Controlling Groudwater System by Pattern Fracture

Home

Search

Collections

Journals

About

Contact us

My IOPscience

Controlling Groudwater System by Pattern Fracture Approach in Subsurface Volcanic Deposit: Mt.Salak- Mt.Pangranggo, West Java, Indonesia

This content has been downloaded from IOPscience. Please scroll down to see the full text. 2016 IOP Conf. Ser.: Earth Environ. Sci. 29 012029 (http://iopscience.iop.org/1755-1315/29/1/012029) View the table of contents for this issue, or go to the journal homepage for more

Download details: IP Address: 172.245.146.225 This content was downloaded on 20/01/2016 at 13:21

Please note that terms and conditions apply.

International Symposium on Geophysical Issues IOP Conf. Series: Earth and Environmental Science 29 (2016) 012029

IOP Publishing doi:10.1088/1755-1315/29/1/012029

Controlling Groudwater System by Pattern Fracture Approach in Subsurface Volcanic Deposit: Mt.SalakMt.Pangranggo, West Java, Indonesia Cipta Endyana1, Hendarmawan2, Emmy Sukiyah3, Irwan Ary Dharmawan4 1,2,3

Faculty of Geology, Universitas Padjadjaran, Indonesia Departement of Geophysics, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Indonesia

4

E-mail: [email protected] Abstract. In general, the volcanic region has high potential of water resources. However, volcanic field are very complex in structure and texture of rock compared with sedimentary rocks. They also have different porosity in type and distribution, with the spread of the highly different within a short distance. Consequently, groundwater in this volcanic area is quite difficult to predict groundwater flow. Those rocks should be identified as vertical and lateral spreading. In fact, the groundwater a is not flowing in the volcanic rock pores only, but also flow in fractures that developed by the volcanic and tectonic processes. Ciherang area which is located between Mount Salak and Mount Gede-Pangrango and bypassed by tectonic faults, has a complex fracture pattern. The result of this fracture pattern research indicated that at least four pattern of fracture systems were developed. All fracture patterns were suggested in relation with the imposition of volcanic rocks. Groundwater in these fractures have to consider for water resources calculation. Therefore fracture media has become one of the important parameters in the calculation of water resources. The modelling of subsurface volcanic deposit was developed by resistivity value of rock deposits. They can describe the distribution of volcanic deposits until 150 meters below surface. The fracture that constantly developed up to certain depth will be exposed by contrast enhancement of resistivity model of rock deposits. Delineation of fracture pattern will be known which each fracture pattern is associated with the flow of groundwater. Furthermore, there are also fractures are influenced by tectonic faults, and fractures caused by both of the processes. Fractures with high intensity indicated direction of porous media have a trend with relatively north-south direction and the fracture which is constantly up to certain depth is indicated as a pathway of groundwater flow, but several fractures which are affected by tectonic regional process will become a barrier of groundwater flow. To control the validity of fracture development, the stable isotope deuterium and oxygen content were used in groundwater as well as flowing water between one fracture systems to other systems.

1. Introduction Mount Salak is a mountain that formed by volcanism process in quaternary period. This volcanic area has a high potential of groundwater. Mount Salak has a large content of groundwater caused by high fracture intensity. The fractures in volcanic areas have contributed for great potential groundwater resources Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd 1



Fractture patterns mapping is important to o gain knowlledge of the fracture systtem prevailinng in this area, both of whichh are influennced by tectoonic fracturees or pattern n formed on the clottingg time of D et.al in i his paper on methods of structure mapping thaat control volcanicc rocks. As reevealed by Denny the aquifer, the fraccture as a strructural elem ment of regional or locaal geology sttrongly influuence the o groundwatter recharge zone z [1]. determinnation and thhe presence of Somee results proovide two-dimensional form f of lineaaments in thhe valleys an nd hills of aanalog or digital m maps, satellitte imagery annd DEM, wiith lineamennt analysis ussed as refereence to deterrmine the cracks inntensity levell of an area [2]. [ Researchh area was shhown at Figu ure 1.

