干旱区生态环境知识资源中心(Arid): 福建晚白垩世古土壤特征及其古环境意义

Arid

	福建晚白垩世古土壤特征及其古环境意义
其他题名	Late Cretaceous paleosols in Fujian and their paleoenvironmental implication
	毛学刚; 陈金牛; 师永辉; 刘秀铭
来源期刊	地球环境学报
ISSN	1674-9901
出版年	2021
卷号	12 期号:1 页码:32-43
中文摘要	古土壤是重建古气候的重要手段,第四纪以前古土壤因受各种地质作用影响不易被识别。本研究以福建西部连城盆地晚白垩世红层冠豸山剖面为研究对象,通过野外观察、土壤微结构和地球化学元素迁移等方法识别和获得古土壤发育特征,并分析古土壤形成环境。冠豸山剖面共有10个薄层古土壤,主要为新成土和始成土两种类型,土壤发育较弱,没有明显的黏化层和钙结核层。沉积物颗粒和稀土元素分布特征显示剖面中含有一定的风积组分,风积物经短暂流水搬运再次沉积,形成沉积层理。红色碎屑颗粒在沉积之前已经历相当程度的风化,沉积后在干旱环境下成壤较弱,因此,对其古气候或古环境的认识需依据古土壤发育特征,这为研究类似红层提供了新的思路。
英文摘要	Background, aim, and scope Paleosol, the soil formed and preserved in geological periods, is the product of the climate, parent sediment or rocks, time, and vegetation when it formed, of which the climate is the most important driving force. Consequently, paleosol plays an important role in paleoclimate reconstruction, e.g. the successful application of loess-paleosol in Chinese Loess Plateau. Pre-Quaternary paleosols are not easy to be identified due to effects of post diagenesis. Soil horizons are susceptible to be mistaken for sedimentary beddings, which hinders our understanding in their paleoclimatic implication. The present study focuses on Guanzhaishan (GZS) section of Late Cretaceous in western Fujian. It is aimed to identify paleosols in this section combined by field observation, soil micromorphology and geochemistry analysis, and discuss the paleoenvironments when the paleosols formed. Materials and methods GZS section (25°42′18N, 116°46′01E) is located 2 km east of Liancheng County, Longyan City, western Fujian. GZS section is 15.8 m thick, and composed of interbedded red siltstones and sandstones, belonging to the upper part of Shaxian Formation of Late Cretaceous in age. 66 samples (G1 G66) were collected with 10 40 cm increment. A few intact samples were collected for thin sections. Major element concentrations were measured by Epsilon 3 XLE. Rare earth elements (REE) were measured by ICP-MS. Thin sections were made manually with paraffin instead of water to avoid clay expansion. Results Paleosols were identified in field based on root traces, soil horizon and soil structures. Root traces were most companied with animal burrows. Slickensides indicated soil formation due to shrinkage and expansion of clay. 10 paleosols of two different pedotypes (Inceptisol and Entisol) were identified in GZS section. Soil micromorphology and geochemical transport confirmed the paleosols, also indicate that all the paleosols were weakly developed. Discussion The particle grain size, distribution and shape of the red sediment were similar with aeolian dusts. REE distribution was similar with loess-paleosol from Chinese Loess Plateau and subtropical areas, indicating thoroughly mixed. The aeolian dust deposited or transported by temporary water, rather than typical fluvial or lacustrine sediment. Geochemical analysis suggested that the sediment had undergone to an extent chemical weathering (CIA = 80 on average) before deposition. After deposition, the arid climate prevented weathering thus resulted in weakly developed paleosols. Therefore, paleoclimate reconstruction of such red sediment could not rely on sediment geochemistry, but paleosol features. Conclusions 10 paleosol sequences of 2 different pedotypes (Inceptisol and Entisol) were identified, which were weakly developed lacking Bt and Bk horizons and indicating arid condition. The red sediment included aeolian dusts, which were transported and deposited by temporary water, forming sedimentary beddings. The inconsistence between weak paleosol and high weathering intensity suggested that paleoclimate and paleoenvironment reconstruction should rely on paleosol features. Recommendations and perspectives There is long lasting debate on whether red beds indicate paleoclimate and what climate. Paleosols generally occurring in the red beds likely provide an alternative perspective, i.e. paleosol is important archive of paleoclimate. The present study demonstrates a good case to identify paleosols in red beds, and what paleoenvironments were indicated by these paleosols. Paleosols should be emphasized in studying paleoclimate and paleoenvironment.
中文关键词	古土壤 ; 白垩纪 ; 地球化学 ; 红层 ; 福建
英文关键词	paleosol Cretaceous geochemistry red beds Fujian
类型	Article
语种	中文
收录类别	CSCD
WOS类目	Geology
CSCD记录号	CSCD:7047738
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/377573
作者单位	毛学刚, 福建师范大学地理研究所;;福建省湿润亚热带山地生态重点实验室省部共建国家重点实验室培育基地, ;;福建省湿润亚热带山地生态重点实验室省部共建国家重点实验室培育基地, 福州;;福州, ;; 350007;;350007.; 陈金牛, 福建师范大学地理科学学院, 福州, 福建 350007, 中国.; 师永辉, 福建师范大学地理科学学院, 福州, 福建 350007, 中国.; 刘秀铭, 福建师范大学地理研究所;;福建省湿润亚热带山地生态重点实验室省部共建国家重点实验室培育基地;;Department of Earth and Environmental Sciences, Macquarie University, ;;福建省湿润亚热带山地生态重点实验室省部共建国家重点实验室培育基地;;, 福州;;福州;;Sydney, ;;;;Australia 350007;;350007;;NSW 2109.
推荐引用方式 GB/T 7714	毛学刚,陈金牛,师永辉,等. 福建晚白垩世古土壤特征及其古环境意义[J],2021,12(1):32-43.
APA	毛学刚,陈金牛,师永辉,&刘秀铭.(2021).福建晚白垩世古土壤特征及其古环境意义.地球环境学报,12(1),32-43.
MLA	毛学刚,et al."福建晚白垩世古土壤特征及其古环境意义".地球环境学报 12.1(2021):32-43.