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A Research of the Cretaceous-Paleogene Boundary in the Pingyi Basin, Shandong Province  [PDF]
Jun Chen, Shengxian Du, Cheng Chen, Fengchen Liu, Zhengguo Ning, Xiangsuo Song, Shucai Liu, Huinan Lu, Yongqing Liu, Hongwei Kuang
Open Journal of Geology (OJG) , 2019, DOI: 10.4236/ojg.2019.910068
Abstract: The Bianqiao Formation (in the Pingyi Basin, Shandong Province, China) is a typical set of continuous lacustrine carbonate deposits during the Cretaceous-Paleogene period, which is considered as an ideal stratigraphic unit for KPB research. This study is based on the borehole PYZK01, which is located at Tongjiazhuang village in Bianqiao Town of Pingyi country. According to biostratigraphy research, the Bianqiao Formtion establishes one charophyte assemblage: Porocharaanluensis-Charayuntaishanensis var. acuta-Turbocharaspecialis, and one sporopollen assemblage: Deltoidosporaadriensis-Rugubivesiculites- Schizaeoisporites. This result indicates that the stratigraphic age during 0 - 12.25 m is the Paleogene, 37.8 m - 60 m is the Late Cretaceous, and 12.25 - 37.8 m is a transition stage from the Late Cretaceous to the Paleocene. By geochemical study, it was established carbon and oxygen isotopic strata in the drill. Through the magnetostratigraphy research, we find eight positive polarity zones and seven reversed polarity zones, build the magnetic polarity sequences of the borehole, and propose a contrast scheme with the international standard magnetic polarity time column. After comprehensive discussion, it is preliminarily believed that the Cretaceous-Paleogene boundary is located at the depth of 31.98 m in PYZK01, namely, in the first section of the Bianqiao Fm.
Cretaceous – Paleogene boundary Fish Clay at H jerup (Stevns Klint, Denmark): Zn, Pb and REE in kerogen
PAVLE I. PREMOVIC,MAJA N. STANKOVIC,MIRJANA S. PAVLOVIC,MILOS G. DJORDJEVIC
Journal of the Serbian Chemical Society , 2008,
Abstract: Geochemical analyses of Zn, Pb and rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in the kerogen of the black marl at the Cretaceous – Paleogene boundary Fish Clay at H jerup were performed. Substantial proportions of the Zn, Pb and rare earths were probably contained in terrestrial humic substances (the kerogen precursor) arriving at the marine sedimentary site. This is in accord with a previous hypothesis that kerogen is mainly derived from humic acids of an oxic soil in of the adjacent coastal areas of eastern Denmark. It is also suggested that humics enriched in Zn, Pb and rare earth elements were transported mainly through fluvial transport into the deposition site of the Fish Clay. Local weathering/leaching of the impact–eject fallout on the land surface and local terrestrial rocks by impact-induced? acid surface waters perhaps played an important role in providing Zn, Pb and rare earths to these humic substances. Apparently, chondritic and non-chondritic Zn originated from the impact fallout; Pb and rare earth elements were most likely sourced by exposed rocks in the coastal areas of eastern Denmark.
Magnetic Susceptibilities in the Cretaceous-Paleogene Section in Uzgruň, Czech Republic  [PDF]
Tiiu Elbra, Petr Schnabl, ?imon Kdyr, Miroslav Bubík
Open Journal of Geology (OJG) , 2019, DOI: 10.4236/ojg.2019.910069
Abstract: A new multidisciplinary study is being carried out in several localities from Outer Carpathians of Central Europe. Outer Carpathians allow studying the Cretaceous-Paleogene (K-Pg) interval of the oceanic facies, including lower bathyal-abyssal sub-CCD turbidites. Preliminary results of field-measured magnetic susceptibilities from Uzgruň K-Pg section in the Czech Republic are presented.
Larger miliolids of the Late Cretaceous and Paleogene seen through space and time  [PDF]
Katica Drobne,Vlasta ?osovi?,Eduard Robinson
Geologija , 2002,
Abstract: Spatial and temporal occurrences of the larger (complex) miliolids are discussed to give more light on biostratigraphy and paleobiogeographic provinces distribution. Seven generaand 47 species from the Late Cretaceous to Oligocene inhabited shallow marine settings in the Indo-Pacific, Tethyan and Caribbean regions. Of all genera only four (Idalina, Periloculina, Pseudolacazina, Lacazina) widespread throughout Tethys in theLate Cretaceous and Paleogene. Single occurrence of Lacazina was recorded further to east (Moluccas). By now the Late Cretaceous genus Adrahentina is known only from the Spain. The newcomer’s Eocene genera were Fabularia and Lacazinella. Fabularia reachedhigh diversity in species term in the Central and Western Tethys and occured as unique genus in Caribbean realm, too. Conversely, during the same period, Lacazinella spread over the southern border of Neo-Tethys reaching New Guinea.On the Adriatic – Dinaric Carbonate Platform, larger miliolids occurred from the Late Cretaceous to Cuisian, having the same biostratigraphically trends and distribution as contemporaneous larger miliolids from the Tethys.
