Questions tagged [geochronology]

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35
votes
5answers
3k views

How do we know the asteroids formed at the same time as earth?

In continuation of the question Why is Earth's age given by dating meteorites rather than its own rocks?, what evidence do we have that the asteroids indeed formed at the same time as earth? Is there ...
19
votes
2answers
5k views

What is the origin of the ocean's salt?

We know we cannot live without salt, but an investigation into the origins of ocean's salt leads one to believe that this issue is not fully resolved yet. What geological phenomenon caused the earth ...
15
votes
1answer
4k views

How old is the Earth?

According to most articles I've read online, the estimated age of Earth is 4.5 billion years. Question: How old is the Earth? So I actually want to confirm that this is the case. Maybe there are ...
12
votes
3answers
390 views

Nuclear testing and the Anthropocene, a chemostratigraphic link?

The Anthropocene is described by Wikipedia as an informal geologic chronological term for the proposed epoch that began when human activities had a significant global impact on the Earth's ...
12
votes
1answer
242 views

How to interpret the use of late and early Tertiary from older literature?

When reading older papers how should I interpret the use of "Late Tertiary" and "Early Tertiary"? Would these periods equate to Paleogene and Neogene, or was there a different accepted boundary age ...
11
votes
2answers
252 views

How to determine how long ago a rock was broken?

I know that there are techniques that help scientists determine the age of a rock. But is it also possible to determine how long ago a rock was broken? For example, how could we date the formation of ...
9
votes
2answers
686 views

How do scientists determine the absolute or 'chronometric' date of fossils?

Absolute dating is the process of determining an approximate computed age of something like a fossil. How does that work?
7
votes
1answer
2k views

Newton's estimate of the age of the Earth

I was reading many articles about estimates of the age of the Earth throughout the ages. I was dumbfounded when I read that Newton, arguably one of the greatest scientists ever to have ‘calculated’ ...
6
votes
1answer
1k views

How do scientists measure the age of old animal remains?

The remains of a mammoth were recently unearthed in a Michigan farmer’s field [1]. This find could provide new information on the activity of early humans in the area, experts at the University of ...
6
votes
1answer
273 views

Unwarranted claim of higher degree of accuracy in zircon geochronology

The uncertainty in the half life of uranium-238 is stated at 0.05% [1]. The same paper gives the date 251.941 myr ± 31 kyr. 251.941 $\times$ 0.05% = 125 kyr. How are the authors justified in ...
6
votes
1answer
89 views

Historically, how did the total amount of salt / NaCl on Earth develop?

After reading this question about the origin of NaCl on Earth, I'm wondering: How did the amount of NaCl develop historically? Is it a more or less linear growth until today? Was it such a linear ...
5
votes
2answers
454 views

Age of fossils found in rocks

I have heard the claim by creationists that geologists date rocks by the fossils they contain and date fossils by the rocks in which they are found. This supposedly invalidates radiometric ages ...
4
votes
2answers
146 views

Relative dating of granite pluton

In selecting a sample for age-dating of a granite pluton, which site is a better site to collect a sample from, the centre, top or side? Why was this site a better choice? Which dating method would ...
2
votes
2answers
150 views

Radiometric dating data sets

I am in the process of learning what sort of data is collected with radiometric dating techniques, used for absolute dating. It sounds like there are two primary ones: Radiocarbon dating (~50k year ...
2
votes
0answers
23 views

Ages of the Andean Cordilleras

What is the timing of the rise of the Andes, especially if focused on the chronosequence differences among (Western, Central, Eastern) Cordilleras uplift.
2
votes
0answers
45 views

How exactly did Patterson determine the parameters in his Pb–Pb geochron equations?

In his famous paper Age of meteorites and the earth (1956), Patterson uses the following expressions: Which I assume are the same as: $$ \left(\frac{Pb^{206}}{Pb^{204}}\right)_P = \left(\frac{Pb^{...
2
votes
0answers
103 views

How should core-rim detrital zircon ages be reported in a sedimentary provenance study?

I understand this might be drifting into the black hole of subjectivity but I would like to know if anyone knows if there is a generally accepted practice. If one has a detrital zircon with a core age ...
2
votes
0answers
23 views

Can zircons be analysed by the (U+Th)/He after being ablated for analysis of U-Pb?

I have zircons that have been mounted in a resin block. They have been polished to approximately half way through the zircons (as is convention) and they have been ablated to attain the U-Pb or Pb-Pb ...
1
vote
1answer
81 views

Would you see a correlation between detrital zircon age and grain shape?

If one was to quantify the shape (particularly roundness) of detrital zircon grains, would there be a correlation between the age of the detrital zircon grains and their shape? For example, if the ...
0
votes
1answer
164 views

Is astrochronology a proper method?

Wikipedia's definition of astrochronology is: "Astrochronology is the dating of sedimentary units by calibration with astronomically tuned timescales, such as Milankovic cycles,1[2] or even ...