粤琼“老红砂”的岩矿特征与成因研究

MINERALOGIC-PETROLGIC CHARACTERISTICS AND ORIGIN OF THE “OLD RED SAND”OF GUANGDONG AND HAINAN

通过野外剖面观察、室内岩矿和沉积学分析、热释光测年分析等，认为粤琼第四纪老红砂为晚更新世晚期海岸风沙作用的产物，其物质来源于邻近的海滩砂，后在湿热的气候环境下风化，造成Si、K、Na等元素的淋失和Fe、Al的富集。

The 'Old Red Sand' is a quarternary sediment appearing along the coastal areas from Shandong Province to Hainan Province. Much controversy has been evoked about its origin, age and paleogeographic significance. In fact, the 'Old Red Sand' has a homogeneous framework with a fine grain-size. But sometimes, there appears a very low angle cross-stratification or some eluvial gravels from weathered granitic ground. The analyses of grain-size and superficial microfeature of quartz sands show that its characters are similar to dune sand. In these sediments the unstable minerals such as hornblende, feldspar, etc, disappear after laterization, that causes an accumulation of quartz, kaolinite and hematite, with a decrease of SiO2/Al2O3, and SiO2/R2O3. The TL dating indicates the depositional ages of 'Old Red Sand' from 51 900 a. B. P. to16 200 a. B P.. The authors consider that the 'Old Red Sand' belongs to the coastal eolian deposit of the last glacial age. The sedimentary materials were transported from proximal exposed sandy beach, and became red after laterization during a humid and warm climate period.