Victoria University of Wellington

ESCI 342

STRUCTURAL FIELD GEOLOGY

2013 Kekerengu Field Exercise

T. A. Little

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SCHEDULE

Friday February 22:

Report to Interislander Ferry Terminal by 7:30 AM sharp (final check-in is 7:40).

Drive to Kekerengu Field Station (about 2 hours)

Reconnaissance excursion, lower Ben More Stream (all groups together)

Saturday February 23:

upper Ben More Stream traverse (all groups together)

Sunday February 24: Scarp of Heaver’s Ck Fault, Valhalla Stream traverses (groups disperse in afternoon)

Monday-Wednesday February 25-27: Groups should traverse Heavers Creek (two forks), Valhalla Stream (two forks),

Kekerengu River, Glencoe Stream, and other traverses as times allows. We will

provide logistical support with the vans if you want to be transported to, or picked-up

at, a specific location.

Thursday February 28

Various stops and Isolation Creek (individual mapping exercise), Flags Creek fault

system, Waima (Ure) River.

Final deadline for submission of group materials is 10 PM

Friday March 1 Morning: clean-up of field station.

Vans depart by 10:30 AM.

1:15 PM Ferry departs Picton for Wellington.

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BASIC INFORMATION

Departure: Friday 22 Feb. on 8:45 AM ferry from Wellington.

You must report to the Interislander Ferry Terminal at no later than 7:30 AM sharp

to check-in baggage and pick-up boarding pass.

Bring lunch for ferry crossing (or pay for your own meal on the ferry).

Return: Fri. 1 March 1:15-4:15 pm, ferry sails to Wellington.

Accommodation: We will stay in rustic shearing quarters that are owned by a local

farmer and maintained (minimally) by the School. We will sleep in a wooden

bunkhouse that is partitioned into 4-person sleeping spaces. You are also encouraged

to bring your own tents. Hot showers are available. The main dining-living-study area

is in a separate building that contains large wooden tables for meals and for working,

and a kitchen.

We will cook our own meals, and each working group will be responsible for

preparing and cleaning up an evening meal or breakfast for the whole class.

Climate and Topography: The weather is both unpredictable and variable. Be prepared

for extremes from hot weather to blustery southerlies. The terrain is moderately

rugged, with steep ridges and incised valleys. Most of our traverses will be along

streams and involve frequent soakings of footwear. Several of the creeks (including

Heaver’s and Valhalla Creeks) have dangerous waterfalls at their headwaters.

An Important Note about Courtesy: We are guests on private land. Please leave all

gates exactly as you find them, and do not enter deer or bull paddocks. Avoid

startling livestock. Avoid areas where stock are being mustered. If you see a farmer,

identify yourself to him or her.

In summer, fire danger is high. Respect this and do not smoke in the field.

Do not write or carve graffiti on any rocks, boulders, outcrops, or buildings. Less

politely said, nobody thinks that inscribing your name constitutes a creative or

inspirational act. Consider other less lame ways of enhancing your self-esteem.

On a more positive note: Fieldwork is remarkably satisfying and fun! Enjoy yourself!

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Hazards and Safety Procedures:

Inform the trip leader of any pre-existing medical impairments or vulnerabilities that

you may have, such as limb injuries, diabetes, asthma, illness, or strong allergic

reactions (e.g., bee stings). He/she also needs to be informed immediately of any

injuries or other medical problems that arise during the field course.

Never work alone.

Be careful if walking along the road, and stay well on the shoulder. Farm trucks and

other vehicles are common and drive fast.

Never attempt to climb up or down waterfalls or any other steep, slippery, or exposed

slope.

Do not go swimming at the ocean beach. This steep, shingle beach has a terrific

undertow and is a very dangerous place to swim.

Do not stand or sit anywhere near the railway tracks.

Do not attempt to cross a stream that is deeper than your knees.

Rock hammering is dangerous. Wear safety glasses to protect your eyes from flying

rock fragments. Striking one rock hammer against another is particularly dangerous, as

it can easily launch steel chips into your eyes or body. You are personally responsible

for supplying and using your own safety glasses.

Most of the fences in the region are electrified.

Ensure that you return to one of the metalled roads at least an hour before nightfall.

