Apps Design. Jan It’s much easier to connect with your partner by thinking about how you feel about them than by thinking about the dating app. I feel happy and my AdCompare & Try The Best Online Dating Sites To Find Love In - Join Today! Online Dating Has Already Changed The Lives of Millions of People. Join Today Dating is a chance — a chance to meet someone new, a chance for them to introduce you to people, places and things that you never knew that you’d love. It’s the chance that you won’t
Rock Hill Singles, Dating Rock Hill SC, Free Rock Hill Chat
When it comes to exploration geology, age matters! The geologic timescale is online dating rock even the most mundane rocks have a unique history stretching back millions, if not billions, of years. While relative timing between rocks can often be determined through intuitive online dating rock like cross-cutting relationships giving rocks an absolute age is much trickier.
This is where geochronology—the scientific process of dating rocks—comes in. Finding absolute dates of rocks is often the work of academics, but it can also be a powerful tool to assist mineral exploration.
It allows geologists to make connections between mineralization and wider tectonic events such as specific episodes of volcanism or mountain-building.
In turn, this facilitates the development of accurate deposit models to guide exploration efforts. Knowing when a deposit formed is often key to understanding how online dating rock formed, which in turn helps predict where ore may be found.
Many types of deposits are strongly associated with certain time periods. Looking for porphyry copper? Most of it is found in or near granites younger online dating rock about 65 Ma. Unconformity uranium? On the finer scale, it predicts if old ore is likely to be deformed, crosscut, or consumed by younger geological events. Geochronology uses the law of radioactive decay to determine how old a rock is and put geologic history into definitive context.
This process is called radioactive decay and forms isotopes. Isotopes are variations of a specific element that have a different number of neutrons and weight due to radioactive decay. The decay of a radioactive isotope is governed by its half-life: the time it takes for half of the radioactive parent isotope to decay to its stable daughter isotope.
The ratio between parent and daughter steadily evolves over time. If the length of the half-life is known, then measuring the current ratio between parent and online dating rock isotopes allows the absolute age of the rock or mineral to be determined. These ages are typically reported in millions of years abbreviated as Ma or billions of years Ga and with a corresponding error, online dating rock. Errors tend to become larger as age increases. While others exist, the systems and methods most commonly applied to ore deposits are summarized below.
In this system, online dating rock, radioactive uranium decays to stable lead. The U-Pb system is the most common method of geochronology for one reason: zircons. These common igneous minerals nearly always contain enough U to be dated, and their extreme durability allows them to survive metamorphism and erosion, so they are often found in metamorphic and sedimentary rocks as well.
Many other minerals, notably uraninite and monazitemay also be dated with the U-Pb method. Thorium, online dating rock, a radioactive element common in many rare Earth element depositsalso decays to lead, online dating rock, enabling thorium minerals to be dated via similar methods.
Although Re is one of the rarest elements on Earth, its decay to Os makes it particularly useful for dating ore deposits. Extremely trace amounts of Re are often present in sulfide mineralssuch as pyrite and molybdenite, allowing these minerals to be directly dated. Since sulfides are the main ore minerals in most base metal depositsthis technique has found wide application, particularly to porphyry deposits.
While K is an extremely common element in rock-forming minerals, it is also weakly radioactive, and its decay to Ar allows minerals such as potassium feldspar and sericite to be dated. Argon, however, being a gas, may escape after its formation, online dating rock, and thus Ar dates online dating rock reflect geological events long after ore deposition. Great care must be taken when interpreting K-Ar and Ar-Ar data, online dating rock.
Secondary Ion Mass Spectrometry SIMS and its beefed-up cousin Sensitive High-Resolution Ion MicroProbe SHRIMP use an ion beam to dislodge secondary ions from the sample, which are then magnetically directed into a mass spectrometer for analysis.
This technique has the advantage of allowing very precise targeting of features as small as zoning within zircons, online dating rock, making it the preferred method for U-Pb dating.
In Thermal Ionization Mass Spectrometry TIMS a sample usually online dating rock whole mineral grain is liquified and heated to generate ions, which are then analyzed in a mass spectrometer. This technique is known for its ability to analyze trace elements at concentrations other methods struggle to detect, online dating rock. This sensitivity makes it ideal for Re-Os dating, and allows superior accuracy in measured ages.
Laser Ablation-Inductively Coupled Plasma Mass Spectrometry mercifully shortened to LA-ICPMS uses a laser to blast ions out of sample for analysis in a mass spectrometer. Argon-Argon dating requires samples of crushed rocks or minerals to be irradiated in a nuclear reactor before being heated to liberate Ar ions which are then measured in a mass spectrometer.
K-Ar dating does not require irradiation but online dating rock considered more vulnerable to contamination and inaccurate ages. As you may have guessed from the above, geochronology is complex and requires specialized and expensive instrumentation as well as qualified personnel, which mining companies generally lack access to.
For this reason, many companies get their dates from previously published academic or government sources. If a company wishes to obtain their own dates, they may contract geochronology to a lab, online dating rock, or even partner with an outside institution or corporation as part of a larger study.
