臺灣上新世之孢粉分析（II）──澐水溪剖面

Pollen Analysis of Taiwan Pliocene (II)–Yunshuichi Section

臺灣上新世的地層除了北部苗栗縣出磺坑有連續性出露外，在嘉義地區也有許多出露良好的剖面可供研究。本研究的主要目的為銜接現有更新世及中新世之孢粉生物地層資料，以供日後地層對比及臺灣植羣史研究所需之基本資料。分析臺灣西南部澐水溪剖面57個樣品，記述了6個新屬，52個新種，5個新記錄種及2個新組合種。新發現之被子植物花粉與其他地區記錄比較，其出現之時序多能相符，而馬錢科之灰莉粉及敗醬科之敗醬粉則尚未有確定之記錄以資對照。隆脊條紋孢型之向心極面網紋，未發現於現生類似孢型中，其可能為一較原始之特徵。將歸屬於冷溫及暖溫熱植羣兩類之孢粉型或生長環境相似之孢粉組合，製作孢粉圖譜。冷溫植羣與暖熱植羣有相對的變化，以其變化為主，劃分了七個孢粉帶。氣候變化在第二帶有趨暖的可能，第五帶有濕熱的環境，第六帶變為乾冷，在第八帶氣溫有劇烈的冷–熱–冷變化，可能已屬更新世。屬於白堊紀晚期及第三紀早期孢粉之再堆積及裸棣農藻之出現，推論澐水溪剖面之地層堆積時有白堊紀海相沉積地層之出露。

Fifty-seven samples taken from the Yunshuichi section in southwestern: Taiwan are palynologically analyzed; six new genera, fifty-two new species, five new records and two new combinations are proposed. The new angiospermous taxa in this study are compared with Muller's review. These new taxa accord with the time course of appearance with several areas outside Taiwan, but Fagraea and Patrinia types have not been sufficiently documented in the past. Some taxa, e. g. Tilia, Pterocarya, Carya, Ephedra, etc., are absent in the present flora of Taiwan, but are still living in southeastern mainland China; therefore, the Pliocene vegetation of Taiwan might be, in part, similar to the present vegetation of southeastern mainland China. Two pollen assemblages, i.e., Subalpine-Temperate and Subtropical-Tropical assemblage are utilized to subdivide the pollen zones. Seven pollen zones are determined, the climate became warmer in Zone II; wet and hot in Zone V; cold and dry in Zone VI; prominent temperature changes from warm to cold, then warm to cold again, occurred in Zone VII. Zone VII, therefore, may belong to the Early Pleistocene stage. Reworked palynomorphs from Cretaceous and Early Tertiary deposits are commonly found. Based on the appearance of these reworked palynomorphs, including Dinogynium, a widespread marine dinoflagellate in upper Cretaceous, the presence of outcrops of Cretaceous marine deposits in the sedimentary cycle of Yunshuichi section can be inferred.