The Studied Sedimentary Succession Of Jamaica

Approximately 17 meters thick, Unit A defines the lowest third of the Juniata Formation. Fragments of marine fossils, including bryozoans, brachiopods, and gastropods, are commonly found in the bottom-most portion of this unit of structureless mudstone and quartz arenite. Quartz grains in the sandstone beds of Unit A are typically immature and fine-grained, though the sandstone packages tend to coarsen upwards. Though typically structureless, intermittent bedding of the sandstone and shale packages is observed in this unit, and some areas display

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.

Sims et al. (1989) synthesized U-Pb zircon ages for the Pembine-Wausau terrane. Sims concluded that the volcanic rocks were generated from around 1889 to 1860 Ma as island arcs and closed back-arc basins above the south-dipping subduction zone (Niagara fault zone). Granitoid rocks in the terrane, emplaced from around 1870 to 1760 Ma, are mainly granodiorite and tonalite but include gabbro, diorite, and granite. These developed as island arcs above the Eau Pleine shear zone. The Niagara fault zone contains a relict ophiolite, suggesting that the rocks in the Pembine-Wausau terrane probably accumulated on

During the Late Kaskaskia (Cratonic Sequence 3), what type of deposition predominated on the craton?

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

Sedimentary rocks interpret dinosaur habitats through encased environmental structures of the past. Through sedimentary rocks, paleoecologists’ can examine the arranged formation of sedimentary structures to specify what type of environment the dinosaurs’ lived in. An example of a specific sedimentary rock structure can be seen through formed weathering and ripple marks by how wind and sand formed distinct patterns in the past layered sediment. These arrangements provide interpretations on the structure of the sediment and the habitat of encased fossils, through modern day comparisons

Below these Carboniferous rocks, Devonian rocks are also exposed. These rocks can be found along the northern edge and southeastern margin of the plateau, where strata is nearly vertical. These two geologic systems have also been subdivided into numerous formations categorized according to their lithologic aspect and the fossil fauna and flora which they

Complete this week’s lab by filling in your responses to the questions from Geoscience Laboratory. Select answers are provided for you in red font to assist you with your lab work. Although you are only required to respond to the questions in this worksheet, you are encouraged to answer others from the text on your own.

The first deformation event (D1) resulted in folding of volcanic rocks in the Wabigoon and Wawa subprovinces (Hooper and Ojakangas, 1971; Hudleston, 1976; Hudleston et al., 1987; Jirsa et al., 1992) and locally within the Quetico subprovince (Bauer, 1985b). Most D1 folds in the Wawa terrane in MN rarely display axial-planar cleavage, with Bauer (1985b), Hooper and Ojakangas (1971), Hudleston (1976), and Jirsa et al. (1992) having identified cleavage (S1) development locally in the Vermillion greenstone belt (Peterson, 2001). In the Wabigoon terrane, D1 resulted in recumbent folding that overturned the stratigraphic sequence and the first regional schistosity (Poulsen et al., 1980). S1 is generally subparallel to the layering in the metavolcanic and metasedimentary rocks, and a gneissic foliation attributed to D1 is well developed in gneissic domes (Czeck and Poulsen, 2010). Although D1 likely created significant thrust or oblique faulting, direct evidence

This formation is a very fine grain Mississippian limestone. To test to see if this was the Bangor formation we used HCL and because there was a reaction we know its limestone. This formation could also be described as gray in color as well as an average thickness of 700 feet. We see the Bangor until stop eight, where we see a very different vertical bedding. Also different at stop eight is the outcrop no longer reacts with HCL. From this we gathered that we had moved into the Hartselle formation. In the Hartselle Formation, Mississippian aged sandstones are dominant. This particular stop had a large amount of jointing. After the Hartselle, we figured the Pride Mountain Formation would be next, however at stop nine we see the Maury Formation present. This stop focused on the rock located inside the creek. Because we were unable to go into the creek to get the strike and dips, we once again had to do a projected orientation. Also found on this stop were natural sulfur springs, easy to notice with the smell that it gives off. The Maury formation consist of Mississippian- Silurian aged shale. At the next stop, stop 10, we encounter the Ft. Payne formation. Although this area location was thickly vegetated, we were able to conduct the acid test and saw that the HCL reacts in some places but not all. From this we concluded that this was the cherty limestone of the Ft. Payne formation. The following stop, 12, we went up section and arrived at the Maury Formation once again. At the final stop, location 13, we see Ft. Payne Formation. All of the metamorphism and deformation in the southernmost Appalachians can be related to the movement of the thrust sheets and stacks (Higgins,

Hildebrand, (2009, 2003) attempts to integrate both observed geologic features (hinterland high grade metamorphism, Laramide basement uplifts, Cordilleran batholiths, regional-scale Neogene extension) and the lack of observed features (large scale strike/slip faults), while matching paleomagnetic data (large amounts of northward motion in the oceanic realm exist with no evidence on land) (Fern Esperanza beetle-Moorcroft, MS Thesis, 2014).

Glaciation that are widespread can be identified based on the subglacial tillite, which is a thick layer of sediments that settle down beneath glaciers or ice caps. On top of this subglacial tillite layer is deposited marine carbonate, also known as cap carbonate. Based on their paleolatitude designated by glacial sediments’ paleomagnetism, it can be determined that these deposits are from equator region. The interaction between two types of sediments, marine (like carbonate) and subgacially deposited sediments, indicate that the glaciers had approached marine coastlines.

Columbus discovered Jamaica on May 5, 1494, one year after he heard of the existence of the island. However, the true history of Jamaica begins with the African-Jamaican people who came to the island twenty years after the English took control from the Spaniards. The history of Jamaica can be broken up into different time periods, which were defined by watershed moments or events. Jamaican history begins with the establishment of the native islanders called the Tainos who inhabited the island for hundreds of years before the discoveries of Columbus. (JNHT 1)

By testing sediment and recording whether it was deposited under conditions of normal polarity and then measuring successive layers, we can build a time chart. By matching different charts from different areas with similar fossils, a more global correlation can be made.