The first find of sedimentary rocks and identification of spore-pollen complexes from the Cenozoic volcanic sequence of Spitsbergen

Abstract

Information about young basalt sheets dominating heights on the Andre Land of Western Spitsbergen Island was obtained for the first time in the early 1900s [1‐3]. Kovaleva and Burov [4] and Prestvik [5] studied the rocks in the 1960s‐1970s, and we studied them in 2003 and 2005. Basalts are exposed between Vud and Veide fjords at the submeridional tectonic boundary of rocks of the Proterozoic basement and orogenic sedimentary sequences of the Devonian graben. They extend for more than 40 km from south to north and for nearly 30 km from the west-southwest to east (figure). The base of the basalt sheet occurs higher than 1000 m in the south of Vud Fjord and descends to 620 m in the north; i.e., it dips gently in the northward direction. Basic rocks overlie with sharp unconformity the Devonian gently dipping variegated rocks and, in one case, Proterozoic metamorphic rocks. The contact is usually interspersed with lumpy basalt masses and confined to steep zones of the slope. The base of basic rocks is more often undulating and composed of amygdaloidal varieties. Devonian siltstones and sandstones near the base (up to the height of 1 m) are compact and “baked.” Therefore, they “clink” when hit with a hammer. More rarely, the base includes a xenotuff horizon (0.5‐2.0 m) made of acute-angled clasts of host rocks cemented by lava. If the volcanic rock section begins with an agglomerate tuff horizon, which is exposed as a single massive body, the latter is apparently separated from host rocks. In this case, one can observe even cavities and the boundary is uneven. Basalts make up outliers from several thousands of square meters to 1‐2 km 2 . They occur as sheets and