The Gushan Formation of Southwestern Hebei

[Isotelus2883]

The Gushan Formation is exposed in extensive sequence of strata in the Taihang Mountains, In the Western part of Hebei. It’s quite nice somewhere north of Shijiazhuang, where I was hoping to find Parablackwelderia, but I decided to stay closer, and focus on the region only a bit Northwest of Shijiazhuang. 
This is a quarry in Jingxing. The bottom 20-30 m is Oolitic and Micritic limestone, very hard and almost devoid of fossils. The total thickness may reach twice that in some places. I didn’t observe the contact with lower strata, but in a picture someone else posted online it’s pretty sharp (unconformity?) and the layers below it are alternating limestone and shale with Proasaphiscids? which are Zhangxia Formation. The dark layer near the top is about two meters of dark shale, gradually becoming light shale and then alternating shale and limestone and finally micritic and oolitic limestone. This repeats again but there are only about 1 meter of dark-light shale and the rest is not exposed. An excellent example of the “shallowing” upwards cycles.

 

 

 

Another quarry in Huangyancun which I hoped would be closer to the darker shale, was instead much further. In the Jingxing one was a short but very steep and grassy climb up to the layer on the western side, and when I reached where is was supposed to be, there was a dirt road which offered a much easier walk up.

When we arrived, we got out of the car, packed up our water and other things, and then promptly managed to lock the keys in the truck guaranteeing a few hours worth of hunting as we had to call a relative to bring a spare key. There was some excavation done because they were installing solar panels on the mountain, and it did expose some of the shale layer. Notice the colour changing from brown to green from the shallowing water. There was some limestone, but the building of the road for the excavator covered it.

 

 

 

 

Here are the trilobites I found. There is amazing diversity, but chances of complete ones are horribly low. They do however represent a relatively complete Blackwelderia Zone fauna.

The anteroir part of a Stephanocare richthofeni cephalon, showing characteristic spines. I found another complete one but it was ventral in the sticky and glassy limestone and didn’t bother to keep it. This was only found later in some dense trilobite hash.

 

 

 

A common trilobite was Bergonites ?ketteleri. The pygidia are likely from the same species. Note the small Parablackwelderia pygidium on the top left of the cranidium, Jiulongshania at top right, and Shantungia free cheek at far right. Also a Jiulongshania on the top right of the pygidium.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Jiulongshania and agnostids were common, here’s some with another Bergonites.

 

 

 

Here are the trilobites the zone is named after, Blackwelderia. Cranidium and pygidium of B. paronai.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Here’s a small damesellid? cranidium next to a Jiulongshania.

 

 

 

 

Here is a lovely plate of pygidia, some smaller Bergonites sp. and larger Hebeia pingquanensis. Also a mystery pygidium. Monkaspis?

 

 

 

An excellent small pygidium. This one looks like it might be a Parablackwelderia, possibly P. alastor. Likely, though, it is another Blackwelderia.

 

 

 

Here is the unusual find. It was in the lower micritic limestones. I have no idea of what it is. 

 

 

 

I felt like the trip was very nice, though a little warm, and the plentiful and unusual trilobite made for a good change. However, when I go back soon, I much prefer my finicky MA material because I got a bit sick of the trilobites being so common.

[bockryan]

Incredible! Thanks for sharing, looks like a very interesting locality.

[rocket]

thanks for sharing! So far away, I think I will never go there in my life. But, now I have an impression about