The sedimentary record is the best archive of basin-forming tectonics and structural processes, particularly in regions with complex tectonic history such as the Eastern Cordillera in the Northern Andes of Colombia. Multiple tectonic episodes have driven fault reactivation and sedimentation in the Cenozoic is related to contractional strain. Sedimentary basins within the Eastern Cordillera contain coarse and fine grained units. The presence of coarse grained units in the distal regions of a foreland basin are in particular used to constrain deformation history on the basis of the conditions governing their deposition. Varying mechanisms are proposed for distal coarse clastic facies including 1) Orography (Masek et al., 1994) and climate …show more content…
The addition of a second chronometer such as ZHe bolsters provenance constrains. Though, different locations can have similar ZHe ages within one region, ZHe and ZPb ages cannot be the same unless related to volcanism (Reiners et al., 2005). Therefore, for accurate tectonic interpretations based on volcanic grain exclusions, we implement the use of double chronometry on the same detrital grains, an approach only used in the axial Eastern Cordillera (Saylor et al., 2012b). ZHe plays a valuable role in determining tectonic and thermal evolution of the thrust belt via lag time analysis (Cerveny et al., 1988, Ruiz et al., 2004, Bernet et al., 2006, Saylor et al., 2012). Changes in Lag time reflects upsection variation in deformation and exhumation rate of the adjacent orogen by interpreting five lag time trajectories. On each end of the spectrum, an upsection decrease in lag time will indicate accelerated thrust induced exhumation and an upsection increase in lag time will indicate reduced exhumation and possible introduction of a new source area. Various studies in the Eastern Cordillera have focused on single chronometry using either ZPb for provenance history (Horton et al., 2010, 2015, Cardona et al., 2010, Nie et al., 2010, Bayona et al., 2010, 2011, 2012, 2013, Saylor et al., 2011, Bande et al., 2012, Ochoa et al., 2012, Ayala et al.,
The claim that is correct is claim 3. The Jalisco Block is convergent to the Rivera Plate and divergent from the North American Plate which best explains the patterns of Earthquakes and Volcanoes on the Jalisco Block. I believe at this claim is correct because fro any plates to be convergent to one plate, they must be divergent to another plate. This case happens for the Jalisco Block. The card that support this statement is card A which tells us that scientists found the same rock on either side of the Tz Rift Zone where they were originally formed a team he same time at the same place when today they are 24 km apart. This matters because it shows that there is volcanic activity at divergent plate boundaries and it also proves the the
The three faults being considered are thought to have influenced the character of some 120,000 square miles. The Big Pine, Garlock, and San Andreas faults are all mutually active, deep, long, and steep and noted as being conjugate shears. In concert, the faults have defined a primary strain pattern of relative east-west extension and north-south shortening of the area of 120,000 square miles. The large region is noted for its deformity, with the source of this being a northeast-southwest counterclockwise compressive couple. The compressive couple was potentially supported through drag as a result of the deep-seated movement of rock material from the Pacific region (Hill & Dibblee, 1953). The interaction of the faults in the San Andreas region since the Jurassic period have served to shape and contour the present geology of the land, while a study of the paleontology of the region likewise requires such knowledge to effectively determine conditions at any given point in time.
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).
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
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.
The Mesozoic tectonic history of the North American Cordilleran region is very complex and involves:
Schulz’s article is split into five sections. The first section introduces the readers to Chris Goldfinger, a paleoseismologist at Oregon State University. Goldfinger was at a seismology conference in Kashiwa, Japan when the 2011 Tohoku
This is a comparative essay and its purpose is to compare old-Earth and young-Earth viewpoints on Dating the rocks of the Grand Canyon. There are different views on this and no scientific method that can prove (completely) the age of the universe or the earth. There are the use of different types of calculations that can provide some guesses on the age of the earth. Many things need to be assumed such as a beginning date and the speed of change along with varying increases and decreases of material over time. “Young-Earth Creationism” (YEC) is based on a precept that earth and the universe were created by God, only 6,000 years ago in six days. Their position is that by examining geological records the scientific details of
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
They documented a flight of six terrace surfaces rising above the modern floodplain of Carrizo Wash. The highest and oldest surface (T6) consists of Pleistocene gravel, and the lowest three surfaces (T1–T3) date to the historical period. The remaining two terraces (T4 and T5) were formed during the prehistoric portion of the Holocene. Anderson and Edwards differentiated the alluvium into four stratigraphic units, and seven radiocarbon dates on detrital charcoal provided temporal control. The oldest deposits, designated Garcia Ranch I, underlie the T5 tread and are associated with radiocarbon dates of 7090 and 6132 14C yr BP. Anderson and Edwards believed that stream down-cutting followed the deposition of Garcia Ranch I deposits. Garcia Ranch II deposits are inset into the older Garcia Ranch I alluvium, but also form part of the T5 surface. The lower portion of this unit contained charcoal that yielded dates of 4250 and 3780 14C yr BP. The upper part of the Garcia Ranch II unit includes paleochannel fill dated at 3890 14C yr BP. Garcia Ranch III deposits contained charcoal dated at 2410 and 2520 14C yr BP. Pueblo I and II materials on the surface of this unit suggest that Garcia Ranch III deposition ended prior to about 1,200 years ago. The youngest prehistoric deposits are inset into T5 and consist of
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
One piece of this history is the subsurface Paleozoic rocks. Paleozoic rocks are for the most part hidden in the Park despite being in the Colorado Plateau, which is likely due to both erosion, and it being buried in other various rocks. Next is the deposition of the Moenkopi Formation during the early Triassic time period. When North America was still apart of Pangea, the area that was the Colorado Plateau was located within close range of the Equator. 300-600 feet of sand and mud were accumulated during this time, with marine life being included which tells Geologists that the sea sometimes was in the area. The climate at the time was warm, with varying times of humid and dry spells. There is very few beds of the Moenkopi Formation left in the area once again due to erosion. Third is the deposition of the Shinarump Member of the Chinle Formation. This basal conglomerate was deposited on top of the Moenkopi Formation. It is made up of gravel and sand, which indicates that there was water depositing it. The Shinarump Member also averages between 35-50 feet thick. Next in the geological history is the deposition of Chinle beds later in the Triassic time period. When the sea regressed to the west of the area, a large plain was left behind. As the climate changed, so did the environment. Soon grasslands and marshes began to form in the area. During this time hundreds of feet of shaly material accumulated which formed both the Lower Petrified Forest Member and the Upper Petrified Forest Member. In some parts, these two members are separated by the Sonsela Sandstone Member, composed of the most petrified wood compared to all other rock units featured in the Park. The Owl Rock Member is at the top of the Chinle Formation, and completes it. Near the end of the Triassic time period, tectonic activity was occurring heavily in the Arizona basin. In the western sea at this time a chain of volcanoes erupted,
The Sangre de Cristo Mountains are a structurally complex block having a Precambrian igneous core that is bounded by major, high-angle reverse faults and highly contorted, steeply dipping to overturned sedimentary beds of Paleozoic and Mesozoic age. The range resulted from uplift and eastward thrusting during the Laramide orogeny commencing in Late Cretaceous time and continuing intermittently to possibly late Tertiary time (Wanek and Read, 1956).
The Grand Canyon has plenty of volcanic rocks near the bottom and the top. ICR, Institute for Creative Research, has been involved in a project for years to date these volcanic rocks. this study has come a long way to show that many of the Grand Canyon strata could have formed rapidly, and that the erosion of the Canyon by the Colorado River has not been going on for millions of years.
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.