Introduction

Abstract

The project named Regional Geological and Mineral Survey of Hanggai (H50E009022), Xianxia (H50E010022), and Chuancun (H50E010023) Map Sheets, Zhejiang Province on a Scale of 1:50,000 (also referred to as the Project) with No. 1212011220527 is a part of Geological and Mineral Resources Survey of Qingzhou–Hangzhou Metallogenic Belt, a geological survey program initiated by China Geological Survey (also referred to as CGS). It lasted from 2012 to 2014 and the numbers of annual task documents issued by CGS during the three years are Ji[2012]02-013-021, Ji[2013]01-016-004, and Ji[2014]01-018-002, respectively.

1.1 Purpose and Task

The project named Regional Geological and Mineral Survey of Hanggai (H50E009022), Xianxia (H50E010022), and Chuancun (H50E010023) Map Sheets, Zhejiang Province on a Scale of 1:50,000 (also referred to as the Project) with No. 1212011220527 is a part of Geological and Mineral Resources Survey of Qingzhou–Hangzhou Metallogenic Belt, a geological survey program initiated by China Geological Survey (also referred to as CGS). It lasted from 2012 to 2014 and the numbers of annual task documents issued by CGS during the three years are Ji[2012]02-013-021, Ji[2013]01-016-004, and Ji[2014]01-018-002, respectively.

1.1.1 Objective and Task

Based on systemic collection and comprehensive analysis of existing geological data and according to applicable technical specifications including General Principles of Regional Geological Survey (1:50,000), Technical Requirements for Regional Geological Survey (Scale: 1:50,000) (provisional), the specifications related to regional geochemical survey, and the Notice on Strengthening the Regional Geological Survey of Metallogenic Belts (1:50,000) issued by CGS, the following tasks are to be performed: (i) carrying out regional geological and mineral survey on a scale of 1:50,000, in order to determine the features of strata, rocks, and structures, establish the stratigraphic sequences of the areas to be surveyed (collectively referred to as the Area), and further break down stratigraphic units and highlight special geological bodies and informal stratigraphic units, (ii) strengthening the research into the relationship between mineralization and ore-bearing strata, magmatism, and tectonic activities, in order to systemically determine the geological conditions of mineralization in the Area, and (iii) verifying the anomalies and inspecting the ore occurrences of key parts of the Area, summarizing the metallogenic regularity, and putting forward key survey areas for geological prospecting in the Area. With an expected total area of the geological survey of 1334 km², the Project is designed to focus on the following work.

• 1. To carry out the research on multiple stratigraphic division of the Area; to conduct lithology mapping and lithofacies mapping by lithostratigraphic or tectonic stratum methods; to determine the stratigraphic distribution, lithologic association, era attribution, and ancient geographical environment of the Area; furthermore, to determine the stratigraphic sequences, further break down the stratigraphic units, and highlight special geological horizons and informal stratigraphic units.

• 2. To further determine the petrological, geochemical, and volcanic tectonic characteristics of the Mesozoic volcanic rocks in Tianmu Mountain based on the sequence division of volcanic strata, in order to ascertain the formation era of the volcanic rocks; to determine the characteristics of filling sequences and investigate the relationship between regional structure and the formation, development and closure of continental volcanic basins, in order to summarize the evolution law of the basins.

• 3. To determine the morphology, occurrence, rock types, contact relation, as well as the petrological and geochemical characteristics of various intrusives of Ma’anshan, Tangshe, Tonglizhuang, Wushanguan, Xianxia, Jiuliwan, and Dongling plutons and Songcun composite pluton within the Area; in addition, to further establish the rock units of the intrusive rocks of different eras and explore the relationship between mineralization and the magma activities of different eras.

• 4. To determine the characteristics of basic geological structures such as folds, fractures, and thrust (gliding) nappe structures in the Area, in order to establish the tectonic framework of the Area; to conduct correct division of the tectonic deformation periods; to focus on the survey of the characteristics of the composition, special distribution, and activities of Zaoxi-Moganshan fracture zone and Xuechuan-Xiaofeng fracture zone; and to analyze the basin-controlling and rock-controlling mechanism of the fracture zones; to summarize the geological development history of the Area.

