What is the impact of volcanic explosion on sediment geochemistry ?5 answersVolcanic explosions have significant impacts on sediment geochemistry. Studies show that explosive eruptions can lead to increased water and sediment fluxes in affected drainage basins, causing high sediment yields and channel instability. Deep sea sediments near active volcanic areas experience reduced microbial activity and diversity, particularly in anammox communities, due to volcanic ash deposition. Additionally, eruptions can alter sedimentation patterns in deepwater cores, affecting climate variations and global temperatures. Varved sediments in lakes reveal distinct changes in grain size following volcanic eruptions, possibly due to increased precipitation and erosion. Furthermore, isotopic investigations in marine sediments suggest that volcanic activity, like large igneous provinces, can release significant amounts of carbon and traceable Pb isotopes into the atmosphere, impacting marine environments.
What factors contributed to the breakup of Pangea?5 answersThe breakup of Pangea was influenced by multiple factors. Mantle plumes played a significant role, particularly in initiating the breakup, while young orogens acted as weak zones guiding continental rift development. Additionally, subduction-related processes, such as marginal drag force and basal traction, also contributed to Pangea's breakup. The fracturing of thick lithosphere crescents surrounding the Tethyan realm, triggered by extensional stresses, further facilitated the breakup in successive phases. Furthermore, the presence of carbonatites and alkaline intrusions, related to amphibole mantle peridotites, in the Ivrea zone during the Early Jurassic breakup of Pangea highlights the role of extension and decompression-driven reactivation of amphibole-bearing lithospheric mantle in rift-related magmatism. Ultimately, the exploitation of structural heterogeneities within the crust, possibly influenced by Late Palaeozoic glacial-interglacial cycles, also played a role in determining the location and timing of rifting activities.
What are the interesting theories about lithosphere breakup?5 answersThere are several interesting theories about lithosphere breakup. One theory suggests that the presence of plumes in the mantle can play a significant role in facilitating continental breakup. Another theory focuses on the role of melting in the evolution of rifting and the spatial and temporal evolution of passive margin geometry. Additionally, it has been proposed that detachment faults in the upper mantle can control the development of mantle core complexes and associated crustal structures during the extension and breakup of cold continental lithosphere. Inherited structures from previous tectonic activity, such as ancient orogenesis, may also influence the generation of continental terranes during breakup. Finally, the interaction between young oceanic lithosphere and a subduction zone has been investigated as a potential mechanism for the breakup of a young and thin oceanic plate.
Large igneous province triggered a lithosphere breakup?5 answersThe breakup of Pangaea and the formation of large igneous provinces (LIPs) were closely related. LIPs, such as the Central Atlantic Magmatic Province (CAMP) and the North Atlantic Igneous Province (NAIP), formed during the breakup of Pangaea. However, the location of major volcanism during the dispersal of Pangaea was typically distal from the locus of rift initiation and initial oceanic crust accretion. LIPs were coincident with major lithosphere-scale shear movements, aborted rifts, and splinters of continental crust rifted far out into the oceanic domain. This suggests that the causes and consequences of breakup-related LIPs need to be reevaluated.The formation of the Cretaceous Caribbean Large Igneous Province (CLIP) was triggered by the accretion of the Caribbean old plateau, which led to subduction initiation and the formation of a subduction-induced plume. This plume resulted in widespread partial melting of the lithosphere and the formation of the CLIP.The Greater Kerguelen large igneous province (LIP) formed during the continental breakup of eastern Gondwana, and its magmatism was not influenced by a mantle plume. Instead, the breakup occurred due to the proximity of the former suture zone associated with the Kuunga Orogeny, which allowed for partial melting of the lithosphere.The ca. 925 Ma Dashigou LIP of the North China Craton represents the initial stage of continental breakup. The magmatic center of this LIP is thought to be located in the Xuhuai basin, where two generations of sill complexes occur. The evolution of the magmatic plumbing systems of the Dashigou LIP and the Bahia-Gangila LIP is interpreted as an indication of rift-to-drift transition tectonics, which resulted in the initiation of seafloor spreading and continental drift.The Central Atlantic Magmatic Province (CAMP) coincides with the breakup of the supercontinent Pangea. Different mechanisms for supercontinent breakup and LIP formation are proposed based on geochemical signatures and tectonic evolution. The greater number of accretionary events on the northern Laurentian margin during the formation of Pangea led to different subduction-related signatures in the mantle source of the northern versus southern CAMP lavas. The Rheic Plate may have underplated the lithosphere then delaminated, triggering both the breakup of Pangea and the formation of CAMP.
How was the lithosphere of the Triassic period?3 answersThe lithosphere of the Triassic period was characterized by stability and changes in thickness and composition. The Triassic period experienced two mass extinctions and volcanic flood basalts, indicating environmental changes and volcanic activity. In the Snake River Plain, the lithosphere showed a decrease in age and thickness from east to west, suggesting a continuous flow of material from the Yellowstone hotspot. In the North Sea, the Triassic normally rested conformably on Upper Permian strata, but erosion during Middle Jurassic doming and late Jurassic rifting episodes produced a major unconformity in the central region. The Triassic period was a time of dispersion and cosmopolitanism of floras and tetrapod faunas due to the existence of a single landmass. Overall, the lithosphere of the Triassic period experienced stability, volcanic activity, and changes in thickness and composition.
How many years would a litosphere called young?3 answersThe term "young" when referring to a lithosphere does not have a specific number of years associated with it in the abstracts provided.