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Quartz

  Quartz   Quartz is hexagonal and commonly occurs as crystals ranging in size form microscopic to crystals weighing several tons. Where it crystallizes unhindered by other crystals, such as in cavities in rock or in a liquid containing few other crystals, it shows well-developed hexagonal prisms and sometimes showing apparent hexagonal pyramids or dipyramid. When it crystallizes in an environment where growth is inhibited by the surroundings, it rarely show crystal faces. It is also found as microcrystalline masses, such as in the rock chert, and as  fibrous masses, such as in chalcedony. Vitreous lusture.   As visible crystals, Quartz is one of the more common rock forming minerals. It occurs in siliceous igneous rocks such as volcanic rhyolite and plutonic granitic rocks. It is common in metamorphic rocks at all grades of metamorphism, and is the chief constituent of sand. Because it is highly resistant to chemical weathering, it is found in a wide variety of sedimentary r
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HIMALAYAN UPLIFT

                                                     THE HIMALAYAN UPLIFT 


DURING TRIASSIC PERIOD –GONDWANA LAND START TO BREAK INTO INDIA ,SOUTH AFRICA , AUSTRALIA, ANTARTICA, IRAN ,ETC….. 



DURING 55 Million Age THE INDIAN PLATE  COLLIDED WITH  EURASIAN PLATE  

First, reconstruction of the speed of the Indian plate in the geologic past indicates that the plate motion drastically decreased in the Eocene. During Cretaceous and Paleocene times (85-55 Ma), India moved northward at rates of 15-20 cm per year but slowed down to only about 5 cm per year by 45 Ma (These data come from examination of magnetic anomalies of rocks on the Indian Ocean floor and from paleo-magnetic analyses of rock samples from the Trans-Himalaya by various scientists)

PHASE 1 : THE TRANS HIMALAYAN UPLIFTMENT

First mountain range is trans - Himalayan igneous arc, Indus and t-sangpo are the first rivers to transport sediment in Eocene period .

 Trans-Himalaya indicate that these rocks rapidly cooled and eroded at about 40 Ma.Trans Himalaya filled with continental sediment ( eg : Kargil , Kailash )

PHASE 2 : EO HIMALAYAN THE TETHYAN HIMALAYA UP LIFTMENT

The sediments in the most Himalaya have escaped metamorphism ( they are still sedimentary rocks ) but they are highly folded and faulted 

The india asian collision continued for million of years 

The north himalaya thrust and the uplift of the granite gneiss domes within the thethyan Himalayan began(40-35 ma).

PHASE 3 : NEO HIMALAYAN HIGHER HIMALAYAN UPLIFTMENT

There is a sample evidence that during the early Miocene , the himalayan rocks were burried 20- 25 km deep and metamorphosed and melted under 600-800°C

The tethyan himalayan zone was detached from the higher himalaya along a normal fault named the south tibetan detachment

The period from 24-17 ma.


PHASE 4 : THE LESSER HIMALAYA UPLIFTMENT

In the late Miocene (11-7 ma) sedimentation rates in the siwalik basin increased the mineral kyanite in the himalayan region is found only in the higher himalayan metamorphic rocks 

The data indicates rapid erosion of the himalaya at that time 

Geo chemical analysis of sample from the Indian Ocean drilled cores and from the siwalik ancient soil indicates the monsoon season related to himalayan topograpy

PHASE 5 : NEO-TECHTONICS THE QUATERNARY PHASE :

The uplift of the siwalik range along the himalayan frontal fault over the past one million years , geochronological evidence ( fission track ages of 1-3 ma) of rapid erosion from various part of the upper himalaya 

Presence of active fault and large earthquakes, deep and narrow gorges in the higher himalaya uplifted traces of young sediments and enoromous amount of coarse grained fluvial sediments in the quaternary records


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