Lesson 1: Ore Deposit
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Questions and Answers

The geologic history of the Philippines pertinent to ore deposition covers which periods?

  • Mesozoic to Tertiary (correct)
  • Jurassic to Cretaceous
  • Paleozoic to Mesozoic
  • Cambrian to Ordovician

    • What is the main axial part of the archipelago in the Philippines?

  • Static Belt
  • Mobile Belt (correct)
  • Pacific Belt
  • seismic Belt

    • The ore deposits in the Mobile Belt are genetically related to which processes?

  • Erosion and sedimentation
  • Magmatism and tectonism (correct)
  • Weathering and erosion
  • Deposition and compaction

    • Which deposits are considered in the paragraph?

    <p>Chromite, massive pyritic, pyrometasomatic, porphyry copper, gold-bearing vein</p> Signup and view all the answers

    Which chromite deposits represent refractory and metallurgical ores?

    <p>Masinloc and Acoje</p> Signup and view all the answers

    What is suggested by the unusually high alumina content of the Masinloc chromite?

    <p>It is an earlier crystallate than Acoje</p> Signup and view all the answers

    The structural settings of Masinloc and Acoje suggest what about these deposits?

    <p>They have undergone considerable deformation</p> Signup and view all the answers

    Which deposits exemplify a range of geologic settings in which structure plays an increasingly direct role in localizing the ore?

    <p>Bagacay, Barlo, and Hixbar</p> Signup and view all the answers

    The massive pyritic deposits originated toward the close of which period?

    <p>Tertiary</p> Signup and view all the answers

    The pyrometasomatic deposits are mined mostly for which content, except in one case?

    <p>Iron</p> Signup and view all the answers

    The largest pyrometasomatic deposit in the Philippines, which exhibits the most mineralogical complexity, is?

    <p>Larap</p> Signup and view all the answers

    The Thanksgiving deposit is known for high values in which metals?

    <p>Gold and zinc</p> Signup and view all the answers

    How many known porphyry copper deposits are there in the Philippines?

    <p>Eight</p> Signup and view all the answers

    Porphyry copper deposits are closely associated with which rock facies?

    <p>Porphyritic dacite and andesite</p> Signup and view all the answers

    Which mineral is the main copper mineral in porphyry copper deposits?

    <p>Chalcopyrite</p> Signup and view all the answers

    Which secondary minerals are closely associated with porphyry copper ores?

    <p>Quartz, biotite, and sericite</p> Signup and view all the answers

    The enargite-luzonite-telluride deposit at Lepanto is localized along the intersection of what?

    <p>An unconformity and a fault zone</p> Signup and view all the answers

    Which district is known for quartz-telluride-gold vein deposits?

    <p>Baguio</p> Signup and view all the answers

    The gold deposits in the Paracale district are associated with which type of deposit?

    <p>Quartz-base metal sulfide</p> Signup and view all the answers

    This article is an outgrowth of how many years of work in the Philippines?

    <p>Four years</p> Signup and view all the answers

    The work in the Philippines was done as a staff member of which institution?

    <p>Institute of Applied Geology</p> Signup and view all the answers

    Which organizations were involved in the joint project in the Philippines?

    <p>United Nations Development Program, Philippine Bureau of Mines, University of the Philippines</p> Signup and view all the answers

    The work included geologic studies in which locations?

    <p>Mining districts</p> Signup and view all the answers

    The article reflects the scarcity of what type of studies of Philippine ore deposits?

    <p>Intensive geologic studies</p> Signup and view all the answers

    Which types of ore are most important commercially but are excluded from this paper?

    <p>Mercury and manganese</p> Signup and view all the answers

    The types of deposits described account for about what percentage of the value of metals and ores produced recently in the Philippines?

    <p>98 percent</p> Signup and view all the answers

    Mercury and manganese deposits are not included because of what reason?

    <p>Lack of first-hand knowledge</p> Signup and view all the answers

    Who are some of the references mentioned for published information on mercury and manganese deposits?

    <p>Fernandez, 1968; Fernandez et al., 1956; de la, 1967; Sorem, 1956</p> Signup and view all the answers

    What type of deposits are also not included in the paper?

    <p>Lateritic deposits</p> Signup and view all the answers

    When was a geological map of the Philippines published?

    <p>1963</p> Signup and view all the answers

    Who are the authors working on a metallogenic map of the Philippines?

    <p>Gervasio and Fernandez</p> Signup and view all the answers

    Which publications by Gervasio appeared in 1966?

    <p>Articles on tectonics</p> Signup and view all the answers

    Who published a paper on metallogeny in January 1967?

    <p>Gervasio and Fernandez</p> Signup and view all the answers

    The outline of general geology is based in large part on which sources?

    <p>These sources of information</p> Signup and view all the answers

    The oldest rocks in the Philippines, known as the 'Basement Complex,' are of probable age from which period?

    <p>Paleozoic</p> Signup and view all the answers

    What type of lava and intrusion followed the accumulation of shales and graywackes in the Basement Complex?

    <p>Mafic lava effusion and some gabbroic intrusion</p> Signup and view all the answers

    What types of rocks are represented by the Basement Complex outcrops?

    <p>Gneiss, amphibolite, chlorite-epidote-mica schist, and meta-igneous rocks</p> Signup and view all the answers

    How many geosynclinal basins developed in the Mesozoic time in the Philippines?

    <p>Three</p> Signup and view all the answers

    The northern geosynclinal basin coincides with which areas?

    <p>Mindoro and Marinduque, and parts of Luzon north of these islands</p> Signup and view all the answers

    The Mobile Belt is characterized by which features according to Gervasio (1966)?