• 5. To carry out the study on geological conditions of mineralization and ascertain the stratum horizons, rock types and geological structures closely related to the mineralization; to inspect key ore occurrences and verify key geochemical anomalies, in order to determine prospecting clues and provide prospecting target areas; to summarize metallogenic regularity of the Area; and to propose the key survey areas for geological prospecting.

• 6. To systematically collect and collate existing data obtained from previous geochemical prospecting; to carry out stream sediment survey on a scale of 1:50,000 and delineate the geochemical anomalies; to verify and evaluate the key geochemical anomalies, preliminarily determine the causes of anomalies, and provide information for geological prospecting; to analyze more than 15 elements including Au, Ag, Cu, Pb, Zn, As, Sb, Bi, Cd, W, Mo, Sn, Cr, Co, and Ni.

1.1.2 Desired Production

• 1. A geological and mineral survey report of the joint survey areas; 1:50,000 geological maps based on map sheets and their explanations; 1:50,000 mineral resource maps based on map sheets; 1:100,000 ore-bearing tectonic maps base on map sheets and their explanations.

• 2. A report on stream sediment survey on a scale of 1:50,000 as well as related series of maps and databases attached.

• 3. Raw data (including the database of actual work material maps), the spatial database of the resulting maps, the geological survey report from the regional geological survey should all be submitted according to the requirements of the Guideline on the Building of Spatial Databases of Geological Maps and Standard on Spatial Databases for Digital Geological Maps (2006) issued by CGS.

1.2 Location, Transportation, Geography, and Economy

1.2.1 Overview of Location and Transportation of the Area

The Area is located at the junction of northern Zhejiang Province and southern Anhui Province, with east longitude of 119°15′00″–119°45′00″ and north latitude of 30°20′00″–30°40′00″. Administratively, it is a part of Lin’an City and Anji County of Zhejiang Province and Ningguo City and Guangde County of Anhui Province. It consists of three map sheets named Hanggai, Xianxia, and Chuancun, respectively, according to international sheet division on a scale of 1:50,000, covering a total area of about 1334 km².

The Area features a convenient road network, with provincial highways S11 and S13 directly passing through the Area as well as tarred roads connecting all the towns and villages of the Area (Fig. 1.1).

Fig. 1.1

Transportation and location of the area

1.2.2 Overview of Natural Geography and Economy

Situated within the mid and low mountainous area of Tianmu Mountain in northern Zhejiang Province, the Area is high in the south and low in the north, with the average elevation of 500–1500 m. The highest elevation is 1587 m and is located in Longwang Mountain. Owing to dangerously steep and deep dissection as well as decades of afforestation, the Area is characterized by thick vegetation, sparse population, and rugged mountain roads, which comprise arduous conditions for geological survey in the Area.

The Area is featured by subtropical monsoon climate with four distinctive seasons, warm and humid. The annual average temperature is about 17 ℃. The annual average precipitation is about 1602 mm, with rainy seasons lasting from March to June and from August to September mainly. The duration of the annual frost-free period is about 257 days. July and August constitute the midsummer of the Area, during which the temperature is usually 37–39 ℃.

The Area boasts of the strong economy, rich and deep ecological culture, and an integrated economic pattern in which a number of animal and plant industries comprehensively develop including crops, oils, forestation, bamboo, tea, mulberry, fruits, vegetables, livestock, poultry, and fishery. Furthermore, the Area enjoys a sound market economy, individual economy with a long history, as well as agriculture and rural areas with high degrees of industrialization. Besides, the national forest reserves and resorts named Tianmu Mountain and Tianhuangping are also distributed in the Area.

1.3 The Past Geological Survey and Research

The systematic geological survey in the Area can be dated back to the 1960s. From then, the regional geological survey, mineral geological survey, hydrogeological survey, geophysical prospecting, and geochemical prospecting on a scale of 1:200,000 and part of geophysical prospecting and geochemical prospecting on a scale of 1:50,000 have been successively conducted in the Area. As of the beginning of this century, a regional geological survey of scale 1:250,000 had been carried out in the whole area. In addition, a number of mineral resource exploration, as well as special survey and research, have been performed in the Area.

