Constraining paleo-latitude of a biogeographic boundary in mid-Panthalassa: Fusuline province shift on the Late Guadalupian (Permian) migrating seamount |
| |
| Authors: | Akihisa Kasuya Yukio Isozaki Hisayoshi Igo |
| |
| Institution: | 1. Department of Earth Sciences, University of Geneva, Rue des Maraîchers, 13, 1205 Geneva, Switzerland;2. Department of Geology, Northeastern University, Wenhua Road 3-11, Heping district, Shenyang, Liaoning 110819, PR China;3. University of Fukuoka, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan;1. University of Geneva, Department of Earth Sciences, rue des Maraîchers, Geneva 1205, Switzerland;2. Geneva Petroleum Consultants International, Geneva 1211, Switzerland;3. Department of Earth and Environmental Sciences, Kumamoto University, Kumamoto 860-8555, Japan;4. UMR CNRS 5023 Laboratoire d'' Ecologie des Hydrosystèmes Naturels et Anthropisés, Université Claude Bernard Lyon 1, 27-43 Boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex, France |
| |
| Abstract: | The Guadalupian paleo-atoll limestone (Iwato Formation) in SW Japan was primarily formed in low-latitude mid-Panthalassa and was later tectonically accreted to South China (Japan) margin during the Jurassic. The present biostratigraphic study clarified that the Iwato Formation consists of 5 biostratigraphical intervals; i.e. four fusuline assemblage zones (Assemblage zones 1 to 4) and a barren interval on the top. Assemblage zones 1 to 4 correspond to the Neoschwagerina craticulifera Zone, N. margaritae Zone, Yabeina globosa Zone, and Lepidolina multiseptata Zone of the conventional Tethyan fusuline stratigraphy, respectively. The present study newly clarified the following significant aspects of paleobiogeography of the Permian fusulines as to the extinction of large-tested taxa in the latest Guadalupian. 1) The long unknown stratigraphic relationship was documented for the first time between the Yabeina-dominant interval and the overlying Lepidolina-dominant one within a single limestone unit. 2) The occurrence of Lepidolina cf. kumaensis Kanmera, the unique last runner of large-tested fusuine, was detected for the first time in mid-oceanic paleo-atoll limestones. 3) With respect to the northbound migration history of the paleo-seamount capped by the Iwato Formation, the development of the two coeval fusuline biogeographic territories in the low-latitude Panthalassa, i.e., the Yabeina territory on the south and the Lepidolina territory on the north, was confirmed. 4) The paleo-latitude of the biogeographic boundary between the Yabeina and Lepidolina territories is constrained around 12° in the southern hemisphere on the basis of the latest geomagnetic data from the same limestone. This new approach utilizing biostratigraphy on ancient migrating seamounts coupled with geomagnetic paleo-latitude data is applicable to other cases in different time-space co-ordinates and of other fossil groups for constraining position of ancient biogeographic boundaries within lost oceanic domains of deep past. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
