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在湘南地区发现的一种“全硅质”陆相火山机构,为一截头近圆形的火山锥,内部负地形,呈完好的闭合漏斗状火山口。从火山口住外明显地可分出三个不同的岩相带:近火山口带(集块熔岩)、中间带(角砾熔岩)及远火山口带(似层非层状的凝灰熔岩)。该区火山岩在化学成分方面最显著的特征是:1.SiO_2含量极高,5个样平均为97.98％,2.从火山口往外SiO_2含量逐渐降低;3.FeO高于Fe_2O_3,PeO/Fe_2O_3=2.6(平均值).
A “all-siliceous” continental volcano found in the southern Hunan region is a volcanic cone with a nearly circular shape and an internal negative topography. It is an intact closed funnel-shaped crater. Three different lithofacies belonged distinctly from the crater: the near-volcanic belt (massive lava), the middle belt (brecciated lava) and the far-crater belt ). The most prominent chemical composition of volcanic rocks in this area are: 1.SiO2 content is very high, the average of 5 samples is 97.98%; 2. The content of SiO 2 from crater decreases gradually; 3. FeO is higher than that of Fe 2 O 3, PeO / Fe 2 O 3 = 2.6 (average).