1.3.1 Regional Geological Survey

In the 1950s, the Regional Geological Survey Team of Geological Exploration Bureau of Zhejiang Province conducted a regional geological survey on a scale of 1:200,000 in Lin’an map sheet (H–50–18). During this survey, the structures and magmatic rocks exposed in the Area were systematically investigated and were divided into 28 formations and 10 members. In the early 1960s, the Zhejiang Regional Survey Team of the Department of Geology, Nanjing University performed a comprehensive regional geological survey of the volcanic rock area of Tianmu Mountain and preliminarily investigated the lithology and lithofacies of the volcanic rocks. In the 1980s and 1990s, the Regional Geological Survey Team of Geological Exploration Bureau of Zhejiang Province and Zhejiang Bureau of Geology and Mineral Resources systematically summarized the lithostratigraphic condition of Zhejiang Province and the Area successively.

At the beginning of the twenty-first century, Anhui Institute of Geological Survey conducted a regional geological survey of Xuancheng map sheet (H50C002004) on a scale of 1:250,000, covering the work scope of this Project. The latest geological theory and methods were applied in the systematic study and summary of the strata, structures, and magmatic rocks in the Area, especially in the survey and comparative study on the movement history, association patterns, and nature of regional structures such as Jixi-Ningguodun Composite Anticline, Jixi-Ningguo fracture zone, and Xuechuan-Xiaofeng fracture zone as well as the rock association, petrology and intrusive sequence of Ma’anshan, Tangshe, Xianxia, and Wushanguan plutons.

1.3.2 Geophysical, Geochemical, and Mineral Exploration

• (1) During 1955–1965

In the 1950s, the Regional Geological Survey Team of Geological Exploration Bureau of Zhejiang Province investigated the heavy concentrate and dispersed flow in Lin’an map sheet (H–50–18) while conducting the regional geological survey on a scale of 1:200,000 in the map sheet. As a result, 40 heavy concentrate anomalies and 65 metallic and dispersion flow anomalies were delineated; 25 mineral types and 94 ore occurrences were newly discovered; and 313 ore occurrences were inspected. Furthermore, 12 important metallogenic prospect areas were delineated, including Lujiashan tungsten-beryllium deposit, Zhangcun polymetallic scheelite, Baofu-Huanghu polymetallic magnetite deposit, Litali-Yucun fluorite deposit, Yujiakou-Tongguanshan boron-iron lead-zinc cassiterite deposit, Zhangcun-Henglutou fluorite deposit, Xixi polymetallic deposit, Xuechuan tungsten-beryllium-polymetallic-fluorite deposit, Machebu tinstone-polymetallic deposit, Xianlinbu-Wanshiqiao polymetallic-barite deposit, Fuyang lead-zinc-magnetite deposit, and the major deposits beyond these prospect areas.

In the early 1960s, the Fourth Group of the Geophysical Exploration Team of Geological Exploration Bureau of Zhejiang Province conducted a comprehensive reconnaissance survey of the geology, geophysical exploration, and geochemical exploration in Lin’an map sheet. The First Geological Team of Geological Exploration Bureau of Zhejiang Province conducted a comprehensive reconnaissance survey on a scale of 1:50,000 in the south of Anji (which was in the north of Tianmu Mountain). During this survey, 561 anomaly areas with various diffusion halos were delineated. Furthermore, 31 mineralized points and 21 mineral types were discovered. According to the comprehensive reconnaissance survey, it was believed that the widely distributed skarn and marble belts possibly contained the mineral resources (e.g., beryllium deposit) related to greisenization and albitization existing widely. However, systematic sampling and survey were not conducted. During the same period, the First Geological Team of Geological Exploration Bureau of Zhejiang Province conducted preliminary evaluation of the reconnaissance survey of Gaocun stibium deposit, Henglutou fluorite deposit, Zhujiashan-Yinshuidong boron deposit, while the Forth Geological Team of Geological Exploration Bureau of Zhejiang Province conducted preliminary evaluation of the reconnaissance survey of Gangkou-Zhangcun boron deposit and Gangkou Yujiawu fluorite deposit. The survey results are as follows: the fluorite deposits in Henglutou-Gangkou Yujiawu were all controlled by NW-trending faults; the NW-trending fracture zone near the pluton was the priority in the prospecting of the fluorite deposits; and skarnized breccia was an important prospecting indicator. The survey results also showed that the Zhujiashan-Yinshuidong boron mineralization was mainly born in the external contact zone between granodiorite and Sinian stratum, and the ore-bearing horizon was located in forsterite-bearing dolomitic marble that was about 10–20 cm to the stratum top. Besides, the boron mineralization was magnesium-bearing skarn ludwigite-magnetite deposit.

