Abstract The Changbaishan volcanic field located on the Gaima (Gaema, Gaiman) Plateau has witnessed plateau-forming eruptions along with the uplift of the Gaima Plateau. The Tianchi basaltic lava shield volcano was formed at the main peak of Changbaishan, with cone construction eruptions that formed a huge and steep trachytic composite cone on the gentle lava shield. At the peak of the Millennium Eruption (ME), the height of the eruption column reached 25 km and the bulk volume of tephra was about 120 km 3 . The ME eventually formed Tianchi caldera, after which several eruptions occurred, albeit of a much smaller scale. The magmas involved in the shield-forming eruptions are characterized by both alkalic series trachybasalt and basaltic trachyandesite and subalkalic tholeiite and basaltic andesite. In the cone-construction and ignimbrite-forming eruption stages, the magma is completely composed of alkalic series trachyte and comendite. The largest negative Eu anomalies observed in ME magmas indicate that plagioclase was strongly crystallized and differentiated.

Abstract The Cenozoic alkali basalts are widely exposed in the Jingpohu Volcanic Field, NE China. Previous volcanology and geochronology research has revealed that they were formed in three periods in the Miocene ( c. 29.23–13.59 Ma), Pleistocene ( c. 83.7 ka) and Holocene ( c. 5.5–5.2 ka BP). The Miocene and Pleistocene basalts consist of alkali olivine basalts, while the Holocene basalts are composed of alkali olivine basalts and leucite tephrites. Petrogenetic studies reveal that the primary magmas of the Miocene and Pleistocene alkali olivine basalts originated from partial melting of EM2-like garnet peridotites, and those of the Holocene alkali olivine basalts were derived from melting of EM1- and EM2-like garnet peridotites with higher garnet proportions. In contrast, the primary magmas of the Holocene leucite tephrites were derived from the melting of eclogites and peridotites. Combined with previous research, we suggest that melting of the mantle source region to generate Jingpohu alkali basalts was triggered by decarbonization and dehydration of the slabs stagnated in the mantle transition zone.

Abstract Ashikule volcanic field, developed in the western Kunlun mountain of north Tibet, is composed of approximately 10 volcanoes, and covers a total area of about 200 km 2 at an average altitude of approximately 5000 m, one of the highest volcanic fields in the world. In this study, we conducted detailed field investigations of the geological and geomorphological features of volcanic rocks and volcanic edifices in Ashikule basin, and compiled a large-scale geological map of the study area for the first time. We also collected a series of samples for petrochemistry analysis, as well as a high-precision 40 Ar/ 39 Ar geochronology study of selected lavas from Ashikule volcanic field. Finally, we refined the eruption history for the volcanic activity in the basin, which provides some new volcanological evidence for the study of the tectonic evolution of the Northern Tibetan Plateau.

Abstract The Tengchong Volcanic Field (TVF) is one of the youngest volcanic areas in China, and is located in the southwestern part of Yunnan Province, China, adjacent to the collision zone between the Indian and Eurasian plates. This paper summarizes the results of previous research on the eruption history, petrochemistry and geodynamic background of the TVF and presents a detailed analysis of the available data. Eruptions took place from the Pliocene to the Holocene and were divided into five stages. The composition of the magma went through two cycles: the N 2 − Q P 1 − Q P 2 volcanic rocks went through the evolutionary process from basalt to dacite and the Q P 3 − Qh magma evolved from trachybasalt to trachyte. The evolution of magma is mainly related to the fractional crystallization of pyroxene and ilmenite. The mantle source area of the TVF volcanic rocks was caused by mixing between the mid-ocean ridge basalt-source mantle and the eastern Indian continental margin sediments to different degrees. Geophysical data also showed that the Indian plate has been subducted under the TVF area. There are also magma chambers in the crust within a depth of 25 km in the TVF that are replenished by mantle magma.

Abstract Northern Hainan Island and the Leizhou Peninsula volcanic fields (Leiqiong), the southernmost continental Cenozoic volcanism in China, cover an area of c. 8000 km 2 with 177 volcanoes recognized. Far from the subduction areas, volcanoes in this area provide an ideal opportunity to study the geodynamics of intraplate volcanoes. Here, we review the geochronological and geochemical data of the volcanic rocks in Leiqiong volcanic fields, and discuss their magma sources and geodynamics on the basis of the geological and geophysical observations. Chronological data (34.78–0.01 Ma) show that the volcanic activities started approximately in the Miocene and continued to the Quaternary. These basalts show typical geochemical characteristics of oceanic island basalts, and tomographic images reveal that a mantle plume is situated beneath Hainan Island and extends down to the core–mantle boundary. Thus, we suggest that the Hainan mantle plume is responsible for the Cenozoic volcanism in Leiqiong volcanic fields and this plume is sourced from the lower mantle with additions of dehydrated slab fragments. These mixed plume materials were brought to the upper mantle and produce solid pyroxenites, which are the major source of Leiqiong magmas. Although there is no documental record of volcanic eruptions in Leiqiong volcanic fields, the volcanic danger cannot be neglected.