    <p>Mesozoic and Tertiary igneous rocks, greater deformation, and rich in volcanic debris</p> Signup and view all the answers

    What characterizes the geosynclinal stage's spilite-graywacke sequence?

    <p>5,000 m in thickness, minor spilite and basic lava flows, intercalated with clastics and chert, followed by limestone and clastics</p> Signup and view all the answers

    What geological activities marked the close of the geosynclinal period?

    <p>Folding, thrust-faulting, and intrusion of ultramafic and mafic magmas</p> Signup and view all the answers

    How long is the ultramafic complex in Zambales Province?

    <p>150 km</p> Signup and view all the answers

    During the Tertiary, the Mobile Belt experienced great volcanic and intrusive activity. How many main periods of dioritic intrusion and orogeny were there?

    <p>Two</p> Signup and view all the answers

    Which epoch of volcanism and diastrophism occurred during late Eocene to intra-Oligocene?

    <p>Mainly andesitic, dacitic, and keratophyric volcanism</p> Signup and view all the answers

    What type of relationship is common among Philippine igneous rocks?

    <p>Gradational relationship and close association of diorite and andesite</p> Signup and view all the answers

    The Philippine Deep Trench is located adjacent to which parts of the Philippines?

    <p>East coasts of Samar and Mindanao</p> Signup and view all the answers

    The Philippine Fault extends in which direction from southeastern Mindanao to northern Luzon?

    <p>North-northwest</p> Signup and view all the answers

    How many metallogenic epochs are believed to have occurred in the Philippines between Permian and Quaternary time?

    <p>Seven</p> Signup and view all the answers

    The major epigenetic deposits in the Philippines are considered to range in age from which periods?

    <p>Cretaceous to Pliocene</p> Signup and view all the answers

    What is a common problem encountered in geologic mapping in the Philippines?

    <p>Gradational relationship and close association of diorite and andesite</p> Signup and view all the answers

    What types of rocks are found in the Stable Region according to Gervasio (1966)?

    <p>Rich in quartz and alkali feldspar, with simple deformation effects</p> Signup and view all the answers

    Which ore deposits are located in the Mobile Belt?

    <p>Practically all ore deposits and some manganese deposits</p> Signup and view all the answers

    Which deposits are located in the Stable Region?

    <p>Mercury deposits and a few massive pyritic deposits</p> Signup and view all the answers

    Which two mines in Zambales Province are the largest producers of chromite in the Philippines?

    <p>Masinloc and Acoje</p> Signup and view all the answers

    What types of chromite ore are represented in the Masinloc and Acoje mines?

    <p>Refractory and metallurgical</p> Signup and view all the answers

    Which type of chromite ore is represented in the Masinloc mine?

    <p>Refractory</p> Signup and view all the answers

    Which type of chromite ore is represented in the Acoje mine?

    <p>Metallurgical</p> Signup and view all the answers

    The Masinloc and Acoje deposits occupy belts of what type of rock?

    <p>Peridotitic</p> Signup and view all the answers

    These belts of peridotitic rock are located on opposite sides of a belt of what type of rock?

    <p>Gabbroic</p> Signup and view all the answers

    How long is the north-northeasterly-trending belt of gabbroic rock?

    <p>40 km</p> Signup and view all the answers

    Approximately how wide is the belt of gabbroic rock between the Masinloc and Acoje mines?

    <p>5 km</p> Signup and view all the answers

    The rocks in which the chromite deposits are found are part of which ultramafic complex?

    <p>Zambales ultramafic complex</p> Signup and view all the answers

    How did Thayer (1960) classify the Zambales ultramafic complex?

    <p>Alpine type</p> Signup and view all the answers

    The smaller deposits of chromite in Zambales Province are associated with which type of rock?

    <p>Peridotite</p> Signup and view all the answers

    The belt of gabbroic rock between Masinloc and Acoje mines trends in which direction?

    <p>North-northeast</p> Signup and view all the answers

    How wide is the belt of gabbroic rock between the Masinloc and Acoje mines?

    <p>Approximately 5 km</p> Signup and view all the answers

    Who operates the Masinloc refractory chromite mine of Consolidated Mines, Inc.?

    <p>Benquet Consodilated, Inc.</p> Signup and view all the answers

    Where is the Masinloc mine located?

    <p>Coto, Masinloc, about 150 km N40øW of Manila</p> Signup and view all the answers

    The Masinloc deposit lies close to a mass of which type of rock?

    <p>Olivine-rich gabbro</p> Signup and view all the answers

    According to Sulit (1967), what rock has been injected into saxonite as tongues from a main body?

    <p>Dunite</p> Signup and view all the answers

    How thick is the main dunite body that separates saxonite from gabbro?

    <p>Over 300 m</p> Signup and view all the answers

    In which direction does the layering in saxonite, dunite, and gabbro strike?

    <p>Northeast</p> Signup and view all the answers

    The saxonite layers dip in which direction?

    <p>Northwest</p> Signup and view all the answers

    The dunite and gabbro layers dip in which direction?

    <p>Southeast</p> Signup and view all the answers

    The ore deposit consists of lenses of chromite parallel to which contact?

    <p>Saxonite-dunite contact</p> Signup and view all the answers

    What is the size of the "Coto" orebody according to Stoll (1958)?

    <p>600 m long and 300 m wide</p> Signup and view all the answers

    How thick is the Coto orebody estimated to have been before erosion?

    <p>80 m</p> Signup and view all the answers

    Prior to 1958, how much shipping ore did the Coto orebody yield?

    <p>1 million tons</p> Signup and view all the answers

    The belt of chromite orebodies coincides with a zone of what in the saxonite?

    <p>Intense serpentization and fracturing</p> Signup and view all the answers

    Signup and view all the answers

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