Figure 1. Researchh Area locatted between n Mount Salak and Mouunt Gede Paangrango at Ciherang (indicateed by red boxx), West Javva, Indonesia 2. Regioonal Geologgic Setting Ciherangg areas incluuded in Boggor Sheet onn regional geological g m maps. Based on data on regional geologiccal map is knnown the olddest rocks ex xposed in thee study area consists c of tuufa pumiceoous which belong to the old voolcanic rock units u that sppread in the east, e north an nd south areeas of researcch. Other lithologyy is also in the form of o andesitic basalt lava, which belo ongs to the volcanic deeposits of Pangranggo Unit. In the west of the study arrea is compoosed of lava deposit, tufffaceous brecccias and lapilli, bbasaltic andessite lava flow ws, which beelong to th volcanic v depo osits of Mouunt Salak Unnit. These volcanicc deposit unitts belong to tthe old Quateernary volcanic deposit. (Figure 2). Tectoonic activity in this areaa began in the Early Teertiary, follow wed by Plioo-Pleistocenee tectonic activity that reactiv vate the product tectoniic Early Tertiary periodd. These evvents resulteed in the establishhment of faullts which havve generally northeast - southwest s annd northwest - southeast direction. d Fractures that has been formed become a weaak zone for young y volcannic quaternarry rock. Base on regional geological study, s researcch area are generally g com mposed by roock quarter ggroups, in which thhe existing deposits d depoosition is a young volcaano that can not be sepaarated betweeen sandy pumice tuff and tufffaceous lavaa breccia deerived from deposition Pangrango. P This young volcanic sedimennt has a thickkness sufficieent. Then, unnder the quarrter rock gro oup, that old volcanic roccks group o andesitic basaltic breeccia, andesiitic lava, tufffs and aggllomerates has beenn deposited composed of which iss the inseparaable depositiion. In the soouthern part of research area, there iss a fine-coarrse clastic sedimennts as a tertiarry rocks which have beenn folded and faulted by teectonics [4]. Mostt researcherss agreed thaat the volcannic eruption in this areaa relates to the activity of plate collisionn [5]. Based on geophyssical data, it is known thhat the subd duction pathw ways in the southern island off Java, is a continuous c z zone, but thee volcanic erruption on thhe surface iss separated from f one

2



another. This phenom menon indicaates that the activity maggmatism or volcanism v do oes not by itsself come to the suurface, but th here must be some fractuures that have a function as a media to t release the magma to the suurface. Fractuure is alwayys a fault linees, for exam mple on the island of Javva, the positioon of the active voolcanoes aree in the volccanic arc envvironment on o the surfacce appearancce was in thee Baribis Fault Zoone [5]. With geological facts f describbed above, it is in Java which w is alsoo found volcaanic (from thhe age of S Paleogenne to the preesent) associiated with faault zones coonfirmed [6]]. Examples Katili and Sudradjat connect the presencee of volcanoes around West W Java andd the surroun nding areas with Cimanddiri Fault mples are the appearance of Volcano Ciremai in Cirebonzones annd fault Citaanduy. Somee other exam Kuningaan which is at the inteersection off the fault zzone and Fault Baribiss Citanduy; Volcano Tangkubbanprahu-Buurangrang aree in fault zoones Cimanddiri; and Mouunt Krakatauu in the Sunnda Strait was in thhe Sunda Strrait fault zonee [7].