Carry rain-gear, extra warm clothing, a safety blanket or tarpaulin, dry matches, and

extra food in your daypack for use in case you are stuck out in the field overnight.

Carry this kit with you even if the weather is fine. If you become lost, remain at a

nearby sheltered spot until a search party finds you (try to make this spot conspicuous

from a distance).

Each evening indicate both in words on the posted itinerary sheet and with symbols on

the posted traverse map where you, and everyone else in your party, will be working

on the following day. Do not go into the field unless these sheets have been completed

in full.

Protect yourself from the sun. Wear a hat and sunscreen.

Always carry plenty of water with you (min. 2 litres). Do not drink from any of the

rivers or streams, as you may contract the disease Giardia.

Do not go out in the field if you feel ill. Tell an instructor about your condition right

away.

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Equipment to Bring: General

sleeping bag and sleeping pad (if you do not have a pad, there are some at the quarters)

personal tent, recommended (but there is a communal sleeping block)

warm clothing/outerwear (fleece, etc)

cool clothing/shorts

sturdy boots (not sandals, and not runners or tennis shoes).

gum boots (optional, but recommended for some stream traverses).

extra pair of dry shoes or sandals for the evenings.

abundant extra socks

rain gear

eating utensils (incl. plate, bowl, cup, and cutlery).

towel

sunscreen

sun hat

sunglasses

personal soap, toothbrush, shampoo, etc.

musical instruments (please bring!)

Personal Stuff:

You are responsible for bringing along on the ferry any personal food items that you may

require. We will stop briefy at the New World in Blenheim on our drive down to the site.

A grocery trip to Blenheim or Kaikoura will be made by a staff member in mid week. You

may request further purchases to be made during this trip in your behalf (cash must be

supplied ahead of time for these).

Geological Stuff:

cheap sunglasses or safety glasses (for eye protection when rock hammering)

day-pack (bigger is usually more useful).

map case (e.g., sturdy clipboard), preferably with a waterproof cover flap.

water bottles (at least 2 litres, and recommend 3 litres)

emergency blanket, extra warm clothes to put in day-pack; nylon line also recommended

rock hammer (personal one is required)

pocket knife

matches or lighter (to light fire in case of emergency)

hand lens, 10x or 14x recommended (personal one is required)

geological compass with clinometer (personal one is required)

field notebooks (recommend “Rite-in-the-Rain” waterproof field books).

protractor (protractor-ruler recommended; some people use their Silva-style compass).

rulers or scale (metric). You need to take some sort of ruler or measuring tape with you

in the field so you can measure things like fault offsets, bed thicknesses, etc.

mechanical pencil or waterproof pen for writing in notebook (0.5 mm and HB or 2H

leads recommended)

sharp, fine, hard pencils for map plotting (4H leads recommended for film; use 0.5 mm or

finer mechanical pencil or technical drawing pencil with sharpener)

pencil sharpener and/or extra leads

a roll of transparent "sticky" tape

non-magnetic pencil (or cigar) for measuring lineations

a dozen or more different coloured pencils (to color individual outcrops on field sheets)

soft erasers (pencil-shaped with pocket clips are best)

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permanent ink pens with two different line weights: bold and very thin.

other drafting and report-writing materials

personal reference materials (e.g., Rowland & Duebendorfer or Marshak & Mitra)

Waterproofing your map sheets:

You will need to devise a system for carrying, waterproofing, and drafting on your

personal set of topographic field sheets (base map). Before we leave on the ferry, I

recommend that you cut up your topographic base map sheets into A3 sized tiles, folding

them in half to make two outward facing sides that are each A4 (page) sized. Then sheath

the folded sheets in clear plastic report covers with clear tape to waterproof them. Note

that by themselves, the plastic report covers are non-porous and cannot be drafted on.

Therefore, I suggest that you also take along with you a set of about ten pre-cut A4 sized

sheets of clear drafting film (these are made of mylar, and are frosted on one side).

Later on, you will clear-tape these mylar sheets on top of the day's chosen (plastic-

covered) map sheet to form a robust, waterproof surface that you draft on– even in the

pouring rain– with either lead or colored pencils or pen. Typically you will tape on the

mylar sheets in the evening, after you have decided which particular map sheet(s) you will

need during the next day's traverse.

