Báo cáo thực địa Ba Vì

Clastic sedimentary rocks Sedimentary rocks are the product of 1 weathering of preexisting rocks, 2 transport of the weathering products, 3 deposition of the material, followed by 4 comp

Geology of the Ba Vi group and Kien An – Do Son – Hai Phong group

A field trip report of K60 Geology student.

1.1 Clastic sedimentary rocks

1.2 Bio-chemical sedimentary rocks

2 Magmatic formations

2.1 Extrusive rocks

2.2 Instrusive rocks

Contents

1 Objectives

* The fiel trip in Ba Vi and Do Son, Hai Phog city has lasted 7 days from 25/07/2016 to 31/07/2016 With purpose of applying the knowledge that student has learned in the field With the guidance of Pr Ta Hoa Phuong and Dr Nguyen Van Huong , the field trip took place by a nice way

* Main missions of the field trip:

- to know how to note field book

- know how to indentify, distinguish geological, formation and structural element in the field

- to know how to define outcrop location and describe as outcrop

- to know how to use geological compass

A Introduction

∗ Ba Vì National Park (Vietnamese: Vườn quốc gia Ba Vì) is a national park located 48 km (30 mi) west

of Hanoi, Vietnam The park is 7,377 ha (18,230 acres) in area, and is located in the Ba Vì

mountain range The park has rich and diverse tropical and subtropical species of flora and fauna

∗ Ba Vì National Park is located in Ba Vì District of Hanoi and two districts of Hoà Bình Province, namely Lương Sơn and Kỳ Sơn The Park is situated on a mountain range running north-east and south-west with its peak at Vua Peak of 1,296 m and Tản Viên Peak of 1,226 m and Ngọc Hoa Peak of 1,120

m

2 Natural Conditions of Ba Vi and Do Son

∗ Kiến An is an urban district of Hải Phòng, the third largest city of Viet Nam Kiến An district is 29.6 km2 in area, and is located in Hải Phòng city (Figure 2)

∗ Hải Phòng is a coastal city located at the mouth of the Cấm River, in Vietnam's northeastern coastal area, 120 km east of Hanoi The Bính Bridge crosses the Cấm and connects the city with Thuỷ Nguyên District It has a total natural area of 152,318.49ha (2001) It borders Quảng Ninh Province to the north, Hải Dương Province to the west, Thái Bình Province to the south, and the Gulf of Tonkin to the east Bạch Long Vĩ island, Cát Bà Island and the Long Châu islands,

located in the Gulf, are also administered as part of the city The city is located in a convenient position for transportation to domestic provinces, and international networks via road network, railway, sea routes, inland waterway and air

∗ 1 Sedimentary formations

1.1 Clastic sedimentary rocks

Sedimentary rocks are the product of 1) weathering of preexisting rocks, 2) transport of the

weathering products, 3) deposition of the material, followed by 4) compaction, and 5) cementation of the sediment to form a rock

B Geological formations

Đồ Sơn group including the Vạn Cảnh (D1-2-D2e vc), Dưỡng Động and Vạn Hương (D2gv vh).

This formations found in Bà Đế temple, Xóm Chẽ area, Hòn Dấu resort

At Bà Đế temple, Northeast pole of Đồ Sơn peninsula, Hải Phòng,students can see a cliff with 25m height and 50m long (from Bà Đế temple to 295 Hospital or healthcare facility) – Vạn Cảnh

formation It also has expression of living organism

1.1.1 Do Son area

A cliff at Ba De Temple about 20m height

∗ At Hòn Dấu resort, Hải Phòng, students also can see sandstone, siltstone, shale as same as Xóm Chẽ rocks (Terrigenous sediment) At first observation Hòn Dấu resort is an artificial expression about 100m height.

b Duong Dong Formation

Not appear in the region

c Van Huong Formation

At Bà Đế temple, Northeast pole of Đồ Sơn peninsula, Hải Phòng far from 1.5 km is Vạn Hương

formation ( go with sealine)

