• Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep
  • e-gmat Exclusive Offer
    Get 300+ Practice Questions
    25 Video lessons and 6 Webinars for FREE

    Available with Beat the GMAT members only code

    MORE DETAILS
    e-gmat Exclusive Offer
  • Target Test Prep
    5-Day Free Trial
    5-day free, full-access trial TTP Quant

    Available with Beat the GMAT members only code

    MORE DETAILS
    Target Test Prep
  • Kaplan Test Prep
    Free Practice Test & Review
    How would you score if you took the GMAT

    Available with Beat the GMAT members only code

    MORE DETAILS
    Kaplan Test Prep
  • Varsity Tutors
    Award-winning private GMAT tutoring
    Register now and save up to $200

    Available with Beat the GMAT members only code

    MORE DETAILS
    Varsity Tutors

OG Archean-age gold-quartz vein systems

This topic has 0 member replies
AbeNeedsAnswers Master | Next Rank: 500 Posts Default Avatar
Joined
02 Jul 2017
Posted:
191 messages
Followed by:
2 members
Thanked:
1 times

OG Archean-age gold-quartz vein systems

Post Sun Sep 17, 2017 3:07 pm
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    According to a recent theory, Archean-age gold-quartz vein systems were formed more than two billion years ago from magmatic fluids that originated from molten granite-like bodies deep beneath the surface of the Earth. This theory is contrary to the widely held view that the systems were deposited from metamorphic fluids, that is, from fluids that formed during the dehydration of wet sedimentary rocks.
    The recently developed theory has considerable practical importance. Most of the gold deposits discovered during the original gold rushes were exposed at the Earth's surface and were found because they had shed trails of alluvial gold that were easily traced by simple prospecting methods. Although these same methods still lead to an occasional discovery, most deposits not yet discovered have gone undetected because they are buried and have no surface expression.
    The challenge in exploration is therefore to unravel the subsurface geology of an area and pinpoint the position of buried minerals. Methods widely used today include analysis of aerial images that yield a broad geological overview; geophysical techniques that provide data on the magnetic, electrical, and mineralogical properties of the rocks being investigated; and sensitive chemical tests that are able to detect the subtle chemical halos that often envelop mineralization. However, none of these high-technology methods are of any value if the sites to which they are applied have never mineralized, and to maximize the chances of discovery the explorer must therefore pay particular attention to selecting the ground formations most likely to be mineralized. Such ground selection relies to varying degrees on conceptual models, which take into account theoretical studies of relevant factors.
    These models are constructed primarily from empirical observations of known mineral deposits and from theories of ore-forming processes. The explorer uses the models to identify those geological features that are critical to the formation of the mineralization being modeled, and then tries to select areas for exploration that exhibit as many of the critical features as possible.

    104. The author is primarily concerned with
    (A) advocating a return to an older methodology
    (B) explaining the importance of a recent theory
    (C) enumerating differences between two widely used methods
    (D) describing events leading to a discovery
    (E) challenging the assumptions on which a theory is based

    105. According to the passage, the widely held view of Archean-age gold-quartz vein systems is that such systems
    (A) were formed from metamorphic fluids
    (B) originated in molten granite-like bodies
    (C) were formed from alluvial deposits
    (D) generally have surface expression
    (E) are not discoverable through chemical tests

    106. The passage implies that which of the following steps would be the first performed by explorers who wish to maximize their chances of discovering gold?
    (A) Surveying several sites known to have been formed more than two billion years ago
    (B) Limiting exploration to sites known to have been formed from metamorphic fluid
    (C) Using an appropriate conceptual model to select a site for further exploration
    (D) Using geophysical methods to analyze rocks over a broad area
    (E) Limiting exploration to sites where alluvial gold has previously been found

    107. Which of the following statements about discoveries of gold deposits is supported by information in the passage?
    (A) The number of gold discoveries made annually has increased between the time of the original gold rushes and the present.
    (B) New discoveries of gold deposits are likely to be the result of exploration techniques designed to locate buried mineralization.
    (C) It is unlikely that newly discovered gold deposits will ever yield as much as did those deposits discovered during the original gold rushes.
    (D) Modern explorers are divided on the question of the utility of simple prospecting methods as a source of new discoveries of gold deposits.
    (E) Models based on the theory that gold originated from magmatic fluids have already led to new discoveries of gold deposits.

    108. It can be inferred from the passage that which of the following is easiest to detect?
    (A) A gold-quartz vein system originating in magmatic fluids
    (B) A gold-quartz vein system originating in metamorphic fluids
    (C) A gold deposit that is mixed with granite
    (D) A gold deposit that has shed alluvial gold
    (E) A gold deposit that exhibits chemical halos

    109. The theory mentioned in lines 1-5 relates to the conceptual models discussed in the passage in which of the following ways?
    (A) It may furnish a valid account of ore-forming processes, and, hence, can support conceptual models that have great practical significance.
    (B) It suggests that certain geological formations, long believed to be mineralized, are in fact mineralized, thus confirming current conceptual models.
    (C) It suggests that there may not be enough similarity across Archean-age gold-quartz vein systems to warrant the formulation of conceptual models.
    (D) It corrects existing theories about the chemical halos of gold deposits, and thus provides a basis for correcting current conceptual models.
    (E) It suggests that simple prospecting methods still have a higher success rate in the discovery of gold deposits than do more modern methods.

    110. According to the passage, methods of exploring for gold that are widely used today are based on which of the following facts?
    (A) Most of the Earth's remaining gold deposits are still molten.
    (B) Most of the Earth's remaining gold deposits are exposed at the surface.
    (C) Most of the Earth's remaining gold deposits are buried and have no surface expression.
    (D) Only one type of gold deposit warrants exploration, since the other types of gold deposits are found in regions difficult to reach.
    (E) Only one type of gold deposit warrants exploration, since the other types of gold deposits are unlikely to yield concentrated quantities of gold.

    Q104:B
    Q105:A
    Q106:C
    Q107:B
    Q108:D
    Q109:A
    Q110:C

    Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!

    Best Conversation Starters

    1 LUANDATO 138 topics
    2 lheiannie07 91 topics
    3 Roland2rule 79 topics
    4 AAPL 71 topics
    5 swerve 66 topics
    See More Top Beat The GMAT Members...

    Most Active Experts

    1 image description EconomistGMATTutor

    The Economist GMAT Tutor

    160 posts
    2 image description Jay@ManhattanReview

    Manhattan Review

    128 posts
    3 image description GMATGuruNY

    The Princeton Review Teacher

    125 posts
    4 image description Rich.C@EMPOWERgma...

    EMPOWERgmat

    118 posts
    5 image description Brent@GMATPrepNow

    GMAT Prep Now Teacher

    114 posts
    See More Top Beat The GMAT Experts