Finally, to carry your map sheets into the field, and to back them with a hard surface that

you can draft on, you will need some sort of map case (e.g., sturdy clipboard), preferably

with a waterproof cover flap.

Optional Geological Field Gear to Consider:

Every geologist has a different style of carrying their "office" with them into the field, and

for placing the items they use the most (compass, field book, protractor, pencils, camera,

etc) in places that are both readily accessible and physically secure (i.e., where they won't

fall off and be lost while you are crawling through dense manuka thickets, for example).

Some people choose to wear a:

geological or survey (or even a fishing) vest, with many pockets of various sizes

Others opt for a geological field pouch (again with various pockets, including for the

field notebook) that is attached to your belt.

Geological vests and field notebooks can be ordered on line, for example at:

http://www.prospectors.com.au

I also recommend that you make a palm-sized, thin (~5 mm), stiff, flat, non-

magnetic plate or board ("compass plate") of wood, plastic, plexiglass, or clip-board

material for taking strike/dip measurements directly against an outcrop face.

Regardless of what other staff members may have told you previously, field books do not

work well for this task because they are too large and too bendy.

IMPORTANT: You will not be allowed to attend this fieldtrip without first

demonstrating to us that you possess your own:

a ) fully functional geological compass with inclinometer and preferably also with a

bull's eye bubble (also called a pocket transit) and

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b) hand-lens and

c) rock hammer

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THE FIELD MAPPING EXERCISE

Introduction:

The Kekerengu area lies along the East Coast of the South Island. The area includes

rocks primarily of Jurassic to Miocene age. There are three main stratal associations,

a Mesozoic accretion complex (Torlesse Supergroup), a transgressive sequence of

Cretaceous and Early Tertiary sedimentary rocks, and a Miocene basinal sequence.

These Mesozoic and Cenozoic rocks were deformed during the Cenozoic Kaikoura

orogeny, and are still deforming within the active Pacific-Australian plate boundary

zone. Quaternary marine terraces and alluvium mantle the bedrock units and are

locally cut and offset by active faults of Marlborough fault system.

Objectives:

This is an exercise in geological mapping, field structural geology, and stratigraphic

synthesis. Our goal will be to describe the structure of the Kekerengu region and to

interpret the tectonic evolution of this region from Cretaceous-Recent on the basis of

our field observations. The field project is designed to give you practical experience in

mapping of complexly deformed rocks, recording and synthesizing field observations,

presenting structural data and constructing cross-sections, and writing a clear and

logically presented report. Most important, this exercise is intended to stimulate and

develop your powers of geologic observation, original thought, and hypothesis

testing. We are not looking for the “right answer”. We will judge your performance

chiefly by its originality and thoughtfulness (not by whether it is “right”). Parroting of

the literature or of staff members’ comments will be obvious in your reports and will

work against you.

Working Groups:

Prior to arrival at Kekerengu you will be assembled into 4-person working groups.

Within these groups, each person will follow a rotating "division-of-labour" so that

he/she gains experience and capability in all of the practical tasks that we undertake as

field geologists (i.e., taking structural measurements, note-taking, use of hand-lens,

locating yourself on the map, plotting contacts, faults, and structural data on the field

sheet). These roles will alternate on a daily basis. By the third or fourth day most of

the groups will split into 2-person subgroups so that each group can cover the entire

study area by the end of the week. Never work alone.

Each working group (4 people) will be responsible for creating their own geologic

map of the entire study area, as well as preparing two cross-sections. These will be

collected at different times prior to our arrival back in Wellington. Each individual

will be responsible for submitting: 1) a form sheet of geological outcrop sketches, 2) a

map of our Thursday traverse up Isolation Creek, and 3) his/her own final report (due

after our return to Wellington). Your field notebooks will not be collected or marked

for assessment, but it is obviously in your best interest to take good notes.

Geologic Map:

The geologic map should show the aerial distribution of mappable rock units and the

surface outcrop of major geologic structures in the region. Planar surfaces such as

formational contacts (conformable, unconformable or intrusive types), axial surfaces

of folds, and faults. These intersect the earth’s surface as linear traces (hence the

popular misnomer “fault line”). In general these traces are curved or sinuous because

of, 1) topography and 2) the folded or curved nature of most geologic surfaces. Field

measurements of the local orientation of planar and linear structures at sites are neatly

plotted as separate symbols on the map.

