Margineanu Dragos

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Margineanu
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Dragos
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  • Article
    Radiocarbon investigation of the Superlative African Baobabs from Savé Valley Conservancy, Zimbabwe
    (Universitatis Babes-Bolyai, Department of Chemistry, 2019) Patrut, Adrian ; Patrut, Roxana T. ; Rakosy, Laszlo ; Lowy, Daniel A. ; Margineanu, Dragos ; von Reden, Karl F.
    The article reports the radiocarbon investigation results of the superlative African baobabs from Savé Valley, Zimbabwe. Several wood samples collected from these baobab were analysed by AMS (accelerator mass spectrometry) radiocarbon dating. The radiocarbon dates of the oldest samples were 1529 ± 14 BP for Matendere Big baobab, 1179 ± 19 BP for Chishakwe Big tree and 1096 ± 35 BP for Mokore Giant baobab. The corresponding calibrated ages are 1430 ± 15, 1090 ± 40 and 1020 ± 25 calendar yr. The oldest tree from Savé Valley, which we described previously, is the Humani Bedford Old baobab. The radiocarbon date of its oldest sample, 1655 ± 14 BP, corresponds to a calibrated age of 1580 ± 30 calendar yr.
  • Article
    Radiocarbon investigation of the pedunculate oak of Botosana, Romania
    (Studia Chemia, 2018) Patrut, Adrian ; Robu, Nicolae ; Savu, Vasile ; Patrut, Roxana T. ; Rakosky, Laszlo ; Ratiu, Ileana-Andreea ; Lowy, Daniel A. ; Margineanu, Dragos ; von Reden, Karl F.
    The article discloses the AMS (accelerator mass spectrometry) radiocarbon dating results of the pedunculate oak of Botoşana. Four wood samples were extracted from its trunk. Five segments extracted from these samples were analyzed by AMS radiocarbon. Their radiocarbon dates were found to be between 161 ± 21 BP and 260 ± 20 BP. These values correspond to calibrated ages of 235 – 365 years. The dating results extrapolated to the geometric center of the trunk indicate an age of 645 ± 50 years for the oak of Botoşana.
  • Article
    Fire history of a giant African baobab evinced by radiocarbon dating
    (Dept. of Geosciences, University of Arizona, 2010-08) Patrut, Adrian ; Mayne, Diana H. ; von Reden, Karl F. ; Lowy, Daniel A. ; Van Pelt, Robert ; McNichol, Ann P. ; Roberts, Mark L. ; Margineanu, Dragos
    The article reports the first radiocarbon dating of a live African baobab (Adansonia digitata L.), by investigating wood samples collected from 2 inner cavities of the very large 2-stemmed Platland tree of South Africa. Some 16 segments extracted from determined positions of the samples, which correspond to a depth of up to 15–20 cm in the wood, were processed and analyzed by accelerator mass spectrometry (AMS). Calibrated ages of segments are not correlated with their positions in the stems of the tree. Dating results indicate that the segments originate from new growth layers, with a thickness of several centimeters, which cover the original old wood. Four new growth layers were dated before the reference year AD 1950 and 2 layers were dated post-AD 1950, in the post-bomb period. Formation of these layers was triggered by major damage inside the cavities. Fire episodes are the only possible explanation for such successive major wounds over large areas or over the entire area of the inner cavities of the Platland tree, able to trigger regrowth.
  • Article
    Radiocarbon dating of a very old African baobab from Savé Valley, Zimbabwe
    (Studia Chemia, 2016) Patrut, Adrian ; Rakosy, Laszlo ; Patrut, Roxana T. ; Ratiu, Ileana ; Forizs, Edit ; Lowy, Daniel A. ; Margineanu, Dragos ; von Reden, Karl F.
    The article reports the radiocarbon investigation results of the Humani Bedford baobab, an old African baobab from Savé Valley, Zimbabwe. Two wood samples were collected from the large inner cavity. Several segments were extracted from these samples and analysed by AMS (accelerator mass spectrometry) radiocarbon dating. We found that the age values of segments increase with the distance into the wood. This major anomaly is characteristic to multi-stemmed baobabs with a closed ring-shaped structure and a false cavity inside. The investigation of the Humani Bedford baobab evinced that the baobab consists of three fused stems. The fourth stem of the ring is missing. The oldest dated segment was found to have a radiocarbon date of 1655 ± 14 BP, which corresponds to a calibrated age of 1575 ± 30 yr. The dating results show that the stems which build the ring stopped growing toward the false cavity more than 600 yr ago. By considering the position of the oldest segment in the investigated stem, we concluded that the Humani Bedford baobab is around 1800 yr old. According to our dating results, the Humani Bedford baobab becomes the oldest living African baobab.
  • Article
    Radiocarbon dating of a very large African baobab from Limpopo, South Africa : investigation of the Sagole Big Tree
    (Studia Chemia, 2017) Patrut, Adrian ; Patrut, Roxana T. ; Van Pelt, Robert ; Lowy, Daniel A. ; Forizs, Edit ; Bodis, Jeno ; Margineanu, Dragos ; von Reden, Karl F.
    The article reports the AMS (accelerator mass spectrometry) radiocarbon dating results of Sagole Big tree, a giant African baobab from Limpopo, South Africa. Several wood samples were collected from the walls of its inner cavity and dated by radiocarbon. The age values along the cavity samples increase with the distance into the wood. This anomaly shows that the cavity is a false one. The oldest sample segment had a radiocarbon date of 781 ± 29 BP, which corresponds to a calibrated age of 740 ± 15 yr. We estimate that the oldest part of the Sagole baobab has an age of 800-900 yr. We determined that the tree has a closed ring-shaped structure, which consists of a large unit with six fused stems and of two additional leaning stems.
  • Article
    Age and growth rate dynamics of an old African baobab determined by radiocarbon dating
    (Dept. of Geosciences, University of Arizona, 2010-08) Patrut, Adrian ; Mayne, Diana H. ; von Reden, Karl F. ; Lowy, Daniel A. ; Venter, Sarah ; McNichol, Ann P. ; Roberts, Mark L. ; Margineanu, Dragos
    In 2008, a large African baobab (Adansonia digitata L.) from Makulu Makete, South Africa, split vertically into 2 sections, revealing a large enclosed cavity. Several wood samples collected from the cavity were processed and radiocarbon dated by accelerator mass spectrometry (AMS) for determining the age and growth rate dynamics of the tree. The 14C date of the oldest sample was found to be of 1016 ± 22 BP, which corresponds to a calibrated age of 1000 ± 15 yr. Thus, the Makulu Makete tree, which eventually collapsed to the ground and died, becomes the second oldest African baobab dated accurately to at least 1000 yr. The conventional growth rate of the trunk, estimated by the radial increase, declined gradually over its life cycle. However, the growth rate expressed more adequately by the cross-sectional area increase and by the volume increase accelerated up to the age of 650 yr and remained almost constant over the past 450 yr.