Geochronological Evidence for the In situ Tectonic Relationship in the Dabie UHP Metamorphic Terrane, Central China

<p>This study uses C-band polarimetric radar (C-POL) measurements to classify the hydrometeors and retrieve rain drop size distributions (DSDs) during the IMFRE (Investigative Monsoon Frontal Rainfall Experiment) field campaign in central China. &#160;Three types of precipitation in a Meiyu frontal heavy rainfall case are classified to further investigate the microphysical characteristics and processes based on C-POL observations and classified hydrometeors. When raindrops fall from the freezing level, collision&#8211;coalescence plays an equally important role as break-up and/or evaporation in stratiform regions, but is the dominant process for convective-related precipitation and is an attribute of intensive precipitation. There are more supercooled liquid water droplets above the freezing level in convective cores due to strong updrafts, which can bring more cloud droplets into the upper levels to help the formation of graupel and hail. To the best of our knowledge, this work is the first time that C-POL-classified hydrometeors and rain-parameter retrievals have been validated against in-situ aircraft and surface disdrometer measurements over the middle reaches of the Yangtze River Valley in central China, which will pave the way for future studies related to Meiyu frontal rainfall systems.</p>

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Microdiamonds, their classification and tectonic implications for the host eclogites from the Dabie and Su-Lu regions in central eastern China

Mineralogical Magazine ◽

10.1180/0026461056940267 ◽

2005 ◽

Vol 69 (4) ◽

pp. 509-520 ◽

Cited By ~ 99

Author(s):

Shutong Xu ◽

Yican Liu ◽

Guanbao Chen ◽

Shouyuan Ji ◽

Pei Ni ◽

...

Keyword(s):

Raman Spectroscopy ◽

Eastern China ◽

Dabie Mountains ◽

Thin Sections ◽

The North ◽

First Occurrence ◽

Metamorphic Terrane ◽

Central Eastern ◽

Mixed Types

AbstractWe have found >10 in situ microdiamonds in thin sections of eclogites from the Dabie and Su-Lu regions of central eastern China since the first occurrence of microdiamond in eclogites from the Dabie Mountains (DMT) reported in 1992. The microdiamonds are found not only in the central part but also in the northern part of the DMT. Several free crystals have been recovered from the crushed eclogites from the central DMT. Most in situ microdiamonds are inclusions in garnets but a few larger ones are intergranular. Most of the diamondiferous eclogites in the central part of the DMT are associated with coesite. Most importantly, the observation of microdiamonds in northern Dabie lead us to question the supposition that this is a low-P metamorphic terrane. All the diamondiferous eclogites from both the north and central DMT are of continental affinity as demonstrated by their negative εNd values. Therefore, both the north and central eclogite belts in the DMT are considered to be from the deep subducted terrane. Five in situ microdiamonds and two free crystals are first reported in this paper. The dimensions of the in situ microdiamonds are 30–180 µm and the free crystals are up to 400–700 mm across. All the microdiamonds are confirmed as such by Raman spectroscopy. The results of an infrared spectroscopic investigation on two larger free crystals and two in situ microdiamonds show that all the microdiamonds from both the Dabie and Su-Lu regions are mixed types IaA and IaB diamonds and there is no indication of any synthetic microdiamonds in our samples because such synthetic microdiamonds are always rich in type Ib.

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