台湾恒春半岛的隆起珊瑚礁台地

UPLIFTED REEF LIMESTONE TABLELANDS IN HENGCHUN AREA, TAIWAN

台湾本岛南端的恒春半岛,出露隆起珊瑚礁石灰岩和现代珊瑚礁海岸。隆起珊瑚礁石灰岩在地貌上的表现是多阶的台地。最高的公园面可达海拔300m,依次向下,是海拔约100～160m的笼仔埔面,海拔70～80m的埔顶面以及海拔10～20m的垦丁面。在恒春半岛的西侧,珊瑚礁台地面已经倾斜,因此高度的表现不同。ESR及^(14)C定年表明,抬升的更新世珊瑚礁台地形成于0.5Ma B.P.前后及0.13Ma B.P.两时期;海拔10～20m的全新世珊瑚礁台地约形成于6 000a B.P.的时期。这些证据显示了地质时期里全球变迁的蛛丝马迹。

Uplifted reef limestone tablelands and fringing reefs occur in the southermost tip of Taiwan Island. This landform indicates the geomorphological history of the area during Pleistocene and Holocene. Global change during this geological time can also be read from such geomorphological records. This paper describes the landform in the Hengchun area and presents the dating data available by now. Tablelands of the Hengchun area surfaced by reef limestone have been studied by geomorphologists for many years. Four levels of tablelands can be identified, they range separately from 300m, 100～160m, 70～80m and 10～20m. Only the 10～20m level was formed during Holocene. Others are formed during Pleistocene epoch. Electron Spin Resonance indicates an age of 500 thousand and 130 thousand years for the formation of Pleistocene reefs. ^(14)C dating give an age of 6 000 years for the Holocene reefs. All reefs were uplifted afterwards to form tablelands which characterize the landform of southern Hengchun area. Geological history of the Hengchun area reflects the tectonic setting of Taiwan, which is at the margin of Euroasia Plate neighboring Pacific Plate. Taiwan is an island located to the southeast of China's Mainland. The island is tectonically active since Early Pleistocene. Earthquakes are often, which may be accompanied by faulting and sudden uplifting of some areas. These tectonic movements might occur during the whole Pleistocene and Holocene geological time. Thus, created the above mentioned tablelands. Reef limestone cover the surfaces of these tablelands. In which, minor karst features were developed, including solution caves, dolines, flow stones and dripstones. Flora developed in these reef limestone areas are also unique in Taiwan. These high quality landforms and flora are the foundation of Taiwan's first national park Kengding National Park. It is interesting to know that the National Park Administration has financed many geomorphological and geological researches.