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| Main Authors: | , , , , |
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| Format: | Dataset Open Access |
| Language: | en |
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PANGAEA
1978
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| Online Access: | https://doi.org/10.1594/PANGAEA.762151 |
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| _version_ | 1867168098429173760 |
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| author | Reddy, V Viswanatha Subbarao, K V Reddy, G R Matsuda, J Hekinian, Roger |
| author_facet | Reddy, V Viswanatha Subbarao, K V Reddy, G R Matsuda, J Hekinian, Roger |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | The basalts and oceanic andesites from the aseismic Ninetyeast Ridge display trachytic, vesicular and amygdaloidal textures suggesting a subaerial volcanic environment. The normative composition of the Ninetyeast Ridge ranges from olivine picriteto nepheline-normative alkaline basalt, suggesting a wide range of differentiation. This is further supported by the fractionation-differentiation trends displayed by transition metal trace elements (Ni, Cr, V and Cu). The Ninetyeast Ridge rocks are enriched in rare earth (RE) and large ion lithophile (LIL) elements and Sr isotopes (0.7043-0.7049), similar to alkali basalts and tholeiites from seamounts and islands, but different from LIL-element-depleted tholeiitic volcanic rocks of the recent seismic mid-Indian oceanic ridge. The constancy of 87Sr/86Sr ratios for basalts and andesites is compatible with a model involving fractional crystallization of mafic magma. The variation of 87Sr/86Sr ratios between 0.97 and 2.79 may possibly be explained in terms of a primordial hot mantle and/or chemically contrasting heterogeneous mantle source layers relatively undepleted in LIL elements at different periods in the geologic past. In general, the Sr isotopic data for rocks from different tectonic environments are consistent with a "zoning-depletion model" with systematically arranged alternate alkali-poor and alkali-rich layers in the mantle beneath the Indian Ocean. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_762151 |
| institution | PANGAEA |
| language | en |
| publishDate | 1978 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | (Table 3) Chemical analyses from DSDP Holes 22-214, 22-215 and 22-216 in the Indian Ocean Reddy, V Viswanatha Subbarao, K V Reddy, G R Matsuda, J Hekinian, Roger 22-214; 22-215; 22-216; Caesium; Cerium; Chromium; Copper; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Emission spectrometry; Europium; Event label; Glomar Challenger; Indian Ocean//BASIN; Indian Ocean//RIDGE; Lanthanum; Lanthanum/Samarium ratio; Lanthanum/Ytterbium ratio; Leg22; Nickel; Potassium; Potassium/Caesium ratio; Potassium/Rubidium ratio; Rock type; Rubidium; Samarium; Sample code/label; Strontium-87/Strontium-86 ratio; Terbium; Vanadium; Ytterbium The basalts and oceanic andesites from the aseismic Ninetyeast Ridge display trachytic, vesicular and amygdaloidal textures suggesting a subaerial volcanic environment. The normative composition of the Ninetyeast Ridge ranges from olivine picriteto nepheline-normative alkaline basalt, suggesting a wide range of differentiation. This is further supported by the fractionation-differentiation trends displayed by transition metal trace elements (Ni, Cr, V and Cu). The Ninetyeast Ridge rocks are enriched in rare earth (RE) and large ion lithophile (LIL) elements and Sr isotopes (0.7043-0.7049), similar to alkali basalts and tholeiites from seamounts and islands, but different from LIL-element-depleted tholeiitic volcanic rocks of the recent seismic mid-Indian oceanic ridge. The constancy of 87Sr/86Sr ratios for basalts and andesites is compatible with a model involving fractional crystallization of mafic magma. The variation of 87Sr/86Sr ratios between 0.97 and 2.79 may possibly be explained in terms of a primordial hot mantle and/or chemically contrasting heterogeneous mantle source layers relatively undepleted in LIL elements at different periods in the geologic past. In general, the Sr isotopic data for rocks from different tectonic environments are consistent with a "zoning-depletion model" with systematically arranged alternate alkali-poor and alkali-rich layers in the mantle beneath the Indian Ocean. |
| title | (Table 3) Chemical analyses from DSDP Holes 22-214, 22-215 and 22-216 in the Indian Ocean |
| topic | 22-214; 22-215; 22-216; Caesium; Cerium; Chromium; Copper; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Emission spectrometry; Europium; Event label; Glomar Challenger; Indian Ocean//BASIN; Indian Ocean//RIDGE; Lanthanum; Lanthanum/Samarium ratio; Lanthanum/Ytterbium ratio; Leg22; Nickel; Potassium; Potassium/Caesium ratio; Potassium/Rubidium ratio; Rock type; Rubidium; Samarium; Sample code/label; Strontium-87/Strontium-86 ratio; Terbium; Vanadium; Ytterbium |
| url | https://doi.org/10.1594/PANGAEA.762151 |