Post by Admin on Nov 14, 2021 0:46:50 GMT -7
Hot or Cold, For the most part we usually only encounter 8 elements -
HOT ROCKS arrive on the surface in TWO WAYS - From above (Impactites) and from below (Igneous).
1. IMPACTITES arrive at tens of miles per second!
Due to Earth's escape velocity, the minimum impact velocity is 11 km/s with asteroid impacts averaging around 17 km/s on the Earth. The most probable impact angle is 45 degrees. Impact conditions such as asteroid size and speed, but also density and impact angle determine the kinetic energy released in an impact event.
en.wikipedia.org/wiki/Impact_event
Objects with a diameter less than 1 m (3.3 ft) are called meteoroids and seldom make it to the ground to become meteorites. An estimated 500 meteorites reach the surface each year, but only 5 or 6 of these typically create a weather radar signature with a strewn field large enough to be recovered and be made known to scientists. . . . The two to four-meter-sized asteroids 2008 TC3, 2014 AA, 2018 LA, 2019 MO, and the suspected artificial satellite WT1190F are the only known objects to be detected before impacting the Earth.[24][25]
I'm sure the larger impacts generated more heat than that.
They are different from igneous rocks in that they consist of every possible combination of elements.
2. Igneous
Most of the heavier elements are deep in the earth's core.
Igneous Rocks are divided by the weight of the elements in them and the temperatures at which they melt or crystalize.
They arrive on the surface at much cooler temperatures than large impacts
Olivine, Basalt, Andesite, Dacite, Granite - Rhyolite - Obsidian.
Abbreviations:
en.wikipedia.org/wiki/QAPF_diagram
A QAPF diagram is a double ternary diagram which is used to classify igneous rocks based on mineralogic composition. The acronym QAPF stands for "Quartz, Alkali feldspar, Plagioclase, Feldspathoid (Foid)". These are the mineral groups used for classification in QAPF diagram. Q, A, P and F percentages are normalized (recalculated so that their sum is 100%).
QAPF diagrams are mostly used to classify plutonic rocks (phaneritic rocks), but are also used to classify volcanic rocks if modal mineralogical compositions have been determined. QAPF diagrams are not used to classify pyroclastic rocks or volcanic rocks if modal mineralogical composition is not determined, instead the TAS classification (Total-Alkali-Silica) is used. TAS is also used if volcanic rock contains volcanic glass (such as obsidian). QAPF diagrams are also not used if mafic minerals make up more than 90% of the rock composition (for example: peridotites and pyroxenites).
An exact name can be given only if the mineralogical composition is known, which cannot be determined in the field.
Reading QAPF diagram
The QAPF diagram utilizes four minerals, or mineral groups, to classify igneous rocks. These minerals are quartz (Q), Alkali feldspars (A), plagioclase feldspars (P), and feldspathoids (F). F and Q cannot form in plutonic rocks simultaneously due to the difference in their respective silica contents. Other minerals may occur in samples, but they are not utilized by this classification method.
The QAPF diagram is composed of two ternary plots (QAP and FAP) joined along one side. To use this classification method, the concentration (the mode) of these minerals must be determined and normalized to 100%. For example: a plutonic rock that contains no alkali feldspar and no feldspathoids, but contains many pyroxenes (unlabeled in QAPF diagram), plagioclase-feldspar, and few quartz grains is probably gabbro (located at the right edge of the diagram, near P). This diagram makes no distinction between rock types of the same chemical composition in QAPF, but different chemical compositions with respect to other minerals (such as gabbro, diorite, and anorthosite).
The QAPF diagram is not used for all plutonic rocks; ultramafic plutonic rocks are the most important group that have separate classification diagrams.
QAPF diagrams are mostly used to classify plutonic rocks (phaneritic rocks), but are also used to classify volcanic rocks if modal mineralogical compositions have been determined. QAPF diagrams are not used to classify pyroclastic rocks or volcanic rocks if modal mineralogical composition is not determined, instead the TAS classification (Total-Alkali-Silica) is used. TAS is also used if volcanic rock contains volcanic glass (such as obsidian). QAPF diagrams are also not used if mafic minerals make up more than 90% of the rock composition (for example: peridotites and pyroxenites).
An exact name can be given only if the mineralogical composition is known, which cannot be determined in the field.
Reading QAPF diagram
The QAPF diagram utilizes four minerals, or mineral groups, to classify igneous rocks. These minerals are quartz (Q), Alkali feldspars (A), plagioclase feldspars (P), and feldspathoids (F). F and Q cannot form in plutonic rocks simultaneously due to the difference in their respective silica contents. Other minerals may occur in samples, but they are not utilized by this classification method.
The QAPF diagram is composed of two ternary plots (QAP and FAP) joined along one side. To use this classification method, the concentration (the mode) of these minerals must be determined and normalized to 100%. For example: a plutonic rock that contains no alkali feldspar and no feldspathoids, but contains many pyroxenes (unlabeled in QAPF diagram), plagioclase-feldspar, and few quartz grains is probably gabbro (located at the right edge of the diagram, near P). This diagram makes no distinction between rock types of the same chemical composition in QAPF, but different chemical compositions with respect to other minerals (such as gabbro, diorite, and anorthosite).
The QAPF diagram is not used for all plutonic rocks; ultramafic plutonic rocks are the most important group that have separate classification diagrams.