Figu ure 2. Regioonal Geologiccal Map of research area-Bogor sheett [3]. 3. Meth hod Fractures can define easily with satellite imaage such as L Landsat, Raddarsat, or Dig gital Elevatioon Model (DEM). There are a lot of fracturre tracks provide by lineaament in surface, in this case the lineeament of ulate of fractuures intensityy and delineaate of fracturre pattern hills andd valley. The surface metthod to calcu is used F Frequency Domain Decom mposition (F FDD) [7]. FD DD is useful for lineamen nt analysis. The T result of FDD is the intenssity of distribbution of fracctures in reseearch area, not n only the value v of inteensity but also patttern of fracture distribuution and thhe main direection of tecctonic or voolcanic stylees. Those fracturess were appeaar in DEM has h a pattern and can be described thhe force that occurred inn research area. Thee fractures patterns can be b classified according too the style inffluence that occurs o in thee research area, whhether the fractures patterrn caused by effect of tectonic, volcan nic, or both processes p [7, 8]. Geo-eelectric methhod used to determine the t conditionn of the disttribution of subsurface lithology. l Resistiviity value prooduced by thhe geo-electriic instrumentts very well and efficienntly used to determine d the conddition of grou undwater andd subsurfacee rocks in voolcanic depossits. Its valuee is highly ddependent on severral factors, namely n grounndwater, salinnity, saturatiion, and lithoology aquifeer. Resistivityy method is alwayys used to so olve many problems p succh as grounddwater to determine the depth, thickkness and boundariies of the aqquifer. Rockk resistivity value reflects the hardnness of rockss in accordaance with

3



Table-1 in relative terms, t with known k resisttance value and classifieed rock typee. It can be predicted p subsurfaace rock cond ditions up to a depth of 150 meters. [110] Table 1. Resistivity value v for each h lithology at a volcanic deeposit at reseearch area. Resistivity (Ωm)

Material Value

Resistivity Ran nge

6

19

Welded tufff

Imp permeable Layer

30

Fine tuff

Imp permeable Layer

31

40

Medium tufff

Imp permeable Layer

103

41

60

Coarse tufff

Aquifer

103

61

90

Lapili Tuff

Aquifer

10 ‐10

5

91

200

Gravelly sand/Lapilli Tuff

Aquifer

1‐10

103

201

400

pported Breccia matrix sup

Aquifer

401

900

Breccia grain supp ported

Imp permeable Layer

102‐108

S Sedimentary Rock k

10‐108 10‐1‐108

G Groundwater P Pure water

Hydrogeology Interpretation

20

Iggneous & &Metamorphic

U Unconsolidated

Typical

Lithology Interpreetation

‐1

4

104

4. Fractture Pattern n of Mt. Salaak-Mt. Panggrango As a dettail result off surface fraccture patternn analyzing, there are sevveral fracturres pattern have h been developeed by volcan nism and tectonic processsed in this research areaa. There are at a least four different types off fracture patttern in Mouunt Salak areea, which aree formed by volcanic annd tectonic processed. First typpe formed by b volcanic processed, p s second and third t types formed f by both b of volccanic and tectonic processed, and a four typee is affected by b tectonic processed. p Figure 3 The fourr types of fraacture patternns described as follows: • Type A, is affectted by volcaanic process, has a relativvely North-S South directiion, good poorosity of aquiffer. • Type B, is affectted by both volcanic annd tectonic process, p has a relatively Northwest-S Southeast orosity, but in i a few placce are imperm meable. directtion, good po • Type C, is affectted by both volcanic andd tectonic prrocess, has a relatively East-West direction., d ut in a few place are impeermeable good porosity, bu h a relatively the same direction witth trend of Pelabuhan P • Type D, is affecteed by tectoniic process, has Ratu fault along research area, and the poossibility of this fracturee pattern is impermeablee in many locatiions.

Figurre 3. Four typpes of Surfacce fracture paattern in Ciherang researcch area By uusing resistiv vity model as a verticallyy analysis. W We obtainedd an overvieew of distribbution of subsurfaace volcanic deposits of the study arrea. In the Figure F 4 below describe that fracturre pattern occurrennces with noorthwest-souttheast directiion, represennted by the red line, thee fracture patttern that 4



have chharacterized as a media of o fractures to be a pathhway of grouundwater flo ow. In addition to the fracture pattern, therre is a fractuure pattern with w relativeely the northh-south direcction has chaaracter of urface, but constantly fracture as a barrier of groundwaater flow. Thhe fracture noot only appeears on the su appears uuntil at depth hs greater thaan 50 meterss Figure 5 [122].

