Terrane and Faunal Studies in Southern Alaska

阿拉斯加东南部的亚历山大地体拥有阿拉斯加地体中最长、最完整的古生代地层学，其地层和化石记录从早奥陶世一直延伸到二叠纪。许多工人认为，它的悠久历史始于西部的“原太平洋”，直到中生代晚期才到达北美附近。一些初步的动物群证据表明，亚历山大地体在整个古生代历史上一直与北美大陆密切相关，或者可能与东西伯利亚密切相关。已描述的动物群包括志留系牙形刺和腕足类，下、中、上泥盆统牙形刺和腕足类，密西西比纪牙形刺，以及宾夕法尼亚系牙形刺和腕足类。所描述的动物群属于东半球领域，主要显示了科迪勒兰地区和加拿大北极的亲缘关系。尽管在这个化石序列中发现了几个动物群，但也发现了其他埃米西亚、艾菲尔、吉韦特和密西西比的牙形刺动物群和硅化的中泥盆世和密西西比纪腕足类动物群，但仍未收集和描述。1988年发现了其他宾夕法尼亚期的化石矿床，但没有收集到。对这些动物群的继续研究将提供关于地体起源的更多证据。

The Alexander terrane, SE Alaska, has the longest and most complete Paleozoic stratigraphy of the Alaskan terranes, with a stratigraphic and fossil record extending from the early Ordovician to the Permian. Many workers believe it began its long history in the western "Protopacific" and only arrived in the vicinity of North America in late Mesozoic time. Some preliminary faunal evidence indicates that the Alexander terrane has been closely associated throughout its Paleozoic history with the continent of North America or possibly with eastern Siberia. Faunas that have been described include Silurian conodonts and brachiopods, Lower, Middle and Upper Devonian conodonts and brachiopods, Mississippian conodonts, and Pennsylvanian conodonts and brachiopods. The faunas described belong to the Old World Realm and show mainly Cordilleran Region and Canadian Arctic affinities. Although several of the faunas that occur in this fossiliferous sequence have been described, other Emsian, Eifelian, Givetian and Mississippian conodont faunas and silicified Middle Devonian and Mississippian brachiopod faunas have been discovered but remain uncollected and undescribed. Other fossiliferous Pennsylvanian deposits were discovered but not collected in 1988. Continued work on these faunas will provide additional evidence concerning the terrane's origin.