Temperatures and isotopic evolution of silicic magmas, Taupo Volcanic Zone and Coromandel, New Zealand
Temperatures and isotopic evolution of silicic magmas, Taupo Volcanic Zone and Coromandel, New Zealand
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新西兰陶波火山带和科罗曼德硅质岩浆的温度和同位素演化
DOI：
10.1080/00288306.1996.9514719
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Caroline Houston‐Eleftheriadis
中科院分区：
文献类型：
--
作者：
P. Blattner;Hu Rui;I. Graham;Caroline Houston‐Eleftheriadis
摘要：陶波火山区（TVZ）和科罗曼德尔半岛流纹岩熔岩及熔结凝灰岩的一组新的氧同位素和锶同位素数据为岩石成因模型提供了新的限制条件。对于氧同位素而言，岩石基质经常发生蚀变，所以岩浆的值需要基于斑晶。在陶波火山区内，较近期的岩浆似乎有朝着更负的δ18O值变化的趋势（约100万年前以及科罗曼德尔半岛的平均值接近8.0‰；100万年后接近7.5‰）。这可能表明地壳表层的污染物从岩浆聚集和喷发区域逐渐被移除。科罗曼德尔半岛内的类似趋势还无法确定。发现岩浆的氧同位素和锶同位素普遍呈正相关。大多数岩浆的同位素值范围有限，这就成为一种有用的鉴别特征（例如，马马库、马塔希纳和怀奥塔普熔结凝灰岩）。根据石英 - 斜长石分馏为0.98±0.25‰δ得出喷发温度范围较窄，为880±60°C。
Abstract A new set of oxygen and strontium isotope data on rhyolitic lavas and ignimbrites of the Taupo Volcanic Zone (TVZ) and the Coromandel Peninsula provides new limits for petrogenetic models. For oxygen isotopes, the rock matrix is frequently altered, so that values for magma need to be phenocryst based. Within TVZ a trend towards more negative 818O values for more recent magmas appears likely (average before about 1 Ma and for Coromandel near 8.0%o; after 1 Ma near 7.5%o). This could indicate the gradual removal of supracrustal contaminants from the zones of magma accumulation and extrusion. Similar trends within Coromandel cannot yet be resolved. A generally positive correlation is found for oxygen and strontium isotopes of magmas. Most magmas have a limited range of isotopic values, which then becomes a useful fingerprint (e.g., the Mamaku, Matahina, and Waiotapu Ignimbrites). A narrow range of eruption temperatures of 880 ± 60°C is derived from quartz‐plagioclase fractionations of 0.98 ± 0.25‰ δ...