Premium
A MIDDLE JURASSIC FOSSIL FOREST FROM NEW ZEALAND
Author(s) -
THORN VANESSA
Publication year - 2005
Publication title -
palaeontology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.69
H-Index - 63
eISSN - 1475-4983
pISSN - 0031-0239
DOI - 10.1111/j.1475-4983.2005.00490.x
Subject(s) - paleontology , gondwana , geology , clearance , paleoclimatology , fossil wood , physical geography , climate change , structural basin , geography , oceanography , medicine , urology
A Middle Jurassic fossil forest, thought to have been growing at high southern palaeolatitudes on the Gondwana margin, is described from New Zealand. Fossil stump horizons are exposed in stratigraphic section within the Urawitiki Measures Formation, Murihiku Supergroup. Tree bases were preserved by silica permineralisation in a sandy braided river setting. Fossil wood is referred to ‘abietinean‐type’ and Agathoxylon . A total of 238 stumps were mapped with measured diameters allowing tree height estimates of 9–40 m. A two‐dimensional area (102 m 2 ) allows an interpretation of tree density (2353 trees/ha), biomass (579 t/ha) and stand basal area (146 m 2 ). This horizon is interpreted as a highly productive, young, dense tree stand probably actively regenerating on a flood‐cleared surface. Annual growth rings suggest a clearly defined growing season with a rapid onset of favourable temperature, light and water supply conditions at the start and a similarly rapid deterioration at the end. Mean ring width is 1·10 mm and the maximum 9·67 mm. Mean Sensitivity values suggest both ‘complacent’ and ‘sensitive’ growth patterns. Broad palaeoclimate interpretations suggest a humid, warm regional climate throughout the growing season.