摘要:罗家窝棚组是哈尔滨地区的第四纪下限地层，其岩性是紫红色砂砾石，被认为是冰碛物堆积。早期的区测资料对其进行了岩性描述，对于其它地层属性，特别是地球化学属性的认识尚未涉及。为此，本文选择黑龙江五常拉林镇罗家窝棚村层型剖面作为研究对象，首次对其沉积学、矿物学、元素地球化学展开综合研究，以揭示其沉积过程和沉积环境。结果表明，这套砾石分选和磨圆较差，风化程度很高，无定向性排列，砾石成分以陆源碎屑岩（砂岩和粉砂岩，44.2%）和花岗岩（37.4%）为主，其次为凝灰岩（11.2%），石英质、闪长岩、流纹岩和玄武岩等少量出现。重矿物组成以赤/褐铁矿占绝对优势（87.5%），其次是白钛石（5.0%），其它重矿物含量较少。元素地球化学揭示，罗家窝棚组中的细颗粒碎屑以及泥质基质经历了很强的化学风化过程，是初次循环的结果。砾石岩性和地球化学组成共同揭示了这些碎屑主要来源于长英质母岩，但中性和铁镁质母岩也有少量贡献。综合沉积学、矿物学和地球化学地层属性，本文认为罗家窝棚组地层是在炎热气候条件下的洪积物堆积，而非寒冷气候条件下的冰碛物。这项研究对于哈尔滨地区第四纪地层的划分和早更新世构造—地貌—气候—水系演化等地质事件的重建具有重要意义。
关键词: 罗家窝棚组/
地球化学组成/
沉积循环/
化学风化/
物源/
沉积环境
Abstract:The Luojiawopeng Fm. is the lower limit of Quaternary strata in Harbin area. Its lithology is composed of purplish red sand and gravel, which is considered to be accumulation of moraine. Early sporadic studies mainly focused on lithologic characteristics, but other stratigraphic properties, especially geochemical properties, have not been involved. Therefore, the stratigraphic profile of Luojiawopeng Village, Lalin Town, Wuchang City, Heilongjiang Province, is chosen as the research object to study its sedimentology, mineralogy and element geochemistry in order to reveal its sedimentary process and sedimentary environment. The results show that the gravel accumulation of this section is characteristics by poorly sorting and roundness, and has a high degree of weathering. The lithology composition of the gravel accumulation is mainly terrigenous clastic rock and granite, followed by tuff. Hematite is the dominant heavy mineral, followed by leucoxene, and other minerals are less in content. The elemental geochemistry reveals that the fine particles and argillaceous substrates in the Luojiawopeng Fm. have undergone strong chemical weathering process, which is the result of the primary cycle. The lithology and geochemical composition of the gravel reveal that the parent rock are dominated by felsic with minor contribution of internediate and mafic igneous rocks. Based on the stratigraphic properties of the sedimentology, mineralogy and geochemical, this paper considers that the strata of Luojiawopeng Fm. was diluvial deposits under torridity climate rather than moraines under cold climate. This study is of great significance to the division of Quaternary strata and the reconstruction of tectonic, geomorphological, climatic and drainage evolution of the Early Pleistocene in Harbin area.
Key words:Luojiawopeng Fm./
Geochemical composition/
Sedimentary cycle/
Chemical weathering/
Provenance/
Sedimentary environment
PDF全文下载地址:
http://www.dzkx.org/data/article/export-pdf?id=1f1daad3-5e66-435f-9ee7-b14b162d70a7
