Volcanism in the Longgang Volcanic Field of Northeast China: Insights from eruption history, volcano types, and geochemical characteristics

The Longgang volcanic field (LVF) is a monogenetic volcanic field in China that erupted in the Quaternary, forming more than 100 scoria cones and maars in an area of over 1500 km2. The most recent eruption occurred approximately 1500-1700 years ago. By summarising the results of previous and recent research, this paper reviews the geological background, volcano distribution, eruption history, typical volcanoes, and geochemical characteristics of the LVF. The volcanic activities in the LVF were structurally controlled by near-EW, NW-, and NE-trending faults. An analysis of typical volcanic edifices reveals that at least two eruptive episodes occurred in the Holocene, and most of the maars in the LVF have characteristics of multiple eruptive styles. It is concluded that the eruption types included effusive eruptions, magma explosive eruptions, and phreatomagmatic eruptions. The results of geochemical studies of LVF eruptive products show that most of the rock is trachybasalt and that the magma rarely interacts with crustal rocks. Compared with the previous results for the neighbouring Changbaishan polygenetic volcanic field, the probable origins of their differences in volcanism are discussed.

Geomorphological Classification and Landforms Inventory of the Middle-Atlas Volcanic Province (Morocco): Scientific Value and Educational Potential

Through the tabular morphology of northwestern part of the Middle-Atlas in Morocco, numerous uncovered monogenetic volcanoes arise structured of pyroclastic product layers and lava flows. Our fieldwork results witness a wide-ranging volcanic shape spectrum, as cones, maars, tuff-rings, and cone-maar mixes, generally associated with a later lava flow discharge that could develop many surfaces and appearances. There are withal sundry eruptive products such as pahoehoe lava, scoria, tuff, lapilli, peperites, base-surges, bombs, etc. This monogenetic volcanic field of practically 1000 km2 offers remarkable eruptive landforms, referred to as the largest, and the youngest volcanic field in Morocco, which consists of a large area within the Ifrane National Park. This fieldwork study provides a renewed volcanic geomorphological classification table and GIS data to be used by a wide public range for both educational and geo-touristic interest and access effectively to such a high-mountain natural museum. In the event that these volcanic structures were appropriately dealt with, the high educational scientific content and the notable touristic vocation would almost certainly create business openings and new financial wages for neighborhood populaces. This work focuses to share our outcomes and emphases the scientific value about the monogenetic volcanic field around the tabular Middle-Atlas in Morocco.

Paleomagnetism and tectonics from the late Pliocene to late Pleistocene in the Xalapa monogenetic volcanic field, Veracruz, Mexico

The Xalapa monogenetic volcanic field, Veracruz, Mexico is located at the eastern end of the Trans-Mexican Volcanic Belt. This study uses specimens from 0.8 ka to 5.96 ± 0.156 Ma Xalapa lava deposits and from 4.5 ± 0.028 Ma La Concha ignimbrite. The study identifies the magnetic mineralogy by reflected light microscopy, thermomagnetic curves, and coercivity estimates. It further defines the magnetic domain size distribution by hysteresis plots, Day diagrams, and first-order-reversal-curves. Characteristic remanent directions and virtual geomagnetic poles are also calculated. The characteristic remanent directions are used to establish the magnetostratigraphy and to identify the net rotation experienced, at each site, since the emplacement. The results allow the identification of the rotation domains, and R′-, P-, and Y-shears, active since the past ∼2.5 m.y. in the region and a better characterization of the displacement along the Río Actopan fault, active in the Xalapa monogenetic volcanic field.