Observation, description and recording format of geological observation points

Geological observation point is the place where geological phenomena are observed and studied on the field geological route. Its layout should follow the following three principles:

The layout of (1) point is based on the principle of effectively controlling various geological boundaries and geological elements.

(2) Geological observation points must be arranged in the following positions: stratigraphic boundaries, different rock contact points, lithofacies changes, structural points, alteration zones, mineralization and ore occurrences, important fossil points, marker beds, representative occurrence factor observation points, sampling points, mountain engineering and other meaningful geological phenomenon observation positions.

(3) According to the actual geological conditions, the lithologic control points are reasonably arranged. Lithologic control points generally do not exceed 30% of the total geological points, and mechanical equidistant distribution is prohibited.

3.4. 1 General working procedures and precautions for geological observation points

(1) Use hand-held GPS to fix points or use terrain and features to fix points on topographic maps, indicate the dot number, and describe and record the geographical position and coordinates of observation points. In a work area, these points must be numbered consecutively and uniformly. If several operation groups are working in the same work area at the same time, the observation point numbers must be uniformly assigned before field operation, and the phenomenon of duplicate numbers is never allowed in the same work area.

(2) Observe and study the rock outcrop at the observation point, and determine the outcrop type (natural or artificial) and outcrop degree (good, average, poor and poor), which will determine the visual field of the observation point and the reliability of the data.

(3) Observe and study the stratigraphic characteristics, paleontological characteristics (fossils), petrological characteristics of geological bodies and the contact relationship between various rocks near the observation point.

(4) Observe and study the structural features such as folds, joints and faults near the observation point.

(5) Observe and study the mineralization phenomenon, alteration zone and ore body characteristics near the observation point.

(6) Observe and study the landform and Quaternary geological and hydrogeological characteristics near the observation point.

(7) Measure various occurrence factors and related data (mineral granularity, gravel granularity, rock thickness, exposed width of fault zone, length and width of ore seam or vein, etc.). ).

(8) After the above observation and research, make detailed written records and descriptions.

(9) Draw a geological sketch or outline the profile of the alphabet hand or take necessary geological photography.

(10) Collect various specimens and samples.

In the process of field geological observation, we must first adhere to a serious and realistic scientific attitude and collect data objectively, and the selection of observation content should not be subjective and arbitrary. Secondly, we should follow objective laws in our work and avoid blindness. It is necessary to do more observation and research on the route between points along the way to understand and master the changes of various geological phenomena between points.

3.4.2 Observation and description of common geological observation points

Common geological observation points mainly include: lithologic point, boundary point, structural point, ore body (mineralization) point, landform point, Quaternary geological point and hydrogeological point. The description of the observation point should not be limited to one point, but should include all geological phenomena in the observation point and its vicinity. The types of observation points are different, and the description content should also be focused.

ⅰ. Observation and description of lithologic points (boundary points)

The observation and description of lithology is the basis of field geological observation and description. Only by observing the lithologic characteristics in detail and correctly determining the rock name can we further study its spatial change and its relationship with other geological bodies. Lithology is described as follows:

(1) About the color of rocks. Is the overall color of the fresh face of the rock (weathered color is written in brackets after the fresh color).

(2) Mineral composition, crystalline state, particle size, content and their changes. Generally, the main components are described in the order of the first and second components. Note that the gross mineral content estimated by naked eyes cannot be greater than 100%. For porphyry, first describe the composition, content, shape, size and changes of porphyry crystals, and then describe the matrix; Clastic rocks and pyroclastic rocks are described in the order of detritus and cement.

(3) Description of structure and structure.

Intrusive rocks: coarse-grained, medium-grained, fine-grained, fine-grained, porphyritic and porphyritic structures. Blocky, mottled, flowing and banded structures.

Volcanic rocks: grayish green, coarse-grained, spherical, porphyritic, lumpy, volcanic breccia, tuff and other structures. Structures such as slag, pillows, ripples, pores, almonds, etc.

Sedimentary rock: clastic rock structure, such as coarse, medium and fine grained sandy, silty and argillaceous structure. And describe the characteristics of cement composition, cement type and bedding structure.

Metamorphic rocks: residual structure, granular metamorphic structure, scale metamorphic structure and other structures. Redundant structure, flake, flake, thousand flake, plate, strip and other structures.

(4) Description of alteration and mineralization. Alteration description mainly refers to the alteration of rocks, including altered parts, altered minerals and residual minerals. Mineralization description mainly refers to the types of metal minerals, the estimated mesh content and the morphology of aggregates.

(5) Observation and description of the spatial characteristics of rock stratum (rock mass). On the basis of lithologic observation, the observation range is expanded to describe the overall characteristics of the spatial distribution of rock strata and rock masses. Description: Lithofacies division; Lithologic change and interlayer; The occurrence and change of bedding and schistosity; Fossil output, etc.

