1. Olivine decreases the concentration of magnesium in the melt. It helps decrease the amount of iron in the melt as well. On the graph of magnesium versus silica cation percentage the Magnesium amount decreases and the silica percent increases in the melt when olivine starts forming. This creates a downward sloping line. This downward slope is also true for the Iron versus silica graph. Plagioclase decreases sodium and potassium concentrations in the melt. Both Plagioclase and Olivine decrease the amount of silica and oxygen in the melt. On the graph of silica versus calcium it also shows a rapid downward trend just like olivine because they are both made up of compatible elements. However, potassium has an upward trend versus silica because …show more content…
The initial rocks are very ultramafic and as time goes on they became more felsic. The magma during the formation of the ultramafic to mafic rocks the magma becomes more felsic until these rocks stop forming. This is because compatible elements were crystallizing into minerals. These minerals then made up rocks after each step finished. Slowly the minerals and rocks formed became more felsic and the melt became less felsic. It will continue to get less felsic until all the magma has crystallized. For example, we went from Dunite (step1) all the way to Granodiorite(step ten). Dunite was very ultramafic while Granodiorite was more felsic since it had more silica in it. The last melt could have formed a Quartzolite or a Quartz-rich Granitoid depending on how much silica, alkaline feldspars, and plagioclase was left. Silica was the most abundant element in the melt so therefore the percentage of it in the melt remained high even after a decent amount of it had been removed. For example, at the end of step six there was still 125 silica atoms left in the melt. The steps that created ultramafic rocks were steps one through six since they had olivine, plagioclase, and pyroxenes in them. The mafic rocks were created in steps seven and eight since they had no olivine or felsic minerals in them, but still had pyroxene and plagioclase in them. The steps nine and ten created felsic rocks since they had felsic minerals (quartz and Alkali feldspars) as well as the mafic minerals in …show more content…
In a magma that is involving equilibrium crystallization only a few minerals if any are not interacting with the melt. In a system with complete equilibrium fractionation the mineral modes would increase from 0% to 100% at the different steps. In fractionalization crystallization, each step adds to 100% on it’s own. For example, step two would not equal 75% Olivine and 25% Plagioclase because these minerals would interact with the two previously crystallized Olivines as well as the melt. Therefore the percent of olivine and plagioclase would be completely different and would be a percentage of the melt that was crystallized. If the whole melt became a rock, then you would have a step that everything is equal to 100%, but you won’t have any earlier step equal 100%. This then will change the types of rocks formed and their IUGS
The new volcanic material welling up into the void, which forms a ribbon of new materials and breaks down its center gradually, when the plates move apart from the axis of the mid-oceanic ridge system. Therefore, every separating plate accretes one half a ribbon of new lithosphere, and, thus, a new surface is added (Pitman, W.C, 2007). The process is continuous, and separation is always happening at the
The youngest of these rocks are dated at about 220,000 years ago. Rhyodacties and quartz latites in the modern caldera area extruded from about 320,000 years ago to 260,000 years ago, and then silica-rich rhyolites at Glass Mountain northeast of the caldera erupted from about 210,000 years ago to 80,000 years ago. The scattered distribution of the initial mafic eruptions indicates that they were erupted from the mantle, while the slightly younger domes and flows were from a deep-crustal source. The youngest rhyolite eruptions erupted at the northeast rim of the caldera at Glass Mountain and were the first activity of the silicic Long Valley magma chamber (Bailey, et. al., 1989).
Next, we can see that the rock displays a subtle porphyritic texture with plagioclase comprising the phenocrysts. The overall texture of the surrounding groundmass is granoblastic equigranular. Under thin section we also see a weakly defined foliation evidenced in the preferential alignment of actinolite grains and to a lesser extent chlorite grains. Undulose extinction is also observed in quartz indicating the rock was subject to deformation. The normalized quartz, alkali-feldspar, and plagioclase (QAP) values of this rock indicate that it is classified as a grano-diorite according to the IUGS QAPF classification system which is consistent with the hand sample interpretation.
Amethyst is purple quartz; the color is caused by iron (Fe4+) impurities. Azurite is a copper mineral. Calcite is a very common and widespread mineral and has highly variable forms and colors. Lodestone is a natural magnet. Mica is a sheet silicate. Rose quartz is translucent and a variety of the silica mineral quartz, found in pegmatite. Talc almost always found in foliated masses in metamorphic rocks with many carbonate minerals. Pyrite is a very common mineral. The brassy-yellow metallic color of pyrite has lead people to mistaking it for Gold, so its common nickname is
Cenozoic sedimentary rocks predominated to the west and east of the central mountain while plutonic rocks predominated in the peninsular ranges. The irregular contact between these geologic regions reflects the ancient topography of the area. The ancient oceanic crustal plate created an archipelago of a volcanic island. The former's subduction created immense volumes of magma. This resulted to the congealation of plutonic rock in the crust. The local rocks that existed before the tectonic forces uplifted, and erosion capped the deeply buried plutonic rocks that formed a steep and rugged mountains coastline, similar to that present one, which in the west coast of south America.
