Geological mapping in the Owari area, Japan
Preface
1
Outline of Geology (Link)
2
Geology
(Link)
3
Geological mapping (Link)
4
Practice course (Link)
5
Radiation dose survey (Link)
6
Water quality survey (Link)
7
Geographical Information System (Link)
Preface
This
is prepared for a person who want to study geological mapping by oneself. Model field area is selected from the
Owari area. Some examples of
practical mapping are shown in the following chapters.
1.
Outline of Geology
Fig.
1-1 Geological map
The areas of III to X are the geological maps in Geologic guide for Hiromi Rail Line.
Geologic
guide for HIROMI Rail Line, http://y95480.g1.xrea.com/hiromi_line_geology.htm
Cenozoic;
a, Alluvium; t, Terrace depoists; N3cg, Sandy gravel; N1ss, Miocene sandstone
and mudstone; N1v, Miocene tuffaceous sandstone and conglomerate
Mesozic;
gK, Granite; Jss, Sandstone and mudstone; Jms, Mudstone; Jch, Chert
|
Geologic age |
Geologic division |
Abbr. |
Lithology |
Geological history |
|
Quaternary Holocene Pleistocene |
Alluvium Gentle slope deposits Mudflow deposits Terrace deposits |
(a) (s) (m) (t) |
Gravel, sand and mud Gravel, sand and mud Gravel, scoria and mud Gravel and sand |
Alluvial plain Volcanic detritus Terrace |
|
Neogene Pliocene Miocene |
Toki Sandy Gravel F. Nakamura Formation Hachiya Formation |
(N3cg) (N1ss) (N1v) |
Gravel and sand Sandstone and mudstone Pyroclastic rocks |
Terrestrial Terrestrial Terrestrial volcanics |
|
Paleogene |
|
|
|
|
|
Cretaceous |
Granite |
(gK2) |
Granitic rocks |
Felsic magmatism |
|
Jurassic Triassic Permian |
Mino Complex Kamiaso Unit |
(Jms) (Jss) (Jsi) (Jch) |
Mudstone with clasts Sandstone and mudstone Siliceous mudstone Chert |
Melange Sedimentation Sedimentation Sedimentation |
Based on
Yoshida and Wakita (1999).
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2．Geology
2．1 General remarks
The district covers the border area of Aichi and Gifu Prefectures
and is topographically occupied by the Mino Mountains in northern half and the
Nobi Plain in southern half. The
Kiso River runs from northeast to southwest in northern area.
The Mino Mountains consist of Mino Sedimentary Complex and the Nobi
Plain is floored with Middle to Late Pleistocene and Holocene sediments. Small granitic bodies in Late Cretaceous
age are intruded into the Mino Complex.
The Early Miocene Hachiya and Nakamura Formations and Early Pliocene
Toki Sandy Gravel Formation overlie the complex in the hilly region and
underlie Pleistocene and Holocene deposits in the Nobi Plain.
2．2 Geology
Mino Sedimentary Complex (Jch, Jsi, Jss,
Jms)
The Mino Sedimentary
Complex of Jurassic to earliest Cretaceous age is the oldest formation in this
guide area. The complex in this
guide is tectonically characterized by the assemblages of the tectonic slices
that are composed of siliceous claystone (Late Permian to Early Triassic),
bedded chert (Middle Triassic to Early Jurassic), siliceous mudstone (Middle
Jurassic), alternation of sandstone and mudstone, and massive sandstone (Middle
to Late Jurassic).
Cretaceous Granite (gK2)
The granitic rocks crop out south of the Mitake station and east of
the Haguro station. They may belong
to Cretaceous Naegi Granite, Sanyo Zone.
They may be petrographically granite to granodiorite. K-feldspar phenocryst shows ENE-WSW
direction and gentle plunge in lineation structure in the Mitake area.
Upper Cenozoic (N1v, N1ss, N3cg,
t, s, a)
The upper Cenozoic in this guide are divided into the Lower
Mizunami Group, the Lower Pliocene Tokai Group, Middle to Late Pleistocene
sediments (mostly terrace deposit), and Holocene alluvial sediments.
The Mizunami Group is divided into the Hachiya and Nakamura
Formations in ascending order. The
Hachiya Formation consists chiefly of andesitic pyroclastic rocks. The U-Pb age in zircon is 22.38±0.17Ma
in the lowest part of the formation.
The Nakamura Formation is mostly composed of interbedded sandstone and
mudstone. These formations are of
non-marine origin.
The upper sediments of the Tokai Group are alluvial fan origin and
called the Toki Sandy Gravel Formation.
It is composed of gravel and sandy gravel. Zircon in this formation gives
3.94±0.07Ma of U-Pb age and 3.97±0.39Ma of fission track age.