(6) Observation and description of contact relationship. Describe the relationship between different rock strata and rock masses. Description: ① Contact zone type: according to the obvious degree of contact boundary, it can be divided into two types: abrupt type and gradual type; ② Contact relationship is divided into: deposition (overlap), fault, intrusion (pulsation, surge), integration, parallel unconformity, angular unconformity, etc. ③ Characteristics and changes of contact zone; ④ Occurrence change of contact zone.

Ⅱ. Examples of lithologic observation and description

Biotite adamellite: fleshy red, grayish white, medium-coarse grained granite structure, massive structure. Main mineral composition: about 25% of the mineral is timely, about 30% ~ 35% of potash feldspar, about 30% ~ 35% of plagioclase and about 10% of biotite. Feldspar is a flaky automorphic-semi-automorphic crystal with a size of 2 ~ 4mm；; When it is in season, it is irregular and granular, with a size of 2.5 ~ 3.5 mm; The biotite is brown-black, flaky and about 3 mm in size. No mineralization or alteration was found.

Dingyi olive basalt: grayish green, deep purple, porphyritic texture, almond-shaped texture. Mineral composition: the phenocryst is olivine from Dingyi Petrochemical Company, accounting for about 65,438+05%, and a few are replaced by chlorite and limonite. The matrix is cryptocrystalline plagioclase and pyroxene with coarse (granular) structure (visible under the microscope, a large number of fine illite, hydromica plagioclase and magnetite particles are filled in the triangular gap composed of relatively authigenic banded plagioclase microcrystals). Pores are round or irregular, and are mostly filled with white secondary mineral-calcite, forming amygdala. In the later period, the whole rock suffered from strong carbonization.

Composite conglomerate: purplish red, gravelly structure and medium-thick layered structure. Gravel composition is complex, mostly cuttings, including metamorphic sandstone, quartzite, tuff, feldspathic sandstone, seasonal sandstone, basalt, granite and so on. , the content exceeds 70%. Gravel size is 2 ~ 60mm, with a small amount of 100 ~ 150m. Poor roundness, angle division-circle division; Different sizes, poor sorting; Basement cementation, the cementation is argillaceous and calcareous, with weak weathering resistance, easy peeling of gravel and depression of rock surface. The thickness of the rock stratum is 20 ~ 40 cm. Combined with paleogeographic analysis, it is speculated that the river-lake facies accumulated rapidly at the edge of the lake. No mineralization or alteration was found. It is named in detail as: purplish red medium-thick layered composite conglomerate.

Ⅲ. Observation and description of structural points

Observation and description of (1) fold structure. Fold elements: measure the attitude of two wings, fold hinge, axial plane and angle between wings; Lithology, old-new relationship, etc. It constitutes a fold. Geometric shape: Observe and describe the shape of the turning end, the thickness change of each fold layer, the symmetry and spatial relationship of folds, etc.

(2) Observation and description of fault structure. Description of structural rocks: structural breccia mainly describes the composition, gravel size, shape, arrangement, cementation composition and cementation degree of structural breccia. The structural characteristics and deformation characteristics of mylonite are mainly observed.

Fault structure description: strata (rocks) on both sides of the fault and their occurrence changes; Determination of attitude of fault plane and width of fault fracture zone; The mechanical properties of the fault and the relative movement direction of the two plates are mainly determined according to the new-old relationship between the two plates, traction folds, scratches, steps, pinnate joints, small folds on both sides and fault breccia. Fault combination, shape and its relationship with other structures; Other features of faults: geomorphological signs, fault triangle; Mineralization and alteration in faults.

(3) Observation and description of joints. Including: the properties of joints and the characteristics of joint surfaces; Joint filling (pay attention to ore-bearing property); The relationship between joints, bedding and large structures; Staging matching and combination form of joints (focus on observation); The appearance of seams, etc.

Ⅳ. Observation and description of mineralization point (ore body)

Firstly, the characteristics of ore and mineralization are observed in detail in geological particles or engineering, and the ore and mineralization are named. On this basis, the observation range is expanded and the overall characteristics of ore bodies are tracked and observed.

A. nomenclature of ores and mineralization

(1) Any useful element whose content reaches the cut-off grade should be defined as ore as its basic name. If chalcopyrite is ≥ 1% (that is, Cu is ≥ 0.3%), it is named as ×× rock chalcopyrite; When the content of useful components exceeds a certain limit and fails to reach the cut-off grade, it can be called mineralization. When naming, take the name of rock as the basic name, and add "×× mineralization" in front of it. Such as chalcopyrite metamorphic siltstone (when the Cu grade is 0. 1%≤Cu≤0.3%).

