Stop 1. 谭道岭（N39°27′02″, E113°23′25″） 
[内容]：新第三纪火山岩，描述岩性，观察气孔、杏仁及柱状节理。

Stop 2. 下黑峪（N39°27′02″, E113°23′25″）
[内容]：恒山灰色TTG片麻岩、混合岩化作用、基性麻粒岩块体与花岗质脉体， TTG年龄2.5Ga；基性麻粒岩原岩1.915Ga；麻粒岩相变质1.85Ga

此点出露有灰色TTG片麻岩及其中的麻粒岩透镜体（原岩年龄19.2亿年，变质年龄18.5亿年, Kröner et al., 2006）。且透镜体中穿插红色钾质花岗岩脉体（原岩年龄23.5亿年）。

基性麻粒岩核部新鲜面灰黑色，可见红色粒状石榴石（粒径小，约1mm），白色板条状斜长石（粒径约2mm）与黑绿色粒状辉石（几毫米），角闪石含量较少。麻粒岩边部新鲜面黑色，无石榴石，可见较多的白色长英质脉体，粗细不一（几毫米到几厘米），暗色矿物包括角闪石、辉石、黑云母，矿物有一定定向。边部角闪石含量明显高于核部，辉石含量则较低，因此边部颜色比核部更黑。

钾质花岗岩脉宽约50厘米，富含钾长石，还有斜长石、石英和少量暗色矿物，如角闪石、黑云母等。钾质花岗岩脉原岩年龄是23.6亿年（Kröner et al., 2005a），理论上会受到18.5亿年的变质作用影响而发育透入性面理，可实际却没有观察到。


Stop. 3 下黑峪公路饭馆后沟及河谷（N39°27′02″, E113°23′03″） 
[内容]：基性麻粒岩露头及变质辉长质岩墙

在公路边“面馆”房后的河沟里发育有NW走向的基性岩墙，这些岩墙具有典型的麻粒岩相矿物组合。岩墙中的石榴石呈细粒且含量高，且具有蠕虫状的单斜辉石+斜长石后成合晶白眼圈，后期斜方辉石和角闪石叠加（图 III-3c），其矿物组成为：石榴石32% +单斜辉石25% +斜长石15% +石英12% +角闪石8% +斜方辉石5% +金红石+钛铁氧化物3%。此外，红色花岗质岩脉穿切此高压麻粒岩岩墙，表明存在一期晚于高压麻粒岩岩墙侵位的岩浆事件。沿沟前行，红色花岗质片麻岩为主，其中可见一些不见高压矿物组合的基性包体。

基性高压麻粒岩H934的锆石为无色透明的浑圆状或短柱状，长宽比1:1–2:1，粒度约100–200 μm。CL图像锆石的Th/U比值均很低为0.02–0.05。U-Pb谐和图上，定年结果除一颗较老的略偏谐和线上方的锆石外，其余结果可分为两组。第一组24颗锆石均落在谐和线上，207Pb/206Pb年龄范围在1830–1897 Ma，加权平均值为1862±11 Ma，MSWD=0.40。该组锆石的Ti含量为1.21–3.24，以a(TiO2)=1用锆石Ti含量温度计计算得温度为580–650 °C，平均值为619°C，以a(TiO2)=0.7用锆石Ti含量温度计计算得温度为604–678 °C，平均值为645°C。第二组5颗锆石，不同程度的偏离谐和线上方，207Pb/206Pb年龄范围在1793–1802 Ma，加权平均值为1799±26 Ma，MSWD=0.015，组成的不一致线与谐和线交点年龄为1803±76 Ma，MSWD=0.02。该组锆石的Ti含量为1.09–2.59，以a(TiO2)=1用锆石Ti含量温度计计算得温度为573–633 °C，平均值为606 °C，以a(TiO2)=0.7用锆石Ti含量温度计计算得温度为597–660 °C，平均值为631 °C。以上两组锆石的稀土特征并无明显区别，有明显的Ce异常而无Eu异常，具有强烈亏损重稀土的石榴石印记，重稀土甚至低于中稀土。（引自张颖慧博士论文）

Stop 4. 饭馆对面大石峪河谷（N39°27′02″ E113°23′03″）
[内容]：侵入的辉长质岩墙及其变质特征

此点可见保留辉长岩原始结构的基性岩墙，其中的斜长石具定向生长。Kröner et al.（2006）对其中的锆石进行了离子探针定年。他认为其中保留了部分岩浆锆石和岩浆锆石+变质增生边以及变质锆石。据此，Kröner et al.（2006）认为两个~1915 Ma (图III-8)的年龄值解释为原岩（侵入岩墙）形成的年龄。新的定年数据表明其变质年龄介于1.85－1.96Ga。

Stop 5. 下黑峪大峡谷（N39°27′02″ E113°23′02″） 
[内容]：混合岩化TTG片麻岩，巨型高压麻粒岩布丁，二辉麻粒岩块体；花岗质岩脉。 

下行到河谷中可见混合岩化TTG片麻岩和其中的巨型高压麻粒岩布丁，与上一点的麻粒岩相比，此点岩石中的石榴石呈现粗粒，含有颗粒较大的石榴石斑晶和较高含量的角闪石，不含斜方辉石，其矿物组成为：石榴石25% +单斜辉石15% +角闪石20% +斜长石20% +石英10% +黑云母7% +钛铁氧化物3% ±金红石。此外，在TTG片麻岩中还保存新鲜的斜长角闪岩，显然与达到高压麻粒岩相的包体是不平衡的，但其变质年龄为1.85Ga，。

