Radiolarian biostratigraphy in sediments of ODP Site 202-1237

Site 1237 is located on Nazca Ridge ~140 km off the coast of Peru and thus within the offshore region of the Peru-Chile Current. A total of 83 samples were used to provide an initial radiolarian biostratigraphic framework for Site 1237; radiolarians are present to Sample 202-1237B-19H-2, 58-60 cm (186.45 meters composite depth [mcd]) and are of good to fair abundance and preservation. Site 1237 is influenced by both subtropical and northward-transported southern latitude waters, has 55 ash layers within the uppermost 166 m, and has minimal to gross reworking. Shipboard paleomagnetic results showed that the upper 200 m spanned the last 12 m.y., and in the upper 100 mcd, the paleomagnetic inclination pattern could be directly correlated to the geomagnetic polarity timescale (GPTS). Tropical biostratigraphy was used to establish the zonal boundaries for Site 1237, and the paleomagnetic and radiolarian stratigraphy were well correlated.1237站位位于秘鲁海岸外约140公里的纳斯卡海岭（Nazca Ridge）之上，因此处于秘鲁-智利海流（Peru-Chile Current）的近海海域。本数据集共采用83个样品，为1237站位建立了首个放射虫（radiolarian）生物地层学框架；放射虫的产出层位延伸至样品202-1237B-19H-2的58~60 cm深度（复合深度186.45米[mcd]），其丰度与保存质量为良好至中等水平。1237站位同时受亚热带水域与北向输送的南纬度水域影响，其上部166米地层内发育55层火山灰，且存在轻微至严重的地层再改造作用。科考船现场古地磁测试结果显示，上部200米地层覆盖了过去12百万年的沉积序列；在100 mcd以浅的地层中，古地磁倾角模式可直接与地磁极性年表（geomagnetic polarity timescale, GPTS）进行对比关联。研究采用热带生物地层学方法划定了1237站位的地层分带界线，且古地磁地层与放射虫地层的对比结果良好。