(Table 5) Nannofossil occurrence at DSDP Holes 57-438B and 57-439@en

Abundance abbreviations: Abundant (A) = 10-100 specimens per field of view; Common (C) =1-10 specimens per field of view; Few (F) = one specimen in 1-10 fields of view; Rare (R) = one specimen in 10-100 fields of view. The preservation states of nannofossils are designated as follows: G = Good preservation, little or no evidence of etching, dissolution, or overgrowth. All specimens readily identifiable. M = Moderately good preservation, slight etching or overgrowth which has destroyed or obscures delicate structures and ornamentation. Most specimens readily identifiable. P = Poor preservation, a majority of specimens strongly etched or overgrown, often fragmented. Diversity is low and species identification often difficult.丰度缩写定义如下：丰富（A）：单个视野内可见10~100份标本；常见（C）：单个视野内可见1~10份标本；少见（F）：每1~10个视野内可见1份标本；稀少（R）：每10~100个视野内可见1份标本。超微化石（nannofossils）的保存状态分级标准如下：G级为保存良好，几乎无溶蚀、溶解或次生增生迹象，所有标本均可轻松识别；M级为保存中等，存在轻微溶蚀或次生增生，破坏或遮蔽了精细结构与纹饰，多数标本仍可轻松识别；P级为保存较差，多数标本被强烈溶蚀或次生增生，常呈破碎状态，物种多样性偏低，种类鉴定难度较高。