Geology topics
Research about Mexico
Source-linked reports with geographic coverage including Mexico.
Origin of the compositional variation of the lavas of Paricutin volcano, Mexico
No abstract available.
Phosphate deposits of the Concepcion del Oro district, Zacatecas, Mexico
The two small Mexican plants that are currently producing acid-phosphate fertilizer from phosphate rock have a productive capacity of about 45,000 metric tons annually. The larger plant processes pebble phosphate imported from Florida, while the other is utilizing material from the small, widely scattered phosphate deposits of Nuevo Leon. Large-scale expansion of this young superphosphate industry is dependent upon the discovery of new, larger domestic deposits in Mexico.
Lava movement at Parícutin Volcano, Mexico
The lava flows of Parícutin Volcano, Mexico, offer an exceptional opportunity to study details of lava movement, because many flows are accessible throughout their length and can be watched from their birth to the cessation of their movement. Petrographically the lavas show no significant difference from one flow to another or in different parts of the same flow. The maximum lava temperature observed was 1070°C.; the maximum estimated rate of flow was 60 meters per minute; the viscosity is probably on the order of 10 5 to 10 6 poises. The flows start in fissure zones cutting older Parícutin lavas near the southwest base of the volcano. Within a short distance of its orifice a flow is covered with cooled blocks which are broken and slightly abraded as they are carried downstream. Differential movement in a flow takes place principally at its edges, where a reddish breccia and grooved and slickensided surfaces form. Like a glacier, a lava flow develops transverse crescentic ridges and lateral moraines. At its front movement is normally effected by the rolling forward of molten lava within, which carries down cooled blocks from the surface and piles them up ahead of the flow. As a flow dies the lava level lowers in the channel, and small side tongues break through the moraines. Some Parícutin lavas move considerable distances beneath older lava. The longest flow, which covered the town of San Juan in 1944, has a surface of rough curved slabs very different from the blocky surface of other flows but similar to the surface structures developed near lava orifices and by movement of viscous lava through fissures.
Activity of Parícutin volcano from April 12 to May 3, 1946
The activity of Parícutin varied greatly during the period April 12 to May 3. The strong eruptive activity that began in mid‐March, marked on March 17 by the formation of a new boca with a short‐lived volcancito and by external changes in the form of the cone, continued until April 18, The period April 12–18 was marked by bomb‐showers and explosive blasts at the rate of ten to 15 a minute, mostly from the south vent of the double crater. Most of the bombs fell into the north crater and on the north flank of the cone. From April 19 to 26 the activity was, in general, very weak, and little ash and few bombs were projected beyond the rim of the cone, Explosions were very rare, and the weak vapor column from the Volcano was accompanied by a dull surf‐like roar. Most of the vapor emerged from a small vent near the center of the divide between the two coalescing craters. A heavy ash column, at times approaching in intensity that of 1943, emerged from the Volcano from April 27 to 29. The ash was erupted from both the north and south vents of the crater, though the south vent is believed to have contributed the most. From April 30 to May 3 the activity was again very weak, and only a feeble column rose above the cone.