此点中的片麻岩熔融程度较高，明显可见浅色体和暗色体的分带，混合岩化程度较高。成分以花岗闪长质为主，钾长石含量较多的样品颜色略发红，多具褶皱状构造，可见后期的花岗质脉体切穿其片麻理。条带状片麻岩可理解为TTG原岩深熔后一部分熔体分凝和运移出去，未排出的熔体和熔融残留体部分反应后得到的混合部分。作为熔融产物的钾质花岗岩脉规模较大，宽1 m到几十米不等，穿切变质基性岩和TTG片麻岩，或杂糅其中但明显晚于片麻岩面理。岩石中未发现特征富铝矿物（石榴石、蓝晶石、夕线石等），而是出现一些富钙矿物（榍石、磷灰石、绿帘石、褐帘石等），显示出了I型花岗岩的特征。

对两个TTG 片麻岩样品进行LA-ICP-MS 锆石U-Pb 定年得到其变质锆石年龄为1916.7±9.9 Ma 和1850~1930 Ma, 残留岩浆锆石年龄~2.5 Ga, 两类锆石均为重稀土富集型稀土配分特征（ 张颖慧等，2013）。

Stop 9. 圭峰寺（N39°12′32″ E113°36′05″）
[内容]：五台杂岩下部金岗库组变质沉积岩组合。

The stop is situated at the foot of the mountain [lat. 39º 06' 43.4"; long. 113º 14' 2.0"] with a temple called Guifengsi (Fig. 35). Exposed here is the Jingangku ‘formation’ of the ‘lower’ Wutai sequence. One of the most characteristic features of metamorphic mineral assemblages in this outcrop is the presence of kyanite +gedrite or kyanite + chlorite in the rocks within a contact zone between the meta-ultramafic to mafic rocks and metapelites. Meta-ultramafic to mafic rocks are exposed in the ridge of the mountain, including serpentinites, talc schist, tremolite schist, actinolite schist, anthophyllite schist, amphibolite and various greenschists. Between the meta-ultramafic to mafic rocks and metapelites is a transitional zone that is located on the mountain slope and comprises kyanite-gedrite schist, kyanite-phengite-chlorite greenschist, kyanite-gedrite-staurolite-garnet schist, kyanite-tourmaline-phengite greenschist, and kyanite-gedrite-cordierite schist. Based on the available petrogenetic grids, Wang et al. (1996) estimated that these assemblages formed at pressures of 0.9-1.4 Gpa. However, another alternative interpretation is that the formation of kyanite-gedrite assemblages may be related to the interaction (e.g. fliud metasomatism) of the meta-ultramafic to mafic rocks with the metapelites. Because of time limitations, we cannot go up to the mountain to examine all these rock assemblages. What we will examine at this stop are garnet porphyroblasts -bearingmica schist, and kyanite-gedrite schist where gedrite crystals do not show any preferred orientation, indicating post-tectonic growth.

Stop 10. 安头村：峨口花岗岩，TIMS定年数据2520～2555Ma，展布面积为25-30 km2。

This is a quarry opened-up in the Ekou granite (Fig. 35), which outcrops over an area of 30 Km2. The granite is in tectonic contact with rocks of the Wutai Complex, exposed at the rear of the nearby iron ore processing plant. The rock is chiefly a pink, medium grained, deformed granitoid with a strong gneissic fabric. Elongate ribbons of strongly undulose quartz alternate with layers composed of perthitic microcline, plagioclase, biotite and rare garnet.

Liu et al. (1985) initially obtained a some-what imprecise U-Pb multigrain zircon age of 2520 ± 30 Ma for the Ekou Granite. Based on the simple interpretation that 2520 Ma was the real age and the belief that the granite intruded the Wutai Complex, it has generally been considered that the Ekou Granite is younger than the Wutai Complex. This interpretation, and the highly siliceous nature of the rocks, led Wang et al. (1992) to conclude that the Ekou Granite is related to late, post-collisional events in the area. Several samples of Ekou Granite were collected for analysis, of which only two provided suitably concordant data points to enable the age to be determined (Wilde et al., 1997). In both samples, the number of concordant zircon grains is small, reflecting the extensive disturbance to the isotopic systems and explaining the large uncertainties in the multigrain zircon data. The zircon crystals are mostly dark brown in colour with numerous inclusions and brown discolouration patches. Sample PC-95-33 (lat. 39° 06' 30"; long. 113° 14° 48") defines a 207Pb/206Pb age of 2566 ± 13 Ma, based on 5 concordant analyses (Fig. 36). The data for sample 95-19 (Fig. 37) from the same location are more tightly constrained and 10 analytical points define a 207Pb/206Pb age of 2555 ± 6 Ma. These latter are considered to be a better representation of the true age of the granite, which was emplaced ~2555 Ma ago.
The results indicate that the Ekou Granite is older than the felsic volcanic rocks of the Middle Wutai Complex, with ages of ~2525 Ma (see later section) and we now interpret this granite as forming prior to development of the Wutai arc, possibly at the western margin of the Eastern block of the North China Craton (Zhao et el., 2001a).

Stop 11. 岩头乡政府路边，复杂褶皱群

Stop 12. 太平沟公路旁；［内容］：枕状熔岩

On a roadside [lat. 39º01′08.1"; long. 113º19′44.2"]~500 meters south of Taping Village (Fig. 35), we will examine the pillow lava metabasalts from the Baizhiyan Formation of the Middle Wutai sequence. Delineating the pillows are 1~2 cm epidote-rich rims surrounding fine-grained 0.1-0.3 m-wide pillow cores, which consist of chlorite, albite carbonates, epidote, and opaque minerals. Most pillows have been elongated and flattened to form a foliation parallel to the regional schistocity (079/60°). Some pillows show a flat lower edge and a convex upper edge, possibly indicating way-up structures.