LA-ICPMS U-Pb dating of zircons dates granites in the area to Ma. Re-Os dating of online dating rock from ore-bearing veins yielded ages of This indicates that ore deposition in the area is linked to the formation of these granites. Furthermore, online dating rock ages are online dating rock identical to the Taken as a whole, this indicates all three of these deposits share a similar origin, suggesting that ~ Ma granites in the area may be highly prospective for copper-gold-molybdenum mineralization.
Companies can use this geochronology data to narrow their exploration focus on the most promising areas. What is surprising is that despite years of mining, no one can agree on how these deposits formed. The question is anything but academic. Since placers only form in river gravels and conglomerates, their ancient equivalents, the placer deposit theory implies that spending money exploring outside of these conglomerates would be nothing but a waste.
Hydrothermal depositson the other hand, may form in any type of rock. If this theory is correct the next multi-billion-dollar deposit may well await discovery in rocks that have remained underexplored. This is where geochronology comes in. If the deposits are placer-style, the gold would have to be older than the host conglomerates the age of which is known through SHRIMP U-Pb dating of zircons.
If the deposits are hydrothermal, the gold would have to be younger than the conglomerates. This age is old enough to seemingly prove the placer theory correct. The validity of this age, however, has been heavily challenged on technical grounds.
While the Witwatersrand is famous for gold, variable and occasionally economically interesting amounts of U in the form of uraninite are also present in many deposits. Recent SIMS U-Pb dating of this uraninite found it to be as old as ± 19 Ma, again strongly supporting the placer model.
Geochronology can be complex and difficult to obtain, but when used properly it may yield a great deal of knowledge about ore deposition. Although this knowledge does not guarantee success in exploration and miningit certainly makes it more likely. Get notified when we add new content at Geology for Investors. We won't email you unless we have new content for you! The Secondary Ion Mass Spectrometer SIMS machine used for U-Pb geochronology at the University of Manitoba.
Photographed by Ian Burron, What Is Geochronology? How Does Geochronology Work? From NOAA Ocean Explorer, Outcrop photo by Courtney Antolik, zircon photo by Michael P. The Uranium-Lead U-Pb System In this system, radioactive uranium decays to stable lead.
The Rhenium-Osmium Re-Os System Although Re is one of the rarest elements on Earth, online dating rock, its decay to Os makes it particularly useful for dating ore deposits.
On the left, the Secondary Ion Mass Spectrometer SIMS machine used for U-Pb geochronology at the University of Manitoba.
Photographed by Ian Burron in On the right, online dating rock, Zircons dated to over 4 billion years old via SHRIMP U-Pb geochronology. Online dating rock method allows very precise targeting of cores and rims which may be different ages within these tiny grains.
From Bellucci et al, online dating rock. TIMS In Thermal Ionization Mass Spectrometry TIMS a sample usually a whole mineral grain is liquified and heated to generate ions, which are then analyzed in a mass spectrometer. LA-ICPMS Laser Ablation-Inductively Coupled Plasma Online dating rock Spectrometry mercifully shortened to LA-ICPMS uses a laser to blast ions out of sample for analysis in a mass spectrometer.
Argon Techniques Argon-Argon dating requires samples of crushed rocks or minerals to be irradiated in a nuclear reactor before being heated to liberate Ar ions which are then measured in a mass spectrometer. How Is Geochronology Used In Mining? Molybdenite-quartz hydrothermal veins Mount Emmons Molybdenum Deposit, online dating rock, Early Miocene, Ma; Keystone Mine, west of Crested Butte, Colorado, USA.
Photo by James St. John from the Denver Museum of Nature and Science. Figure 4. Witwatersrand gold ore, with visible gold, online dating rock, hosted within a pyrite-rich conglomerate. From Horscroft et al. Further Reading Geochronology and Nd-Sr-Pb isotopic compositions of Early Cretaceous intrusions and associated porphyry Cu deposits in eastern Alaska scientific article — pdf Evidence of a reducing Archean atmosphere from 3. Facebook Twitter LinkedIn Tumblr Pinterest Reddit VKontakte Share via Email Print.
Ian Burron Ian is a geologist and PhD candidate at the University of Manitoba. He is currently studying the geochemistry of uranium mobility in Canadian deposits to better understand their origin and histories, as well as guiding government policy for disposal of high-level nuclear waste. He also worked as a geologist on the Madsen Gold Project in Red Lake, Ontario prior to beginning his PhD. Stay in the Know! Subscribe for Updates Get notified when we add new content at Geology for Online dating rock. Enter your Email address.
Related Articles. The Dixie Project: A New Gold Camp on the Horizon?
Online Dating Rock Bottom: The Worst of Tinder, Hinge, Bumble \u0026 OKCupid Vol. 1
, time: 6:16Rock Music Dating | Meet Single Rockers Today
AdCompare & Try The Best Online Dating Sites To Find Love In - Join Today! Online Dating Has Already Changed The Lives of Millions of People. Join Today AdReal Singles. No Games No Gimmicks! Meaningful Relationships Start Here. Start Living and Meet Amazing 40+ Men. Isn't it Time to Embrace Your Moment? Complete the form to create your punk dating account. Quick and easy. Express yourself with your punk rock profile. Add some photos of yourself. Search through punk profiles both locally
No comments:
Post a Comment