Geological Model for Mineplan Method to Support Economic Activities

in a Remote Island

Kurniawan

1,2

, Tien Veny Vera

and Nindyo Cahyo Kresnanto

Samgeobor Drilling Company, East Jakarta, Indonesia

Department of Civil Engineering Janabadra University, Yogyakarta, Indonesia

Keywords:

Geological model, Onyx, Selective mining.

Abstract:

Mining materials are natural resources that cannot be renewed and require a long time to form so that their

management and utilization must be wise. Mining has high economic value but is also a major cause of natural

disasters. In this study the method of investigation is by conducting a literature review, survey and investigation

of the geological and geomorphological processes that occur, then analyzing the genesis and mining activities

that are in accordance with the conditions and characteristics of the onyx marble. The onyx marble mining on

Bawean Island is manually very suitable because it is selective mining, which only takes onyx potential by not

dismantling the entire limestone so that it is more environmentally friendly. The onyx marble marketing on

Bawean Island is also not good due to the limited transportation that operates 3 times a day out / to the island

in the form of cargo ships.

1 INTRODUCTION

The types of mining materials are differentiated based

on economic value, beneﬁts and difﬁculties in obtain-

ing them. In Indonesia, based on Government Reg-

ulation number 27 in 1980, the materials are divided

into 3 types, namely excavation materials A, B and

C where onyx is included. C can be used directly as

the main raw material for industry without or little

through the processing process and does not require

an international market.

Bawean Island Stratigraphy starts from the Gelam

Limestone (Early Oligocene-Miocene) Unit, Kepon-

gan Sandstone Unit (Late Miocene-Pliocene), Bal-

ibak Volcanic Rock Unit and the youngest is an allu-

vial precipitate aged Resen(Aziz et al., 1993). Phys-

iography, Bawean Island has its own characteristics

compared to the Rembang - Madura and Kendeng

Zones which incorporate into magmatism behind the

outer arc which is likely to be built by products from

submarine volcanic activities(Van Bemmelen, 1949).

Onyx is a chalcedony coating which is a group of sil-

ica minerals (WHITTEN and BROOKS, 1976), usu-

ally layered, compact, translucent with variations of

calcite such as travertine coating having a good gloss

and usually deposited in the form of stalactites in

caves (Bates and Jackson, 1987). The deﬁnition of

onyx marble is applied to layered calcite minerals,

yellowish white, gray to reddish, translucent, crys-

talline, compact, massive, hardness of 3 Mohs scale.

There are 5 important mechanisms that can explain

how the deposition of CaCO3 and the increase in CO2

that can be dissolved in water, (1) by the increase in

temperature and evaporation, (2) by water movement,

(3) by addition of salinity, (4) by organic activity, and

(5) by pressure changes.

Onyx on Bawean Island in its formation process

is only found (Aziz et al., 1993)in a few places with

certain conditions and requires a long time so that its

existence is limited / rare and different from onyx

in other regions in Indonesia such as Tulungagung

- East Java. Bawean Island itself is an island lo-

cated on the north side of Gresik with connecting ac-

cess only in the form of ships from the Gresik pier

(East Java). Rural development issues in Bawean Is-

land have previously been compared to a similar set

of challenges in sub-Saharan Africa, particularly in

regards to inadequate infrastructure and remoteness

of markets (Booth*, 2004). The parallels further in-

clude low agricultural production, a history of supple-

mentary livelihoods supporting subsistence agricul-

ture and poverty-driven de-agrarianization (Booth*,

2004). These livelihood characteristics, which have

been associated with the shift towards ASM in sub-

Saharan Africa, are also evident in West Timor. Onyx

mining in Bawean Island has been carried out by the

Kurniawan, ., Vera, T. and Kresnanto, N.

Geological Model for Mineplan Method to Support Economic Activities in a Remote Island.

DOI: 10.5220/0009877800540057

In Proceedings of the 2nd International Conference on Applied Science, Engineering and Social Sciences (ICASESS 2019), pages 54-57

ISBN: 978-989-758-452-7

community (artisanal and small-scale mining /ASM)

and is one of the reliable livelihoods because it has

good economic value. . It is in this context that

the artisanal miner themselves trying to strategically

manoeuver a complex, dynamic in- stitutional envi-

ronment to secure their livelihoods (Bersaglio and

Cleaver, 2018). Not only did income from mining

provide a safety net when crops failed, it also acted

as an opportunity to ‘step up’, with money reinvigo-

rating farming opportu- nities and creating new liveli-

hood opportunities.(Fisher et al., 2019).

On the other hand, there are at least three factors

which contribute to the underestimation of mining’s

impact on the local economy. The ﬁrst is the exis-

tence of money ﬂows that result from the company’s

activity on the island, but which are not taken into ac-

count in the context of input–output analysis, the most

glaring example being the incomes and expenditures

of retired employees who still live in the island.13 The

second concerns the importance of the economic and

social effects that cannot even be expressed in mon-

etary terms, such as the contribution of mining activ-

ity to the preservation of the local community and the

prevention of demographic decline or migration. Fi-

nally, mining activity possesses some special charac-

teristics that cannot be embedded in the input– output

model, the most important being that it implies the

frequent development of new productive installations

(mines), as well as the restoration of old ones, hence

the accumulation of high expenditures (Tserkezis and

Tsakanikas, 2016). This research is expected to pro-

duce genetic geological models for planning mining

methods that are good and environmentally friendly.

2 METHODOLOGY

The procedure of this study is illustrated in Figure 1,

however this paper only presents geology and geo-

morphology process in order to explain onyx genetic

geological model. Base material of onyx is limestone.