Middle to Late Pleistocene sediments can be divided into gravelly
terrace deposits and mudflow deposits. The terrace deposits are
subdivided into a few deposits in the Seamless Geologic Map of GSJ but will be
described as only terrace deposits in this guide. The mudflow deposits may be originated
from the Kiso-Ontake Volcano.
Holocene alluvial sediments are made up of gravel, sand and mud. Most of
them are valley bottom plain deposits.
2．3 Mineral resources
Manganese ore is embedded in the chert of the Mino Complex. Small manganese mines were once operated
in the mapped area and were all closed by the end of the 1970’s.
---------------------------
3. Geological mapping
The geologic map shows the
distribution of rocks and strata with a color and a design on the topographical
map. It is a required for mineral prospecting, engineering and disaster
prevention.
Preparations for a geological survey:
Carry the rucksack containing some materials on your back for being both hands
free. The tools for geological mapping are a map, a notebook, writing
implements, a hammer, a clinometer and a loupe (or insect glasses). A plastic
bag or an old newspaper may be useful for sample collections.
A geological survey: Observe
geological feature of strata and rocks. You write down the location name in the
notebook and the location point on the map. You write latitude and longitude if
you can know. You should measure strike and dip of strata of a sedimentary
rock.
Strike and dip: You will distinguish
the border of the stratum in difference of grain size and composition. The
boundary surface is called a stratification plane. The direction, an
intersection of the stratification plane and the horizontal plane is a strike
and the angle between two planes is dip.
A geologic map: If there are many
strata data, you can draw a geological feature border by freehand. Mostly you
presume a geologic border geometrically.
Fig. 3-1 Strike and dip of the
strata
Fig. 3-2 Dipping of strata.
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4.
Geologic mapping courses
4.1
Strata
Area;
Kani-Forest Park
Fig.
4-1-1 Mudstone
Fig.
4-1-2 Route map
Legend;
sd, Sandstone; md, Mudstone; sd_md, Sandstone and Mudstone; gravel, Gravel; red
dash line, mapping route.
(North)
<‐‐‐‐‐‐‐‐‐‐‐> (South)
Gravel (unconformity)
Mudstone
Sandstone
Sandstone and
Mudstone
Sandstone
Fig.
4-1-3 Geologic map
Legend;
sd, Sandstone; md, Mudstone; sd_md, Sandstone and Mudstone; gravel, Gravel.
A
geologic boundary is almost parallel to contour lines due to low dip of a
stratum.
4.2
Fold structure
Bent rock strata is fold.
Anticline A fold of rock layers that is convex upwards.
Syncline A fold of rock layers that is convex
downwards.
Area; West of Tajimi and Koizumi
stations
Fig. 4-2-1 Route map
Legend; ch, Chert; ss_ms, Mesozoic Sandstone and Mudstone; gravel,
Gravel.
(North) N-NW dipping of the strata
(Anticline)
(South) S-SE dipping of the strata
Fig 4-2-2 Geologic map
Legend;
ss_ms, Sandstone and Mudstone; ch, Chert; red line with arrow symbol, Anticline
axis.
Micro-folding
Micro-folding
occurs in chert around Mt. Ikeda-Fuji.
Fig.
4-2-3 Micro-folding
Near
Mt. Ikeda-Fuji.
4.3
Deducing geological structure from strata distribution
Geological
structure can be deduced from the distribution of strata.
Area;
Kasugai three tops
Kasugai
three tops are Mt. Dojyu-san, Mt. Otani-san, and Mt. Miroku-san in order from
south to north.
Fig.
4-3-1 Route map
Legend;
ls, limestone; ch, chert; ss_ms, sandstone and mudstone; gr, granite; gravel,
gravel.
Fig.
4-3-2 Geologic map around Kasugai three tops
Legend;
ls, Limestone; ch, Chert; ss_ms, Sandstone and Mudstone; gr, Granite; gravel,
Gravel; a_t, alluvium and terrace deposit.
Geological
boundary near Mt. Dojyu-yama in SE part of the map can give geological
structure. The boundary crosses
350m contour. Two crossed points
run one direction, strike direction.
Assume a line with a point crossed 250m contour parallel to the strike
direction. Direction normal to this
line is dipping direction. Distance
in horizontal plane between 350m and 250m is 200m.
Therefore,
tan D = (350 – 250)/200 = 0.5, D is dipping angle.
D
= 27°, dipping direction is SSE.
General
trend of the strata is ENE-WSW in strike and 27°SSE in dip.
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--------------------------
5. Radiation dose
survey
Radiation dose
is different in rock types. For
example, dose of granites is generally higher than dose of sedimentary
rocks. A dose meter for home
environment is cheap and can be got in a drugstore. In this survey, “Air Counter S” is used.
Area; Tokai
Natural Pass around Jokoji station, JR.
