(Appendix A) Organic facies at DSDP Hole 93-603B

The Palynology of two sections recovered during Leg 93 drilling by the Deep Sea Drilling Project in the continental rise along the western margin of the North Atlantic is reported. In Hole 603B at Site 603, the dinoflagellate stratigraphy indicates that the interval from Cores 603B-82 to 603B-26 ranges in age from late Berriasian to Santonian. The BlakeBahama Formation ranges from late Berriasian to Aptian. The Hatteras Formation ranges from Aptian to Cenomanian, although the uppermost part may be Turonian. Dinoflagellate evidence from the middle part of the Plantagenet Formation indicates an age from late Coniacian or early Santonian to Santonian within the interval of Cores 603B-28 to 603B-26. Magnetic polarity evidence of the stratigraphy of the Early Cretaceous for the western North Atlantic indicates a reliable correlation with the dinoflagellate zonation. The stratigraphic sequence of palynologically defined organic facies in carbonaceous claystone lithologies in Hole 603B shows that organic stratigraphic units consisting predominantly of fecal-pellet-derived, pelagic organic matter (xenomorphic facies) alternate with units consisting predominantly of terrigenous organic matter (tracheal and exinitic facies), corresponding to that described from other sites in the North Atlantic. A terrigenous organic facies is identified for the first time from the Plantagenet Formation. The claystone organic facies and major lithofacies are closely correlated. The tracheal and exinitic facies occur in carbonaceous terrigenous claystones and claystone turbidites associated with sandstone/siltstone terrigenous turbidites. The xenomorphic facies occurs in claystones within pelagic limestones lacking any turbidites, and in blackish, noncalcareous claystones which correlate in age with the marine-carbon-rich sapropels which are widespread in the North Atlantic Cenomanian. This facies also occurs with an admixture of terrigenous organic particles in the Blake-Bahama Formation, but the mixture is consistent with the submarine fan setting of this interval. The concentration of refractory organic matter (carbonized particles) in the micrinitic and carbonized tracheal facies is considered to be the result, at least in part, of the oxidation of sediment buried below a surface slowly accumulating pelagic clays below the carbonate compensation depth. The progressive increase in number of dinoflagellate species per stage through the Early Cretaceous (except for the late Barremian-Aptian) may have resulted indirectly from the generally progressive rise in global sea level during this time. At Site 605, the dinoflagellate stratigraphy across the Cretaceous/Tertiary boundary is remarkably close to that published from the Maestrichtian and Danian of Denmark. The Maestrichtian/Danian boundary is placed precisely within Section 605-66-1 by dinoflagellate evidence, agreeing with that predicted by other microfossils. The new dinoflagellate-cyst-based genus, Pierceites and its new species P. schizocystis, and the new combination P. ( = Trithyrodinium) pentagonum (May) are proposed. Diacanthum hollisteri Habib, type species of Diacanthum, is emended to accommodat e cysts with the archeopyle formulas P3'', 2P2''-3'', 2P3''-4'', and 3P2''-3''-4''.本文报道了沿北大西洋西缘大陆隆地带开展的深海钻探计划（Deep Sea Drilling Project）第93航次钻井所获取的两段剖面的孢粉学（Palynology）研究结果。在603站位的603B钻孔中，沟鞭藻（dinoflagellate）地层学结果显示，603B-82至603B-26岩心段的形成时代为贝里亚阶晚期（late Berriasian）至桑托阶（Santonian）。布莱克-巴哈马地层（Blake-Bahama Formation）的时代为贝里亚阶晚期至阿普第阶（Aptian）；哈特拉斯地层（Hatteras Formation）的时代为阿普第阶至森诺曼阶（Cenomanian），但其最顶部层位可能属于土仑阶（Turonian）。来自普兰特杰尼特地层（Plantagenet Formation）中段的沟鞭藻证据表明，603B-28至603B-26岩心段的形成时代为科尼亚克阶晚期（late Coniacian）或桑托阶早期至桑托阶。北大西洋西部早白垩世地层的磁极性（magnetic polarity）证据显示，其与沟鞭藻分带结果具有可靠的对应关系。 603B钻孔中碳质泥岩（carbonaceous claystone）岩性单元内，经孢粉学定义的有机相（organic facies）地层序列显示：以粪粒起源的远洋有机质为主要组分的他形有机相（xenomorphic facies），与以陆源有机质（terrigenous organic matter）为主要组分的管胞相（tracheal facies）和壳质体相（exinitic facies）交替出现，这一特征与北大西洋其他站位的报道一致。本次研究首次在普兰特杰尼特地层中识别出陆源有机相。泥岩有机相与主要岩相具有密切的对应关系：管胞相与壳质体相赋存于与砂岩/粉砂岩陆源浊积岩伴生的碳质陆源泥岩及泥岩浊积岩（claystone turbidites）中；他形有机相则见于无浊积岩发育的远洋灰岩（pelagic limestones）夹层泥岩，以及与北大西洋广泛分布的森诺曼期海相富碳腐泥层（sapropels）时代匹配的暗灰色非钙质泥岩中。该有机相在布莱克-巴哈马地层中还与陆源有机质颗粒混合出现，这一混合特征与该层段的海底扇沉积环境相符。微晶炭质相与碳化管胞相中的难降解有机质（碳化颗粒）浓度，至少部分被认为是沉积于碳酸盐补偿深度（carbon compensation depth）之下、缓慢堆积的远洋黏土表面之下的沉积物被氧化的结果。早白垩世各阶内沟鞭藻物种数量的逐步增加（巴雷姆阶晚期-阿普第阶除外），可能间接与该时期全球海平面的整体持续上升有关。 在605站位，跨越白垩纪/古近纪边界的沟鞭藻地层学结果，与丹麦地区马斯特里赫特阶（Maestrichtian）和达宁阶（Danian）的已发表研究结果极为接近。沟鞭藻证据将白垩纪/古近纪边界精准定位于605-66-1剖面内，这与其他微化石的推断结果一致。 本文建立了基于沟鞭藻囊孢的新属皮尔斯藻属（Pierceites）及其新种裂囊皮尔斯藻（Pierceites schizocystis），并提出新组合五角皮尔斯藻（Pierceites pentagonum (May)，原归为三叉沟鞭藻属（Trithyrodinium））。修订了双刺藻属（Diacanthum）的模式种Hollisteri双刺藻（Diacanthum hollisteri Habib），以容纳具有古沟盖（archeopyle）公式为P3'', 2P2''-3'', 2P3''-4''及3P2''-3''-4''的囊孢。