(2) When there are more than two kinds of useful minerals (mineralization), only two main minerals are selected, and no more than three are allowed. According to the principle of "less front and more back", say the name of the rock first, and describe the rest in the description. Such as brass gold ore, jarosite, sphalerite, etc.

(3) Contents of useful elements involved in naming:

If the copper grade reaches the cut-off grade ≥0.3%, it will be named as ×× rock copper mine; When the grade is 0. 1%≤Cu≤0.3%, it is designated as × copper mineralization, such as chalcopyrite timely sandstone.

If the gold grade reaches the cut-off grade ≥ 1× 10-6, it will be named as ×× rock gold deposit; When 0.3×10-6 ≤ au ≤1×10-6, it is defined as gold mineralization.

For other minerals, about one third of the cut-off grade value is generally taken as the lower limit of mineralization naming.

B. description content and sequence of ore and mineralization

Ore rock: the fresh color of the ore as a whole, and the weathered color is written in brackets.

Structure, construction: the main one is put in front, and the secondary one is put behind.

Mineral composition, content and occurrence characteristics: firstly, describe the types, content percentage and occurrence characteristics of metal minerals; The variety and content changes of gangue minerals are described later.

Mineral symbiotic combination: the main (rich) is in the front, the secondary is in the back, and finally the gangue minerals are connected by short lines. Such as: hypopyrite-pyrite-chalcopyrite-timely.

General characteristics of mineralization: firstly, the overall mineralization degree of this ore block is summarized, including rich and poor, uniformity and its relationship with rocks and structures; Secondly, the changing characteristics of composition, content and occurrence state of metal minerals in each profile are described from top to bottom.

Secondary change of ore: if conditions permit, the generation order of main metal minerals can be determined according to the metasomatism relationship between minerals, with early generation in front and late generation in the back, which are connected by arrows in turn. Such as pyrrhotite → pyrite → chalcopyrite → limonite and malachite.

C. observation of ore (mineralized) body characteristics

Measuring the width and occurrence of ore bodies; Surrounding rock characteristics of roof and floor of ore body; Changes of mineralization intensity, thickness and orebody occurrence along strike; The structural position of ore (mineralized) body and the influence of structure after mineralization on ore body; Combination of mineralization and alteration.

Examples of ore observation and description

Diopside skarn pyrrhotite and brass ore: bronze (brown), semi-autogenous-irregular granular texture, disseminated texture and massive texture.

Mineral composition: metallic minerals include chalcopyrite (2% ~ 5%), pyrrhotite (20% ~ 25%) and pyrite (3%); The gangue minerals are mainly diopside (40% ~ 50%), garnet (5% ~ 10%), calcite and chlorite.

The mineral assemblage is pyrrhotite-pyrite-chalcopyrite.

Chalcopyrite is in the shape of irregular granules and distributed between pyrrhotite and a few veinlets in a star shape. Pyrrhotite is mostly produced in massive and granular aggregates, with the upper part being massive and the lower part being massive.

The mineralization of metal minerals is uneven, with rich upper part and poor lower part. Pyrite and chalcopyrite veinlets interspersed with pyrrhotite can be seen in the ore, and it is speculated that the generation order is pyrrhotite → pyrite → chalcopyrite. Carbonation and chloritization are seen locally, and chlorite is mostly distributed along the fault surface.

The boundary between ore body and footwall rock is unclear, and there is a gradual transition relationship.

ⅵ. Observation and description of surrounding rock alteration

(1) alteration types: According to the main alteration mineral types, there are silicification, sericitization, chloritization, etc.

(2) Distribution characteristics of altered minerals: such as star distribution, banded distribution and areal distribution of altered minerals.

(3) Scale and intensity of alteration: regional alteration describes its range, such as the alteration range of 500 m× 400 m; Strip alteration indicates the length and width of the altered zone.

(4) Alteration zoning and its relationship with surrounding rocks: For example, porphyry deposits are zoned with K-timely sericitization-porphyrization from the interior of porphyry to the distance from surrounding rocks.

(5) Relationship between alteration and mineralization: If alteration intensity is positively correlated with mineralization intensity, pyrite is closely related to sericitization, and molybdenite is closely related to potassium (biotite).

3.4.3 Principles that must be observed in the description of field records.

In the field work, all kinds of geological and mineral conditions observed and studied must be described in words or geological sketches or photos in the field record book in time. Field route observation records are the main raw materials and important basic materials for comprehensive research and geological report compilation. Field record books are extremely important field raw materials, which must be carefully recorded and kept strictly and properly.