The Lilliput Effect in Colonial Organisms: Cheilostome Bryozoans at the Cretaceous–Paleogene Mass Extinction  [PDF]
Caroline E. Sogot, Elizabeth M. Harper, Paul D. Taylor
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0087048
Abstract: Consistent trends towards decreasing body size in the aftermath of mass extinctions – Lilliput effects – imply a predictable response among unitary animals to these events. The occurrence of Lilliput effects has yet to be widely tested in colonial organisms, which are of particular interest as size change may potentially occur at the two hierarchical levels of the colony and the individual zooids. Bryozoans are particularly useful organisms in which to study colonial size response as they have well-defined zooids. Additionally, a number of analyses of present-day bryozoans have shown that zooid size reflects local environmental conditions, most notably seawater temperature and possibly also food supply. Following the hypothesised decline in primary productivity at the Cretaceous–Paleogene (K–Pg) mass extinction, it is predicted that bryozoan zooid size should decline in the early Paleogene, resulting in a Lilliput effect. To test this prediction, zooid size was compared across the K–Pg boundary at the assemblage level and also within 4 surviving genera. Analysis of 59 bryozoan species from assemblages on either side of the K–Pg boundary showed no significant change in zooid length. Zooid size was also measured in 98 Maastrichtian colonies and 162 Danian colonies belonging to four congeneric species. Only one of these genera showed a significant size decrease across the K–Pg boundary, the other three maintaining constant zooidal lengths, widths and areas. Additionally, the sizes of 210 Maastrichtian colonies and 163 Danian colonies did not show consistent size decrease across the K–Pg boundary in these same species, although maximum colony size did decline in three out of four genera. Furthermore, this lack of consistent size change is uniform between two distinct biogeographical regions, Denmark and the southeastern USA.
Geochronology and petrochemistry of Late Cretaceous-(?)Paleogene volcanic sequences from the eastern central Patagonian Cordillera (45°-45°40'S)
Demant,Alain; Suárez,Manuel; De la Cruz,Rita;
Revista geológica de Chile , 2007, DOI: 10.4067/S0716-02082007000100001
Abstract: in the eastern part of the central patagonian cordillera (45°15?-45°40?s), northeast of the town of coihaique, the chronology of volcanic sequences are documented by detailed field work and twelve new k-ar dates that have established their late cretaceous-(?)paleogene age. the oldest sequence corresponds to the rhyolitic and rhyodacitic domes of the casa de piedra volcanic complex, of campanian age, which were emplaced on volcanic rocks of the aptian-(?) albian divisadero formation. the plagioclase and two pyroxenes andesitic to dacitic lavas of the el toro formation and the basalts from morro negro have a similar maastritchian age. however, dacitic lavas with chemical signature similar to that of el toro formation crop out below the morro negro sequence showing that the basalts were the latest erupted lavas. petrologic and geochemical data are used to characterize the three volcanic episodes. the casa de piedra volcanic rocks and the andesitic to dacitic lavas of the el toro formation have the mineralogy and geochemical signature of subduction-related magmas: enrichment in light rare earth elements (lree), highly incompatible elements (rb, th, u and k), and strong depletion in nb-ta. basalts from morro negro show distinct ree and multi-element patterns. their geochemical signature is similar to that of the murta quaternary basalts, inferred to be related to slab window opening, but distinct from that of the eocene balmaceda basalts, more akin to within-plate volcanism
Cretaceous/Paleogene Floral Turnover in Patagonia: Drop in Diversity, Low Extinction, and a Classopollis Spike  [PDF]
Viviana D. Barreda, Nestor R. Cúneo, Peter Wilf, Ellen D. Currano, Roberto A. Scasso, Henk Brinkhuis
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0052455
Abstract: Nearly all data regarding land-plant turnover across the Cretaceous/Paleogene boundary come from western North America, relatively close to the Chicxulub, Mexico impact site. Here, we present a palynological analysis of a section in Patagonia that shows a marked fall in diversity and abundance of nearly all plant groups across the K/Pg interval. Minimum diversity occurs during the earliest Danian, but only a few palynomorphs show true extinctions. The low extinction rate is similar to previous observations from New Zealand. The differing responses between the Southern and Northern hemispheres could be related to the attenuation of damage with increased distance from the impact site, to hemispheric differences in extinction severity, or to both effects. Legacy effects of the terminal Cretaceous event also provide a plausible, partial explanation for the fact that Paleocene and Eocene macrofloras from Patagonia are among the most diverse known globally. Also of great interest, earliest Danian assemblages are dominated by the gymnosperm palynomorphs Classopollis of the extinct Mesozoic conifer family Cheirolepidiaceae. The expansion of Classopollis after the boundary in Patagonia is another example of typically Mesozoic plant lineages surviving into the Cenozoic in southern Gondwanan areas, and this greatly supports previous hypotheses of high latitude southern regions as biodiversity refugia during the end-Cretaceous global crisis.
