阿根廷非海相白垩纪孢粉生物地层学概述

Abstract

摘 要: 通过总结已发表的含有孢粉的地质体的资料, 评价了阿根廷白垩纪的孢粉地层序列。在阿根廷由北向南 的 7 个白垩纪盆地中确立了正式与非正式的生物带框架。这些盆地从北至南分别是: 萨尔塔群盆地, 圣路易斯盆 地, 内乌肯盆地, 南方盆地, 德赛多地块盆地, 圣豪尔赫湾盆地, 泛安第巴塔戈尼亚盆地。阿根廷早白垩世的孢粉 组合相对被人熟知, 但描述和讨论晚白垩世的微古植物群的文献则很少。在凡兰吟期至阿普特期的所有孢粉植物 群中, 松柏类裸子植物的花粉组合 Cyclusphaera-Balmeiopsis-Classopollis 占主导。Celyphus rallus（丝状蓝菌）与 Cyclusphaera 一起出现, 但是在巴列姆期时, 它们在整个巴塔戈尼亚盆地全部消失。早期被子植物的花粉化石是阿 普特期和更年轻地层的重要标志 , 它们已被用于定义孢粉化石带。在阿根廷与山龙眼科的首现相当的 Peninsulapollis gillii 是出现于所有晚坎潘期至马斯特里赫特期的孢粉组合中的少数物种之一, 有时也与 Grapnelispora loncochensis 一起出现。这些物种的出现可能是一个孢粉化石带的标志。本文提供了孢粉化石带和 白垩纪主要地层单位的初步对比表。

An evaluation of the Cretaceous palynostratigraphy of Argentina has been undertaken, by reviewing published data of the geological units with palynomorphs. Formal and informal biozonation schemes were compiled from seven Cretaceous Argentinean basins presented from north to south: the Salta Group Basin, San Luis Basin, Neuquen Basin, Austral Basin, Deseado Massif, San Jorge Gulf Basin, and extra-andean Patagonia. The Early Cretaceous palynological associations are relatively well-known in Argentina; however there is sparse published literature describing and discussing Late Cretaceous miofloras. The association of gymnosperm pollen grains, with conifer affinity Cyclusphaera-Balmeiopsis-Classopollis dominates in all the palynofloras from the Valanginian to the Aptian. Celyphus rallus (filamentous cyanobacteria) appears together with Cyclusphaera but disappears in the Barremian in all the Patagonian basins. Pollen grains belonging to basal angiosperms are important stratigraphic markers in Aptian sediments and younger, and have been used to define palynozones. Peninsulapollis gillii which corresponds to the first record of the Proteaceae family in Argentina is one of the few species, which occurs in all the late Campanian−Maastrichtian associations, sometimes together with Grapnelispora loncochensis. Their presence could be indicative of a provisional palynozone. A preliminary correlation chart of the palynozones is presented together with a chart of the main Cretaceous stratigraphic units.