The Outer or Sub-Himalaya is the main zone of the Cenozoic sedimentation. The Paleogene-Neogene sequences of the Sub-Himalaya occurs in the northern states of India. The Subathu, Murree and Dharamshala are the main Paleogene groups of rocks where Siwalik is a major Neogene group of Cenozoic sequences of the Sub-Himalaya. Other deposits belongs to the […]
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An unconformity is a plane of discontinuity that separates two rocks, which differs in age. The younger of these rocks are nearly always of sedimentary origin and must have been deposited on the surface of the older rock, which is a surface of erosion. Formation of unconformity : The formation of unconformity may be defined
At a coarse level of time resolution, episodes of speleothem growth record relatively wet periods in semi-arid climates or relatively warm periods in cool temperate climates.
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The Redfield ratio is the consistent atomic ratio of carbon, nitrogen and phosphorous found in marine phytoplankton and throughout the deep oceans (C:N:P = 106:16:1). When nutrients are not limiting, the molar elemental ratio C:N:P in most phytoplankton is 106:16:1 In the ocean, a large portion of the biomass is found to be nitrogen-rich plankton. Many of these plankton
Quaternary time period is from 1.8 Ma to today, during this time period a lot of climate fluctuations happened which are discussed below :-
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The study of geology offers a captivating journey through time, unveiling the intricate tapestry of Earth’s history. Spanning billions of years, this narrative is composed of distinct epochs, each characterized by unique geological events and transformations. In this article, we delve into the fascinating world of geological time, exploring the epochs that have shaped our
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As the amount of available data has multiplied over the past ten years, the number of apparently distinct reservoirs has risen from two (primitive and depleted mantle, respectively) to five (PREMA, Depleted, HIMU = high U/Pb and Two types of EM or enriched mantle reservoirs). The depleted reservoir produces “normal” (N-type) MORB probably more than
Anorthosites are defined as plutonic rocks with over 90% plagioclase. They are highly felsic, felsic minerals, however is a Calcic plagioclase, which along with subordinate associated high temperature mafic minerals. The anorthosites can be classified as Archaean and Proterozoic – Archaean Anorthosites :- Most Archaean anorthosites cluster in the range 3.2 to 2.8 Ga. They
An oceanic core complex or magnalium is a seabed geological feature that forms a long ridge perpendicular to a mid-oceanic ridge. It contains smooth domes that are lined with transverse ridge like a corrugated roof. They can vary in size from 10 to 150km in length, 5 to 15 km in width, and 500 to
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An ancient landform or landscape that had been buried beneath younger rocks or sediment and that is exposed by their subsequent erosion. This process is called Exhumation. Exhumation refers to any geological mechanisms that brings the rocks from deeper crustal levels to shallower crustal levels. While erosion or denudation is fundamental in eventually exposing these
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