• (2) During 1976–1996

In the late 1970s, the Geophysical Exploration Team of Geological Exploration Bureau of Zhejiang Province conducted an aeromagnetic survey in the north of Zhejiang Province on a scale of 1:50,000, covering the part in Zhejiang Province of the Area.

In the early 1980s, the Ninth Geological Team of Geological Exploration Bureau of Zhejiang Province carried out the reconnaissance survey of tungsten deposits in Tangshe and Ma’anshan areas. As a result, 12 various kinds of heavy concentrate anomalies were delineated including six anomalies of scheelite and wolframite, and one mineralized point of scheelite was newly discovered. The lardite vein was found in the thick stratiform dolomitic marble on the top of Xifengshi Formation during the reconnaissance survey. Besides, Yinshanjian scheelite-tinstone mineralized point, Tangsheling scheelite mineralized point, Baishawu scheelite-containing polymetallic mineralized point, and Shuangshekuling tungsten-beryllium ore occurrence was inspected by field reconnaissance. The First Geological Team of Geological Exploration Bureau of Zhejiang Province summarized the metallogenic regularity of the tungsten deposit in Anji-Chun’an area and made the preliminary prediction. According to the prediction, Ma’anshan pluton was featured by the successive distribution of tungsten-beryllium quartz-vein deposit (i.e., wolframite and beryl), fluorite deposit, skarn tungsten polymetallic deposit, polymetallic deposit, and stibium deposit from inside out; Tangshe granodiorite was featured by the distribution of disseminated scheelite mineralization, skarn scheelite polymetallic deposit, fluorite, and polymetallic deposit from inside out; and Xianxia pluton was characterized by the distribution of granodiorite, scheelite mineralization of skarn and quartz-vein types, and mineralization of chalcopyrite and pyritization from inside out. Based on this, Ma’anshan W–Be (Mo–Cu–Pb–Zn–CaF₂) and Tangshe Tungsten metallogenic prospect areas were delineated. In the late 1980s, the Ninth Geological Team of Geological Exploration Bureau of Zhejiang Province inspected the gold anomaly of Talishan, Tangshe area and accordingly determined that the gold mineralization degree was closely related to the alteration and broken degrees of the rocks as well as the development of tectonic cracks. However, the gold anomaly of Talishan, Tangshe area was characterized by weak mineralization and alteration, low development of tectonic cracks, unobvious anomaly concentration center or multiple anomaly concentration centers, low anomaly strength, and poor element association. Besides, the Ninth Geological Team of Geological Exploration Bureau of Zhejiang Province verified the anomalies in the West Gangkou Road–Yujiawu area including Zn–Pb polymetallic anomalies of Yezhutang, Hongmiaoqiao, and Yujiawu, as well as gold anomalies of Yezhutang anomaly area. Furthermore, the team determined that Zn–Pb polymetallic mineralization occurred in diopside, garnet, and skarn in the lower part of Dachenling Formation, which lied in the external contact zone of granodiorite pluton, the fractured zone of the NW-trending fault, as well as the garnet, diopside, and skarn in the external contact zone of Xiyangshan Formation. The team believed that factors of polymetallic mineralization included horizon, lithology, crack fracture, and contact plane structure. During Grade 3 verification of polymetallic anomalies in Shangmei Village, Hanggai Town, it was determined that there were no visible anomalies of Cu, Pb, and Ag according to soil survey. According to geological reconnaissance survey and assessment of the deposits of Ag, Au, and Cu, it was believed that the deposits of meso-epithermal hydrothermal filling type were distributed in the Area, including dominant Ag deposits and associated polymetallic deposits of Cu, Pb, and Zn. Furthermore, the team believed that the chambered, moniliform, veined, lenticular, columnar, and stratiform mineral (mineralized) bodies were distributed in plane or profile in an echelon arrangement, with complex morphology and poor continuity. Besides, it was thought that the mineral (mineralized) bodies were closely related to fractured (caused by compression along with rock layers) and conjugated transtensional insequent faults. In addition, the mineral (mineralized) bodies occurred in the cores of synclines and microplissement development areas at the turning of synclines and anticlines, with extremely uneven distribution and very poor surface. However, the mineralization tended to be slightly more favorable downwards from the surface.

