作　　者： ; ; ; ; ; ; ; ;

机构地区： 中山大学地理科学与规划学院

出　　处： 《地质论评》 2010年第3期355-364,共10页

摘　　要： 地处华南之粤东北丘陵区的蕉岭红土属粉砂质粘土,形成于末次间冰期。红土的细粘粒含量为12.15%～24.64%(平均值18.46%)、Mz为5.91Φ～7.53Φ(6.72Φ)、概率累积曲线和频率曲线分别呈现以"四段式"和"三峰式"构型;主元素氧化物以SiO2、Al2O3、TFe2O3为主,含量依次为50.10%～53.14%(51.36%)、23.07%～24.44%(24.00%)、10.18%～11.40%(10.77%),其它如CaO、Na2O、MgO、K2O的含量均小于1%。这一趋向于细粉砂分布的粒度特征和脱硅富铝化的化学元素特征说明红土形成于较强的风化—淋溶作用下,硅铝系数(3.49～3.86,平均为3.64)指示多数层位属次强度富铝化。其气候环境,以<2μm和<1μm颗粒的含量、硅铝系数、CIA值为指标,与我国的南亚热带—北热带一些地点的现代赤红土和砖红土作一详细对比后认为蕉岭红土发育在湿热于现今南亚热带,相似于热带北缘的气候环境之下。这一看法与前人有关同期"大熊猫—剑齿象动物群"指示的古生态的研究结果相吻合。由此表明,末次间冰期的粤东北甚至整个华南地区可能都处在类似现今热带北缘的气候环境之下,其时的热带—亚热带界线向北推移了至少3个纬度。 It is revealed by our studies that the Jiaoling red earth in the hilly area, northeastern Guangdong, South China, developed in the last interglacial period and belongs to silty clay in terms of lithology. Meanwhile, the red earth’s fine-grained clay content 12.15%～24.64% （average 18.46%）,Mz 5.91Φ～7.53Φ（6.72Φ） and the four-segment distribution of cumulative probability curve is roughly consistent with the three-peak distribution of frequency curve for each sample. The primary oxides of major elements are mainly SiO2, Al2O3 and TFe2O3（Fe2O3＋FeO）, of which the contents are 50.10%～53.14%（51.36%）,23.07%～24.44%（24.00%）, 10.18%～11.40%（10.77%） , respectively, whereas the CaO, Na2O, MgO and K2O contents are all below 1%. Moreover, The approximative fine silt distribution of grain size and the desilicification—allitization phenomenon indicating a strong chemical weathering and eluviation. In addtition, the Si/Al ratios of most red earth horizons indicate a less intensive allitization. A thorough comparison of the content of grains smaller than 2μm or 1μm, Si/Al ratio, and CIA between Jiaoling red earth and mordern latosolic red soil, and laterite in some of China’s north tropical and south subtropical zones reveals that the red earth developed in a climatic environment that is more warm—humid than that of the present south subtropical zone, and similar to that of the north margin of the present tropical zone. Such a viewpoint is roughly consistent with predecessors＇ conclusion on the paleoecology indicated by the Ailuropoda—Stegodon fauna during that period. Therefore, we conclude that the last interglacial northeastern Guangdong and even the full extent of South China were in a climatic environment similar to that of the north margin of present tropical zone, and the boundary between the tropical and subtropical zones experienced a northward migration of at least 3 degrees of latitude.

关 键 词： 蕉岭红土 末次间冰期 粒度 主量化学元素 热带气候环境

领　　域： [天文地球] [天文地球]