惠州凹陷HZ21钻孔珠江组地球化学特征及其物源指示意义
摘要: 过对珠江口盆地惠州凹陷HZ21井珠江组碎屑岩的主量元素、微量元素和稀土元素进行综合分析，发现研究区碎屑岩中MnO、Na2O、P2O5和TiO2含量与PAAS中这几种组分的含量相近，但是，与PAAS相比，研究区碎屑岩富集SiO2，贫Al2O3、Fe2O3、K2O和MgO。泥岩中亲石元素Ba的含量略低于上地壳丰度，而远高于下地壳丰度；过渡元素Cr的含量略高于上地壳丰度，而远低于下地壳丰度；不相容元素Th的含量略高于上地壳丰度值，远远高于下地壳丰度。砂岩中亲石元素Ba的含量与上地壳丰度相近，但远高于下地壳丰度；不相容元素Th在NSQ1、NSQ2层序略低于上地壳丰度值，在NSQ3、NSQ4层序中则高于上地壳丰度值。REE分布模式与上地壳相似，轻稀土元素富集，重稀土元素均一，Eu负异常，且在NSQ1、NSQ2中，Eu异常值大于PAAS的Eu异常值，而NSQ3、NSQ4的Eu异常值小于PAAS的Eu异常值。主量元素比值和非迁移性微量元素图解显示源岩以长英质岩石为主，NSQ1、NSQ2层序以沉积岩钙质泥岩物源为主，而NSQ3、NSQ4层序为花岗岩、碱性玄武岩和沉积岩钙质泥岩混合物源的特点。从SiO2—K2O/Na2O、La—Th—Sc判别图及Ce异常值的分析认为，源区的构造背景具有被动大陆边缘的特征。Al2O3/Na2O比值及化学蚀变指数（CIA）反映了该地区整体处于湿热气候条件，但NSQ1、NSQ2层序湿热程度较高，风化程度较强，而NSQ3、NSQ4层序湿热程度较低，风化程度较弱。
Geochemical Characteristics and Provenance Indication of the Zhujiang Formation in Well HZ21 at the Huizhou Depression
Abstract: It has been found that the components of MnO, Na2O, P2O5 and TiO2 in the clastic rock of the Zhujiang Formation in well HZ21 at the Huizhou Depression, Pearl River Mouth Basin are similar to those in PAAS through a comprehensive analysis on the major elements, trace elements and rare earth elements. Comepared with PAAS, a fact that the clastic rock of the Zhujiang Formation is richer in SiO2 while poorer in Al2O3, Fe2O3, K2O and MgO. Referring to the mudstone, the content of Ba is slightly lower than the supracrustal abundance, but it is far higher than lowercrustal abundance; the content of Cr is slightly higher than the supracrustal abundance, but it is far lower than lowercrustal abundance; the content of Th is higher than the supracrustal abundance, and it is far greater than lowercrustal abundance. As regards to the sandstone, the content of Ba is similar to the supracrustal abundance, but it is far higher than lowercrustal abundance; the content of Th is slightly lower than the supracrustal abundance in NSQ1 and NSQ2 while it is far greater than supracrustal abundance in NSQ3 and NSQ4. The REE distribution pattern is similar to that of the upper continental crust, characterized by enrichment of LREE, uniform of HREE and negative Eu anomalies. Eu anomalous value of NSQ1 and NSQ2 is higher than the Eu anomalous value of PASS and it has the opposite situation in NSQ3 and NSQ4. The ratios of major elment and the diagrams of nonmigration trace elments show that the source rocks are mainly felsic, and the principal source of detritus in NSQ1 and NSQ2 are derived from the sedimentary rock and calcareous mudstone, and the principal source of detritus in NSQ3 and NSQ4 are derived from compositon of the granite, alkali basalt, sedimentary rock and calcareous mudstone. According to SiO2 K2O/Na2O, La ThSc discrimination diagrams and the anomalies of Ce, it can be inferred that the tectonic setting of the provenance is similar to that of passive continental margin. The value of Al2O3/Na2O and chemical index of alteration (CIA) suggest that it was warmwet climate in the area, but the degree of dampheat was relatively higher in NSQ1 and NSQ2, and that is one of the reason why the intensity of weathering was relatively strong. But, it has an opposite situation in NSQ3 and NSQ4: the warmwet degree was relatively lower and the intensity of weathering was relatively weak.
惠州凹陷HZ21钻孔珠江组地球化学特征及其物源指示意义[J]. 沉积学报, 2013, 31(3): 440-449.
| 引用本文: |
惠州凹陷HZ21钻孔珠江组地球化学特征及其物源指示意义[J]. 沉积学报, 2013, 31(3): 440-449.
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Geochemical Characteristics and Provenance Indication of the Zhujiang Formation in Well HZ21 at the Huizhou Depression[J]. Acta Sedimentologica Sinica, 2013, 31(3): 440-449.
| Citation: |
Geochemical Characteristics and Provenance Indication of the Zhujiang Formation in Well HZ21 at the Huizhou Depression[J]. Acta Sedimentologica Sinica, 2013, 31(3): 440-449.
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