37 research outputs found
Stable carbon Isotope evidence for neolithic and bronze age crop water management in the eastern mediterranean and southwest asia
In a large study on early crop water management, stable carbon isotope discrimination was determined for 275 charred grain samples from nine archaeological sites, dating primarily to the Neolithic and Bronze Age, from the Eastern Mediterranean and Western Asia. This has revealed that wheat (Triticum spp.) was regularly grown in wetter conditions than barley (Hordeum sp.), indicating systematic preferential treatment of wheat that may reflect a cultural preference for wheat over barley. Isotopic analysis of pulse crops (Lens culinaris, Pisum sativum and Vicia ervilia) indicates cultivation in highly varied water conditions at some sites, possibly as a result of opportunistic watering practices. The results have also provided evidence for local land-use and changing agricultural practices
The fifth leaf and spike organs of barley (Hordeum vulgare L.) display different physiological and metabolic responses to drought stress
Late Oligocene-Miocene mantle upwelling and interaction inferred from mantle signatures in gabbroic to granitic rocks from the Urumieh-Dokhtar arc, south Ardestan, Iran
The south Ardestan plutonic rocks constitute major outcrops in the central part of Iranâs Cenozoic
magmatic belt and encompass a wide compositional spectrum from gabbro to granodiorite. UâPb
laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) dating of zircon three
granodiorites yielded ages of 24.6 ± 0.1, 24.6 ± 0.1, and 24.5 ± 0.1 Ma. For tonalitic rocks, internal
RbâSr isochron ages (biotite, feldspars) indicate cooling ages of 20.4 ± 0.1, 20.5 ± 0.1, and
22.3 ± 0.1 Ma, which are slightly younger than the zirconsâ ages. The limited variations in their
SrâNd isotope ratios indicate derivation from an asthenospheric mantle source. A geodynamic
model is presented in which late OligoceneâMiocene rollback of the Neotethyan subducting slab
triggered asthenospheric upwelling and partial melting in the south Ardestan. These melts were
subsequently modified through fractional crystallization and minor crustal contamination en-route
to the surface. Plagioclase + orthopyroxene-dominated fractional crystallization accounts
for differentiation of gabbro to gabbroic diorite, whereas fractionation of clinopyroxene, titanomagnetite,
and orthopyroxene led to differentiation of gabbroic diorite to diorite. Amphibole
fractionation at deeper levels led to the development of tonalites
Petrogenesis of Neogene plutonic rocks from south Ardestan, Iran; mantle-derived arc magmatism
The south Ardestan region in the Urumieh-Dokhtar arc covers an area of about 250 km2 that is characterized
by plutonic rocks with a compositional spectrum ranging from gabbro, gabbro-norite, gabbroic diorite, diorite,
tonalite to granodiorite. Gabbroic rocks are mainly tholeiitic in character, whereas the diorites, tonalites and
granodiorites show increasingly stronger calc-alkaline affinity. Gradual compositional variation and limited
variation in radiogenic isotopic ratios indicate that these different rock types are petrogenetically related and most
probably are derived from a common primitive source. U-Pb LA-ICP-MS dating of zircon from four granitoids
yielded ages that range from 25 to 24 Ma. For tonalitic rocks, internal Rb-Sr isochron ages (biotite, feldspars)
indicate cooling ages that lie in the range 20.4 +/- 0.1 to 22.1 +/- 0.5 Ma, slightly younger than the zirconsâ
ages. Their uniform initial Sr-Nd isotopic values imply that the major source component has probably been
an asthenospheric mantle domain. This is further supported by the mantle-derived geochemical affinity of the
plutonic rocks. A geodynamic model is presented in which the asthenospheric upwelling and partial melting in
the south Ardestan has been triggered by Late Oligocene-Miocene rollback of the Neotethyan subducting slab.
These melts were subsequently slightly modified through assimilation, fractional crystallization (AFC) en-route to
the surface (A less than 6%). The trace element rich and high radiogenic Sr signature of some gabbros, this is the
likely perturbation and then mobilization of Sr in the rock system during alteration. 43% fractional crystallization
dominated by plagioclase and orthopyroxene is found responsible for magmatic evolution from gabbro to gabbroic
diorite. Whereas, 44% fractional crystallization of a plagioclase-dominated mineral assemblage that also include
clinopyroxene, titanomagnetite and orthopyroxene is found responsible for the evolutionary path from the gabbroic
diorite to diorite. 22% fractional crystallization of amphibole and plagioclase is calculated as responsible for the
differentiation path from diorite to tonalite. Assuming 6% crustal contamination effect inferred from isotopic
trace elemental modelling by Cadomian crust, the major elemental crustal contamination effect on AFC product is
found to be trivial. That is for K2O it is 10% and for other major elements less than 5%. M-REE abundances of the
tonalites likely imply that a parental melts of these rocks have experienced significant amphibole differentiation
due to a greater depth of magma chamber formation. We do not claim that our petrogenetic model for the south
Ardestan plutonic rocks is representative for the whole UDMA. However, the new isotopic age and bulk rock data
along with the mantle-dominated geochemical characteristics of the studied plutonic rocks open a new window for
geodynamic interpretation and support a model suggesting that subduction still affected the UDMA in Miocene
time
Dry matter accumulation and remobilization of durum wheat as affected by soil gravel content
Selection for water-soluble carbohydrate accumulation and investigation of genetic x environment interactions in an elite wheat breeding population
Water-soluble carbohydrate accumulation can be selected in wheat breeding programs with consideration of genetic x environmental interactions and relationships with other important characteristics such as relative maturity and nitrogen concentration, although the correlation between WSC traits and grain yield is low and inconsistent