Эволюция кайнозойского вулканизма и его источники в зоне Дариганга-Чифэн (Дачи): вовлечение в тектоническую активизацию киля Северо-Китайского кратона и глубокой мантии под сопредельными геологическими структурами

Abstract

In this paper, volcanism of the fields of the Dachi zone (Dariganga, Abaga, Dalinuoer, and Chifeng) that extends for more than 500 km in the border regions of southeastern Mongolia and northern China is considered. It is inferred that the zone has undergone a common evolution in the last 24 Ma, starting from the boundary of the North China Craton. Volcanism propagated northward, through the west-east Solonker suture zone into the Xing'an block. It is suggested that the Solonker suture zone was involved in left-lateral motions after 15–14 Ma eruptions in the Dariganga, Abaga, and Dalinuoer fields and after the final (ca. 5 Ma) eruptions in the northern margin of the Chifeng field. The nature of source changes during the evolution of volcanism is assessed from Pb isotopes of volcanic rocks with additional information on the Sm/Nd ratio based on Nd isotope variations. In sources of volcanic rocks from the southern part of the Dachi zone (Chifeng field), a component of the cratonic mantle keel is determined. The development of the process of cratonization of the mantle and crust is assumed to have occurred about 2.23 billion years ago due to degassing of the mantle originated from the Hadean magmatic ocean, which solidified 4.47 billion years ago. Volcanic rocks of the Abaga and Dalinuoer fields are characterized by the youngest protolith, corresponding to a geochron of 4.44 billion years.