Early Devonian alkaline intrusive complex from the northern North China craton: a petrological monitor of post-collisional
tectonics
Xiaohui Zhang
Hongfu Zhang
Neng Jiang
Mingguo Zhai
Yanbin Zhang
10.6084/m9.figshare.3454823.v1
https://geolsoc.figshare.com/articles/dataset/Early_Devonian_alkaline_intrusive_complex_from_the_northern_North_China_craton_a_petrological_monitor_of_post-collisional___tectonics/3454823
<p>Laser ablation inductively coupled plasma mass spectrometry zircon U–Pb dating and geochemical data document the Early Devonian
Sandaogou alkaline complex (409 Ma) from the northern margin of the North China craton. The rock suite includes pyroxene syenite,
quartz syenite and monzonite. These rocks exhibit high contents of K<sub>2</sub>O (5–13 wt%), strong enrichments in large ion lithophile elements and light REE, slightly negative Eu anomalies, and pronounced
depletions in high field strength elements. They are characterized by moderate <sup>87</sup>Sr/<sup>86</sup>Sr<sub>i</sub> ratios of 0.7052–0.7071, low ε<sub>Nd</sub>(t) values of −12.7 to −17.9 and zircon ε<sub>Hf</sub>(t) values from −27.8 to −32.3. These geochemical features and quantitative isotopic modelling suggest that they might have
been formed through simultaneous fractional crystallization and lower crustal assimilation of a metasomatized mantle-derived
alkali basaltic magma. These trachytic rocks, together with the Middle Devonian alkaline rocks and mafic–ultramafic complex
from neighbouring regions, constitute a linear post-collisional magmatic belt along the northern North China craton, possibly
formed under a tectonic regime of slab breakoff. They serve not only as a magmatic milestone for marking the termination of
Early Palaeozoic orogenic cycle around the northern North China craton, but also as a spatial tracer for locating the position
of the potential ancient slab breakoff at the surface.
</p>
2016-06-21 12:22:34
pyroxene syenite
geochemical data document
field strength elements
geochemical features
ion lithophile elements
Palaeozoic orogenic cycle
neighbouring regions
crustal assimilation
rocks exhibit
Devonian Sandaogou
light REE
Sr
tectonic regime
rock suite
Middle Devonian
magmatic milestone
zircon
quartz syenite
slab
trachytic rocks
North China craton
Eu anomalies
Geology