Figgure 4. Modeel of Iso-resisstivity descriibe the charaacteristic of fracture f patteern in subsurfface.

5. Results and Disccussions Volcanissm and tecto onic process has highly affected a in reesearch area. The influennce of their processed p made m many differennt in develooping of eacch fracture pattern p characterization. The fracturre media become an importannt parameter for groundw water, which is fracture media m as an secondary s poorosity in e stages of research, lineament analysis a can be used to determine d volcanicc aquifer systtem. In the early the fractuure pattern on o the surface morphologgy of the reseearch area. Based B on thiss research thee fracture pattern w with affected d by volcanicc processed have h a better porosity theen fracture paattern develooped with affected by regional fault. Actuaally, there arre many fracctures that deevelop in research area as a laterallyy or verticallly, but in this research describe only for exxtreme fractuure that reallyy influence to t the flow of o groundwatter. As an s at early staage of researcch related to the fracture pattern contrrolled groundwater flow in volcanic system surface aarea, on the stage of thee research off fracture pattterns that occcurs in the subsurface area. a The purpose of this reesearch is tto determinne the fractture pattern vertically in subsurfaace area. Determinnation of frracture that continues until u subsurrface becom mes more essential to know k the groundw water flow syystem in volccanic rocks.

5



Figure 55. Two diffeerent charactteristics of frracture patteern with diffeerent effect. The tectonicc involve for fractture pattern inndicated by red circle as a barrier of groundwaterr flow. Referen nces mapping [1] Denny SC, Alllen DM andd Journey JM M 2007 DRA ASTIC-Tm: a modified vulnerability v method forr structurallyy controlled aquifers In the southern n Gulf Island ds, British C Columbia, Canada. Hyydrogeology Journal 15:4483-493. (Sppringer-Verlaag) ment in grouundwater exxploration: a Review of applicatiions and [2] Saander P 20007. Lineam limitations.. Hydrogeoloogy Journal 15:71-74. (S Springer-Verllag) [3] Effendi AC annd Hermantoo B 1998 Peta P Geologii Regional Lembar L Boggor, skala 1::100.000. (Pusat Peneelitian dan Pengembangaan Geologi, Bandung) B [4] M Muertianto E 2006 Petaa Hidrogeollogi Regionaal Lembar Bogor, skalla 1:100.0000. (Pusat Penelitian dan d Pengembbangan Geollogi, Bandunng) [5] Haryanto I 20013 Strukturr Sesar di Puulau Jawa Bagian B Baratt Berdasarkaan Hasil Intterpretasi Geologi. Bulletin of Sciientific Contrribution (Geeologi Unpadd) 11 1 1 Tectonics of the Inndonesian Reegion: Geoloogical Surveyy Professionnal Paper [6] Hamilton W 1979 1078, (US. Governmennt Printing Offfice) B J and a Triumf CA 2007 Detection D off lineament using airborne laser [7] Nyyborg M, Berglund scanning technology: Laxemar-S Simevarp, S Sweden. Hydrogeology Hy y Journal 15:29-32 (Springer-V Verlag) [8] Siinghal BBS and a Gupta RP P 2010 Appllied Hydrogeeology of Fraactured Rockks. (Springer London) [9] Enndyana C, Hirnawan H F, Hendarmaw wan and Marrdiana U 20111 Pendugaaan nilai tahannan jenis batuan sebbagai upaya untuk meng getahui strukktur geologi yang berkem mbang pada endapan vulkanik dii Kec. Padariincang, Prov vinsi Banten. Buletin Sum mber Daya Geologi G 63

6