Scholarlink

<p>The early Cambrian is the first greenhouse climate period of the Phanerozoic, often accompanied by the distribution of coeval evaporite and calcrete deposits, strong chemical weathering, and enhanced dolomitization. Abundant lithological climate indicators are widely developed in the mixed siliciclastic carbonates of tidal flats to limestones of carbonate platforms in the study area. It is generally believed that evaporite is a typical product of the greenhouse climate background, while the fenestral fabric, dolomite breccia, and ruiniform horizon in the carbonate rock in the study area represent the formation of sediments in the long-term exposure environment, and whether they represent the arid and hot paleoclimate is not clear. This paper attempts to reveal their relevance with paleoclimatic variation during Cambrian Stage 4 on the southern North China Block. The results reveal that lithological indicators, such as fenestral fabric, dolomite breccia, ruiniform horizon, and gypsum, halite pseudomorphs, are characteristic of the lower part of Stage 4, suggesting an exposed, hot, and arid climate. In contrast, lithological indicators reflecting a warm and humid climate, including oolitic limestone and oncoid&#xa0;bearing oolitic limestone are more prevalent in the upper part. Geochemical data (Sr, Ba, and Mg, etc.) further support this climatic transition, with a marked accumulation of dry-associated elements in the lower part of Stage 4 and a significant increase in moisture-associated elements in the upper part. The paleoclimatic transformation during Cambrian Stage 4 is characterized by the extensive development of various types of dolomites and abundant lithological indicators reflecting hot and arid paleoclimatic conditions in the lower part of Stage 4 and the disappearance of dolomites and relevant lithological climatic indicators in the upper part. It exhibits a transition from a hot and arid environment to a warm and humid environment, analogous to the modern sabkha dolomite model (supratidal-intertidal evaporation pump dolomitization). This similarity provides critical insights into the greenhouse climate of the early Cambrian period.</p> Graphical Abstract <p></p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Paleoclimatic variation during the Cambrian Stage 4 on the southern North China Block: insights from lithological and geochemical indicators

  • 期刊论文

  • 发表日期：

    2025年3月19日

查看全文
  • Wenyi He,
  • Yongan Qi,
  • Mingyue Dai,
  • Yaogang Du,
  • Min Wang

摘要

The early Cambrian is the first greenhouse climate period of the Phanerozoic, often accompanied by the distribution of coeval evaporite and calcrete deposits, strong chemical weathering, and enhanced dolomitization. Abundant lithological climate indicators are widely developed in the mixed siliciclastic carbonates of tidal flats to limestones of carbonate platforms in the study area. It is generally believed that evaporite is a typical product of the greenhouse climate background, while the fenestral fabric, dolomite breccia, and ruiniform horizon in the carbonate rock in the study area represent the formation of sediments in the long-term exposure environment, and whether they represent the arid and hot paleoclimate is not clear. This paper attempts to reveal their relevance with paleoclimatic variation during Cambrian Stage 4 on the southern North China Block. The results reveal that lithological indicators, such as fenestral fabric, dolomite breccia, ruiniform horizon, and gypsum, halite pseudomorphs, are characteristic of the lower part of Stage 4, suggesting an exposed, hot, and arid climate. In contrast, lithological indicators reflecting a warm and humid climate, including oolitic limestone and oncoid bearing oolitic limestone are more prevalent in the upper part. Geochemical data (Sr, Ba, and Mg, etc.) further support this climatic transition, with a marked accumulation of dry-associated elements in the lower part of Stage 4 and a significant increase in moisture-associated elements in the upper part. The paleoclimatic transformation during Cambrian Stage 4 is characterized by the extensive development of various types of dolomites and abundant lithological indicators reflecting hot and arid paleoclimatic conditions in the lower part of Stage 4 and the disappearance of dolomites and relevant lithological climatic indicators in the upper part. It exhibits a transition from a hot and arid environment to a warm and humid environment, analogous to the modern sabkha dolomite model (supratidal-intertidal evaporation pump dolomitization). This similarity provides critical insights into the greenhouse climate of the early Cambrian period.

Graphical Abstract