Occurrence and source of quartz in six basaltic soils from Northland, New Zealand
Occurrence and source of quartz in six basaltic soils from Northland, New Zealand
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新西兰北部地区六种玄武岩土壤中石英的赋存情况和来源
DOI：
10.1071/sr9840365
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
J. Syers
中科院分区：
文献类型：
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作者：
R. Stewart;V. Neall;J. Syers
测定了新西兰北部地区6种玄武岩土壤中石英的丰度、分布和氧同位素组成。在Kiripaka和Ruatangata两种土壤中发现了大于125 µm的石英。两种土壤中粒径>250 µm的石英的a18 O值均为8.2%，而土壤中粒径>250 µm的石英的a18 O值均为8.1-8.4？对于Ruatangata的250-125 µm粒度部分，表明这种石英的高温成因。一种可能的起源是从北岛中部喷发的空气降落流纹岩火山灰（特别是Kaharoa Ash）。另一个潜在的来源是来自北国西部（迎风）海岸的石英质海滩砂。这些海滩砂中的石英的a18 O值为8.7？，也表明是高温源。玄武质土壤中63-20 µm粒度级石英的平均6180值为12.0？，这与从当地沉积岩如黄土中提取的结果一致。土壤中5-2 µm级石英的平均a18 O值为13.9？，类似于以前在这个纬度报告的气溶胶尘埃。Kiripaka土壤具有非常高的a18 O值为17.3-19.6？对于5-2 µm尺寸的石英。这种石英可以被证明是源于海洋页岩附近的土壤剖面采样，并表明当地的来源可能有助于“气溶胶”的大小部分的土壤除了对流层气溶胶粉尘。
Quartz abundance, distribution and oxygen isotope composition was determined for six basaltic soils from Northland, New Zealand. Quartz > 125 µm in size occurred in two soils, the Kiripaka and Ruatangata. a18O values of 8.2% for the >250 µm sized quartz in both soils and 8.1-8.4? for that in the 250-125 µm size fraction of the Ruatangata indicate a high temperature origin for this quartz. A probable origin is from air-fall rhyolitic tephra (particularly Kaharoa Ash) erupted from the central North Island. Another potential source is quartzose beach sand from the western (windward) coast of Northland. Quartz from these beach sands has a a18O value of 8.7?, also indicating a high temperature origin. Quartz in the 63-20 µm size fractions of the basaltic soils has a mean 6180 value of 12.0?, consistent with derivation from local sedimentary rocks as loess. Quartz in the 5-2 µm fraction of the soils has a mean a18O value of 13.9?, similar to that of aerosolic dusts previously reported from this latitude. The Kiripaka soil had anomalously high a18O values of 17.3-19.6? for 5-2 µm sized quartz. This quartz can be shown to originate from marine shales in the vicinity of the soil profile sampled and indicates that local sources may contribute to the 'aerosolic' size fraction of soils in addition to tropospheric aerosolic dust.