Geomagnetic field intensity in the middle jurassic - oligocene  [PDF]
A. Yu. Kurazhkovskii,N. A. Kurazhkovskaya,B. I. Klain
Physics , 2014,
Abstract: The present paper summarizes results of the studies on the intensity of geomagnetic field in the (167 - 23) Ma interval by sedimentary rocks of the Russian Plate and adjacent territories. The joint analysis of the data paleointensity obtained by sedimentary and thermomagnetized (from PINT12) rocks within this temporal interval is conducted. It is shown that the changes of the paleointensity were occurred chaotically. Alternating bursts and periods of quiet regime of the geomagnetic field are typical for intermittent processes and is a characteristic of the geological interval Jurassic-beginning of Paleogene. The distributions of the paleointensity corresponding to different intervals of geologic time were investigated. It is revealed that the cumulative distribution function (CDF) of the paleointensity values is best approximated by a power function. The indices of the power functions varied depending on geologic time intervals.The analysis of the paleomagnetic data suggests that the medium in which the geomagnetic field is generated is turbulent. Turbulence in the Earth's liquid core is enhanced in the Cretaceous compared with Jurassic and Paleogene.
Plant Ecological Strategies Shift Across the Cretaceous–Paleogene Boundary  [PDF]
Benjamin Blonder ,Dana L. Royer,Kirk R. Johnson,Ian Miller,Brian J. Enquist
PLOS Biology , 2014, DOI: 10.1371/journal.pbio.1001949
Abstract: The Chicxulub bolide impact caused the end-Cretaceous mass extinction of plants, but the associated selectivity and ecological effects are poorly known. Using a unique set of North Dakota leaf fossil assemblages spanning 2.2 Myr across the event, we show among angiosperms a reduction of ecological strategies and selection for fast-growth strategies consistent with a hypothesized recovery from an impact winter. Leaf mass per area (carbon investment) decreased in both mean and variance, while vein density (carbon assimilation rate) increased in mean, consistent with a shift towards “fast” growth strategies. Plant extinction from the bolide impact resulted in a shift in functional trait space that likely had broad consequences for ecosystem functioning.
Biostratigraphy and Mass Extinction Pattern across the Cretaceous/Paleogene Boundary, Northern Alborz, Iran  [PDF]
Masoud Asgharian Rostami, Mohammad Vahidinia, Ebrahim Ghasemi-Nejad, Abbas Sadeghi
Open Journal of Geology (OJG) , 2013, DOI: 10.4236/ojg.2013.31005
Abstract:

High resolution sampling across the Cretaceous/Paleogene boundary (K/Pg) at the Galanderud section in northern Iran provides the most expanded and continuous section for us to consider biostratigraphy and the mass extinction pattern of Cretaceous planktic foraminifera. Based on planktic foraminifera, four biozones and five sub-biozones have been identified across the K/Pg boundary. These biozones include the Abathomphalus mayaroensis Biozone (Plummerita hantkeninoides subbiozone), the Guembelitria cretacea Biozone (including two sub-biozones: the Hedbergella holmdelensis and the Parvularugoglobigerina longiapertura), the Parvularugoglobigerina eugubina Biozone (including two subbiozones: the Parvularugoglobigerina Sabina and the Eoglobigerina simplicissima) and finely the Parasubbotina pseudobulloides Biozone. Planktic foraminiferal extinction occurred over a brief period, with 3% of the species disappearing in the late Maastrichtian, and 72% of the species becaming extinct at the K/Pg boundary. About 25% of the species survived into the early Danian. Extinction of 73% of the species at the K/Pg boundary is very compatible with the effect of a large asteroid impact.

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