∗ The upper layer at Xóm Chẽ, Hải Phòng contain thick – beded layer follow one direction– show the

ocean enviroment

∗ Some charateristic of Vạn Hương formation: Almost they have bigger grain-side than Vạn Cảnh formation Geologist can find quartzitic sandstone easier than Vạn Cảnh formation Fossil appear at this place is Lepidodendropsis ( Vietnamese name: Hóa thạch cây dạng vảy)

The boundary between Vạn Cảnh and Vạn Hương formation (at Tổ Chẽ, Hải Phòng)

∗ Terrigenous sediment in this area in part of Kien An formation ( Nguyen Quang Hap 1967) It has been dated as Silurian and exposed in the Đại Hoàng, Phủ Diệm, Voi, Phủ Liễn, Xuân Sơn ( Kien

An, An Lao, Hai Phong City)

∗ The setting of this formation is: about 550m thick Including:

− sandstone, quartz, siltstone with interbeds of marl

- thick- bedded limestone and marl with some interbeds of marl shale

1.1.2 Kiến An area

Kien An Formation

1.1.3 TRUNG HA BRIDGE AREA

- In Ma Chay Hill area : Neogene conglomerate :the size is different, sorting is poorly – sorted, the composition include in quartz, sandstone and claystone, shape: rounded The common color is gray, brown The arrangement has orientation cross

Think in the past : formed in condition that water current flowed though The age of conglomerate is older than formation

- Cliff near Da river bank : Neogene conglomerate: the size is small, well-

sorted, the age of conglomerate is the same as formation

- Gas sation in Thai Hoa commune: hard coal have been foliated with 6m height, black- shinny

Trias age

1.1.4 XOM QUYT AREA

- Cliff on the way to see Da ONG: claystone have been foliated Composition include in

sandstone mixture foliation claystone and

floliation limestone The color from black- gray

to light gray

Sipay formation, Permian age

1.2 Bio-chemical sedimentary rocks/ Đá trầm tích sinh hóa

Formed by water-soluble substances deposited down and coalesce Small grains, mineral composition that is relatively simple and more uniform uniform clastic sedimentary rocks Limestone is mainly

1.2.1 Núi Voi Area

Composed of limestone with some interbeds of cherty shale At the lowest of Con Voi formation, students can see fossil: tetracoral and favositid fossil Most of Con Voi information are fossil and foraminiferal

In this area primarily limestone Medium-bedded, thick-bedded

Episode 5: Clean limestone no limestoneEpisode 4: Sand limestone

Episode 3: Siliceous limestoneEpisode 2: Dark grey limestoneEpisode 1: Dolomit limestone

Tetracoral fossil in Nui Con Voi ( hóa thạch san hô 4 tia)

Phtanite in Nui Con Voi (đá phiến sillic)

Con Voi Formation

1.2.2 Hon Che Area

Here is pure limestone , thickness of about 150-200m, including, in the lower part, black- grey, medium-bedded to massive, fine-grained limestone, dolomitized in some places

Limestone in Hon Che

2 Magmatic formations

2.1.Extrusive rocks/ Đá magma phun trào

2.1.1 Khoang Xanh Area

In this area, students see agglomerate (dăm kết núi lửa) Above the stone is located Siamese cross systemBasalt little Pebble, boulder is primarily

In the source, the flow of power, the size grows glicial boulder

Basalt in Khoang Xanh

2.1.2 Ba Vi National Park

The stones were weathering -> red, lamination

Claystone but harder beacause of the oxit Fe

Greater than 1300m basalt floors Foliation of basalt slabs weak

There are oriented parallel, Extrusive rock crystal with original architecture -> Eruptive activity in the past

Here, extrusive rocks exposed in blocks, laminated signs

Extrusive rocks here resemble Yen Ngua Hill, phanerocryst geometry

Conglomerate with phanerocryst architecture is original product of volcanic activity -> Volcanic bomb

Conglomerate in Nui Voi

Volcanic bomb

2.2 Instrusive rocks/Đá magma xâm nhập

− Xom Quyt

Observed dark ultramafic rocks containing fiber

If it is light-coloured stones, many quartz

If it is dark stone, little quartz

Instrusive rocks in Xom Quyt

C- GEOLOGICAL PROCESSES

∗. a/ Weathering

∗. Weathering is one of the most common expression of exogenous geological process

which contain three main types: chemical weathering, physical weathering and biological

weathering.