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The geologic map is a quantitative database from which cross-sections and other

geometric projections can be constructed and can present an enormous amount of

information. Photographic and topographical maps are provided as base maps upon

which to locate and plot and compile your field data. Detailed aerial photos (and

stereoscopes) are available at the station house, but these should not be taken into the

field.

Mapping Strategy:

Each group should map along the boldly marked traverses on the map posted on

the wall in the dining area. Other important traverses are marked by dashed lines

and should also be examined as time permits. We will work as a class during the

first two days to familiarise ourselves with the stratigraphy and geographic features

of the area. Then each group should decide on the best strategy for covering the

remainder of the area (filling in the holes).

Since the area is large (about 70 km2), it is necessary to budget your time in order

to cover the entire area in the time we have allotted. A vital aspect of the mapping

is to delineate the distribution of units and major structures by tracing their

boundaries laterally across the study region. The amount of time that you spend

collecting stratigraphic and structural detail must be balanced with increasing the

area of coverage of your map. Spend the most amount of time on outcrops that

expose a mappable contact or structure, that indicate important time relationships

between units, or that reveal geologic structures in three dimensions. Note that

once you have recognised and described each unit in sufficient detail, repeating

lithologic descriptions may not be necessary unless you observe something new.

Although we are mapping the bedrock geology, also pay careful attention to the

Quaternary deposits and terraces! These reveal critical information about the

nature of active faulting and deformation in the modern plate boundary zone.

Study the Quaternary terraces carefully for deformation, especially where they are

transected by fault scarps. Are the terraces offset? (How much vertically,

horizontally?). Do the thickness, lithology, or surface slope of the terraces change

across the fault? Are the terraces warped or folded? Are they deposited

unconformably across underlying bedrock structures? Are they marine or

nonmarine? These observations should be included as an important part of your

final summary.

Daily Mapping Routine:

The night before each working day, each group must fill out an itinerary sheet

indicating where each person will be working that day, and if there will be any special

logistical needs for members of the group (such as van transport or pick-up). There

will also be a traverse map on which to mark the expected path of each group (or

subgroup) for that day. Both the itinerary sheet and traverse map must be filled in

before you leave on a traverse in the morning.

There are two basic "jobs" for geologists in each group (or subgroup). These roles are

complementary, and require cooperation for efficient team-work. Individuals must

assume different roles on alternate days. We will be keeping track of your “job

history” and will “debrief” plotters each evening by examining and discussing their

day’s field sheets.

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1) Map Plotter: Responsible for plotting on the map in the field on location all

contacts, unconformities, major faults, etc. traversed, all station locations, as well

as symbols for measured structures (e.g. strike, dip, and younging direction of

bedding; strike and dip of fault planes). This person will spend much of his/her

time in accurately locating on the map the position of each station occupied by the

group (an important task that may require the whole group's help). The map

plotter should return in the evening with a completed field map recording all the

main observations of the day's traverse. Note that in addition to the other duties,

the map plotter is still responsible for recording basic geologic observations in her

notebook (not including that day's structural measurements).

2) Crawler: Responsible for helping the map plotter to locate the group on the map,

for measuring and recording (in the notebook) all structural data, for scampering

up and down the outcrop to obtain samples or follow contacts where necessary,

and observing and recording as much geologic detail as possible in the time

available before the map plotter is finished with his/her tasks. The crawler may be

required to climb a ridge or stream bend in order to gain a perspective view that

will help determine the regional geologic structure or the group's location on the

map.

Plotting Locations on Base Maps: A fundamental aspect of field mapping is determining as accurately as possible your

location on a topographic map or aerial photograph. The accuracy of your map

depends on this ability. Even experienced geologists become “lost”. Knowing where

you are on a map requires concentration and forethought.

•Keep looking ahead; identify prominent geographic or topographic markers that

you head towards or expect to pass.

•Study the topographic map for subtleties, for example breaks in slope represented

by differences in contour spacing, widening or narrowing of stream gorges, jogs or

bends in streams or ridges, and major vegetative changes on the aerial photograph.

Fence lines, farm tracks, overhead wires, and even buildings or sheds can be useful

landmarks on the map, but remember that such cultural features are subject to

change, and may not be shown correctly on your map.