Fig. 5-1 Survey result. Date; April 20, 2024.
Unit; μSv/h.
Fig. 5-2 Relationship with geology
Geologic map referred to GSJ
seamless map.
Geology; Jch，Chert; Jss，Sandstone; Kgr, Granite.
Granite area shows high dose value.
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-----------------------
6.
Water quality survey
Handy
survey instruments, LAQUAtwin meters, Horiba, are used. Data of pH，conductivity
(EC) and calcium ion (Ca2+) are shown in the following.
Example
1 Area of Owari-Fuji, Iruka-ike lake and Mt. Hongu
Map;
http://y95480.g1.xrea.com/water_owari_map.jpg
Survey
result example
|
|
River Gojogawa |
Owari Fuji，Ginmei-sui |
Owari Fuji，Kinmei-sui |
Irukaike Pond |
Mt. Hongu，N point |
Mt. Hongu，Miyaike |
|
Date |
2023/11/23 0835 |
2023/11/23 0925 |
2023/11/23 0940 |
2023/11/23 1040 |
2023/11/23 1210 |
2023/11/23 1240 |
|
pH |
7.4 |
7.6 |
7.5 |
7.2 |
7.3 |
7.3 |
|
EC (µS/cm) |
231 |
39 |
49 |
112 |
36 |
61 |
|
Ca ion (ppm) |
58 |
5 |
8 |
26 |
4 |
25 |
|
Dose (µSv/h) |
0.06 |
0.06 |
<0.05 |
0.06 |
<0.05 |
0.08 |
|
Water T. (℃) |
10 |
10 |
10 |
15 |
10 |
9 |
Example
2 Area around the Nagoya University of Economics
Map;
http://y95480.g1.xrea.com/water_nue_map.jpg
Survey
result example
|
|
1Drain |
2Drain，Grave |
3R.Gojo before drain confluence |
4R. Gojo after drain
confluence |
6Rice field, Ashihara |
7Rice field, Shrine |
8Pond |
|
Date |
2023/6/20 PM |
2023/6/20 PM |
2023/6/20 PM |
2023/6/20 PM |
2023/6/20 PM |
2023/6/20 PM |
2023/6/20 PM |
|
pH |
7.0 |
7.5 |
7.5 |
7.4 |
8.0 |
9.4 |
8.2 |
|
EC (µS/cm) |
166 |
173 |
139 |
141 |
211 |
181 |
78 |
|
Ca ion (ppm) |
47 |
58 |
35 |
37 |
55 |
42 |
22 |
|
Water T. (℃) |
|
|
|
|
|
|
|
Variation
of pH in rice fields
|
|
6Rice field, Ashihara |
7Rice field, Shrine |
8Pond |
|
Date |
2023/6/26 0805 |
2023/6/26 0810 |
2023/6/26 0815 |
|
pH |
6.9 |
6.8 |
7.2 |
|
|
6Rice field, Ashihara |
7Rice field, Shrine |
8Pond |
|
Date |
2023/6/26 1005 |
2023/6/26 1010 |
2023/6/26 1015 |
|
pH |
7.3 |
7.0 |
6.8 |
|
|
6Rice field, Ashihara |
7Rice field, Shrine |
8Pond |
|
Date |
2023/6/26 1150 |
2023/6/26 1155 |
2023/6/26 1200 |
|
pH |
7.6 |
7.7 |
7.4 |
|
|
6Rice field, Ashihara |
7Rice field, Shrine |
8Pond |
|
Date |
2023/6/26 1400 |
2023/6/26 1405 |
2023/6/26 1410 |
|
pH |
7.8 |
8.3 |
7.0 |
|
|
6Rice field, Ashihara |
7Rice field, Shrine |
8Pond |
|
Date |
2023/6/26 1555 |
2023/6/26 1600 |
2023/6/26 1605 |
|
pH |
8.0 |
8.4 |
7.6 |
Summary of pH variation at Locality 7,
2023/6/26
|
2023/06/26 |
|||||
|
Time |
8:10 |
10:10 |
11:55 |
14:05 |
16:00 |
|
Minutes(8:00=0) |
10 |
130 |
235 |
365 |
480 |
|
pH |
6.8 |
7 |
7.7 |
8.3 |
8.4 |
Interpretation
Phytoplankton
and the alga breathe by night, and they photosynthesize in the daytime.
Breathe;
Organic material ＋ O2 → CO2 ＋ H2O ＋ Energy
Photosynthesize;
CO2 ＋ H2O ＋ Sun energy → Organic materials ＋ O2
Carbon
dioxide occurs when they breathe, and pH falls because underwater carbon
dioxide increase.
Underwater
carbon dioxide decreases to use carbon dioxide by the photosynthesis, and pH
rises.