∗. In Ba Vi group, there is a expression of weathering process that show exogenous

geological activity:

∗. + Weathering crust: A place from Đà river (observation place)

∗. to Development center of Ba Vi National Park From a huge and hard rock is wrapped by

weather mud – clay layer, the rock is transformed to laterite (lower than chemical

weathering and to mechanical weathering

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∗ In Kien An – Do Son, Hai Phong group, there are some

expression of weathering processes that show exogenous

geological activity:

That is the process limestone and marble is eroded by rain

contain carbonic acid

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There’s another type of weathering: oxidation For

example: Pyrite in Minh Quang pyrite ore mine is

weathered into iron oxide that is the factor changing

the color of rock and soil here to red And the

oxidation Fe of basalt rock at Ba Vi National Park

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b/ The geological activity of the sea:

There are 3 geological activities occur due to the sea

wave: transportation, abrasion, and deposition Like

the stream, Wave with high energy brings materials

dash coastal In there, abrasion process strongly

happen, hence sea shore will be destroyed gradually,

creat sea platform

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Beside, the rock layer leaning toward the sea tends

to be less vulnerable to erosion than the layer

leaning toward the shore because the cracks of

rock layer do not expose directly sea water cannot

be trapped inside to destroy the rock Or else, the

layer of rock will be eroded and collapsed,

forming sea cliff

Rock incline to ward the sea

c/ Geological activities of organism:

The organism did their job toward geological

process, for example in Do Son, it can be observe

that there’re a lot of oyster as well as crab parasite

on the rock Wich result changing physic and

chemical properties of rock

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2. Endogenous geological process

a/ Extrusive activity:

Throughout the trip, a lot of evidence of vocano activities can be clearly

seen, especially in Ba Vi (Vua and Tan Vien peak) Most of the layer in

this area form from vocanic eruption and vocano bomb The vocano

material was blasted and blowed up by volcanic eruption, then be

transported by the wind then fall down, If the ejected materials are

compacted and cemented into the rock, it will be called "tuff".

Sometime, volcanic bomb explode to strong enough to destroy the

pre-existing material on bedding rock and material from the vent as well, this

mixture blowed up and fall down, con solidated and formed

“agglomerate”, which can be seen many in Khoang Xanh

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b/ Deformation:

∗ Rocks change their shape and

volume when they are subjected

to stress Stresses are caused by

forces that are exerted on the edges

or interior of a material A wide

variety of physical processes exert

stresses on rocks Temperature

changes cause thermal expansion

and contraction that can cause rocks

to fracture Wetting and drying

similarly can induce or enhance rock

fractures On a large scale,

horizontal plate movement exerts

lateral (horizontal) and vertical

Rocks exhibit two principal responses to stresses that

are exerted on them At high temperatures and

pressures, many rocks flow in response to

stress Alternatively, They may deform like

a brittle material, meaning that they fracture and

fault, or create joint

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normal fault in Hau Dau resort

Another sign of fault in Hon Che mountain.

Metamorphism is a process of transforming a pre-existing rock into a new one by high temperature and pressure This phenomenom can be seen seaily at Hon Che mountain, in which limestone crystalline into marble

GEOLOGICAL RESOURCES

1 Building material

They are limestone, pebble, gravel, sand and other

material in brick

+ Limestone: Kiến An, Hải Phòng is place

containing big reserves – a main material of

cement for the building Black or grey limestone

with hard texture is used for intercommunication

buildings and irrigation system

+ Quartzitic: Good material for building which can

find in Kiến An – Đồ Sơn, Hải Phòng

+ Other is rocks at Tổ Chẽ ( Vạn Cảnh and Vạn Hương formation

2 Laterite

Laterite for Buildings, statues

There mainly in Binh Yen, Ba Vi