西班牙萨拉戈萨大学Ana R. Soria研究组近日取得一项新成果。他们报道了伊比利亚大陆白垩纪中纬度地区的浮冰坠石。该项研究成果发表在2023年10月10日出版的《地质学》上。

研究人员表示，白垩纪被广泛认为是一个受超温室条件影响的时期。

该研究组提供了古中纬度(~45°N)伊比利亚大陆在豪特里维亚寒流期间冰川发育的多尺度沉积学证据。在西班牙喀麦隆盆地东部的恩西索群的一个湖泊三相序列中，出现了条纹状和面状的冰筏状冰川坠石(鹅卵石到巨石大小)和条纹状和沟槽状的粉砂状到沙粒大小的颗粒(冰筏状碎屑[IRD])。这些浮冰构成了欧洲白垩纪大陆冰冻圈记录的第一个证据，它们被认为是冰川口的崩解，将冰山释放到一个与冰接触的湖泊中。沉积序列类似于加拿大北极东部晚更新世劳伦泰德冰盖覆盖的湖泊的冰川-去冰记录。

伊比利亚冰川演替与亚洲的高原永久冻土以及北极和澳大利亚的IRD记录是同步的，揭示了在全球豪特里维亚寒流期间，一个比以前认为的更强大的冰冻圈。

附：英文原文

Title: Ice-rafted dropstones at midlatitudes in the Cretaceous of continental Iberia

Author: Juan Pedro Rodríguez-López, Carlos L. Liesa, Aránzazu Luzón, Arsenio Muoz, María J. Mayayo, Julian B. Murton, Ana R. Soria

Issue&Volume: 2023-10-10

Abstract: The Cretaceous is widely considered to have been a period subjected to super-greenhouse conditions. Here, we provide multiscale sedimentologic evidence of glaciers developing at mid-paleolatitudes (～45°N) in continental Iberia during the Hauterivian cold snap. Striated and faceted ice-rafted glacial dropstones (cobble to boulder size) and striated and grooved silt- to sand-sized grains (ice-rafted debris [IRD]) occur in a lacustrine sequence of the Enciso Group in the eastern Cameros Basin, Spain. The ice-rafted materials constitute the first evidence reported for a Cretaceous continental cryospheric record in Europe, and they are attributed to calving of glacier snouts, releasing icebergs into an ice-contact lake. The sedimentary succession resembles glacial-deglacial records in lakes overridden by the late Pleistocene Laurentide Ice Sheet in eastern Arctic Canada. The Iberian glacial succession was coeval with plateau permafrost in Asia and IRD records in the Arctic and Australia, revealing a stronger than previously thought cryosphere during the global Hauterivian cold snap.

DOI: 10.1130/G51725.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G51725.1/628547/Ice-rafted-dropstones-at-midlatitudes-in-the