•If you are following a stream that makes bends or meanders, keep track of major

bends as you walk, and use your compass to help confirm which bend or reach you

are on. The same can be said of jogs on ridgetops. Also keep track of major

tributaries and side vallies that feed into your stream (or off your ridgetop). As

you walk, say to yourself things like, "there should be a small tributary intersecting

the right side of this stream, just around this next bend." Locating yourself

requires constant vigilance and concentration.

•Don't "assume" that you know where you are, or carelessly believe someone else's

idea of your location- they are almost always wrong.

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•Use your compass to take bearings on known points in the distance, such as

peaks. The most useful objects to take sights on have bearings that are at a high

angle to the linear feature (e.g., stream or ridge) that you are following.

•Use the clinometer on your compass to level with a conspicuous peak, saddle, or

bench that you can identify on the topographic map. Now you know what contour

line you are on.

•If you are not sure about your exact location, try to get the "big picture" by

climbing an adjacent knob or terrace and locating yourself by inspection on the

map.

•As a last resort, try pacing from known points (e.g., stream junctions) into

adjacent unknown areas where geographic markers cannot be identified. Do you

know your pace?

Taking Field Notes:

•Note-taking should be neat enough for anyone to read it easily. Pencils should be

kept well sharpened. I find that 0.5 mm mechanical pencils with moderately hard

(HB) lead work well. Others prefer to use fine-tipped technical pens (not ball-

points) with waterproof ink.

•Field notes should begin each day's traverse on a separate page. At the top of the

page write down the names of each person on the traverse with you that day, their

role (i.e., plotter or crawler) the date, the location of the traverse, and the weather

(as this will affect the quality of your observations).

•Each data station (locality) should be given a consecutive number on the left-hand

side of the page. This number should be underlined, and be identical with both the

station number plotted on the map and with the number in your partner's

notebook.

•For each station: (1) write the location in words of that station (e.g. “junction of

Heaver’s Ck and Kekerengu River”), (2) include rock descriptions (colour, grain-

size, sedimentary structures, bed thicknesses, etc), (3) describe deformational

structures and tabulate structural measurements, and, most importantly, (4) make

sketches. Each sketch should be clearly labelled and have some sort of scale and

geographic direction on it. Record structural data in columnar format wherever

possible. Skip a few spaces between the entries for each station number so that the

data for each station is clearly demarked from those of its neighbours.

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Sample notebook sketch. From Compton, 1985

•Try to make observations and measurements at a variety of scales, from

mountainside to hand-lens. Approach an outcrop from a distance and soak in the

"big picture" before focusing in for a closer look.

•Describe the units succinctly from the outcrop; be especially attentive to the

details of contact relationships, and keep your eye out for lateral variations in

lithology or structure. Be sure to be explicit about which lithologies you include in

each formation that you map as a separate unit and the criteria that you use to

define each of these units.

•When you are in the field, try not to be partial to a given geologic theory or idea

about the region (especially someone else’s) as these should change on almost a

daily basis. A closed mind may prevent you from collecting important types of

data that you would later realise to be quite valuable. Keep an open mind: 1)

observe and reobserve, 2) continually pose questions to yourself about what you

see, and 3) devise simple ways of answering those questions by observing the

outcrop again in more detail or by going somewhere else.

•Don’t forget to write down summaries of what you are seeing on the traverse that

day and any hypotheses or ideas you have about what is “going on”.

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Sample notebook page. From Compton, 1985

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Example of tabular structural data in a notebook

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Plotting Information on Map Sheets: Use only a well-sharpened pencil, not ink.

We recommend a 4H or harder lead for drafting film. Neatness on field sheets and

on compilation maps and cross-sections is essential and will be marked. Show on

the field sheet as many bedding and other attitudes as is possible, but not so many

that symbols obscure other data (i.e., if two nearby measurements are similar, it

may be best to plot only one of them on the map). The field sheets must be neat

enough so that any geologist can read and understand all the information plotted

on it. All text labels must read left-to-right as if reading a book when the

North arrow is pointing directly up the “page.”