For geological route observation records, we must first ensure their objectivity, and at the same time pay attention to the integrity, continuity, unity and intuition of the records. The contents of records and descriptions shall, in principle, include all geological phenomena seen, and important or first-time observed geological phenomena shall be described in detail. For general or repeated geological phenomena, the contents described above can be slightly explained, focusing on recording their particularity or changes, so that the text is accurate, substantial, focused and clear. At the same time, the observer's analysis, judgment, reasoning and comprehensive induction of objective phenomena can be properly described in field records. When observing and describing, we should also make necessary geological sketches and profiles. Mine (ore body) should draw a large-scale geological sketch, and properly collect specimens and samples. At the end of each route, a route summary should be made.

The field record book is not allowed to be altered casually, and administrative affairs cannot be recorded on it. When the recorded contents need to be modified, they must not be erased or altered at will, and only the original contents can be crossed out and annotated. The field record book must be kept neat and beautiful, and the handwriting should be neat and clear. Generally, writing is done with H-3H pencil, and recording with ballpoint pen or pen is not allowed.

3.4.4 Record format of field record book

The right page of the field record book is the horizontal grid of written records; The left page is a centimeter grid, which is used for sketching, cross-section or posting photos.

First, fill in the time, weather and place at the top of the right page. Indent 1cm inward on both sides of the right page, and draw a straight line on each side. Pay attention to the subheadings outside the left line, such as routes and tasks; Record the specific content in the middle of two straight lines; Record the specimens and sample numbers collected outside the right line. Then, record in the following order and format:

Route: ××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××

Task:

1. Observe and understand XXX rock and its characteristics. Observe the characteristics of ×× pulse and ×× pulse and their mutual connection.

2. Geological mapping of XX rock area or XX stratum distribution area; Investigate the contact relationship between XXX rock mass and XXX surrounding rock; Tracking ×× marker layer; ×× Strata profile observation stratification, etc.

Personnel: ××× record, ×××× palm diagram, ××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××

(There must be a blank line here)

No.00 1

Location: Mountain Road 700 meters northwest of Shi Hui Village.

Coordinates: X: 2029.430, Y: 29887.063.

Outcrop: Natural or artificial.

Sharpness: demarcation point: C 1g/Z (or lithologic points and structural points, considering upper and lower strata and upper and lower fault plates).

Description: The point north is Sinian (Z) blue-gray phyllite mixed with metamorphic sand ... without mineralization and alteration. Occurrence: 140 ∠ 40. Southern Yunnan is gray-white thick layered chronological conglomerate (C 1g) of Guanshanling Formation of Lower Carboniferous ... without mineralization alteration. Frequency of occurrence: 135 ∠ 56. The two are in angular unconformity contact.

Structure: In the Sinian System (Z) about 5m north of the unconformity surface, a structural fracture zone with a width of about 2m is seen, with lenticular arrangement of rock fractures and extremely developed flow cleavage structure, forming a negative landform-gully on the landform. Could be a thrust fault. No mineralization or alteration was found. Number of occurrences: 296 ∠ 63.

Fold: ...

Mineralization: …

Others: geological descriptions such as hydrology, geomorphology and Quaternary geology. ...

Specimen: write directly outside the right line.

B001——1(display sample)

GP00 1— 1 (spectral sample)

B00 1— 1 (Zhang)

Sample: h001-1(chemical sample)

(There must be a blank line here)

Between points:

(1)d 00 1→ 50 meters northeast

Gray-white medium-thick layered gravelly quartz sandstone ... without mineralization and alteration.

(2)50m→ northeast 150m

Gray-white medium-thick layered seasonal coarse sandstone ... without mineralization and alteration.

Measure the occurrence of rock stratum at130m 165 ∠ 38.

(3)150m to D002

Gray-white medium-thick layered timely sandstone. No mineralization and alteration.

(There must be a blank line here)

Contents of route summary (on new page)

(1) Purpose: Geological mapping (surface scanning), special geological and mineral survey or geological understanding practice, achievements or failure degree.

(2) Workload: route length, total number of observation points, observation points of different nature, sample type and quantity.

(3) Geological achievements: comprehensive analysis of various lithology and rock assemblage characteristics, ownership, contact relationship, structure, mineralization, alteration and their changes of rock mapping units; This practice is mainly to understand the geological phenomena seen along this route, including the identification of the characteristics of geological phenomena and the causal relationship with geological processes.

(4) Suggestion: If it can be used as a place to control the section of rock mapping unit and collect supporting samples.

(5) Main geological problems: explain the weather, vegetation, traffic, humanities, work, etc. that affect the quality of route geological survey.

Some explanations

(1) Writing and drawing must be done with an H-3H pencil in the field. After indoor sorting, the data recorded every day (point number, orientation, occurrence, specific content of mineral components, etc. ) ink with a black ink pen. Samples should be painted with paint strips, numbered and classified, and sample labels and sample lists should be filled in.

(2) The summary of the route and the observation record of the next day should start a new page. The record book shall not record anything irrelevant to the field geological survey.