In the early 1990s, the Geophysical and Geochemical Exploration Team of Zhejiang Province conducted a stream sediment survey of Lin’an map sheet on a scale of 1:200,000. Consequently, the single-element geochemical maps and integrated anomaly maps were plotted, and several fourth-class geochemical prospecting areas were delineated including Ma’anshan-Tangshecun Ag–Cu–Pb–Zn–Mo–Sb–F–CaO, Shangshi-Gangkou Ag–Pb–Zn–Mo–Cu–Au, Sanqiaobu-Huanghu Au–Ag–Cu–Pb–Zn–F–CaO, Xixi Pb–Zn–Ag–Mo–Cu, Changchunqiao-Yuhang Pb–Zn–Cu–Ag–Mo and nonmetal, Heqiao-Wanshiqiao Sn–Mo–Bi–Pb–Zn–Au–Ag, and Fuyang Pb–Zn–Cu–Au–Ag prospecting areas. According to later aeromagnetic computation on a scale of 1:50,000 in Anji and Hanggai map sheets and the stream sediment survey on a scale of 1:200,000 by single-point sampling, the geochemical maps of 14 elements were plotted. Furthermore, the mid-deep and shallow geological bodies in the Area were inferred by the aeromagnetic calculation. It was pointed out that the middle part was the thickest area of the Lower Paleozoic Erathem with weak magmatic activities, while the eastern and southern parts were the active areas of magmatic rocks. According to the stream sediment survey, the remaining aeromagnetic anomalies were caused by andesite and stock-like granodiorite in Laocun Formation of Cretaceous Period, and the remaining aeromagnetic anomalies associated with granodiorite were closely related to metallic deposits. Besides, the metallogenic prospect areas were delineated during this survey (including Ag-bearing polymetallic metallogenic prospect areas of Yaocun, Hanggai-Shizhu area, Tongkengcun, Shangshi-Shishancun area, and Gangkou).

• (3) During 2004–2014

In the twenty-first century, with the development of modern metallogenic theory and high-precision prospecting and test methods, various geological exploration institutions conducted further prospecting evaluation in the Area and its peripheral areas.

Zhejiang Geological Prospecting Institute of the China Chemical Geology and Mine Bureau conducted prospecting evaluation of the fluorite deposits in Changshan-Anji area of Zhejiang Province. It investigated and studied the metallogenic geological conditions and metallogenic model of fluorite, divided the deposits into the ones of meso-epithermal hydrothermal fissure filling type and the ones of hydrothermal filling and superposition type after contact metasomatism, conducted the prospective evaluation of fluorite resources in the NW-trending and SE-trending metallogenic zones, and evaluated the resources of important fluorite mining area. For example, according to the evaluation of the Jiantouwu (Yonghe) fluorite deposits within the Area, fluorite ore bodies occurred within the external contact zone between Ma’anshan pluton and keratinized silt sandstone of Yinzhubu Formation (O₁y). In addition, two fluorite ore bodies were found within the NW-trending tectonic fracture in the silicified zone with fluorite resources of 21,100 tonnes, and the fluorite resources in Tangshe-Zhangcun area were estimated to be 109,900 tonnes.