•Plot station locations on your map to specify the location of:

--Lithologic descriptions

--Sketches of contacts, stratigraphic relations, or structures

--Points of significant lithologic change

--Large structural data sets

--Geological samples

--Photographs of important geological features (indicate roll and exposure number

in your notebook). Try to make your rock photos as close-up as possible (use a

zoom or macro lens if possible). Make sure to include a scale of some kind.

•New station locations need not be defined for every structural measurement, but

every measurement should be recorded in your notes (and its location relative to

nearby stations) for use in later data compilation.

Do NOT plot station localities or labels on your group’s clean compilation

map. They clutter the map without aiding the reader. I recommend that you

plot station locations only on your own individual cut-up field sheets, and/or on a

separate copy of the map, and/or on a clear overlay so that the field map does not

become cluttered with numbers.

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•Make sure you distinguish between observed facts (outcrops) and inferences

drawn from those facts (e.g., your hypothetical “connecting of the dots” between

outcrops). Fact should be specified by colouring outcrops on the map in the

colour of that unit and/or by outlining the perimeter of outcrops in pencil. I

recommend that you lightly colour in outcrops as part of your standard field

plotting procedure at each site.

•Plot contacts, fault traces, and other planar structures in pencil directly in the

field, as you see them. After you have plotted where a contact or fault trace

crosses your particular stream or ridge, stand back and get the "big picture."

Sketch how you think the contact traverses the topography beyond that particular

spot. Can you see the contact wind up and over the next ridge? Think in terms of

the “rule of V’s” which determines how a planar surface will intersect the

sculptured topography. If you draw a straight-line contact across rugged

topography, then you are making a statement that the contact or fault is absolutely

vertical.

•With a protractor, carefully and neatly plot strike and dip symbols for measured

planar attitudes of bedding, faults foliation directly in the field as you see them.

Check your symbols in the field against the outcrop to be sure that they have been

plotted on the map correctly. Have you plotted the dip direction correctly (ie. NE

vs SW?). The direction of younging of strata is a critical observation and

should always be recorded and plotted on the map.

•Use a lineation symbol to denote the orientation of measured linear structures

such as fault slickenline striae or fold hinges (see appendices). In metamorphic

rocks other linear structures include stretching lineations, crenulation lineations,

intersection lineations, and boudin axes, each of which can be given a different

symbol for plotting.

Map Compilation in the Evenings: The best way to produce a geologic map is to

compile field data on a clean, separate base map each evening. This allows you to

continually update and revise your map, identify where important data gaps exist,

formulate new working hypotheses, and to make predictions and plan the next day’s

traverse. It is also important to ink in field sheets in the evening so that your hard-

earned field data is not smudged by rain or by wear on the maps. Use waterproof ink.

In addition, this is the time to plot the day’s structural information on stereonets and

compile stratigraphic information. You will develop a much better understanding of

the structure of the area if you/your working group, construct cross-sections of daily

traverses. These will help you to think in three dimensions.

Map Explanations: These must include:

--List of geologists and date

--North arrow, showing true and magnetic north

--Scale bar

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--Source of basemap(s) used

--Contour interval on map

--Map unit or formation descriptions (oldest at the bottom)

--Map symbol explanation

including all structural symbols used, and fault and contact traces (use bold

and fine line weights).

•Use a separate map symbol for airphoto lineaments that have not been field

checked, as these should be differentiated from observed geologic contacts.

•Be sure to use appropriate symbols for indicating certainty of contacts and fault

traces, such as known (solid line), approximate (long dashes), inferred (short

dashes), covered beneath younger deposits (dotted), or speculative (queried).

Indicate the up-thrown and downthrown side of each fault on the map with "U"

and "D" symbols.

•Use the correct map symbol for the axial traces of map-scale antiforms and

synforms (see appendices). Note that the symbol for the axial trace of overturned

folds is not the same as that for upright folds. If you measure the trend and plunge

of the hinge of a map-scale fold, plot it as a separate lineation symbol. TRY NOT

TO CONFUSE fold hinges (linear), axial surfaces (hinge plane), and axial traces

(line of outcrop of axial surface across topography).

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ASSESSMENT of ESCI 342

The following assessment will be handed in for the 2013 Kekerengu field course.

Please note the hand-in Dates and Times.

