Kenny Ray
Geosciences Department, Fort Lewis College, Durango, CO, 81301, USA.
Geochem Trans. 2018 Jan 16;19(1):2. doi: 10.1186/s12932-017-0047-y.
The upper carbonate member of the Kaibab Formation in northern Arizona (USA) was subaerially exposed during the end Permian and contains fractured and zoned chert rubble lag deposits typical of karst topography. The karst chert rubble has secondary (authigenic) silica precipitates suitable for estimating continental weathering temperatures during the end Permian karst event. New oxygen and hydrogen isotope ratios of secondary silica precipitates in the residual rubble breccia: (1) yield continental palaeotemperature estimates between 17 and 22 °C; and, (2) indicate that meteoric water played a role in the crystallization history of the secondary silica. The continental palaeotemperatures presented herein are broadly consistent with a global mean temperature estimate of 18.2 °C for the latest Permian derived from published climate system models. Few data sets are presently available that allow even approximate quantitative estimates of regional continental palaeotemperatures. These data provide a basis for better understanding the end Permian palaeoclimate at a seasonally-tropical latitude along the western shoreline of Pangaea.
美国亚利桑那州北部凯巴布组的上部碳酸盐岩段在二叠纪末期曾暴露于地表，含有典型岩溶地貌的破碎且具分带性的燧石角砾滞后沉积。岩溶燧石角砾含有次生（自生）二氧化硅沉淀，适合用于估算二叠纪末期岩溶事件期间的大陆风化温度。残余角砾岩中次生二氧化硅沉淀的新氧同位素和氢同位素比值：（1）得出大陆古温度估计值在17至22摄氏度之间；（2）表明大气降水在次生二氧化硅的结晶历史中发挥了作用。本文给出的大陆古温度与已发表的气候系统模型得出的最新二叠纪全球平均温度估计值18.2摄氏度大致相符。目前几乎没有数据集能够对区域大陆古温度进行哪怕是大致的定量估计。这些数据为更好地理解泛大陆西部海岸线季节性热带纬度地区的二叠纪末期古气候提供了依据。