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----------------------
７ Introduction to GIS
Targets in this
data processing
・Location point is defined on the map by
coordination (GPS data).
・Input each point analytical data.
・Each point data is distinguished by color
and/or size in the map.
7.1 Geographical map
Your map should be scanned. Coordination of some points in the map
should be referred.
・Geographical map in Geographical Survey
Institution
https://maps.gsi.go.jp/#6/37.640335/140.119629/&base=std&ls=std&disp=1&vs=c1g1j0h0k0l0u0t0z0r0s0m0f0
Coordination can be known in this map. Coordination of the center point (center
of cross mark) can be known in Lower left part.
・If this map is not available, choose
the map in the following GSI site.
https://www.gsi.go.jp/tizu-kutyu.html
7.2 GIS (Geographical Information System)
soft wear
TNT mips of Microimages
Download TNT mips of Microimages
http://www.microimages.com/downloads/tntmips.htm
If we use small data size, we can use freely
this soft wear.
7.3 Map Raster
The map image should be raster sytle.
Menu bar
[Main Image Geometric Terrain Database
Script Tools]
↓(Pull down)
Display
Edit
Georeference
Process List
Import
Export
TNT atlas
Exit
Open Import.
「Select Files」
Select a file of the map.
Push “+”, then “OK”.
Next
「Import from …」
Push “Import”, then OK.
Raster map is made.
Folder, File and Object should be named.
This new raster style map runs in GIS.
7.4 Georeference
Menu bar
[Main Image Geometric Terrain Database
Script Tools]
↓(Pulldown from Main)
Display
Edit
Georeference
Process List
Import
Export
TNT atlas
Exit
Open Georeference
Select the object and mark +.
「Coordination Reference System」, 「OK」
「Select georeference model」, 「OK」
「Georeference Input View」
Put + (Cross mark) to the point which was defined
coordination.
Input coordination data, and push 「✔」. The other points should be also
defined. Save in the file menu.
7.5 Input the point data on the map
Map will be shown.
Menu bar
[Main Image Geometric Terrain Database
Script Tools]
↓(Pull down)
Display
Edit
Georeference
Process List
Import
Export
TNT atlas
Exit
Open “Edit”
「Editor – Layer
Manager」
In Layer Manager,
Push +Mark Symbol (Add reference object)
Select object to display
「Editor View
and Layer Manager」
Select file and then select objects (raster
style map) and vector object (new).
Push OK, then open “Layer Manager” and “Editor – View”
In Layer Manager, Select “vector object” and push a pencil mark button.
“Vector Tools –
Point” appears.
In “Add Element”, select point (+□).
In case of having GPS data, Input
coordination data in “Add Point Parameters”.
Put data into Longitude and Latitude
(decimal). Then push “Add”.
For example,
Plant3 (2017, G4 206): 47_53_55.4, 106_52_01.9 pH
6.76, EC 28.9, Ca 52.2, NO3 7.2
Latitude:47+53/60+55.4/3600
=47.883+0.015=47.898,
Longitude:106+52/60+1.9/3600
=106.867+0.001=106.868
In case of having no GPS data, use Manual
Entry.
Push allow mark (↖).
Cross mark (+) should be on the point in the
map.
Then push “Add”.
データ入力
個々の点の属性を定める。点に番号や名前をつけ，その点のデータを入力する。
編集画面(Editor-Layer Manager)でオブジェクトの「＋」を押すと各種のベクター要素(点，線，ポリゴン，ノード，ラベル)が出てくる。
誤操作がないよう，点以外の要素の「↖」を閉じる。
点(Points)の「＋」を押すと，表のマークが出る。
Input data in a table
In Editor-Layer Manager
Push “+” of the
object
(+)
(Vector object mark)
(+)Points
Lines
Polygons
Nodes
Labels
Push “+” of points
Creation of New Table
Click the square point (- ↖ ■ 5points)
Menu｛Mark All ・・・ New Table ・・｝
Select New Table
User Defined、Next
Input Name of a table, e.g., GEO. Next.
Data Select “Exactly one record for each element”, Next, Finish.
Table Properties
Table
Field
Add new field (Yellow sandwich shape)
Open new field
Input style, select Unicode.
Add data space.
Push next table mark「✔」, then Table appears.
Push “Arrow mark” for
the new point in the Editor View.
Input data of the new point.
Showing
Data symbol (size and color) is shown
automatically on the map.
You can modify style. Push the object mark in the layer
manager.
“Vector Layer
Control”
Menu: Object Points Lines Polygons
Nodes Labels 3D
Select “Points”/ Show {By Attribute}/ Select by Attributes
or New one.
For example, Color by “spread”. Size “spread”, “2.0” to “5.0” millimeters.
Size is shown in the map
scale, for example, at scale “User defined”, “1:1000000”.
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