Minimum quadratic helicity states

Building on previous results on the quadratic helicity in magnetohydrodynamics (MHD) we investigate particular minimum helicity states. Those are eigenfunctions of the curl operator and are shown to constitute solutions of the quasi-stationary incompressible ideal MHD equations. We then show that these states have indeed minimum quadratic helicity.Comment: 13 pages, 2 figure

Late Paleocene Flora of the Northern Alaska Peninsula: The Role of Transberingian Plant Migrations and Climatic Change

For the first time, the Late Sagwon Flora is described from the upper beds of the Prince Creek Formation (Upper Paleocene) at the Sagavanirktok River (northern Alaska Peninsula). The flora is dominated by the angiosperm Tiliaephyllum brooksense Moiseeva et Herman sp. nov. and conifer Metasequoia occidentalis (Newb.) Chaney. The Late Sagwon Flora is most similar to the Danian or Danian-Selandian flora from the middle part of the Upper Tsagayan Subformation (Amur Region) and lower part of the Wuyun Formation (Heilongjiang Province, China). This similarity allows us to hypothesize that the genus Tiliaephyllum, which dominated in the Late Tsagayan Flora, migrated via the Bering Land Bridge from southern paleolatitudes of the Far East to high latitudes of the Arctic Pacific, due to the progressively warming climate of the Paleocene. Additional new angiosperm species are described from the Late Sagwon Flora: Archeampelos mullii Moiseeva et Herman sp. nov., Tiliaephyllum brooksense Moiseeva et Herman sp. nov., and Dicotylophyllum sagwonicum Moiseeva et Herman sp. nov

Lectostratotype of the Maikopian Group in the Belaya River Section Upstream of the Town of Maikop (Western Ciscaucasia) in the Oligocene Part

The section of Maikop deposits on the Belaya River upstream of the town of Maikop is characteristic of Western and Central Ciscaucasia; it is well exposed and well-studied and can be considered as the type section of the Maikop Group. The section shows a continuous transition from the underlying white marl of the Belaya Glina Formation to dark clay lying at the base of the Maikop Group. The lower Oligocene part of the section exposes an almost uninterrupted outcrop of the Pshekha Formation and shows unconformities at the base and top of the Polbian Bed. These are overlain by the lower non-carbonate and upper carbonate subformations of the Morozkina Balka Formation and the Batalpashinsk and undivided Upper Oligocene Septarian + Zelenchuk formations. This paper contains a detailed lithological description of the section with a summary of its fossils. The composition of the studied microphytoplankton and animal remains, including nannoplankton, planktonic and benthic foraminifers, mollusks, and ichthyofauna is described and paleomagnetic study results are presented. The study of palynology and dinocysts from the same series of samples was previously completed. The history of the study of the Maikop Group and its subdivision into formations are discussed. This paper discusses the possibility of using the data for correlation and reconstruction of the depositional environment

Lectostratotype of the Maikopian Group in the Belaya River Section Upstream of the Town of Maikop (Western Ciscaucasia) in the Oligocene Part

The section of Maikop deposits on the Belaya River upstream of the town of Maikop is characteristic of Western and Central Ciscaucasia; it is well exposed and well-studied and can be considered as the type section of the Maikop Group. The section shows a continuous transition from the underlying white marl of the Belaya Glina Formation to dark clay lying at the base of the Maikop Group. The lower Oligocene part of the section exposes an almost uninterrupted outcrop of the Pshekha Formation and shows unconformities at the base and top of the Polbian Bed. These are overlain by the lower non-carbonate and upper carbonate subformations of the Morozkina Balka Formation and the Batalpashinsk and undivided Upper Oligocene Septarian + Zelenchuk formations. This paper contains a detailed lithological description of the section with a summary of its fossils. The composition of the studied microphytoplankton and animal remains, including nannoplankton, planktonic and benthic foraminifers, mollusks, and ichthyofauna is described and paleomagnetic study results are presented. The study of palynology and dinocysts from the same series of samples was previously completed. The history of the study of the Maikop Group and its subdivision into formations are discussed. This paper discusses the possibility of using the data for correlation and reconstruction of the depositional environment

Lectostratotype of the Maikopian Group in the Belaya River Section Upstream of the Town of Maikop (Western Ciscaucasia) in the Oligocene Part

The section of Maikop deposits on the Belaya River upstream of the town of Maikop is characteristic of Western and Central Ciscaucasia; it is well exposed and well-studied and can be considered as the type section of the Maikop Group. The section shows a continuous transition from the underlying white marl of the Belaya Glina Formation to dark clay lying at the base of the Maikop Group. The lower Oligocene part of the section exposes an almost uninterrupted outcrop of the Pshekha Formation and shows unconformities at the base and top of the Polbian Bed. These are overlain by the lower non-carbonate and upper carbonate subformations of the Morozkina Balka Formation and the Batalpashinsk and undivided Upper Oligocene Septarian + Zelenchuk formations. This paper contains a detailed lithological description of the section with a summary of its fossils. The composition of the studied microphytoplankton and animal remains, including nannoplankton, planktonic and benthic foraminifers, mollusks, and ichthyofauna is described and paleomagnetic study results are presented. The study of palynology and dinocysts from the same series of samples was previously completed. The history of the study of the Maikop Group and its subdivision into formations are discussed. This paper discusses the possibility of using the data for correlation and reconstruction of the depositional environment