The dissolution process causes changing of limestone

to onyx. The main factor: (1) Hot water, (2) Evapora-

tion, (3) hot air and (4) fracture.

The presence of underground rivers, caves, stalac-

tites, and travertine deposits is an indication of geo-

morphological processes which also greatly inﬂuence

the control of onyx formation.

Figure 1: Flowchart of study on Onyx in Bawean Island

3 RESULT

Genesis is the sequence of events in the formation

of an object in geology related to the trigger force,

namely exogenous energy (originating from outside)

that works on the surface of the earth and endogenous

energy (from the inside) that works below the surface

of the earth. The two forces that cause the formation

of various forms that exist in this earth but also there

are natural processes on the surface of the earth such

as the process of erosion, transporting the results of

erosion, transportation and sedimentation that affects.

Onyx on Bawean Island is a type of onyx marble

which is milky white, milk chocolate, gray, and red-

dish milk chocolate, translucent, crystalline, straight

wavy and homogeneous, massive and hollow, with

hardness of 3-4 Mohs scale. The difference of onyx

silica and onyx marble namely onyx silica is com-

posed of quartz, the composition of SiO2, hardness of

7 on the Mohs scale while onyx marble is composed

of calcite, composition of CaCo3, hardness of 34 on

the Mohs scale.

The process of forming onyx starts from the crys-

talline deposits of calcium carbonate carried by water

containing carbon dioxide ﬂowing into the limestone

and can convert calcium carbonate to soluble plus the

help of hot water, air heat and evaporation, stalactite

and stalagmite in the limestone cave. The metamor-

phosis process then changes the deposits to be harder

and increase density. The number of onyx spreads is

very limited compared to the extent of the surround-

ing limestone distribution because onyx which is the

result of dissolution of the limestone itself and its for-

mation is controlled by typical geological and geo-

morphological factors also requires a long time (thou-

sands to millions of years) so that onyx has high eco-

nomic value.

Geological Model for Mineplan Method to Support Economic Activities in a Remote Island

Figure 2: Onyx Genesis Process

Figure 3: Outcrop of Onyx and Limestone

Figure 4: Outcrop of Onyx and Limestone

4 DISCUSSION

Onyx quality is a combination of the properties pos-

sessed including objective genetic factors and subjec-

tive market tastes. Quality based on genetics is objec-

tive, namely:

a Scarcity where the onyx formation takes a long

time in the geological time scale, the distribution

is not evenly distributed only in places that meet

the requirements for the formation of onyx, so the

less frequent onyx is in the price, the more expen-

sive the price.

b Violence where increasingly hard onyx is increas-

ingly expensive, because the retrieval process

(cutting and forming) requires a large amount of

special and special equipment.

c Purity is deﬁned as authenticity, passivity, clean-

liness which all determine quality and price.

d The layer pattern shows the ﬂow structure and

onyx. The bawean island forms straight or wavy

and homogeneous layers, following the slope of

ancient slopes.

e Pore where onyx has a high pore level will reduce

the level of quality onyx because it is easily bro-

ken.

Quality based on market tastes is subjective,

namely:

a Beauty is determined by high aesthetics when

it has artistic and suitable properties when com-

bined with other objects in a layout arrangement.

The smoother the reﬁnement, the higher the qual-

ity and the more expensive the price.

b The larger the size of the onyx, the higher the

quality and the more expensive the price.

c Color is closely related to beauty because it usu-

ally depends on the nature and tastes of each per-

son.

d Complexity where the more complex the shape,

the higher the quality and the more expensive the

price because it requires special expertise and the

time and cost of production.

Onyx marble mining activities on Bawean Island

are still manual work by man (human) and simple

equipment that has the character of ”selective mining”

where mining concentrations are only on the onyx

marble excavation material whose unique position is

not to spread across limestones but only in certain

places so that damage to limestone or soil around it

can be minimized, making it more environmentally

friendly. In addition to positive values, manual min-

ing has a negative value, namely the risk of workplace

accidents is very large, this is due to the lack of equip-

ment and operational security and safety (K3) stan-

dard in the mine location.

The marketing of onyx marble in the form of raw

materials as well as those that have been processed at

this time is still minimal due to inadequate access to

the entry and exit of goods to Bawean Island where it

is only served by cargo ships operating 3 times a week

ICASESS 2019 - International Conference on Applied Science, Engineering and Social Science

5 CONCLUSIONS

The genetic geology model is very important in the

interpretation of determining the presence of mineral

deposits, the geological and geomorphological pro-

cesses that make up deposits of minerals, the asso-

ciation of mineral deposits and the time of formation

of mineral deposits in the geological environment.

Factors that inﬂuence the genetic geology model

are thin volumes of sediment, so descriptive infor-

mation is needed to describe the formation of sedi-

mentary complexes through drawing or sketching the

onyx formation process, site of formation and other

factors that play a role in the formation of onyx.

The genetic geological model illustrates the re-

lationship of each data and fact in the ﬁeld to the

geological environment, namely geological and geo-

morphological processes in the form of images and

formation sequences without using long explanations

such as descriptive geological models, but only a short

description of the image.

The geological model of onyx genetic is useful in

knowing the formation process and determining min-

ing activity planning, namely in determining the di-

rection of mining as well as selective and appropriate

manual mining methods where this will have a direct

impact on the spatial layout planning of Bawean Is-

land.

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Geological Model for Mineplan Method to Support Economic Activities in a Remote Island