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首页> 外文期刊>Geological Journal >Succession, palaeoecology, evolution, and speciation of Pennsylvanian non-marine bivalves, Northern Appalachian Basin, USA
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Succession, palaeoecology, evolution, and speciation of Pennsylvanian non-marine bivalves, Northern Appalachian Basin, USA

机译：美国北阿巴拉契亚盆地宾夕法尼亚州非海洋双壳类动物的演替，古生态，演化和物种形成

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Seventeen horizons of non-marine bivalves are described within the Appalachian succession from the base of the Pottsville Group of Westphalian A-B age to the Uniontown coal of Stephanian C age at the top of the Carboniferous System. A new highly variable fauna of Anthraconaia from the roof shales of the Upper Freeport coal near Kempton, west Maryland, dates from late Westphalian D or very early Cantabrian time, on the evidence of non-marine shells and megafloras. Below this horizon, the Appalachian sequence reveals zones of Anthraconauta philipsii and Anthraconauta tenuis in the same order as in Britain, where as faunas of Anthraconaia of these zones are less common and differ from thos of Britain. In all horizons above the Upper Freeport coal all non-marine bivalve faunas consist of stages in the sequences of two natural species, the groups of Anthraconaia prolifera and Anthraconaia puella-saravana. The first shows evidence of having lived in well-oxygenated, probably shallow, fresh water conditions of relatively wide extent. The second group lived preferentially in a plant-rich environment of relatively stagnant fresh water. Both groups are found in horizons associated with coal seams and may be seen together in the same habitats, but a diagrams of variation (pictographs) suggest that there was no interbreeding between the two groups in either the Northern Appalachians or in southern Germany where the species split was first recognized. In the northern Spanish coalfields of Guardo-Valderrueda and Central Asturia, facies evidence suggests how an initial split may have taken place in the same morphological directions and into the same palaeoenvironments as the later split into two species. Appalachian deposition was generally slow and intermittent with frequent palaeosols. There is also evidence of erosion and of small palaeontological breaks in the sequence, especially near the eastern edge of the Northern Appalachian Basin in western Maryland. The amount of accumulated sediment was less than one-tenth of that of western Europe when basin centre deposition is compared. We found no evidence of a major palaeontological break representing Westphalian D strata overlain by Stephanian C strata. We figure non-marine bivalve faunas of Stephanian B age in association with the Pittsburgh and the Little Pittsburgh coals. Two new species of non-marine bivalves are described: Anthraconaia anthraconautiformis sp. nov. and Anthraconaia extrema sp. nov.
机译：在阿巴拉契亚演替过程中，从威斯特伐利亚A-B时代的波茨维尔群的底部到石炭系顶部的斯蒂芬尼亚C时代的Uniontown煤，描述了十七种非海洋双壳类动物。来自西马里兰州肯普顿附近的上自由港煤的屋顶页岩中的一种新的炭疽菌高度可变的动物群，可追溯到威斯特伐利亚时期晚期或坎塔布连时期的早期，这是非海洋贝壳和巨型植物的证据。在此地平线以下，阿巴拉契亚序列揭示了菲律宾炭疽菌和墨西哥炭疽菌的地带，其顺序与英国相同，而这些地区的炭疽菌属动物则较不常见，并且与英国的不同。在上自由港煤层上方的所有视野中，所有非海洋双壳类动物区系由两个自然物种（炭疽热炭疽菌和炭疽热炭疽菌）组成的阶段组成。第一个证据表明生活在充氧程度较高，可能较浅的淡水条件下，范围相对较广。第二组优先生活在富含植物的淡水相对停滞的环境中。两组都在与煤层有关的地层中发现，并且可能在相同的栖息地中一起看到，但是变化图（象形图）表明，在北阿巴拉契亚山脉或德国南部，这两个物种之间没有杂交分裂是第一个被认可的。在西班牙北部瓜迪奥-瓦尔德鲁埃达和中阿斯图里亚斯煤田中，相证据表明，最初的分裂可能是在与后来的分裂成两个物种相同的形态学方向和相同的古环境中发生的。阿巴拉契亚沉积通常缓慢且间歇性，伴有频繁的古土壤。也有侵蚀的迹象，并有少量古生物学断裂，特别是在马里兰州西部阿巴拉契亚盆地北部的东部边缘附近。比较流域中心沉积物，沉积物的沉积量不到西欧的十分之一。我们没有发现证据表明主要的古生物学断裂代表着由史蒂芬尼阶C地层覆盖的威斯特伐利亚D地层。我们将斯蒂芬尼亚B时代的非海洋双壳类动物区系与匹兹堡和小匹兹堡的煤联系起来。描述了两种新的非海洋双壳类动物：炭疽热炭疽菌。十一月和炭疽极端。十一月

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