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Identifying the Cretaceous–Paleogene boundary in North Dakota, USA, using portable XRF

Larsson, Emilie LU (2013) In Dissertations in Geology at Lund University GEOL01 20131
Department of Geology
Abstract (Swedish)
En portabel röntgenfluorescens (XRF) spektrometer användes i denna studie för att identifiera kemiska markörer relaterade till Krita–Paleogen (K–Pg) gränsen i North Dakota, USA. Vid K–Pg-gränsen träffades jorden av en asteroid vilket resulterade i ett av de fem stora massutdöendena. Nedslaget lämnade efter sig ett globalt spritt lerlager bestående av material från asteroiden samt berggrund från karbonatplattformen i dagens Yucatán, Mexico, som utgjorde nedslagsplatsen. De två analyserade sektionerna i denna studie består av terrestra avlagringar och har K–Pg lerlagret bevarat. Ett flertal grundämnen uppvisar förhöjda värden i detta lager och av dessa kan flertalet kopplas samman med K–Pg gränsen då de är beståndsdelar i meteoriter eller... (More)
En portabel röntgenfluorescens (XRF) spektrometer användes i denna studie för att identifiera kemiska markörer relaterade till Krita–Paleogen (K–Pg) gränsen i North Dakota, USA. Vid K–Pg-gränsen träffades jorden av en asteroid vilket resulterade i ett av de fem stora massutdöendena. Nedslaget lämnade efter sig ett globalt spritt lerlager bestående av material från asteroiden samt berggrund från karbonatplattformen i dagens Yucatán, Mexico, som utgjorde nedslagsplatsen. De två analyserade sektionerna i denna studie består av terrestra avlagringar och har K–Pg lerlagret bevarat. Ett flertal grundämnen uppvisar förhöjda värden i detta lager och av dessa kan flertalet kopplas samman med K–Pg gränsen då de är beståndsdelar i meteoriter eller vanliga i berggrunden som utgör nedslagsplatsen. Totalt 19 grundämnen uppvisar förhöjda värden vid gränslagret, av dessa härstammar Cr, Ni och Ti sannolikt från meteoriten medan As, S, Ca och U sannolikt har sitt ursprung i plattformskarbonaterna vid nedslagsplatsen. Jämförande studier av geokemiska trender vid andra K–Pg lagergränser i världen uppvisar i många fall god korrelation. Detta visar att portabel XRF analys är ett bra hjälpmedel för att detektera K–Pg gränsen, användbar vid både laboratorie- och fältarbete. (Less)
Abstract
A portable x-ray fluorescence (XRF) device was in this study used to identify geochemical markers associated with the Cretaceous–Paleogene boundary in North Dakota, USA. At the time of the K–Pg boundary, an asteroid struck the Earth which resulted in one of the five big mass extinctions. The event left behind a globally distributed clay layer consisting of material derived from the asteroid and the impact site. The two analyzed sections consists of terrestrial deposits with the K-Pg boundary layer preserved. The portable XRF device analyses the chemical composition by exposing the samples to x-rays and detect the fluorescence x-rays emitted by exciting electrons. Results obtained in this study show that many elements are elevated in the... (More)
A portable x-ray fluorescence (XRF) device was in this study used to identify geochemical markers associated with the Cretaceous–Paleogene boundary in North Dakota, USA. At the time of the K–Pg boundary, an asteroid struck the Earth which resulted in one of the five big mass extinctions. The event left behind a globally distributed clay layer consisting of material derived from the asteroid and the impact site. The two analyzed sections consists of terrestrial deposits with the K-Pg boundary layer preserved. The portable XRF device analyses the chemical composition by exposing the samples to x-rays and detect the fluorescence x-rays emitted by exciting electrons. Results obtained in this study show that many elements are elevated in the boundary clay layer at both studied sections. Of these, several elements can be linked to the K–Pg event thus they are found as compounds in meteorites or are common constituents in the platform carbonates found in the area of impact in Yucatán. A total of 19 elements display prominent peaks at the boundary and of these Cr, Ni and Ti most certainly derived from the impactor while As, S, Ca and U likely derived from the platform carbonates at the impact site. The results display a good correlation to geochemical trends at other studied K–Pg sections in the world and demonstrate that a portable XRF is a useful tool for detection of the K–Pg boundary with applications in the lab as well as in the field. (Less)
Please use this url to cite or link to this publication:
author
Larsson, Emilie LU
supervisor
organization
alternative title
Identifiering av Krita – Paleogengränsen i North Dakota, USA, med portabel XRF
course
GEOL01 20131
year
type
M2 - Bachelor Degree
subject
keywords
geokemi, K–Pg gränsen, portabel XRF, North Dakota, K–Pg boundary, portable XRF, terrestrial deposits, geochemistry, terrestra avlagringar
publication/series
Dissertations in Geology at Lund University
report number
356
language
English
id
3910967
date added to LUP
2013-06-28 09:02:23
date last changed
2015-09-02 04:13:27
@misc{3910967,
  abstract     = {A portable x-ray fluorescence (XRF) device was in this study used to identify geochemical markers associated with the Cretaceous–Paleogene boundary in North Dakota, USA. At the time of the K–Pg boundary, an asteroid struck the Earth which resulted in one of the five big mass extinctions. The event left behind a globally distributed clay layer consisting of material derived from the asteroid and the impact site. The two analyzed sections consists of terrestrial deposits with the K-Pg boundary layer preserved. The portable XRF device analyses the chemical composition by exposing the samples to x-rays and detect the fluorescence x-rays emitted by exciting electrons. Results obtained in this study show that many elements are elevated in the boundary clay layer at both studied sections. Of these, several elements can be linked to the K–Pg event thus they are found as compounds in meteorites or are common constituents in the platform carbonates found in the area of impact in Yucatán. A total of 19 elements display prominent peaks at the boundary and of these Cr, Ni and Ti most certainly derived from the impactor while As, S, Ca and U likely derived from the platform carbonates at the impact site. The results display a good correlation to geochemical trends at other studied K–Pg sections in the world and demonstrate that a portable XRF is a useful tool for detection of the K–Pg boundary with applications in the lab as well as in the field.},
  author       = {Larsson, Emilie},
  keyword      = {geokemi,K–Pg gränsen,portabel XRF,North Dakota,K–Pg boundary,portable XRF,terrestrial deposits,geochemistry,terrestra avlagringar},
  language     = {eng},
  note         = {Student Paper},
  series       = {Dissertations in Geology at Lund University},
  title        = {Identifying the Cretaceous–Paleogene boundary in North Dakota, USA, using portable XRF},
  year         = {2013},
}