Assessment is split up into 3 components:

Individual Field Grade 20%

Group Work 40%

Individual Report 40%

Assessment Breakdown:

Individual Field Grade 20%

a) Geological Outcrop Sketch Sheet, worth 7.5%

(Due Tue Feb 26 before the end of the nights work, to be placed in

Tim's "black box")

b) Isolation Creek Map, worth 12.5%

(Due Thurs 28 February at Lunch Stop, before our heading back to

the vehicles)

Group Work 40%

a) Ben More Cross-Section, worth 5%

(Due Wed. 27 February by 10 pm, to be placed in Tim's "black box")

b) Group Geologic Map, worth 25%

(Due Thurs. 28 February by 10 pm, to be placed in the "black box")

c) Valhalla/Heavers Cross-Section, worth 10%

(Due Thurs. 28 February by 10 pm, to be placed in the "black box")

IMPORTANT: The best possible interpretation of the entire Kekerengu

field area is expected for each group's geologic map. The map will

necessarily include features in some areas that we did not have time to visit

in the field, but which can be reliably interpreted with the help of the aerial

photographs. Your stereoscopic study of the available aerial

photographs– while not part of any separately assessed exercise– will lead

to your group obtaining a better understanding of the position and identity

of certain key map features, including river terraces, abandoned channels,

and active fault traces. Incorporating and depicting such air-photo

derived information onto your map will result in your group submitting a

more useful and informative map, and one that will be marked more highly.

The added information will probably also end up improving your final

report.

The stereographic overlay data (including an overlay for a) bedding poles

measured North of the Kekerengu fault; and b) bedding poles measured

South of the Kekeregu Fault, and c) outcrop scale fold geometry data from

Ben More Stream) will not be submitted as part of your Group's

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assessment. However, each member of your group will (eventually) need

these data to be included in your individual reports. Therefore as a

group, you should be compiling and sharing these data as you go along

for later use in your individually written reports.

Individual Report 40% (Due date Monday 18 March at 9 AM) THE REPORT MUST BE TYPEWRITTEN IN COMPLETE

SENTENCES, include a formatted reference list, and cite and refer to each

figure appropriately and in sequence.

Report consists of:

o A summary of the regional Tectonic History

o A discussion of the sense and amounts of slip on Kekerengu &

Heaver’s Ck Faults

o A simplified, interpretive page-sized version of your group's

geologic map that includes the Isolation Ck area

o Three stereographical overlays (see below)

o Optional additional diagrams and explanatory cartoons (as

desired by you)

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OUTLINE OF STRUCTURAL REPORT

Important Note: For this summary, include the information that we obtained during

all parts of our Thursday excursion.

Part I. Figures.

These are additional to the 5 pages of typewritten text. They should be cited in the

text in an appropriate way, and in the correct order.

Fig. 1) Simplified page–sized, hand-colored version of your group’s geologic

map that shows and labels the geological structures and major map units in the

region, including those in the Isolation Creek area

Your group’s aggregated stereographic data. Include separate WELL-

LABELLED overlays showing poles to bedding for:

Fig. 2a) to the North of the Kekerengu Fault (mostly Miocene rocks)

Fig. 2b) to the South of the Kekerengu fault (Cretaceous-Eocene rocks)

in both of these, plot poles to bedding, and determine (and label) mean

fold-axis trend & plunge, as calculated by p-technique, and

Fig. 2c) For Ben More Stream only: plot symbols for small-scale (linear) fold

hinges. Decorate these lineation symbols with the observed sense of asymmetry

(either sinistral or dextral-looking, as looking down-plunge). Plot also the

(planar) axial planes (plot as both great circles and as poles to plane).

Fig.’s 3+) OPTIONAL: Explanatory tectonic diagrams, cartoons, and/or

photographs of key exposures. These can be in either map view or cross-

section to accompany or explain the text account.

Part II. Written Structural History (typewritten text).

This should be no more than FIVE PAGES LONG (does not include FIGURES).