The institutions including the Ninth Geological Team of Geological Exploration Bureau of Zhejiang Province and Zhejiang Institute of Geological Survey conducted the resource reserve survey of Fe in the Gangkou mining area, fluorite in Yonghe mining area, and stibium in Gaocun mining area in the Area. As a result, the total accumulative identified resource reserve (122b + 2S22) of magnetite in the Gangkou Fe survey area was 689,000 tonnes, and the resource reserve (333) of stibium deposit in Gaocun was 57.87 tonnes.

According to the arrangement of the national mineral resource evaluation project, the Zhejiang Institute of Geological Survey carried out an evaluation of mineral resource potential in Zhejiang Province. According to the division of related metallogenic zones or belts, the Area was located in the Au–Ag–W–Mo–Cu–Pb–Zn–Sb–Fe–fluorite–Be–bentonite metallogenic subzone of Tianmu Mountain, which was located in the Cu–Pb–Zn–Ag–Au–W–Sn–Nb–Ta–Mn–sepiolite–fluorite–wollastonite metallogenic zone (III-71) in the northeastern part of Qinzhou Bay–Hangzhou Bay area. The Area was divided into the Yonghe (Anji County) fluorite–Sb–Cu, Zhangcun (Anji County)-Pingyao (Yuhang District) fluorite–S–Fe–Cu, and West Tianmu Mountain (Lin’an District) W-Mo-fluorite ore concentration areas, as well as Ma’anshan, Tonglizhuang, and Tanshe integrated pre-survey areas of Anji County.

In addition, 12 commercial survey projects are implemented in the Area currently, which involves pre-investigation, reconnaissance survey, and detailed survey. Most areas with exploration rights are situated in the peripheral parts of old mining areas or in known ore occurrences. According to exploration and reserve assessment, the submitted reserve (111b + 122b + 333) of fluorite resources in the Jianziwu (Yonghe) fluorite mining area was up to 743,000 tonnes (medium scale) as of 2012. According to a detail survey, the submitted resources (332 + 333) of lead and zinc, silver, and copper in the north of Gangkou Fe mining area were 22,500 tonnes, 46.78 tonnes, 5000 tonnes, respectively, as of 2014. As for the north contact zone of Tonglizhuang composite pluton, Tonglizhuang (Puluwu) fluorite deposit and Langcun (Tonglizhuang) W–Mo polymetallic deposit had been discovered as of 2014. The preliminarily estimated resources of fluorite and W–Mo deposit (WO₃) in the two deposits were 2,357,000 tonnes (large scale) and 18,500 tonnes (medium scale), respectively.

1.3.3 Scientific Research on Geology and Minerals

In 2007, Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences and Zhejiang Institute of Geological Survey discovered for the first time deepwater benthos (Evangelia–Dalmanitina (Songxites) combination) in Yuhang area, Hangzhou, which is 2000 m to the east of Chuancun map sheet. Accordingly, the institute considered that Yuhang was one of the refuges during the mass extinction of Late Ordovician organisms. This opened up a new prelude to the biostratigraphy study from Late Ordovician to Early Silurian and as well as offered a good opportunity for the study of biostratigraphy in the Area.

In 2012, the University of Science and Technology Beijing systematically studied the diagenesis and metallization of Wushanguan composite pluton in the east of the Area and published a series of papers. The university considered that the magma activities in the mining area occurred in 141–117 Ma, and the medium-grained biotite monzogranite, medium-grained syenogranite, medium-grained granodiorite, fine-grained granite, and bimodal vein-rock association successively constituted the emplacement sequence. All the rocks except for the bimodal vein-rock association constituted the Wushanguan composite pluton. The university also believed that two mineralization events took place in the Area. The first event was related to the emplacement of medium-grained granodiorite (137 Ma). During this period, skarn Cu–Fe mineralization featured by garnets and skarns took shape and was mainly distributed in the west of the Area. The second event was Pb–Zn (Ag) and Mo mineralization, which was related to the emplacement of fine-grained granite (135–134 Ma). During this period, the skarn Pb–Zn (Ag) mineralization formed with epidote skarn as the dominant mineralized result.

