The formation and genesis of the rhyolite series of the Upper Chegem Highlands (the North Caucasus)

On the basis of new materials this article deals with the structure and origin of a huge (up to 2 km) thick massif of acidic volcanic rocks located in a volcanic-tectonic depression in the Upper Chegem River in the North Caucasus. Discussion on the lava’s, rather than pyroclastic, origin of the main part of the rock mass as a result of repeated outpourings of lava flows, which formed the series of acidic volcanic rocks without interruptions with perfectly pronounced columnar jointing in a limited volume of a deep volcanic-tectonic depression, which was forming simultaneously with eruptions in the Late Pliocene. Volcanic rocks formed as a result of boiling silicate meltas the exit from the vent, which could be due to the nature of the phase transition of the supercritical water fluid.

Geotourism and Mining Heritage: a Potential Gold Mine for Central Nigeria

The potential for geotourism and mining heritage of some landscapes in parts of Kaduna, Plateau, Nasarawa and Kwara states in central Nigeria were studied and compiled. The result show that geological endowments range from insalbergs, flood basalts and dome structures, which presents natural landscape for tourism. The quartzite ridges of the Oreke area in Ilorin host the Owu Falls of 120m cascading waters, the Kafanchan flood basalts that flowed extensively from the Kagoro hills with extensive columnar jointing creating the prestigious water falls of over 30m all present versed potential for geotourism. Mining activity around the Jos Plateau (Bassa, Jos, Bukuru, Barakin Ladi and Bokkos areas), southern Kaduna (Godogodo and Jagindi) create landscapes that if properly beautified can become tourist landmarks. Adopting and harnessing these landscapes can boost and provide alternative revenue for the affected central.

A MODEL OF COLUMNAR JOINTING

We propose to use nonlinear elasticity to model the propagation of cracks in cooling lava. In particular, our work aims to understand the enigmatic fracture process that leads to the formation of column joints. Column joints are plane fracture surfaces fragmenting a basalt flow into prismatic columns. These columns are characterized by their polygonal cross-section and usually exhibit a strikingly high degree of regularity. We present a variational model with the assumption that the fracture process seeks to minimize the total energy of the system. The expression for the elastic energy is simplified and the configuration of minimal energy is analytically determined by a rigorous derivation. Further, we study the behavior of the energy under Steiner and Schwarz symmetrization of the column cross-section. In particular, we prove that the minimum of the energy among all possible convex and bounded column cross-sections B ⊂ ℝ2 is attained when B is the two-disk. Our results thus give strong evidence supporting the conjecture that the minimal energy is attained for a regular hexagon when the column cross-section is further required to tile the plane.