; Caesium; Calculated; Cerium; Depth, bottom/max; Depth, top/min; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Dysprosium; Erbium; Europium; Gadolinium; Hafnium; Holmium; Inductively coupled plasma - mass spectrometry (ICP-MS); Isotope ratio mass spectrometry; Joides Resolution; Lanthanum; Lead; Lead-206/Lead-204 ratio; Lead-207/Lead-204 ratio; Lead-208/Lead-204 ratio; Leg145; Lithologic unit/sequence; Lutetium; Neodymium; Neodymium-143/Neodymium-144 ratio; Niobium; North Pacific Ocean; Ocean Drilling Program; ODP; Praseodymium; Rubidium; Samarium; Sample code/label; Strontium; Strontium-87/Strontium-86 ratio; Tantalum; Terbium; Thorium; Thulium; Uranium; Ytterbium; Yttrium; Zirconium |
| url | https://doi.org/10.1594/PANGAEA.712032 |