Controls on high-frequency sequences formed during super-greenhouse conditions in the Late Cretaceous Western Interior Seaway remain equivocal because of the active foreland basin tectonic setting and the lack of direct evidence of polar glaciations to support a glacio-eustatic origin. This paper quantifies eustatic sea-level changes based on high-resolution sequence stratigraphic analysis and improved chronometry of shallow marine deposits of the Late Cretaceous Gallup Sandstone in New Mexico, USA. Backstripping techniques remove tectonic and compactional subsidence and enable quantification of the magnitude of eustatic sea-level change, that allow evaluation of the dominant controls on the high-frequency sequences to resolve the role of orbitally controlled, climate-driven eustasy versus tectonics. Sixty-five parasequences, constituting 29 parasequence sets and 12 sequences are identified in the ∼1.2 m.y. duration of the Late Cretaceous Gallup system. New 40Ar/39Ar dating of bentonites constrains the durations of the individual parasequences, parasequence sets, and sequences, and that these match Milankovitch periodicity, indicating an orbital climate control. The magnitudes of sea-level changes between parasequences range between −28 m and +22 m, which are compatible with hypotheses of both aquifer and glacio-eustasy. Aquifer-eustasy predicts a reciprocal relationship between floodplain cycles and shallow marine sequences, such that aquifer drawdown and falling water tables should correlate to rising sea levels (highstands), whereas increased aquifer storage and rising water tables should correlate to falling sea levels (lowstands). Our preliminary observations show synchronous, versus reciprocal, relationships that may be more compatible with a glacio-eustatic origin. The results of this study support the hypothesis that the Cretaceous greenhouse was marked by high-frequency, low-amplitude glaciations driven by orbital climate cycles, but further work is required to evaluate the contribution of aquifer-eustasy.

中文翻译：

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地球曾经没有冰吗？高分辨层序地层学对白垩纪温室时代冰河洋相的影响

由于活跃的前陆盆地构造环境以及缺乏支持冰河一成因的极地冰川的直接证据，对晚白垩世西部内陆航道在超级温室条件下形成的高频序列的控制仍然是模棱两可的。本文根据高分辨率层序地层学分析和改进的美国新墨西哥州晚白垩世盖洛普砂岩浅海沉积物的年代学方法，对海平面的欣喜变化进行了量化。反剥技术消除了构造和压实沉降，并量化了海平面上欢乐的海平面变化的幅度，从而允许评估高频序列的主要控制权，以解决轨道控制的，气候驱动的狂喜相对于构造的作用。六十五个副序列，在晚白垩世盖洛普系统的〜1.2年间，确定了由29个副序列组和12个序列组成的序列。新的40Ar / 39Ar膨润土测年法限制了单个副序列，副序列集和层序的持续时间，并且它们与Milankovitch周期相匹配，表明了轨道气候控制。副序列之间海平面变化的幅度在-28 m和+22 m之间，这与含水层和冰川洋地假说的假设是相容的。含水层的狂喜预测洪泛区周期与浅海序列之间存在相互关系，因此含水层的下降和地下水位下降应与海平面上升（高水位）相关，而含水层的增加和地下水位上升应与下降海平面（低水位）相关。 。我们的初步观察结果表明，同步的关系与相互的关系可能与冰川成因关系更为兼容。这项研究的结果支持以下假说：白垩纪温室的特征是由轨道气候周期驱动的高频，低振幅冰川作用，但还需要进一步的工作来评估含水层-摇头丸的作用。