Mineral |Crystal shape |Color |Density |Hardness |Streak |Fizzes in acid? | |Galena (lead ore) |Cubic/ irregular |Gray |7.5 g/mL |3 |Dark gray |No | |Gold |Irregular |Golden yellow |19.3 g/mL |3 |Yellow |No | |Graphite (pencil lead) |Irregular |Dark gray |2.2 g/mL |2 |Gray |No | |Hematite (iron ore) |Irregular |Red-brown to black |5.3
Silicious lava, forced up from deep down below. Soda trachytes extruded in a highly viscous state, building the steep-sides mametons we see in Hanging Rock. And quite young, geologically speaking. Barely a millions years old. (Greene, 11)
One of the major things noticeable from the cross section is that quite a few of the rock layers are over turned, where the older rock layers are above the newer rock layers. This is seen in the contact between the Quartz Monzonite of Papoose Flat and the Campito Formation which is also a disconformity. Next there is some fault zones separating the Camptio, Poleta, and Harkless formations. We then see some more overturned layers with the contacts between Saline Spring Valley Formation (lower and upper members) above the Mule Spring Formation along with some inferred folding. With a normal fault separating the inferred folding event, we see where the overturning occurs. In between the Cambrian layers we see Tertiary Basalt nonconformities also being folded, thus with that we know that the folding event was more recent than the formation of the Basalt. Next there is a large Basalt field with a spot of the Harkless formation. Again we see over tuning as the Basalt field ends there are the Devonian and Mississippian rock Layers on top of the basalt. Separating these overturned layers from the Harkless Formation and the Saline valley Formation (upper member), which are not overturned, is a thrust fault. From this information, there was a major stress event sometime after the Tertiary period causing the rock layers to fold and overturn. And from this stress event and from the folding, normal and thrust faults are formed. Finally we see that there were alluvial and landslide deposits from the Quaternary after the folding, faulting, and over
Convection currents may bring magma to the surface at diverging boundaries. Sedimentary rocks from the ocean floor gets pushed down to the mantle at convergent boundaries. The crust soon melts and rises to the surface creating igneous rock. Typically mountain ranges are metamorphic rock, maybe our mountains are.
A period of volcanism resulted in igneous intrusions within the Raton Basin-Sierra Grande Uplift Province that was sourced from the upper mantle about 26. 6 billion years ago and is associated with parallel dikes and sills (Higley, 2007). Igneous rocks are common within the Raton Basin and include Tertiary dikes and sills that range in age from 6.7 to 29 5 million years ago (Flores and Bader, 1999). One of the main differences between dikes and sills is that dikes are longer lived magma conduits and sills are features that form when magma is in neutral buoyancy with the surrounding rock (Rooper et al., 2006). These volcanic events are associated with hydrothermal alteration of coal within the basin (Higley, 2007).
Many millions of years ago the Sierra Nevada was filled with ocean water until sediments began collecting and formed mountain ranges. Over a large period of time, the mountains began to wear out and became immersed in the ocean once again. Many different particles and materials began to make layers and created the first mountain system. After the Jurassic era, “…new strata were folded and crumpled and invaded by molten granite from below” (Beatty, 1943). A large
All of the volcanic and metasedimentary rocks are metamorphosed, whose grades are extending from greenschist to upper amphibolite, characterized by low-pressure but high-temperature (Isachsen & Bowring, 1994). The influence of basement fracture zone is reflected in the homoclinal and abruptly alternated trends of the volcanic belts, which is more frequently found in the southwestern domain of the province, while north belts show angular patterns (Fyson & Helmstaedt, 1988; Padgham,1992; Padgham & Fyson, 1992). Except for the sharp dips of the volcanics, regional-scale folds, foliations and cleavages over several successions shown in the metasedimentary rocks are studied to understand the deformation and metamorphism (Isachsen & Bowring, 1994). Fyson & Helmstaedt (1988) compare three major types of folds which are ranked by their ages and sizes from oldest, most extensive F0 to minor-sized, cleavage-foliation-associated S3 folds with intermediate type F1 between them and they suggest that the parallel trend and they suggest both foliation and folds are results of syntectonic
The astronauts found on the regolith that the highlands have aluminum in its rocks and the regolith in the maria contains iron and magnesium which happens to be a major component of basalt. There was two main types of rocks found on the Apollo 11 site, basalts and breccias. The first type of rock was basalts were are solidified from molten lava. Basalts are made up of pyroxene and plagioclase which was formed by two chemically different magma sources and are dark gray which is why the Moon contains dark areas. The second type of rock are breccias which is composed of fragments of older rocks by the heat and pressure of meteorites. These samples from the regolith and maria provided facts that the maria was covered in lava flows and in the highlands provided how earth was like like 4.5 billion years ago. Apollo 12 mission contained basalts with low amounts of titanium and Apollo 17 mission had a sample of “orange soil,” which consists of small orange glass beads. The beads are glass because they cooled rapidly with no crystals insider and all had different colors from titanium. Scientists conducted on basalts and pyroclastic glass which showed that they formed when the interior of the Moon partially
Minerals are naturally occurring, inorganic, solid, crystalline substances which have a fixed structure and chemical composition. Minerals are an important part of Geology, especially when studying Crystal and mineral growth. Understanding how crystals grow and the difference between slow and fast cooling rates is also important in Geology. Knowing the difference between cooling rates is important because cooling rate changes the texture of rocks and minerals. The purpose for the Crystal Growth experiment is to identify which Solubility and temperature produces larger crystals, and to simulate natural crystal growth. We will achieve the results we desire by conducting the experiment thoroughly and correctly, as well as correctly
Igneous rocks are classified first by texture. This is broken down mainly into grain size. First there are intrusive, or plutonic igneous rocks. These types of rocks cool within the crust and forms large, visible crystals. The opposite would be extrusive, or volcanic rocks. These cool at the surface rapidly, forming small grains. A combination