1.4 Overview of the Work

1.4.1 Work Stages of the Project

Based on full collection and utilization of existing outcomes obtained from the geological survey of Lin’an map sheet on a scale of 1:200,000, geological survey of Xuancheng map sheet on a scale of 1:250,000, geophysical and geochemical exploration on different scales, and mineral inspection, the Project conducted field survey and integrated research as required by the task documents issued by CGS. According to the task documents, the specific project stages are as follows:

From February to August in 2012, the Project team successively conducted the collection and research of existing information, preliminary remote-sensing interpretation, field reconnaissance, mapping of some sections, and survey of the master traverse. Furthermore, the Project team clearly determined various stratigraphic units and developed overall design.

From September 2012 to December 2014, according to the overall design and work deployment required by annual schemes, the Project team successively completed the digital geological survey on a scale of 1:50,000, stream sediment survey on a scale of 1:50,000 (Hanggai map sheet), the mapping of stratigraphic units and (volcanic) tectonic sections on different scales, and rough inspection of mineral resources. The Project team also collated various original data comprehensively and systemically, prepared various maps, and summarized fieldwork. Furthermore, the Project successfully passed the field acceptance organized by the east China project management office of CGS and was ranked excellent in terms of overall rating.

From January to August in 2015, the Project team resolved the problems proposed during the field acceptance and improved the original data. Furthermore, the Project team prepared the regional geological and mineral survey report as well as geological maps (including their explanations), mineral maps, tectonic maps of ore-bearing formations, and lithological and lithofacies tectonic maps of volcanic rocks. Besides, the Project team completed the spatial database of 1:50,000 digital geological maps.

During August 19–22th, 2015, the east China project management office of CGS organized competent experts to review the report of the outcomes obtained in the Project in Nanjing. The review expert group consisted of seven experts from Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing Center, China Geological Survey, Fujian Institute of Geological Survey, Jiangxi Institute of Geological Survey, Anhui Provincial Institute of Geological Survey, and Geological Exploration Technology Institute of Anhui Province. The expert group determined that the goals and tasks of the Project stipulated in the task documents were completed comprehensively, and the report featured rich content and detailed information. Therefore, the Project was ranked excellent in terms of overall rating.

During November 15–17th, 2015, All China Commission of Stratigraphy organized nearly 20 experts to conduct a field investigation and demonstration for the “Upper Ordovician Wenchang Formation Section of Hanggai Town, Anji County, Zhejiang Province” applied by the Project team, including Academician Xu Chen, Researcher Yuandong Zhang, and Researcher Huawei Cai from Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Researcher Zejiu Wang, Researcher Hongfei Hou, and Researcher Jianxin Yao from Chinese Academy of Geological Sciences, and Researcher Xiaofeng Wang from Nanjing Center, China Geological Survey. All the experts unanimously agreed to rank the section as the “Standard Cross Section of the Lower Yangtze Region in the Upper Ordovician Hirnantian.” Besides, they recommended the Department of Natural Resources of Zhejiang Province, the People’s Government of Anji County, and Zhejiang Institute of Geological Survey to include the protection and research of Hanggai sections into the geological environmental protection and ecological building planning, in order to further enhance the protection, utilization, and scientific research of the sections.

1.4.2 Workload Completed

According to relevant specifications and approved workload, the goals and tasks of the Project have been comprehensively completed. The main work includes 1334 km² of the regional geological survey on a scale of 1:50,000, 1334 km² of remote-sensing interpretation on a scale of 1:50,000, and 440 km² of stream sediment survey on a scale of 1:50,000. The detailed approved and completed physical workload is shown in Table 1.1.

Table 1.1 Main approved and completed physical workload