Geochemistry of sands from the Huatabampo and Altata beaches, Gulf of California, Mexico
Geochemistry of sands from the Huatabampo and Altata beaches, Gulf of California, Mexico
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墨西哥加利福尼亚湾华塔班波和阿尔塔塔海滩沙子的地球化学
DOI：
10.1002/gj.3864
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发表时间：
2020
影响因子：
1.8
通讯作者：
T. Pi
中科院分区：
文献类型：
--
作者：
J. Madhavaraju;J. Armstrong;Rahul B. Pillai;T. Pi
对Huatabampo（HB）和Altata（AA）海滩的砂样进行粒度、重矿物、矿物学和地球化学分析，以推断古风化条件和烃源岩特征。HB和AA砂的平均粒度分别为细粒和细粒至中粒。磁铁矿和紫苏辉石是HB砂中常见的重矿物，而磁铁矿和钛铁矿是AA砂中的主要重矿物。HB砂含有高比例的石英和斜长石，其次是钾长石和沸石。石英是AA砂中的主要矿物，其次是斜长石和钾长石。从地球化学上看，HB砂岩样品属于杂砂岩，而AA砂岩则属于杂砂岩和长石砂岩。在球粒陨石标准化REE图上，HB和AA砂体表现为轻稀土富集、重稀土亏损，Eu负异常。化学蚀变指数（CIA），斜长石蚀变指数（PIA）值和Th/U比值的HB和AA砂表明，在源区的化学风化强度较低。构造判别函数图显示HB砂体为弧形构造背景，AA砂体为裂谷构造背景。球粒陨石标准化的稀土模式、Eu异常、Al 2 O3/TiO 2比值、微量元素比值、判别函数和三元图解表明，HB和AA砂岩主要来自长英质烃源岩。HB和AA砂与研究区附近暴露的源岩的REE模式的比较表明，在索诺拉暴露的Laramide深成岩的中央花岗岩的沉积物的HB海滩，而AA砂接收的沉积物主要来自长英质弗朗西斯科片麻岩在西部索诺巴里复杂的锡那罗亚。
Grain size, heavy minerals, mineralogical, and geochemical analyses were undertaken on the sand samples from Huatabampo (HB) and Altata (AA) beaches to infer palaeoweathering conditions and source rock characteristics. The mean grain size of HB and AA sands is fine‐grained and fine‐ to medium‐grained, respectively. Magnetite and hypersthene are the common heavy minerals identified in HB sands, whereas magnetite and ilmenite are the dominant heavy minerals in AA sands. HB sands have a high proportion of quartz and plagioclase followed by K‐feldspar and zeolite. Quartz is the dominant mineral in the AA sands, followed by plagioclase and K‐feldspar. Geochemically, the sand samples from HB are classified as wacke, whereas AA sands are classified as wacke and arkose. In chondrite‐normalised REE plot, HB and AA sands show LREE enriched and HREE depleted pattern with negative Eu anomaly. Chemical index of alteration (CIA), plagioclase index of alteration (PIA) values and Th/U ratios of HB and AA sands suggest a low intensity of chemical weathering in the source area. The tectonic discriminant function diagram suggestsan arc setting for HB sands, whereas a rift setting for AA sands. The chondrite‐normalised REE patterns, Eu anomaly, Al2O3/TiO2 ratio, trace elemental ratios, discriminant function, and ternary diagrams suggest that the HB and AA sands were dominantly derived from felsic source rocks. The comparison of REE patterns of HB and AA sands with the source rocks exposed near to the study area suggest that the central granites of Laramide plutonic rocks exposed in Sonora were contributing sediments to the HB beach, whereas AA sands received sediments mainly from the felsic Francisco gneiss in the western Sonobari Complex of Sinaloa.
影响因子：
3.5
作者：
T. Ohta
通讯作者：
T. Ohta