It should include two parts:

Part IIA. Regional Tectonic History (incl. Quaternary)

Start with oldest tectonic event in the region, then progress to younger events

Refer to map and other figures, as appropriate. If possible, include:

- constraints on timing of each deformation event

(i.e., stratigraphic bracketing of deformed vs.

undeformed strata; and/or cross-cutting relationships or

superposition)

- relationship between sedimentation and tectonics

- styles & geometries of crustal faulting and folding

during each event

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- where relevant: relationship between stratigraphy

and structural style (i.e., weak vs. strong units)

- if possible, inferred directions or amounts of crustal shortening

Part IIB. Sense and amounts of slip on Kekerengu & Heaver’s Ck Faults

through time (active in Quaternary)

For each, please explain and discuss (referring to figures where appropriate):

- evidence of fault orientation

- nature, expression of the fault zone and

any fault rocks

- evidence for timing of fault activity

- senses of offset, separation in map-view &

cross-section for markers of different ages &

orientation?

- any inferences about true sense of strike- & dip-slip

- inferences about total slip (bedrock markers)

- inferences about Quaternary slip

- inferences about Quaternary slip-rate

- possible timing of onset of faulting?

Cited references (OPTIONAL!).

I suggest that you don’t waste time researching other people's previous work in the

literature. For this exercise, I am interested only in your data. Uncritical (and

especially unreferenced) parroting of the literature will be OBVIOUS and count

against you.

General Guidelines for Writing Scientific Reports:

Remember that the report should be based on your own field observations and should

outline the evidence and logic behind the conclusions that you draw from your work.

A complete description of observations should always presented first, then the

interpretation or conclusions derived from those data. The two should not be

presented in the opposite order, or mixed up, or worse yet, confused. For the

purposes of this project, don't worry about formation names used by others, or any

conclusions that have been drawn by previous workers. You will not be graded on

how "correct" your descriptions or conclusions are, but on the originality and detail

of your observations, and on the logic of the conclusions drawn from them. Be exact

in your language: the phrase “large fold” or “thick-bedded” are meaningless, whereas

“1.5 km wavelength,” or “1 m thick,” say something.

Importantly, you will be graded on how clearly you distinguish on paper:

(1) your own original observations or facts, from

(2) observations cited from other sources (e.g., a scientific paper, or

conversation with another group or person), from

(3) interpretations that are supported by some evidence, in this case your field

data, from

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(4) speculation (B.S.) that is not supported by your data (to be avoided).

If you state an interpretation as if it were a fact, or do not supply a logical and clearly

presented set of data to support that interpretation, then you will lose scientific

credibility. Speculation should not be stated as if it were a fact. If you infer an event

because of 1) this stated observation, 2) that line of evidence (H. Clark, personal

communication, 1999), and 3) this specific pattern on the map (Fig. 4) then you are

writing science.

Not all of your observations turned out to be important, so emphasize those that you

will use to support your interpretations and conclusions.

SELECTED REFERENCES

Van Dissen, R. V., and Yeats, R. S., 1991, Hope fault, Jordan thrust, and uplift of the Seaward

Kaikoura Range, New Zealand: Geology, v. 19, p. 393-396. [Synopsis of modern rates of

horizontal and vertical displacement along faults in the Marlborough system].

Crampton, J., Laird, M. N., A., Townsend, D., and Van Dissen, R., 2003, Palinspastic

reconstructions of southeastern Marlborough, New Zealand, for mid-Cretaceous-Eocene

times: New Zealand Journal of Geology and Geophysics, v. 46, p. 153-175.

Laird, M. G., 1993, Cretaceous stratigraphy and evolution of the Marlborough segment of the

east coast region: Petroleum and Geothermal Unit, Energy and Resources Division, Ministry

of Commerce, 89-100 p.

Reay, M. B., 1993, Geology of the Middle Clarence Valley: Lower Hutt, New Zealand Institute of

Geological and Nuclear Sciences, 144 pp. p.

Rait, G. J.; Chanier, F.; Waters, D. W, 1991, Landward- and seaward-directed thrusting

accompanying the onset of subduction beneath New Zealand: Geology v. 19, p. 230-233.

Rattenbury, M. S., D. B. Townsend, and M. R. Johnson (2006), Geology of the Kaikoura area,

Institute of Geological and Nuclear Sciences Geological Map, scale 1:250,000, 13, 70 pp

(booklet).

Crampton, J. S., and Laird, M. G., 1997, The Burnt Creek Formation and Late Cretaceous

development in Marlborough, New Zealand: New Zealand Journal of Geology and

Geophysics, v. 40, p. 199-222.

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