PART L MULTIPLE CHOICE. Please choose the best possible answer for each question

Question

PART L MULTIPLE CHOICE. Please choose the best possible answer for each question and write it on blank spaces on the page margin. pt/ea) USE A SCANTRON & DONT FORGET TO WRITE TEST VERSION ON IT is a mafic igneous rock with an aphanitic (fine-grained) texture. 1) E) diorite C) granite D) basalt A) tuff B) obsidian 2) In igneous rocks with porphyritic texture, the larger crystals are called and are indicative of cooling rate of magma/lava. B) phenocrysts; faster A) porphyroblasts: slower D) phenocrysts; slower C) groundmass; slower 3) Which of the metamorphic rocks below represents highest grade of metamorphism (highest temperatures/pressures)? D) marble C) phyllite B) gneiss A) mica schist 4) The narrow metamorphic zone in the vicinity of a magma chamber which comes in contact with the host rocks called D) contact zone B) buffer C) baked zone A) aureole 5) of abundant shale with plant fossils in an area is indicative of what kind of depositional environment in the geologic past? D) lagoon B) swamp (marshland) C) shallow marine A) sand dunes 6) Which of the following rocks display a pyroclastic texture? D) volcanic breccia A) pegmatitic granite C) basalt B) andesite porphry 7) Which of the following metamorphic rock metamorphism type pairs is INCORRECT? D) slate regional phyllite regional B) gneiss dynamic A) hornfels contact 8) This nonfoliated metamorphic rock is made up entirely of one mineral and it fizzes with diluted HCI. C) omerate D) slate B) marble A) quartzite 9) Which of the sedimentary rocks below is derived secondarily from the precipitation of new minerals from aqueous solutions, e.g. seawater: D) shale C) limestone A) conglomerate B) coquina 10) Which of the sedimentary rocks below consists of angular, gravel-size rock fragments? A) arkose B) conglomerate C) breccia D) sandstone 11) This rock is formed as a result of the intrusion of hot magma into the country rocks. It is called metamorphic rock. and it is a A) hornfels; nonfoliated B) gneiss: nonfoliated D) hornfels; foliated C) slate; foliated 12) According to the Bowen's Reaction Series, which of the minerals below crystallizes at the lowest temperatures? B) pyroxene A) quartz D) CA-rich plagioclase feldspar B. Bas Geol 101 Physical Geology Lab Page B-1 San Diego Mesa College Fall 2013

Explanation / Answer

1) basalt

Aphanitic texture is the fine grained texture which is resulted y the rapid Cooling of magma. Since basalt is formed In this fashion it has aphanitic texture

2) phenocrystals, slow cooling

Porphyritic texture is the enclosing of large crystals called porphyry crystals in a fine grained .matrix . It results from the cooling of magma at various depths

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